bmaraldo@watdcsu.UUCP (01/01/70)
And how about the crystal structure? THERE ISN'T ONE in mercury! It is
know that linear crystal (lon crytal) configuration wire propagates a
signal with more linear accuracy. In the mercury cables there is now
crystal stucture and this is material dependent.
The Audiophile
--
-------- Unit 36 Research ---------
"Alien Technology Today"
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bmaraldo@watdcsuejm@mas1.UUCP (Eric Mattern) (01/01/70)
> > > I'm an audiophile and I hate CD's and I'm > damn proud of it! So there! NAA! > > Brett L Maraldo I'm with you !!! rick
bblue@crash.CTS.COM (Bill Blue) (01/01/70)
In article <1222@pinney.munsell.UUCP> pac@pinney.UUCP (Paul Czarnecki) writes: >In article <1709@crash.CTS.COM> bblue@crash.CTS.COM (Bill Blue) writes: >>In my view, the big culprit that kills the 'hardware store' variety >>cables is the varying time of arrival of different frequencies at the >>other end of the cable due to skin effect propagation and other factors. > >>I make these statements from personal experience with all sorts of >>cables. Take *any* heavy, stranded, copper cable -- anything from 12/2 >>or 10/2 electrical cable to the 12 guage (standard) Monster cable >>(reasonably cheap at ~$.50/foot) and you'll get a similar sound. The >>number of strands and thickness of each will provide subtle differences, >>but all in all they're about the same. > >Why must you use stranded cable? I realize the mechanical >difficulties in using a solid core cable but are there any electrical >problems? > >I used 12 gauge solid core for many years. It was the cheapest stuff >I could find. (It was UL listed for underground use also. :-) I've tried that too - 12/2 in fact, though it wasn't UG. I even tried it once in a studio between the monitors and power amp to see what the reaction from other engineers would be and if that reaction was similar to mine. It was. I had observed that with 12 gauge solid, there was an extreme loss of high frequency detail. It was replaced with sort of a soft haze, not offensive but very vague. The lower octave (kick drum, etc) seemed to all but disappear as well. I was an engineer at the time (early 70's) when I performed this experiment. All of us (myself and two others) concluded in separate recording sessions (our own clients) that our ability to equalize and balance the various tracks was seriously impaired. In tests repeated recently, the same differences are heard, but with higher grades of speaker cables becoming available, the differences are much greater. I believe the big problem with large gauge solid conductor cable is skin effect related. The diameter is simply too large for reasonable handling of high frequencies. In the above tests which, by the way, were long before there were any 'audiophile' cables, we found that moderately heavy gauge, stranded, non-plated soft copper wire was by far the most revealing. Now this was about '72 -- with many so-called audiophiles in '87 still poo-pooing the sound of cables -- imagine the kinds of comments this topic produced back then? It always has struck me rather funny when engineer types (not recording but electronics) go into long dissertations on how we audiophiles can't be hearing differences in so-and-so cables, or capacitors, or resistors, or (gasp) power supplies, and spout streams of numbers and other specifications that 'prove' such things don't apply to audio frequencies. Years later though, when it becomes generally accepted that such things do in fact make audible differences, the same engineers not only agree that these things do make a difference, but can spout reasons why. I guess all it really has to do with is your current levels of understanding and awareness -- both of what quality audio really can sound like (unless you've experienced it, it's indescribable) and technically in how you associate formulas and specs to the real world. --Bill
bmaraldo@watdcsu.UUCP (09/10/87)
Is there such a product on the market?
I just made a set of 2m long 5mm in diameter mercury filled cables with
copper touch conductors and large lugs. I really do not have a clue as
to the dynamic characteristics of mercury. If you know anything about
what an audio signal might look like after propagating through such a
cable, I'd like to know, especially if you have data to back your
comments up with. I already know about the resistivity of Mercury; it
is about 95 microhms-cm at 20C (Copper is 1.7 microhms-cm). My
calculations show that each 2m Mercury conductor has a resistance of 15
milliohms and that a 10gauge copper wire 3mm in diameter has a resistance
of 0.1 milliohms (these are approximate theoretical values and do not
represent measured data).
Brett L Maraldo
--
-------- Unit 36 Research ---------
"Alien Technology Today"
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bmaraldo@watdcsukoko@uthub.UUCP (09/10/87)
In article <3816@watdcsu.waterloo.edu>, bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > > > Is there such a product on the market? > > I just made a set of 2m long 5mm in diameter mercury filled cables with > copper touch conductors and large lugs. I really do not have a clue as > to the dynamic characteristics of mercury. Metals are metals. Electricity flows in the same way through all metals. This includes copper and mercury. > If you know anything about > what an audio signal might look like after propagating through such a > cable, I'd like to know, especially if you have data to back your > comments up with. You have been reading too many audiophile magazines. As far as audio frequencies are concerned, no cables of typical length (i.e. fitting in your living room) are going to behave like transmission lines. Therefore, the conductor material, wire configuration and spacing, and insulation material are all irrelevant. So audio signals will look the same on copper cables as on mercury ones. > I already know about the resistivity of Mercury; it > is about 95 microhms-cm at 20C (Copper is 1.7 microhms-cm). My > calculations show that each 2m Mercury conductor has a resistance of 15 > milliohms and that a 10gauge copper wire 3mm in diameter has a resistance > of 0.1 milliohms (these are approximate theoretical values and do not > represent measured data). > This is the only significant difference. I would prefer copper cables because for larger currents, as typically found in speaker cables, the copper ones will have less loss. If they were available on the market, I wouldn't buy mercury cables because they are not worth the expense and because any mercury leakage would be hazardous, and would require special equipment for cleanup. > Brett L Maraldo > > > -- > -------- Unit 36 Research --------- > "Alien Technology Today" > ------------------------------------------- > bmaraldo@watdcsu
palmer@tybalt.caltech.edu (David Palmer) (09/10/87)
In article <3816@watdcsu.waterloo.edu> bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > > I just made a set of 2m long 5mm in diameter mercury filled cables with > copper touch conductors and large lugs. Forgive me for asking, but WHY? If you were really into exotics, you would make up a batch of superconducting speaker cable, now that it needs only liquid nitrogen. :-) Of course that would only be unique for a year or so before EVEYBODY had them at room temperature, but if you kept the old system, you could talk about the audible differences due to lower thermal noise. David Palmer palmer@tybalt.caltech.edu ...rutgers!cit-vax!tybalt.caltech.edu!palmer The opinions expressed are those of an 8000 year old Atlantuan priestess named Mrla, and not necessarily those of her channel.
heuring@boulder.Colorado.EDU (Vincent Heuring) (09/10/87)
In article <3816@watdcsu.waterloo.edu> bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > > I just made a set of 2m long 5mm in diameter mercury filled cables with > copper touch conductors and large lugs. > I can see the review by Anthony Cordesman now: "This wire lends a liquid transparency to strings. The fluid quality of horns has to be heard to be believed. There is a silvery quality to the brass, with no sign of the hard-edged, coppery sound normally associated with speaker cable... | Vincent Heuring | | Dep't of Electrical & Computer Engineering | | University of Colorado - Boulder | | heuring@colorado.EDU |
bmaraldo@watdcsu.UUCP (09/11/87)
In article <578@uthub.toronto.edu> koko@uthub.toronto.edu (M. Kokodyniak) writes: > Metals are metals. Electricity flows in the same way through all metals. > This includes copper and mercury. > Crap. Then there should be no difference between coaxial cable, twisted pair and transmission lines in terms of signal propagation. BUT THERE IS! > You have been reading too many audiophile magazines. As far as audio > frequencies are concerned, no cables of typical length (i.e. fitting in > your living room) are going to behave like transmission lines. Therefore, > the conductor material, wire configuration and spacing, and insulation > material are all irrelevant. So audio signals will look the same on > copper cables as on mercury ones. Again: Crap. What you have said here is simply a matter of opinion. I can hear differences between audio cables. I can not report and differences under controlled double-blind tests because I have never taken part in one. I am not attempting to convince you that I can hear a difference, but what I hear is good enough for me. Brett L Maraldo -- -------- Unit 36 Research --------- "Alien Technology Today" ------------------------------------------- bmaraldo@watdcsu
dave@micropen (David F. Carlson) (09/11/87)
> In article <3816@watdcsu.waterloo.edu> bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > > > > I just made a set of 2m long 5mm in diameter mercury filled cables with > > copper touch conductors and large lugs. I hope you cables are *very* well sealed. Mercury is a very hazardous substance to expose yourself and your family to for no good reason. Long term and short term exposure hazards are well documented and just the vapor leakage from whatever cable packaging should be considered a potential hazard. Exercise extreme caution. Again: no good reason. -- David F. Carlson, Micropen, Inc. ...!{seismo}!rochester!ur-valhalla!micropen!dave "The faster I go, the behinder I get." --Lewis Carroll
ron@topaz.rutgers.edu (Ron Natalie) (09/11/87)
> > Metals are metals. Electricity flows in the same way through all metals. > > This includes copper and mercury. > > > Crap. Then there should be no difference between coaxial cable, twisted > pair and transmission lines in terms of signal propagation. BUT THERE > IS! You are both arguing different sides of the picture. In the Copper Vs. Mercury debate, there is essentially no difference other than resistance. So the material there is unimportant. The difference indicated about coax v. twisted pair v. transmission lines (shows an inadequate knowledge of the subject right there, transmission lines do not belong in a group with examples of themselves). Theoretically, if you had the same resistance, dialectric, and relative conductor spacings (and shape) you'd get the same performance regarless of what the conductor was made of.
rck@ihuxv.ATT.COM (R. C. Kukuk) (09/11/87)
In article <2166@sigi.Colorado.EDU>, heuring@boulder.Colorado.EDU (Vincent Heuring) writes: > In article <3816@watdcsu.waterloo.edu> bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > > > > I just made a set of 2m long 5mm in diameter mercury filled cables with > > copper touch conductors and large lugs. > > > > I can see the review by Anthony Cordesman now: > > "This wire lends a liquid transparency to strings. The fluid quality > of horns has to be heard to be believed. There is a silvery > quality to the brass, with no sign of the hard-edged, coppery > sound normally associated with speaker cable... However, when the cables are jarred, an echo chamber effect is heard as compression waves travel back and forth in the mer- cury ... > Ron Kukuk AT&T Bell Labs XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
rdp@teddy.UUCP (Richard D. Pierce) (09/11/87)
In article <3827@watdcsu.waterloo.edu> (Commander Brett Maraldo) writes: ->In article <578@uthub.toronto.edu> (M. Kokodyniak) writes: ->> Metals are metals. Electricity flows in the same way through all metals. ->> This includes copper and mercury. ->> -> Crap. Then there should be no difference between coaxial cable, twisted -> pair and transmission lines in terms of signal propagation. BUT THERE -> IS! -> Double crap. He did not say "there is no difference between conductor configurations" as you contend he did. He said "Electricity flows in the same way through all metals," a markedly different statement than what you contend. Secondly. crap to your "BUT THERE IS". A far more accurate statement would be "BUT I (one of THINK, CONTEND, INSIST, BELIEVE, WISH, etc) THERE IS." The issue of the audibility of wire is far from settled. To insist that there definitely is a difference without being willing to submit the contention to fair, unbiased and revealing tests is to beg dismissal of that contention. ->> You have been reading too many audiophile magazines. As far as audio ->> frequencies are concerned, no cables of typical length (i.e. fitting in ->> your living room) are going to behave like transmission lines. Therefore, ->> the conductor material, wire configuration and spacing, and insulation ->> material are all irrelevant. So audio signals will look the same on ->> copper cables as on mercury ones. -> -> Again: Crap. What you have said here is simply a matter of opinion. I -> can hear differences between audio cables. I can not report and -> differences under controlled double-blind tests because I have never -> taken part in one. I am not attempting to convince you that I can hear -> a difference, but what I hear is good enough for me. -> Again, double crap. The statement "no cables of typical length are going to behave like transmission lines [at or near audio frequencies]" is not a matter of opinion, it is a statement of fact firmly secured in transmission line mathematics. While I may not agree that "conductor material, wire configuration and spacing, and insulation material are all irrelevant," to criticize your respondant on the basis of a strawman you have set up is unfair and unproductive. Commander, you may indeed be able to hear a difference between cables, you may indeed THINK you hear a difference between cables. There may well BE a difference between cables. But to declare established fact (tranmission line performance, etc.) as mere personal opinion simply because it not only does not support your contentions, but refutes them, demonstrates ones misunderstanding at the physical processes and possibly some psycho-acoustic effects as well. Again, let's argue against the point that someone made, not what you think someone made. To add my one two cents woorth to the TECHNICAL discussion, there are a variety of reasons why mercury is very poorly suited to audio-style conductors. 1. It has a relatively high bulk resistivity. For a given cross sectional area, it is much higher than copper, as you suggested. Even per unit mass, it suffers to many other conductors. 2. If you think skin effect is an issue, than multi-stranded solid conductors will far outperform a single liquid conductor 3. Mercury is just plain dangerous stuff. 4. If I heard you right when you sain the mercury is in copper jacketing, your going to be in for a real big surprise. Copper is soluble in mercury. Sooner or later, your little wires are going to start leaking. A lot! (take it from someone who had to deal with another inane mercury based audiophile product, the Keith Monks tone arm.) 5. Mercury, when exposed to air, quickly forms a skin of mercuric oxide, which present a very non-linear electrical junction with whatever interfacing conductor it meets. Most mercury switches are hermetically sealed with dry nitrogen or argon to prevent this from happening. Dick Pierce
larry@kitty.UUCP (Larry Lippman) (09/12/87)
In article <2115@ihuxv.ATT.COM>, rck@ihuxv.ATT.COM (R. C. Kukuk) writes: > > > I just made a set of 2m long 5mm in diameter mercury filled cables with > > > copper touch conductors and large lugs. > > > > I can see the review by Anthony Cordesman now: > > > > "This wire lends a liquid transparency to strings. The fluid quality > > of horns has to be heard to be believed. There is a silvery > > quality to the brass, with no sign of the hard-edged, coppery > > sound normally associated with speaker cable... > However, when the cables are jarred, an echo chamber effect is > heard as compression waves travel back and forth in the mercury ... Actually, you have touched upon a grain of truth. Mercury-filled tubing - expecially of the silicone rubber variety - makes a simple, but effective position transducer. As the cable is stretched, both the length of the mercury column increases and its diameter decreases in the affected area; this results in greater electrical resistance as the tubing is stretched. Knowing the elastic modulus of the tubing, its physical dimensions and the weight of the mercury allow quantitative measurement of stress and strain. Mercury-filled tubing has been used as a stress/position transducer for a number of years, especially in bio-medical applications as a pneumograph transducer (respiration measurement using chest expansion) and as a plethysmograph transducer (limb expansion due to arterial pressure pulse). So, I would think that y'all "audiophiles" out there contemplating the use of mercury-filled cable would, upon further contemplation, reject it since it would obviously be susceptible to microphonics. Now, for a more practicable idea, consider the use of SODIUM-filled cables, which have been available to the electric power industry for a number of years. Sizes go up to at least 500,000 circular mils, and I know for a fact that the cable is available with an insulation rating of 15 kV for direct-burial applications. Be the first on your block to have sodium-filled speaker cables! They'll beat ol' Monster Cable any day... <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|seismo|utzoo}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"
bmaraldo@watdcsu.UUCP (09/12/87)
In article <14647@topaz.rutgers.edu> ron@topaz.rutgers.edu (Ron Natalie) writes: > Mercury debate, there is essentially no difference other than resistance. > So the material there is unimportant. The difference indicated about > coax v. twisted pair v. transmission lines (shows an inadequate knowledge > of the subject right there, transmission lines do not belong in a group > with examples of themselves). Theoretically, if you had the same resistance, > dialectric, and relative conductor spacings (and shape) you'd get the same > performance regarless of what the conductor was made of. This is true, but we DO NOT have the same resistance. Infact, the resistance differs by about a magnitude. Will this not change the dynamic signal characteristics of the conductor? How is skin effect handled (in the same manner as copper, perhaps?)? Impedance? Answer these questions for me and I'll be grateful, but do supply scientific explanations as the intuitive explanations I've been getting just don't cut it. As for why I made the cables (every mail message I've been getting on the topic has asked WHY): It seemed like a neat thing to do. The cables certainly look great and they actually work well. I would have thought that this little project would have been looked apon with interest but the opposite is true. As soon as anyone gives mention to any audiophile trait (ie. cables sounding different) flames start to fly. What do you people listen to, JVC and Sony equipment?!? I'm an audiophile and I hate CD's and I'm damn proud of it! So there! NAA! Brett L Maraldo -- -------- Unit 36 Research --------- "Alien Technology Today" ------------------------------------------- bmaraldo@watdcsu
bblue@crash.CTS.COM (Bill Blue) (09/12/87)
In article <578@uthub.toronto.edu> koko@uthub.toronto.edu (M. Kokodyniak) writes: >In article <3816@watdcsu.waterloo.edu>, bmaraldo@watdcsu.waterloo.edu >> >> I just made a set of 2m long 5mm in diameter mercury filled cables with >> copper touch conductors and large lugs. I really do not have a clue as >> to the dynamic characteristics of mercury. > >Metals are metals. Electricity flows in the same way through all metals. >This includes copper and mercury. This is not at all true. Electrons flow in the same direction, yes, but not in the same manner in all metals. Apart from the varying conductivity of different metals, the shape and size of the conductors, how many of them and their plating, all affect the flow of electrons, especially when the currents are alternating and the frequency of alternations (read that: your typical audio signal) varying. >> If you know anything about >> what an audio signal might look like after propagating through such a >> cable, I'd like to know, especially if you have data to back your >> comments up with. > >You have been reading too many audiophile magazines. As far as audio >frequencies are concerned, no cables of typical length (i.e. fitting in >your living room) are going to behave like transmission lines. Therefore, >the conductor material, wire configuration and spacing, and insulation >material are all irrelevant. So audio signals will look the same on >copper cables as on mercury ones. No, YOU haven't read enough audiophile magazines, or other sources of information that go into detail what actually happens in different conductors. The 'sound of wire' discussion is getting tiring. ANYONE who has done comparisons in speaker wire on even moderately priced gear knows they can sound quite different from each other. The ultimate question is 'which one is right'? This, by the way, also has some interesting implications to the 'straight wire with gain' claim made by a number of high-end audio gear manufacturers, now that it is widely recognized that a 'straight wire' can have a very distinct sonic signature. In the most recent Stereophile magazine, Vol 10 No. 6, there are two very interesting and enlightening articles about the types of things that cause these conductors to sound different. I'll paraphrase a few of the points made. You'll notice that much of this is very basic and long-known information about the electron propagation in a conductor. Bruce Brisson: Phase noise is a degrading by-product of a larger cable problem known as 'delay distortion'. Instead of passing energy uniformly, non-nuetral cable actually stores energy, subsequently releasing this energy -- at the wrong time, and often out-of-phase. Such cables have a large 'settling time', which means that as a signal passes through these cables, substantial information is left behind. This residue then piggy-backs onto the next signal (waveform), producing audible and out-of-phase sonic additions. This gremlin is phase noise, inevitable in any cable not designed to fully pass all frequencies at exactly the same speed. ... Cables with delay distortions may at first seem quicker, with more highs and ambience. Why? As discussed, these frequency dependent delays move energy from one location in a complex waveform to another. This changes the resulting waveform or musical tone. Worse yet, moving energy around within the tone also results in noise, defocusing and removal of low level detail. And from Dick Olsher: A simplistic view is to regard the skin effect as AC resistance to current flow that becomes significant and very high frequencies. This is a fair macroscopic view of the situation, but it glosses over some important physical details. On a microscopic scale, the electromagetic wave nature of the transmitted signal plays an important role. With increasing frequency, a current wave moves into a conductor less and less, the depth of penetration being only about .5mm at 20khz. As the current penetrates the conductor, the relative phase of the current changes. With the current density at a maxmimum at the surface and decreasing inward, the phase is continuously retarded. Again, it follows from the skin effect that since the current density is nonuniform across the conductor, the inductance of the wire decreases slowly with increasing frequency -- the speed of the propagation of the highs is faster than that of the lows. This is a key point. When modeling signal transfer in audio cables, it is not only necessary to take into account the variable AC resistance of the cable, but its variable inductance as well. The shunt capacitance of the cable (but not the capacitive reactance) is fixed by the geometry of the cable and the dielectric properties of the insulation used. Therefore an electrical model of a single leg of cable would look like a variable resistor in series with a variable inductance with a shunt capacitor. Bruce Brisson of MIT (a cable company) has done this sort of modeling on a computer. He has found that a large number of different diameter wires are necessary to control the impedance of the cable while minimizing the phase delays due to differential propagation speeds. ---- Of course, there is a lot more to it than just what I've entered here. There have been some very interesting and objective articles presented on these and other similar subjects by established and reputable people in both Sterephile and The Absolute Sound. In either magazine (and others) there are also letters-to-the-editor, opinions expressed, and non-technical columns that occasionally border on bizarre and unbelievable, which I believe have helped give these magazines a bad name outside of the 'audiophile' circle. Nonetheless, there is still a lot of good information to be had -- the fluff is easily discernable from objective works researched and presented by extrememly credible people. --Bill UUCP: {cbosgd, hplabs!hp-sdd, sdcsvax, nosc}!crash!bblue ARPA: crash!bblue@nosc.mil INET: bblue@crash.CTS.COM
palmer@tybalt.caltech.edu.UUCP (09/12/87)
Just to shed more heat on this subject, it seems to me that most audiophile discussions of this nature are full of buzzwords and little quantitative thought, so let me continue this tradition. Mercury filled cables suffer from signal-induced magnetostrictive non-linear microphonics. The resistive impedance has a temporally varying component with a first derivative w.r.t. time proportional to the second power of the signal current. This causes multiplicative mixing of the signal with a signal with all frequencies doubled, causing objective (as opposed to subjective) sum and difference frequencies. At mechanical resonance, the electrical signal may cause runaway oscillation resulting in cavitation, yeilding chaotic resistance phenomena. Near resonance, high-Q mechanical vibration will cause what laymen call "ringing", continued oscillation after the driving signal is removed. Of course, all of this is non-quantitative, and if you work out the numbers, you will find that these effects would be indetectable for ordinary current densities and wires. Nevertheless, I hope that this article has fanned the flames and opened up new vistas for argument. Please direct follow-ups to rec.audio, as I do not read that newsgroup. From the Cyberpunk Audiophile: David Palmer palmer@tybalt.caltech.edu ...rutgers!cit-vax!tybalt.caltech.edu!palmer The opinions expressed are those of an 8000 year old Atlantuan priestess named Mrla, and not necessarily those of her channel.
gwyn@brl-smoke.UUCP (09/13/87)
In article <3939@cit-vax.Caltech.Edu> palmer@tybalt.caltech.edu.UUCP (David Palmer) writes: >In article <3816@watdcsu.waterloo.edu> bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: >> I just made a set of 2m long 5mm in diameter mercury filled cables with >> copper touch conductors and large lugs. I missed the original posting, but please note that mercury is rather hazardous. I wouldn't advise people to use it like this, especially since if it's really for loudspeaker connection it's pretty damn silly.
heppell@cory.Berkeley.EDU.UUCP (09/13/87)
In article <14647@topaz.rutgers.edu> ron@topaz.rutgers.edu (Ron Natalie) writes: > Theoretically, if you had the same resistance, >dialectric, and relative conductor spacings (and shape) you'd get the same >performance regarless of what the conductor was made of. Actually, transmission line performance can vary greatly with conductor resistance. At low frequencies, (low is relative to the transmission line) most of the conduction is bulk instead of surface, but concuctor resistance still matters. The resistance of the conductor affects such things as signal degradation and propagation velocity, which will in turn affect dispersion. Admittedly, between DC and 20 kHz, there is little difference, but some audiophiles will claim to be able to hear it. If there is interest, or I have time, I'll work through the equations and post results. -------------------------------------------------------------------------------- Kevin G. Heppell USNail: 784 Santa Barbara Rd. USENET: ucbvax!cory!heppell Berkeley, CA 94707-2046 arpa: heppell@cory.Berkeley.EDU (415) 528-6396
jef@unisoft.uucp (Jef Poskanzer) (09/14/87)
In the referenced article, Space Commander Brett Maraldo wrote: >I can hear differences between audio cables. I can not report and >differences under controlled double-blind tests because I have never >taken part in one. Whenever I come across one of these "Emperor's New Ears" types I always ask him about double-blind tests. It's refreshing for once to find one who freely admits his lack of interest in the scientific method. --- Jef Jef Poskanzer unisoft!jef@ucbvax.Berkeley.Edu ...ucbvax!unisoft!jef "No cash down! Up to 60 minutes to pay!" ...and now, a word from our sponsor: "The opinions expressed are those of the author and do not necessarily represent those of UniSoft Corp, its staff, or its management."
max@eros.uucp (Max Hauser) (09/14/87)
In article <1700@crash.CTS.COM> bblue@crash.CTS.COM (Bill Blue) writes: > In article <578@uthub.toronto.edu> koko@uthub.toronto.edu (M. Kokodyniak) writes: > >In article <3816@watdcsu.waterloo.edu>, bmaraldo@watdcsu.waterloo.edu > >> > >> I just made a set of 2m long 5mm in diameter mercury filled cables with > >> copper touch conductors and large lugs. I really do not have a clue as > >> to the dynamic characteristics of mercury. > > > >Metals are metals. Electricity flows in the same way through all metals. > >This includes copper and mercury. > > This is not at all true. Semantics. The important difference is bulk resistivity. This determines resistance, and skin-effect depth, and the relative values of inductance and resistance, and (if you allow for corrosion effects at the surface) indeed all of the properties cited recently on this newsgroup. The differences among metals are essentially quantitative, which I think is what koko was getting at. > The 'sound of wire' discussion is getting tiring. ANYONE who has done > comparisons in speaker wire on even moderately priced gear knows they > can sound quite different from each other. Of course. Competent engineers would have told you this thirty years ago, if asked. Although the sonic effects may indeed be subtle, the physical causes are familiar to the point of boredom to persons trained in E & M (as indeed bblue mentions, next pph). > In the most recent Stereophile magazine, Vol 10 No. 6, there are two > very interesting and enlightening articles about the types of things > that cause these conductors to sound different. I'll paraphrase a few > of the points made. You'll notice that much of this is very basic > and long-known information about the electron propagation in a > conductor. > > "Phase noise is a degrading by-product of a larger cable problem known > as 'delay distortion'. Instead of passing energy uniformly, non-nuetral > cable actually stores energy, subsequently releasing this energy -- at > the wrong time, and often out-of-phase. [Comment: clumsy explanation; > as stated, applies to any cable, not just those with delay distortion > -- MH] ... This residue then piggy-backs onto the next signal > (waveform), producing audible and out-of-phase sonic additions. > This gremlin is phase noise, inevitable in any cable not designed to > fully pass all frequencies at exactly the same speed." Known concisely to the technical world as "dispersion", and mislabeled if called "noise" because it is a repeating, deterministic effect. > And from Dick Olsher: > > "[Mention of skin effect causing freq-dependent resistance and > inductance in wires] ... With increasing frequency, a current wave > moves into a conductor less and less, the depth of penetration being > only about .5mm at 20khz ... -- the speed of the propagation of the > highs [becomes] faster than that of the lows." > > This is a key point. When modeling signal transfer in audio cables, it > is not only necessary to take into account the variable AC resistance of > the cable, but its variable inductance as well... > > --Bill All of which, of course, constitutes eloquent argument against mercury cables, with their much-higher-than-copper resistivity and consequent exaggerated impedance effects, as was obvious at the outset to the technical people on this group (who are now coming in for the usual knee-jerk criticisms). Since skin depth varies as the square root of bulk resistivity [1], but resistance is proportional to resistivity divided by skin depth, the net resistance of the wire increases as the square root of resistivity when skin-depth effects are considered. Also, for large wires and audio frequencies, AC inductance also rises as the square root of resistivity [2]. In other words, higher- resistivity materials like mercury are bad in every respect, both simple and subtle effects. Let us not deceive ourselves: wires have audible differences, but at the same time one can still go to the hardware store, buy some good heavy stranded wire, maybe connect several in parallel for good measure, and come up with cables that will meet the most rigorous analysis (mine, Olsher's, or anyone's) and sound beautiful, for a few bucks, without resorting to precious metals, single crystals, or mercury (this all begins to seem even alchemical at times). There is no need to contribute *hundreds* of dollars to flaky fad-mongering pseudotechnical garage manufacturers who turn out products named after themselves, as though they were Renaissence painters, primarily to suit their egos and incidentally to make a fast buck -- yours. Respectfully, Max W. Hauser, UC Berkeley Some numbers: (415) 642-6666; P1-12-20075; 4,435,655 UUCP: ...{!decvax}!ucbvax!eros!max Internet (domain style): max@eros.berkeley.edu References: [1] Ramo, Whinnery and van Duzer, _Fields and Waves in Communication Electronics_, Wiley, 1965, p. 252. [2] Ramo, Whinnery and van Duzer, pp. 288-297.
ron@topaz.rutgers.edu (Ron Natalie) (09/14/87)
> Apart from the varying > conductivity of different metals, the shape and size of the conductors, > how many of them and their plating, all affect the flow of electrons, > especially when the currents are alternating and the frequency of > alternations (read that: your typical audio signal) varying. I don't think anyone was arguing this point. The point was the difference in using Mercury vs. Copper was more likely to be things like the difference in size and spacing than the nature of the metal itself. (By the way, I don't think plating really helps anything at audio frequencies except for where the wire is exposed to the air). > Phase noise is a degrading by-product of a larger cable problem known > as 'delay distortion'. Instead of passing energy uniformly, non-nuetral > cable actually stores energy, subsequently releasing this energy -- at > the wrong time, and often out-of-phase. Such cables have a large > 'settling time', which means that as a signal passes through these > cables, substantial information is left behind. This cracks me up everytime I read these smokescreen Stereophile stuff. If HiFi addicts would just learn a little about electronics they could discuss things sensibly in the terms that everyone else uses. This temporary storage/blockage of energy in a frequency dependent nature is called REACTANCE. Not only is this caused by size and spacing of conductors but is also effected by loops in the cable. Reactance when combined with plain old DC resistance (constant with respect to frequency) is called IMPEDANCE (gee, haven't I heard that term before?) In addition to the frequency response problems that it generates, impedance plays a significant factor in the performance of your power amplifiers. Despite the nominal impedences given of 4 or 8 ohms, remember that this is frequency dependent. The cable/speaker has it's impedance characturistics and amplifiers have their best performance characturistics. This is why speakers need to be matched to the amplifiers. freqencies at the same speed for our purposes. > As discussed, these frequency dependent delays move > energy from one location in a complex waveform to another. Frequency dependent delays are phase changes (probably). My favorite was the discussion of using a single DAC in CD players and how this causes a phase shift between the two channels. Even worse, a frequency dependent one. That's because it was a (non-frequency dependent) DELAY, which is easily corrected for. Note that nothing they say is probably really wrong with respect to what is probably happening to the audible sound, but it would be MUCH nicer if they would learn the electronics principles when describing the electronic parts (it is probably not possible to characturize the audible sensations, which is another issue). -Ron
bblue@crash.CTS.COM (Bill Blue) (09/14/87)
In article <551@unisoft.UUCP> jef@unisoft.UUCP (Jef Poskanzer) writes: >In the referenced article, Space Commander Brett Maraldo wrote: >>I can hear differences between audio cables. I can not report and >>differences under controlled double-blind tests because I have never >>taken part in one. > >Whenever I come across one of these "Emperor's New Ears" types I always >ask him about double-blind tests. It's refreshing for once to find one >who freely admits his lack of interest in the scientific method. The problem with this is that the differences in cables, especially the speaker cables, is so profound *on high resolution gear* that double blind tests are simply not necessary. It's day and night. Differences between similarly constructed cables are more subtle, however. --Bill
bblue@crash.CTS.COM (Bill Blue) (09/14/87)
In article <1854@ucbcad.berkeley.edu> max@eros.UUCP (Max Hauser) writes: >In article <1700@crash.CTS.COM> bblue@crash.CTS.COM (Bill Blue) writes: > [stuff deleted] >> And from Dick Olsher: >> >> "[Mention of skin effect causing freq-dependent resistance and >> inductance in wires] ... With increasing frequency, a current wave >> moves into a conductor less and less, the depth of penetration being >> only about .5mm at 20khz ... -- the speed of the propagation of the >> highs [becomes] faster than that of the lows." >> >> This is a key point. When modeling signal transfer in audio cables, it >> is not only necessary to take into account the variable AC resistance of >> the cable, but its variable inductance as well... > >All of which, of course, constitutes eloquent argument against mercury >cables, with their much-higher-than-copper resistivity and consequent >exaggerated impedance effects, as was obvious at the outset to the >technical people on this group (who are now coming in for the usual >knee-jerk criticisms). Since skin depth varies as the square root of >bulk resistivity [1], but resistance is proportional to resistivity >divided by skin depth, the net resistance of the wire increases as the >square root of resistivity when skin-depth effects are considered. >Also, for large wires and audio frequencies, AC inductance also >rises as the square root of resistivity [2]. In other words, higher- >resistivity materials like mercury are bad in every respect, both >simple and subtle effects. > >Let us not deceive ourselves: wires have audible differences, but at >the same time one can still go to the hardware store, buy some good >heavy stranded wire, maybe connect several in parallel for good >measure, and come up with cables that will meet the most rigorous >analysis (mine, Olsher's, or anyone's) and sound beautiful, for a few >bucks, without resorting to precious metals, single crystals, or >mercury (this all begins to seem even alchemical at times). >There is no need to contribute *hundreds* of dollars to flaky >fad-mongering pseudotechnical garage manufacturers who turn out >products named after themselves, as though they were Renaissence >painters, primarily to suit their egos and incidentally to make a >fast buck -- yours. While I certainly agree that there are cable companies out there producing stuff that is far worse than what could be realized from any reasonably thick multi-strand copper electrical wire (10-12 guage), I think it's reaching a little too far to say that such cables will meet the most rigorous analysis. Maybe yours, but certainly not mine, Dick Olshers and a lot of other audiophiles. In my view, the big culprit that kills the 'hardware store' variety cables is the varying time of arrival of different frequencies at the other end of the cable due to skin effect propagation and other factors. This simply can not be made up for, or controlled by simply paralleling average cables together. While they'll have a low DC resistance, and will allow good control (damping) of the speakers (assuming the amp has good control in the first place), they will also have a very confused representation of inner detail. They most certainly will not pass the test on any aware audiophile's ears. I make these statements from personal experience with all sorts of cables. Take *any* heavy, stranded, copper cable -- anything from 12/2 or 10/2 electrical cable to the 12 guage (standard) Monster cable (reasonably cheap at ~$.50/foot) and you'll get a similar sound. The number of strands and thickness of each will provide subtle differences, but all in all they're about the same. You don't really get into high definition (the ability to preserve inner detail to the limit of what is there in the first place) until you get to cables that try to maintain equal time propagation of various frequency bands through that cable. But you have to take all this in degrees. There are many many people, including quite a few self-proclaimed audiophiles, who have simply never heard these differences. It could be for any number of reasons, to over-regarded equipment to not believing that wire could make any difference so they never have tried it. So naturally, if such a person did replace their cable with multi-strand heavy gauge copper cable from the 'hardware store' it would probably be an eye-opening experience for them and theyll begin singing the praises of this discovery -- not yet realizing that there is still a whole other world of further improvements they are not yet aware of. And of course, the better your equipment (not always measured in dollar value) and the keener your awareness, the important such differences become. --Bill
bmaraldo@watdcsu.UUCP (09/14/87)
In article <551@unisoft.UUCP> jef@unisoft.UUCP (Jef Poskanzer) writes: > In the referenced article, I wrote: > >I can hear differences between audio cables. I can not report any > >differences under controlled double-blind tests because I have never > >taken part in one. > > Whenever I come across one of these "Emperor's New Ears" types I always > ask him about double-blind tests. It's refreshing for once to find one > who freely admits his lack of interest in the scientific method. I agree that double-blind testing is a method of discovering differences, or lack there-of, in two or more different audio systems. This can also be said for any method of system evaluation, the question is which method provides the most accurate results. Double-blind testing seems to be the most accepted method by those who understand the importance of accurate test results. But is double-blind testing the definitive test method? This is certainly and arguable point, as it is as objective as the golden-ear phenomenon. I do not feel that a simple double-blind test can report more accurate data than an extended listening test. For me, a double-blind test must be rigorous, extended, and thorough; that is, there must be a large number of people involved in the evaluation, and the test procedure must be overseen by at least one member of a group of potentially biased individules (one audio engineer, physicist, golden ear, and stereo salesman). As each procedure is concluded, the overseeres must unanimously agree that the procedure was unbiased before enumerating the results. The listening environment must differ between anechoic and very 'alive', with each group listening in the different situations; one listening environment does not suffice. Unfortunately, this test senario is rarely implemented, let alone documented as it would be very expensive and time consuming. I have yet to read about a double-blind test with and description of test procedure and environment. Most audio magazines report that they have conducted a double-blind test but do not embellish on the procedure; I can not take these reviews seriously. What I do take seriously are what my ears hear. If I hear a difference between signal cable, you can not argue that I do not hear that difference. You can, how ever, argue that my perception is not accurate due to some bias or other influence. This same argument can be overlayed on a poorly conducted double-blind test and most do not meet the requirements of an unbiased controlled environment procedure. Brett L Maraldo -- -------- Unit 36 Research --------- "Alien Technology Today" ------------------------------------------- bmaraldo@watdcsu
rees@apollo.uucp (Jim Rees) (09/14/87)
And from Dick Olsher: This is a key point. When modeling signal transfer in audio cables, it is not only necessary to take into account the variable AC resistance of the cable, but its variable inductance as well... I decided to do an experiment. I connected an audio sig gen to my ultra-cheap stereo amp, put the output of the amp on the H input of my scope and through 100 feet of cheap Radio Shack speaker cable, and put the output of the cable on a 8 ohm dummy load and the V input of my scope. This should show me the phase change of the signal through the cable. At very high frequencies (100KHz) I could detect some phase shift. I was using about 100 feet of cable, so the shift should be about 4 degrees at this frequency. I was unable to determine whether the shift varied non-linearly with frequency (which seems to be what the claim is; am I right?) Olsher also says, The shunt capacitance of the cable (but not the capacitive reactance) is fixed by the geometry of the cable and the dielectric properties of the insulation used. I was trying to calculate the electrical properties of this particular speaker cable, and discovered that vinyl apparently has a dielectric constant that varies over a wide range with frequency. It has close to a 10% change over the audible range (which for me is about 20-25K). This should result in about a 5% change in shunt capacitance. It seems to me that this is a greater effect than skin effect, at least at these frequencies. No matter what numbers I plug in, I can't get any of these effects to account for more than a .05 db change in signal level or a .1 db additional noise due to phase distortion. Here's an idea for audiophile speaker cable. Only vacuum has a dielectric constant completely independent of frequency. Vacuum filled speaker cable! I envision something semi-rigid and metal- clad, sort of like heliax. If you worry about these things, I think the practical solution is to put the amplifier physically close to the speaker. Then you only need to get a low level signal, at reasonable impedances, to the amplifier. And you don't need a ton of copper to carry those watts at 8 ohms. You could use fiber optics to connect the signal source to the amplifier. Olsher must have done some experiments. What were his results?
henry@utzoo.UUCP (Henry Spencer) (09/14/87)
> As for why I made the cables (every mail message I've been getting on the > topic has asked WHY): It seemed like a neat thing to do. The cables > certainly look great and they actually work well. I would have thought > that this little project would have been looked apon with interest but > the opposite is true... Those of us who understand the properties of mercury are looking upon it with horror, mostly. I hope the room where you've got those things is well-ventilated and that humans (and other living things) don't spend long periods of time in it. I also hope you've got some sort of catcher tray under the cables, so that if they leak (say from mercury corrosion of the end seals), the mercury won't end up on the floor. Once mercury gets into a wood floor, it can be damn near impossible to get it out well enough to make the room safe again. (I know chemists often are kind of casual with mercury. I got perhaps halfway to being one before I got diverted into computing. Chemists are often kind of casual with far too many things; this may be one reason why they have a shorter average life expectancy than physicists.) -- "There's a lot more to do in space | Henry Spencer @ U of Toronto Zoology than sending people to Mars." --Bova | {allegra,ihnp4,decvax,utai}!utzoo!henry
phd@speech1.cs.cmu.edu (Paul Dietz) (09/15/87)
In article <1854@ucbcad.berkeley.edu> max@eros.UUCP (Max Hauser) writes:
Lot's of good stuff about Speaker wires...
Here's my 2 cents worth:
For those of you who claim to hear a difference between reasonable cables,
here's a possible explanation: it's not the wire per say; it's the amp.
Yes, some amplifiers are rather finiky about the load they see.
Different cables will significantly alter the impedance, especially at
low frequencies. (i.e. a cable's resistance is often a reasonable
fraction of 4/8 ohms) And it is quite concievable that this shift
in the 'operating point' of your amp can change the frequency response.
The important question is: Do you really care?
From the speakers I've measured,
the input impedance varies quite a bit, even in a
matched pair. Much more so than a piece of heavy zip cord will
change it. So, if the speakers are much more inconsistent than
the wire, why worry about the wire. Another way to look at this
is from an acoustical point of view. Unless you're listening to
your speakers in a perfectly symmetrical environment, the differences
will probably be mostly due to the room, and your position in it.
(Go read Beranek's book "Acoustics" reprinted by the Acoustical
Society, and you'll see how bad this problem really is...")
The point? With an A/B test, you might actually be able
to distinguish between cables, though I know I can't. But you
certainly will be able to distinguish between different speaker
placements, and quite possibly between different speakers, even
when placed in the same position. (By different speakers, I mean
in a matched set.) If you're really picky, go buy a good
equalizer. It will probably help. But don't waste your time/money
on cables more exotic than zip cord.
I don't read rec.audio either, so please feel free to
post there...
--
Paul H. Dietz ____ ____
Dept. of Electrical and Computer Engineering / oo \ <_<\\\
Carnegie Mellon University /| \/ |\ \\ \\
-------------------------------------------- | | ( ) | | | ||\\
"If God had meant for penguins to fly, -->--<-- / / |\\\ /
he would have given them wings." _________^__^_________/ / / \\\\-bmaraldo@watdcsu.UUCP (09/15/87)
In article <8576@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes: > Those of us who understand the properties of mercury are looking upon it > with horror, mostly. I hope the room where you've got those things is ... The ends are sealed with a large plug of hot glue which melts the inside surface of the plastic and forms itself into the wall of the tube. The plugs have been tested and comply with my safty standards which are high. Brett L Maraldo -- -------- Unit 36 Research --------- "Alien Technology Today" ------------------------------------------- bmaraldo@watdcsu
max@eros.uucp (Max Hauser) (09/15/87)
In article <1709@crash.CTS.COM> bblue@crash.CTS.COM (Bill Blue) writes: > In my view, the big culprit that kills the 'hardware store' variety > cables is the varying time of arrival of different frequencies at the > other end of the cable due to skin effect propagation and other factors. OK, I will concede that hardware-store cables of the casual variety may suffer from this problem. When I asserted that one could build hardware-store cables meeting arbitrary specifications, I specifically meant reactance and dispersion as well as resistance, based on some knowledge of these effects and on the properties of copper wire. However I have not tried it, while bblue has, and I value that experience. Nevertheless, I am convinced that high-quality cables, even with these subtle problems resolved, need not be expensive. Understand that in the following I am now speaking of VERY high-quality speaker cables, since even casual hardware-store cable, heavily stranded and paralleled, and kept as short as possible, will palpably outperform even many "audio" cables. Now, to hear it described recently on the net, one would think that Dick Olsher and co. had discovered dispersive propagation and its relation to conductor effects. In reality these are old, prosaic problems, familiar to thousands of people in this country (some of whom are even on the net). In fact, since these problems first surfaced in long-disance wired telegraphy, they even predate electronics (a term, incidentally, coined by McGraw-Hill to title a trade magazine -- the magazine came before the field). Varying time delay for signals of different frequencies (also called dispersion, or phase nonlinearity) comes up in many contexts (phase nonlinearity in analog filters for digital audio was discussed to death on rec.audio), as do such conductor nonidealities as skin effect and distributed inductance. However, these problems also admit creative solutions, which can be as simple as tolerating the cable effects and adding a small compensating network in the preamp, properly done, of course. That the problems are unfamiliar to consumers does not mean that their solution requires genius, or an approach obviously related to the source of the problem, or even (the seemingly inevitable) hundreds of dollars per unit. Moreover, if you are going to seriously regard [good split infin.] "skin effect propagation and other factors" as physical, rather than just rhetorical, effects, and then someone comes up with a nice cheap solution that measurably fixes these physical effects, then you are bound to (as Sam Spade said to Joel Cairo) "take it and like it," or else stop claiming that you know the *physical basis* for cables' sonic imperfections. For many people this is a tall order. Max Hauser UUCP: ...{!decvax}!ucbvax!eros!max Internet (domain style): max@eros.berkeley.edu Internet (old style): max%eros@berkeley
jeffw@midas.TEK.COM (Jeff Winslow) (09/15/87)
In article <1709@crash.CTS.COM> bblue@crash.CTS.COM (Bill Blue) writes: >In my view, the big culprit that kills the 'hardware store' variety >cables is the varying time of arrival of different frequencies at the >other end of the cable due to skin effect propagation and other factors. What is "skin effect propagation", explained in physical terms used in their intended fashion? Reading strangeness such as this makes me suspect the author doesn't really know what he's talking about. But I'm willing to be instructed. Jeff Winslow "A silver platter! Isn't she charming?" - Herod, Salome
mike@ivory.SanDiego.NCR.COM (Michael Lodman) (09/15/87)
In article <8576@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes: >Those of us who understand the properties of mercury are looking upon it >with horror, mostly. I hope the room where you've got those things is >well-ventilated and that humans (and other living things) don't spend long >periods of time in it. I also hope you've got some sort of catcher tray >under the cables, so that if they leak (say from mercury corrosion of the >end seals), the mercury won't end up on the floor. Once mercury gets into >a wood floor, it can be damn near impossible to get it out well enough to >make the room safe again. As an example of a horror story, some people I know had a small bottle of mercury in their home , for one reason or another. A small fire broke out and the mercury bottle was close enough that part of it vaporized. Following the fire, the house was condemned as being unfit for human habitation, even though the damage was easily repaired, just because the bottle of mercury was found by the fire department. The house was completely demolished. I'm not sure what the insurance company thought about it. Also, a book I read once had someone place a single drop of mercury in the shoe of someone that they wanted to get rid of. In three months the person was dead, and the crime was not solved. My advice to you is to not use the mercury filled cables no matter how good the sound quality is and not to permit them to remain in your home. -- Michael Lodman (619) 485-3335 Advanced Development NCR Corporation E&M San Diego mike.lodman@ivory.SanDiego.NCR.COM {sdcsvax,cbatt,dcdwest,nosc.ARPA,ihnp4}!ncr-sd!ivory!lodman When you die, if you've been very, very good, you'll go to ... Montana.
dmt@mtunb.ATT.COM (Dave Tutelman) (09/16/87)
In article <3837@watdcsu.waterloo.edu> bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > Double-blind testing seems to be the most accepted method > by those who understand the importance of accurate test results. But > is double-blind testing the definitive test method? This is certainly > and arguable point, as it is as objective as the golden-ear phenomenon. If I understand what the "golden-ear phenomeneon" is, it isn't at all objective. It's totally subjective. Maybe you could explain what you mean, and disabuse me of this opinion. > > For me, a double-blind test must > be rigorous, extended, and thorough; that is, there must be a large > number of people involved in the evaluation, and the test procedure > must be overseen by at least one member of a group of potentially biased > individules (one audio engineer, physicist, golden ear, and stereo > salesman). As each procedure is concluded, the overseeres must > unanimously agree that the procedure was unbiased before enumerating > the results. The listening environment must differ between anechoic and > very 'alive', with each group listening in the different situations; > one listening environment does not suffice. > > .... This same argument can be overlayed on a poorly conducted > double-blind test and most do not meet the requirements of an unbiased > controlled environment procedure. > Perhaps we ought to review the DEFINITION of a double-blind test, as the description above carries a lot of extra baggage (useful in testing audio equipment, but having nothing to do with double-blind) and misses the fact that double-blind methodology is INHERENTLY unbiased (no "agreement" among the overseers is needed if the methodology is double-blind). In a double-blind experiment, TWO parties are "blind": (1) the subjects (you knew that, of course), and (2) the "overseer" of the experiment. The pattern of the experiment is created by a random number generator, and administered by a tester that doesn't know which experiment is currently going. In a medical experiment, this means that both the patient and the doctor are ignorant as to whether the patient is in the experimental or control group. In an audio experiment, this means that both the "golden ears" and the person doing the switching are ignorant about which equipment is being played. There ARE techniques for assuring this. If they are used, the test WILL be unbiased. You can criticize other aspects of the test (room too "live", statistically insignificant number of subjects, tone-deaf subjects :-), but it is innocent of bias. +---------------------------------------------------------------+ | Dave Tutelman | | Physical - AT&T - Lincroft, NJ | | Logical - ...ihnp4!mtuxo!mtunb!dmt | | Audible - (201) 576 2442 | +---------------------------------------------------------------+
russ@crlt.UUCP (Russ Cage) (09/16/87)
In article <1709@crash.CTS.COM>, bblue@crash.CTS.COM (Bill Blue) writes: >In my view, the big culprit that kills the 'hardware store' variety >cables is the varying time of arrival of different frequencies at the >other end of the cable due to skin effect propagation and other factors. >This simply can not be made up for, or controlled by simply paralleling >average cables together. While they'll have a low DC resistance, and >will allow good control (damping) of the speakers (assuming the amp has >good control in the first place), they will also have a very confused >representation of inner detail. They most certainly will not pass the >test on any aware audiophile's ears. Okay, to put the "differences in arrival time" argument to rest, *permanently*: Let us assume that we have a cable which is *extremely* dispersive. At 20 Hz, signals propogate at .6c (velocity factor of .6); on the other hand, at 20 KHz, they propagate at .4c. (Typical variations in a *real* cable over much larger ranges might be a few percent.) Assume for a moment that our cable has: 1.) Insignificant non-linear effects (not too unlikely), and 2.) A ten-meter length. What happens to a mix of signals from 20 Hz to 20 KHz, going from one end to the other? The 20 Hz signals move off at .6 of the speed of light. They cover the ten meters in 5.56e-8 seconds, or 56 nanoseconds. The 20 KHz signals arrive more slowly; they take 8.33e-8 seconds, or 83 nanoseconds, to arrive. Thus, they get to the speaker 28 nanoseconds later. This 28 nanosecond delay is about one two-thousandth of a cycle time at 20 KHz, or about two-tenths of a degree of phase delay at the *maximum* frequency; it will be much less at the frequencies where phase perception is important. Is there *anyone* who can hear such a phase delay? I doubt it. Note that dispersion in any *real* cable is going to be less by orders of magnitude, and you'll see how ridiculous this discussion about cables is. Dispersion is simply not a factor; resistance, on the other hand, affects the damping of the speaker by the amplifier, and thus has a *large* effect on sound quality. Skin effect can be dealt with by using flat conductors or Litz wire, or (again) *several parallel strands*. Followups to rec.audio.technobabbling; keep this out of sci.*. -- The above are the official opinions and figures of Robust Software, Inc. HASA, "A" division. Go ahead, flame. I bought Dow stock! Russ Cage, Robust Software Inc. ihnp4!itivax![m-net!rsi,crlt!russ]
grelling@mmm.UUCP (09/16/87)
AAARGH! I can't stand it anymore!!! I don't care about Mercury filled speaker wire! In fact, I never cared about mercury filled speaker wire! Please take sci.electronics and sci.physics out of the Newsgroups: header. Continue this rediculous discussion in rec.audio. I, and many others, would be forever in your debt! -- Kevin ------------------------------------------------------------------------- | Kevin P. Grelling Software & Electronics | | Resource Center -- 3M | | Disclaimer? I ain't got no disclaimer... Minneapolis/St. Paul, MN | | I don't need no !#%&%#! disclaimer! | | | | EMail: ...ihnp4!mmm!grelling Ph: (612)736-9272 | -------------------------------------------------------------------------
jj@alice.UUCP (09/16/87)
> = Maraldo on double blind testing... The numbers in parenthises are mine, and refer to comments below. > I do not feel that a simple double-blind test can report more accurate > data than an extended listening test. (1) For me, a double-blind test must > be rigorous, extended, and thorough; that is, there must be a large > number of people involved in the evaluation(2), and the test procedure > must be overseen by at least one member of a group of potentially biased > individules(3) (one audio engineer(4), physicist(5), golden ea(6), and stereo > salesman(7)). As each procedure is concluded, the overseeres must > unanimously agree that the procedure was unbiased before enumerating > the resultsa(8). The listening environment must differ between anechoic and > very 'alive'(9), with each group listening in the different situations; > one listening environment does not suffice. (1) You say "feel", but you do not address the many published references that assert you are completely incorrect. Certainly any test must be done in an unbiased manner, and a careful and thorough description of the test conditions should be in the test report, to show beyond any doubt what the test did, and what the test did not, control. (2) There are simple statistical tests for "how many is enough", and good tests report on their statistical significance as a matter of course. (3) It's not clear what having biased individuals "oversee" a test amounts to. If it's censorship of something that, for example, audio salesmen don't want known (the relationship between small loudness differences and 'quality', for example), then you'll get your way, I'm sure. You say "individuals", you then proceed to name: (4) audio engineer - Perhaps reasonable, certainly the equipment must be working correctly, and all equipment in a subjective test should be periodically verified. Perhaps the engineer will also have some knowledge of what the test is about, if so, the bias must be deliberately EXcluded. (5) physicist - I don't know why you say this. Perhaps you mean acoustician, psycho-acoustician, physiological acoustician, or somethiung like that, but what a particle physicist, for example, would do is beyond me. If you mean something more specialized, say it, after all, you appear to be attempting a concise requirements document. (6) Golden ear - Say what? Define "golden ear". If you mean people who appear to have very good hearing, and can detect differences that other people usually can't, I'd rather have them IN the test. I'd prefer to have one or two try out the equipment beforehand, to ensure correct operation, but what's the POINT of having a non-expert verify the experimental design and operation. (7) Stereo salesman. - This is silly, ridiculous, and downright offensive. While there ARE good stereo salesmen, most stereo salesmen (or women, or critters) are simply out to make a buck. Those in "high-end" stores are very prone to flights of superstition, and most insist that "double blind tests are stupid", hence one such individual would never "pass" a double-blind test. Ever. Perhaps that's your hidden agenda? (not a number, because you left out the important person) - An expert in subjective testing, usually a psychologist or acoustician with extensive experience in subjective testing, test design, test administration, and what-have-you. THIS is it MOST important thing to have oversee a test, and if possible, run it. The fact that you don't even mention it speaks very poorly of your attempted defination of a proper subjective test. (8) Why? You should have your "oversight" folks ensure that the test is working correctly, and indeed tests what it attempts to test, as much as that can be shown. That much is commonly done in some circles, I fear that audio testing often isn't one of them. (9) Now, then, this is just plain, ordinary stupid, unless what you're testing is the effects of listening environments on whatever it is that your subjects are supposed to detect. If you're NOT trying to test that effect, then one, perhaps, might want to try to isolate the subject from these confusing and interfering influences, and try to lower the noise-level of the testing process. If you're trying to isolate the differences in (for example) low-level cables, surely you don't want to mask the effects with the room-induced frequency shaping, auditory masking due to reflections and diffraction, energy-storage effects of the room that provide very-long-term self-interaction of a signal, and so on, do you? All those effects are shown, in careful tests, to reduce the sensitivity of a subject to make a RELIABLE decision. I'm NOT going to post the whole damned bibliography for this AGAIN, damnit. -- TEDDY BEARS HAVE *GREEN* EYES! "...Farewell even to our Scottish name, so ..." (ihnp4;allegra;research)!alice!jj Copyright JJ 1987. All rights to mail reserved, USENET redistribution otherwise granted to those who allow free redistritution.
mitch@stride1.UUCP (Thomas P. Mitchell) (09/16/87)
In article <2166@sigi.Colorado.EDU> heuring@boulder.Colorado.EDU (Vincent Heuring) writes: >In article <3816@watdcsu.waterloo.edu> bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: >> >> I just made a set of 2m long 5mm in diameter mercury filled cables with > >I can see the review by Anthony Cordesman now: > > "This wire lends a liquid transparency to strings. The fluid quality > of horns has to be heard to be believed. There is a silvery > quality to the brass, with no sign of the hard-edged, coppery > sound normally associated with speaker cable... And later as Anthony is slowly poisoned by the Hg vapor from an undetected leak the review flows into a dialogue reminiscent of Edgar Allan Poe. Perhaps there are those on the net who can tell us the name of the famous author who had his study painted a wonderful Cinnabar red in his last years. Cinnabar is a natural mineral, HgS. Mercury is bad stuff!!!! If you wish to live long and prosper. Do not play with that stuff!! Bletch gag :-( borf gorp etc. Thomas P. Mitchell (mitch@stride1.Stride.COM) Phone: (702) 322-6868 TWX: 910-395-6073 MicroSage Computer Systems Inc. a Division of Stride Micro. Opinions expressed are probably mine.
sukenick@ccnysci.UUCP (09/17/87)
Experimenting with mercury in your home <for a `better sound' in speaker wire, yet> is like using lead to sweeten your wine and using powered arsenic to clean your walls. It wouldn't kill you right away, but its effects are cumulative, possibly damaging, and there are better ways to sweeten drinks or clean walls. >As an example of a horror story, some people I know had a small bottle >[of mercury, there was a fire, the house was condemned dur to the mercury] Thats probably all it is, a horror story ... unless: Everyone, quick! throw out your thermometers and barometers or else your house will be condemned too if hit by fire! :-) >Also, a book I read once had someone place a single drop of mercury in >the shoe of someone that they wanted to get rid of. In three months >the person was dead, and the crime was not solved. So, the world population of dentists and electrochemists should have died (and not just gone mad :-) many years ago... >My advice to you is to not use the mercury filled cables no matter >how good the sound quality is and not to permit them to remain in >your home. I agree. Mercury IS a pretty bad substance to handle, and difficult or impossible to get rid of completely if spilled (or the vapors when exposed to air). As with many heavy metals, the body does not have a good mechanism for ridding itself of it. Many of its organic compounds are toxic or cancerous. But someone is already using it so they should know this: The standard procedure for handling a spill (or if it is exposed to the air) is after getting up the visible pieces (shovel it; and use a shiny copper wire to pick it up (stranded is best) - the mercury will form an amalgam on the wire), spread powered sulfur on and beyond the area that the spill took place (those little drops can really travel - once spilled, its everywhere!) The fumes from the sulfur will also help take care of some of the mercury vapors. Clean up the powder and repeat a few times. remember - this will get much of the spill, but not necessarily all. ------ What a pretty sight! While the chemists are turning colors; the physicists are glowing in the dark!
al@gtx.UUCP (09/17/87)
bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes
->
-> I do not feel that a simple double-blind test can report more accurate
-> data than an extended listening test. For me, a double-blind test must
-> be rigorous, extended, and thorough; that is, there must be a large
-> number of people involved in the evaluation, and the test procedure
-> ... If I hear a difference between signal cable, you
-> can not argue that I do not hear that difference....
When you say you "hear a difference between signal cable", I certainly
hope you mean that you have a friend connect the cables, without
telling you which ones you are listening to. You don't have to do a
production number with a cast of thousands, just use common sense. This
is what you meant by a "listening test", isn't it? This is effectively
"double-blind" as long as your friend doesn't talk to you during the
test.
Look first for the beam in the eye of the experimental procedure,
before looking for the mote in the eye of the audio signal. (Note:
this metaphor is probably a result of the fact that we used to play
with Mercury, coat dimes with it, roll it around on our tables, etc. in
high school Chemistry lab.)
----------------------------------------------------------------------
| Alan Filipski, GTX Corp, 2501 W. Dunlap, Phoenix, Arizona 85021, USA |
| {ihnp4,cbosgd,decvax,hplabs,seismo}!sun!sunburn!gtx!al (602)870-1696 |
----------------------------------------------------------------------
"And laughter unquenchable arose among the blessed gods" -- Homercarl@aoa.UUCP (09/17/87)
In article <750@mas1.UUCP> ejm@mas1.UUCP (Eric Mattern) writes: >> >> I'm an audiophile and I hate CD's and I'm >> damn proud of it! So there! NAA! >> >> Brett L Maraldo > > I'm with you !!! > OK, my permittable ( :==>) one flame per month: I'm an "audiophile" and a high quality amateur musician and I say: FOOOOOEEEEY on you snobby slobs!!!!!!!! CDs sound as good as the master recording allows and dont wear out. So, for those of us who refuse to spend more than $1k for speakers or more than $250 for cartridges (phono), CDs are gobs better than LPs. SO THERE. AS THIS is a flame, no responses are permitted. -- Alix's Dad ( Carl Witthoft @ Adaptive Optics Associates) {ima,harvard}!bbn!aoa!carl {wjh12,mit-vax}!biomed!aoa!carl 54 CambridgePark Drive, Cambridge,MA 02140 617-864-0201 " If you're not afraid you're going to die on your windsurfer, the wind isn't high enough to have a good time."
heuring@boulder.Colorado.EDU (Vincent Heuring) (09/18/87)
In article <750@mas1.UUCP> ejm@mas1.UUCP (Eric Mattern) writes: >> I'm an audiophile and I hate CD's and I'm >> damn proud of it! So there! NAA! >> Brett L Maraldo > I'm with you !!! > rick > Right! F'n. A, man. Enough of these bullshit CD's. Everybody knows they leave holes in the music. Alvin Gold said so right there in Stereophile. Caused by the digital sampling. Any fool can hear the difference. Leave us to our 33-1/3 rpm perfection. Why, we'll take the sonic print-through, pops, clicks, poor s/n ratios, and bad dynamic range any time. Hell of a lot better than those little wimpo silver disks with the rainbow on 'em. I want my vinyl, my vacuum tubes, my diamond stylus, and my 450 pound turntable. Fuck rationality. Goddamn technocrat hippie freaks. Get a Horse!
bmaraldo@watdcsu.UUCP (09/18/87)
In article <1067@mtunb.ATT.COM> dmt@mtunb.UUCP (Dave Tutelman) writes: > If I understand what the "golden-ear phenomeneon" is, it isn't at > all objective. It's totally subjective. Maybe you could explain > what you mean, and disabuse me of this opinion. Your right, I meant subjective. Sorry. BLM -- -------- Unit 36 Research --------- "Alien Technology Today" ------------------------------------------- bmaraldo@watdcsu
drw@culdev1.UUCP (Dale Worley) (09/18/87)
koko@uthub.toronto.edu (M. Kokodyniak) writes: > If they were available on the market, I wouldn't buy mercury cables because > they are not worth the expense and because any mercury leakage would be > hazardous, and would require special equipment for cleanup. My high-school chem teacher told me one trick for dealing with spilled mercury: Scatter sulfur dust. Apparently, sulfur will react with the mercury vapor from the tiny drops of mercury that get caught in the cracks, etc. Dale
drw@culdev1.UUCP (Dale Worley) (09/18/87)
bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > What you have said here is simply a matter of opinion. I > can hear differences between audio cables. I can not report and > differences under controlled double-blind tests because I have never > taken part in one. I am not attempting to convince you that I can hear > a difference, but what I hear is good enough for me. I once worked in the engineering section of Bose Corp. (as a computer programmer). Some of the engineers there once discussed the fact that certain audio effects that everybody agreed were real (not placing speakers directly against the wall makes them sound better) could not be reproduced in blindfold experiments. Conclusion: "What one hears" is only a very poor reflection of "what's really out there". The enterprise of science has spent an enormous amount of effort in "learning how to measure", so that the myriad factors that color our perceptions can be avoided. The ability of our expectations and culture to determine what we see is enormous. After all, how could someone believe something as rediculous as the religious beliefs that *other people* believe? But aren't we all very fixed in our religious beliefs, and don't they come from observation of just about the same data? Dale
drw@culdev1.UUCP (Dale Worley) (09/18/87)
larry@kitty.UUCP (Larry Lippman) writes: > Actually, you have touched upon a grain of truth. Mercury-filled > tubing - expecially of the silicone rubber variety - makes a simple, but > effective position transducer. As the cable is stretched, both the length > of the mercury column increases and its diameter decreases in the affected > area; this results in greater electrical resistance as the tubing is > stretched. Though, since the resistance of the cables is around 0.1 ohm, and the speakers are around 4 ohms (they used to be, has this changed? and is this DC or AC resistance?), the bulk of the voltage drop is across the speakers. Or is even such a small effect (if it has an audio period) audible? Dale
drw@culdev1.UUCP (Dale Worley) (09/18/87)
Just to shed more heat on the subject, I'm going to challenge what seems to be a very unlikely statement. I only read this on sci.physics and I've removed it from the newsgroups, so I (hopefully) won't have to read zillions more messages of audiophile nonsense... bmaraldo@watdcsu.waterloo.edu (Commander Brett Maraldo) writes: > And how about the crystal structure? THERE ISN'T ONE in mercury! It is > know that linear crystal (lon crytal) configuration wire propagates a > signal with more linear accuracy. In the mercury cables there is now > crystal stucture and this is material dependent. "It is known"? Has this been confirmed in a laboratory setting? (I mean, in a laboratory not owned by a company selling such things or a magazine accepting ads for such things.) Or is this another "I can HEAR the difference" argument? "It isn't going to sci.physics because there isn't any science in it..." Dale
agn@unh.cs.cmu.edu (Andreas Nowatzyk) (09/18/87)
The phenomenon of dispersion in cables has been brought up to explain alleged differences in speaker cables. Let's see: dispersion is a frequency dependent change in the cable delay that is observed in a transmission line. The delay of a transmission line is roughly: Tpd = 1.017 * sqrt (0.475 * e + 0.67) [ns/ft] where "e" is the relative dielectric constant of the insulator, which in turn is dependent on the frequency. Let's assume a really bad insulator (you won't be able to find one like that) that has e(dc)=5 and e(20Khz)=2.5. So this insulator behaves like PVC at DC and like Teflon at 20Khz. Assuming 30 ft cable legnth, we get: Tpd(DC) = 53 ns, Tpd(20Khz) = 42 ns. That cable must sound awfull: the high frequencies arrive 11ns earlier!! :-) This is a phase error of 0.08 degrees. Audiophile: Someone who can hear the color of the front panel. -- -- Andreas Nowatzyk (DC5ZV) Carnegie-Mellon University Arpa-net: agn@unh.cs.cmu.edu Computer Science Department Usenet: ...!seismo!unh.cs.cmu.edu!agn
pac@munsell.UUCP (Paul Czarnecki) (09/19/87)
In article <1709@crash.CTS.COM> bblue@crash.CTS.COM (Bill Blue) writes: >In my view, the big culprit that kills the 'hardware store' variety >cables is the varying time of arrival of different frequencies at the >other end of the cable due to skin effect propagation and other factors. >I make these statements from personal experience with all sorts of >cables. Take *any* heavy, stranded, copper cable -- anything from 12/2 >or 10/2 electrical cable to the 12 guage (standard) Monster cable >(reasonably cheap at ~$.50/foot) and you'll get a similar sound. The >number of strands and thickness of each will provide subtle differences, >but all in all they're about the same. Why must you use stranded cable? I realize the mechanical difficulties in using a solid core cable but are there any electrical problems? I used 12 gauge solid core for many years. It was the cheapest stuff I could find. (It was UL listed for underground use also. :-) Just curious... pZ -- Paul Czarnecki -- My newsfeed's in Esperanto {{harvard,ll-xn}!adelie,{decvax,allegra,talcott}!encore}!munsell!pz
larry@kitty.UUCP (Larry Lippman) (09/19/87)
In article <1538@culdev1.UUCP>, drw@culdev1.UUCP (Dale Worley) writes: > > Actually, you have touched upon a grain of truth. Mercury-filled > > tubing - expecially of the silicone rubber variety - makes a simple, but > > effective position transducer. As the cable is stretched, both the length > > of the mercury column increases and its diameter decreases in the affected > > area; this results in greater electrical resistance as the tubing is > > stretched. > > Though, since the resistance of the cables is around 0.1 ohm, and the > speakers are around 4 ohms (they used to be, has this changed? and is > this DC or AC resistance?), the bulk of the voltage drop is across the > speakers. Or is even such a small effect (if it has an audio period) > audible? Mercury-filled tubing forms a simple one-axis/one-element strain gage transducer. Its gage factor (strain sensitivity) is pretty small due to the comparatively small resistivity of mercury. Gage factor = (delta_R/R)/(delta_L/L) where (delta_R/R) = resistance change, and (delta_L/L) = strain. Is the strain gage effect audible? To normal, objective people: hell, no! To "Golden Ears": hell, yes! :-) <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|seismo|utzoo}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"
jwl@ernie.Berkeley.EDU (James Wilbur Lewis) (09/21/87)
In article <630@ccnysci.UUCP> sukenick@ccnysci.UUCP (George Sukenick) writes:
- The standard procedure for handling
-a spill (or if it is exposed to the air) is after getting up the visible
-pieces (shovel it; and use a shiny copper wire to pick it up (stranded is best)
-- the mercury will form an amalgam on the wire), spread powered sulfur on and
-beyond the area that the spill took place (those little drops can really travel
-- once spilled, its everywhere!) The fumes from the sulfur will also help take
-care of some of the mercury vapors. Clean up the powder and repeat a few
-times.
-remember - this will get much of the spill, but not necessarily all.
And when you're finished cleaning up and wondering how to dispose of it,
please remember that you're dealing with toxic waste. Your friendly
neighborhood landfill (and users of any nearby water supplies) would probably
not appreciate anything tainted with mercury.
-- Jim Lewis
U.C. Berkeleymike@ivory.SanDiego.NCR.COM (Michael Lodman) (09/21/87)
In article <630@ccnysci.UUCP> sukenick@ccnysci.UUCP (George Sukenick) writes: >>As an example of a horror story, some people I know had a small bottle >>[of mercury, there was a fire, the house was condemned dur to the mercury] > >Thats probably all it is, a horror story ... unless: >Everyone, quick! throw out your thermometers and barometers or else >your house will be condemned too if hit by fire! :-) No, this really did happen. Mercury is sold in plastic bottles, in case you didn't know, and it tends to melt at a much lower temperature than the glass they use in thermometers etc. Also, there really isn't much mercury in a thermometer, and this was a 2 1/2 pound bottle of the straight metal. Please be careful of accusing someone of having an overly vivid imagination! -- Michael Lodman (619) 485-3335 Advanced Development NCR Corporation E&M San Diego mike.lodman@ivory.SanDiego.NCR.COM {sdcsvax,cbatt,dcdwest,nosc.ARPA,ihnp4}!ncr-sd!ivory!lodman When you die, if you've been very, very good, you'll go to ... Montana.
jeffw@midas.TEK.COM (Jeff Winslow) (09/22/87)
I even put a little real physics in... In article <1741@crash.CTS.COM> bblue@crash.CTS.COM (Bill Blue) writes: >In article <1222@pinney.munsell.UUCP> pac@pinney.UUCP (Paul Czarnecki) writes: >> >>Why must you use stranded cable? I realize the mechanical >>difficulties in using a solid core cable but are there any electrical >>problems? >I believe the big problem with large gauge solid conductor cable is >skin effect related. The diameter is simply too large for reasonable >handling of high frequencies... Maybe. But remember that, unless the strands are insulated from each other (as in Litz wire) the current distribution in a stranded conductor will be very similar to that in the same sized solid conductor. And even in Litz wire, proximity effect will tend to push the current to the surface of the wire to some degree. I'm not sure what you mean by "too large for reasonable handling of high frequencies". The larger the wire, the more surface it has to conduct HF current, and the smaller the impedance at *any* audible frequency as compared to the speaker impedance. The larger the better, skin effect or no (assuming you have plenty of room for cables!). I'd be curious to know how you routed the cables. Stranded wire, being more flexible than the same diameter solid wire, would make it easier to minimize the loop area (hence inductance) in the cable. This seems more likely the cause of the problem than any magic involving solid and uninsulated stranded, to me. (Of course, I wasn't there.) >It always has struck me rather funny when engineer types (not recording >but electronics) go into long dissertations on how we audiophiles can't >be hearing differences in so-and-so cables, or capacitors, or resistors, >or (gasp) power supplies, and spout streams of numbers and other >specifications that 'prove' such things don't apply to audio >frequencies. Years later though, when it becomes generally accepted >that such things do in fact make audible differences, the same engineers >not only agree that these things do make a difference, but can spout >reasons why. In the meantime, you have forgotten about the things that you *thought* made a difference at one time, and have turned out, in fact, to make no difference, for the reasons given by the electronics engineers. Everybody remembers the exceptions - the times when the experts were wrong. Who remembers when the experts were right? Shucks, that's not news. Wonder why? Jeff Winslow "Hit him again!!!!" - Elektra/Strauss
drw@culdev1.UUCP (Dale Worley) (09/22/87)
russ@crlt.UUCP (Russ Cage) writes: > Skin > effect can be dealt with by using flat conductors or Litz wire, > or (again) *several parallel strands*. As long as we're debunking things, note that the "skin effect" (if it's the skin effect I know and love) involves a "penetration depth" measured in fractions of a wavelength. Since the wavelength at 20kHz is ... hmmm ... 5 kilometers, it doesn't seem too significant. Humor Dept.: I remember hearing about a great audiophile discovery (I'm not making this up!): The electricity isn't conducted *in* the wire itself, but in a cylindrical shell *around* the wire. Of course, this showed that to get *really good sound* you had to buy very special (and very expensive) cables (from the company that made this discovery). Dale
brianr@tekig4.TEK.COM (Brian Rhodefer) (09/23/87)
The analog guru at the next desk assures me that, with today's amplifiers, the dominant influence on the transient/frequency response of the amplifier/cable/speaker electrical-to-pressure transducing system is the series resistance of the speaker circuit. He mentioned this by way of pointing out how profitless it is to worry about small fractions of an ohm's worth of cable resistance in the face of (typically) 4 ohms of intrinsic speaker coil resistance. If this is so, why wouldn't it be a good idea to arrange for amplifier outputs to look like current sources rather than voltage sources? It ought to be quite simple to implement a current-sensing feedback system so that the output stages faithfully translate audio program voltage into speaker current, within some reasonable (like +/- 60V or so) compliance. Obviously, this would make the resistance of the speakers, as well as the comparatively trivial cable effects, "drop out", by pulling these imperfections inside the amplifier output stages' feedback loops. It wouldn't be a total loss for the audiophiles, though: they could still quibble about shunt losses due to distributed capacitance effects in their cables - why, I'll bet they'd ammount to NANOFARADS! Moreover, forces generated by currents passing through magnetic fields tend to be simple products of the currents and field strengths. A speaker's voice coil, then, should then have a linear current-to-force transfer function. As I'd expect voice-coil force to translate directly into induced air pressure, it seems to me that a current-mode output signal would also be desirable due to a more nearly linear transduction of audio voltage signals into air pressure signals. Am I mistaken in thinking that this is exactly the kind of transducer that an amplifier/speaker system ought to be? There must be some reason, though, for amplifier outputs to be made the way they are; could someone kindly explain why? An Inquiring mind which may not really want to know, but sure loves to ask dumb questions, Brian Rhodefer
jeffw@midas.TEK.COM (Jeff Winslow) (09/23/87)
Let's be careful, debunkers... In article <1549@culdev1.UUCP> drw@culdev1.UUCP (Dale Worley) writes: >As long as we're debunking things, note that the "skin effect" (if >it's the skin effect I know and love) involves a "penetration depth" >measured in fractions of a wavelength. Since the wavelength at 20kHz >is ... hmmm ... 5 kilometers, it doesn't seem too significant. According to a paper I have in front of me, skin depth at 1Ghz in copper is .0002 cm, which is a *lot* less than a wavelength. And it is a fact that windings in power transformers for switching power supplies running at 20kHz must be oversized due both to skin effect and proximity effect. I've designed several such supplies, and have worked closely with the magnetics experts who designed the transformers. >Humor Dept.: I remember hearing about a great audiophile discovery >(I'm not making this up!): The electricity isn't conducted *in* the >wire itself, but in a cylindrical shell *around* the wire. Of course, >this showed that to get *really good sound* you had to buy very >special (and very expensive) cables (from the company that made this >discovery). Find a fields and waves book and look up Poynting's vector. Not that it justifies this particular company's silliness, but it's probably the source of their "justification". Jeff Winslow "Hit him again!!!" - Elektra/Strauss
jong@hounx.UUCP (J.LEE) (09/23/87)
In article <1549@culdev1.UUCP>, drw@culdev1.UUCP (Dale Worley) writes: > As long as we're debunking things, note that the "skin effect" (if > it's the skin effect I know and love) involves a "penetration depth" > measured in fractions of a wavelength. Since the wavelength at 20kHz > is ... hmmm ... 5 kilometers, it doesn't seem too significant. > The wave length of 20 K Hz tone is 5 kilometers??? Nah. The velocity of sound is about 300 m/s at room temperature. This makes the wave length of 20 KHz sinusoid 0.015m (=300/20k) or 1.5 cm (~0.6 in). Granted, this is still much larger than most audio conductor diameter. As to whether this causes audible phase dispersion or not, I am still not sure. I am still experimenting... . Regards. J Lee, Bell Labs, Holmdel, NJ.
rdp@teddy.UUCP (Richard D. Pierce) (09/23/87)
In article <1953@tekig4.TEK.COM> brianr@tekig4.UUCP (Brian Rhodefer) writes: >The analog guru at the next desk assures me that, with today's >amplifiers, the dominant influence on the transient/frequency >response of the amplifier/cable/speaker electrical-to-pressure >transducing system is the series resistance of the speaker circuit. >He mentioned this by way of pointing out how profitless it is to >worry about small fractions of an ohm's worth of cable resistance >in the face of (typically) 4 ohms of intrinsic speaker coil resistance. > In part, your analog guru friend is quite correct, in that the series electrical resistance in the voice coil is the dominant electrical loss, but, as it turns out, it is but one of many total losses in the entire system, and is not the dominant influence on the transient/frequency response of the entire system. > >[A description of what amounts to an active loudspeaker feedback system > that includes the effects of cable interface problems....] > >Moreover, forces generated by currents passing through magnetic >fields tend to be simple products of the currents and field strengths. >A speaker's voice coil, then, should then have a linear current-to-force >transfer function. As I'd expect voice-coil force to translate directly >into induced air pressure, it seems to me that a current-mode output >signal would also be desirable due to a more nearly linear transduction >of audio voltage signals into air pressure signals. > Unfortunately for your theory, voice coil force DOES NOT translate directly into induced air pressure. At its very best, voice coil force (and, hence, voice coil current) translates into volumn velocity. The effective sound pressure level is a complex function of frequency, due to the great variations in sounf pressure level with frequency. (For direct radiator loudspeakers, the radiation impedance goes roughly as the square of the frequency while the driver is operating in its piston region. Below mechanical resonance, the speaker is unable to maintain the constant volume velocity, which is why they roll off. ABove the piston band, the radiation impednace is a complex and only partially understood consequence of driver size, shape, baffle loading, diffraction, etc., etc.) There is also the issue that the force generated by the voice coil in practical drivers is not a linear function of voice coil current, even ignoring frequency-dependent effects. This is due to non-linearities in the mechanical suspension of the driver, non-linearities in the magnetic field, etc. >Am I mistaken in thinking that this is exactly the kind of transducer >that an amplifier/speaker system ought to be? > >There must be some reason, though, for amplifier outputs to be made >the way they are; could someone kindly explain why? > AMplifiers are designed as voltage sources, because the vast majority of loudspeakers have a varying impedance, yet, over the limited range of operation, produce constant sound pressure for constant applied voltage. At low frequencies, at and around mechanical resonance, the effective electrical impedance is much higher than the nominal impedance. (I am, as we speak, looking at the impedance curve for a 10" woofer that has an impedance of 83 ohms at resonance, compared to a DC resistance of 3.2 ohms, and a nominal impedance of 4 ohms. Its output, given a constant applied voltage, at resonance is but 3 dB lower than that in the midband, because its in an enclosure that gives it a Q of .707. Note that the current flowing through the voice coil at that point is 1/20th the current flowing through it in the midband, some 26 dB less, yet the "efficiency" is the same.) Dick Pierce
rdp@teddy.UUCP (Richard D. Pierce) (09/23/87)
In article <1130@hounx.UUCP> jong@hounx.UUCP (J.LEE) writes: > >The wave length of 20 K Hz tone is 5 kilometers??? >Nah. The velocity of sound is about 300 m/s at room temperature. >This makes the wave length of 20 KHz sinusoid 0.015m (=300/20k) >or 1.5 cm (~0.6 in). Granted, this is still much larger than >most audio conductor diameter. As to whether this causes audible >phase dispersion or not, I am still not sure. I am still >experimenting... . > Jesus f****ing Christ, boys and girls, could we PULLEEEEZE make sure we are all talking about the same things, just maybe, huh? Mr. Lee, you are absolutely correct, the velocity of sound is indeed about 300 m/sec (342 m/sec at STP, to be a bit more precise), but that has absolutely not one wit to do with skin effect. Common, the original writer was making a statement about electrical propogation in a cable, and what that has to do with acoustical propogation is simple to understand: nothing! Dick Pierce
larry@kitty.UUCP (Larry Lippman) (09/23/87)
In article <1130@hounx.UUCP>, jong@hounx.UUCP (J.LEE) writes: > > As long as we're debunking things, note that the "skin effect" (if > > it's the skin effect I know and love) involves a "penetration depth" > > measured in fractions of a wavelength. Since the wavelength at 20kHz > > is ... hmmm ... 5 kilometers, it doesn't seem too significant. > > The wave length of 20 K Hz tone is 5 kilometers??? > Nah. The velocity of sound is about 300 m/s at room temperature. > This makes the wave length of 20 KHz sinusoid 0.015m (=300/20k) > or 1.5 cm (~0.6 in). Granted, this is still much larger than > most audio conductor diameter. As to whether this causes audible > phase dispersion or not, I am still not sure. I am still experimenting... Uh, we are talking about ELECTRICAL propagation of signals in the 20 kHz frequency range. So we are talking about velocities around the speed of light, which is roughly 300,000,000 meters/sec. So the electrical wavelength of a 20 kHz signal is approximately 15 km long. SOUND propagates at roughly 300 meters/sec IN AIR at room temperature. We are not talking about sound propagation in copper wire! <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|seismo|utzoo}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"
ornitz@kodak.UUCP (barry ornitz) (09/24/87)
In article <1130@hounx.UUCP> jong@hounx.UUCP (J.LEE) writes: >In article <1549@culdev1.UUCP>, drw@culdev1.UUCP (Dale Worley) writes: >> As long as we're debunking things, note that the "skin effect" (if >> it's the skin effect I know and love) involves a "penetration depth" >> measured in fractions of a wavelength. Since the wavelength at 20kHz >> is ... hmmm ... 5 kilometers, it doesn't seem too significant. >> > >The wave length of 20 K Hz tone is 5 kilometers??? >Nah. The velocity of sound is about 300 m/s at room temperature. >This makes the wave length of 20 KHz sinusoid 0.015m (=300/20k) >or 1.5 cm (~0.6 in). Granted, this is still much larger than >most audio conductor diameter. As to whether this causes audible >phase dispersion or not, I am still not sure. I am still >experimenting... . > >Regards. J Lee, Bell Labs, Holmdel, NJ. Just what goes on here? Certainly the readers of wreck.audio have more sense than this. We are talking electrical wavelength here, not acoustical wavelength. The electrical wavelength is the speed of light divided by the frequency multiplied by the velocity factor of the cable. The velocity factor is the reciprocal of the square root of the dielectric constant of the wire insulation. For polyethylene, as an example, the velocity factor is about 0.66 and the wavelength at 20 KHz is about 32,500 feet. Just what does acoustical wavelength have to do with speaker wire? Maybe since the resistance of the mercury filled wire is mechanical stress dependent, acoustic waves impinging on the cable could cause resistance changes leading to a form of acoustic (and electrical) cross modulation which is certainly nonlinear and hence a no-no to audio phreaks. Besides the sonic velocity of a material is density related; it is much higher in copper than in air. BTW - I won't be sorry to see the Commander disappear but I will miss Pierce. ----------------- | ___ ________ | | | / / | | Dr. Barry L. Ornitz UUCP:...!rochester!kodak!ornitz | | / / | | Eastman Kodak Company | |< < K O D A K| | Eastman Chemicals Division Research Laboratories | | \ \ | | P. O. Box 1972 | |__\ \________| | Kingsport, TN 37662 615/229-4904 | | -----------------
drw@culdev1.UUCP (Dale Worley) (09/24/87)
jong@hounx.UUCP (J.LEE) writes: > The wave length of 20 K Hz tone is 5 kilometers??? > Nah. The velocity of sound is about 300 m/s at room temperature. > This makes the wave length of 20 KHz sinusoid 0.015m (=300/20k) > or 1.5 cm (~0.6 in). I meant, the electromagnetic wavelength. Dale
yoon@gt-cmmsr.GATECH.EDU (Wan Yoon) (09/24/87)
In article <1130@hounx.UUCP> jong@hounx.UUCP (J.LEE) writes: > >The wave length of 20 K Hz tone is 5 kilometers??? >Nah. The velocity of sound is about 300 m/s at room temperature. >This makes the wave length of 20 KHz sinusoid 0.015m (=300/20k) >or 1.5 cm (~0.6 in). Wow, you are mentioning the skin effect of AIR, aren't you? > >Regards. J Lee, Bell Labs, Holmdel, NJ. -- Wan Yoon UUCP: yoon@gt-cmmsr.UUCP ...!{akgua,allegra,hplabs,ihnp4,seismo,ulysses}!gatech!gt-cmmsr!yoon INTERNET: yoon@cmmsr.gatech.edu
lew@ihlpa.UUCP (09/25/87)
In article <2032@kitty.UUCP>, larry@kitty.UUCP (Larry Lippman) writes: > Uh, we are talking about ELECTRICAL propagation of signals in > the 20 kHz frequency range. So we are talking about velocities around > the speed of light, which is roughly 300,000,000 meters/sec. So the > electrical wavelength of a 20 kHz signal is approximately 15 km long. > SOUND propagates at roughly 300 meters/sec IN AIR at room > temperature. We are not talking about sound propagation in copper wire! > Yes. And this is also why we don't hear a doppler shift of the audio signal on a radio carrier when riding in a car. We only move a small fraction of the audio wavelength ( on the carrier ) during one audio cycle. That's one way to think of it, anyway. Of course, this fraction is independent of the wavelength and depends only on the speed of the car relative to the source. Lew Mammel, Jr.
cm450s02@uhccux.UUCP (jeff t. segawa) (10/04/87)
Bill Blue; I couldn't agree more with this business about tecnical specifications and subjective sound quality. I bought my first stereo based on those distortion specs. Figured that if I had an amp that only produced .008% harmonic distortion, it must be great at sound reproduction. Boy, was I ever wrong. It sounded shrill and irritating--not at all like live music I have heard. I also have a couple of CD players which have fantastic specs: almost no noise, fantastic dynamic range, etc, but I still find them (they're a couple of Magnavox players) somehow lacking when I compare them to a 'tweaked' player by PS Audio, though the specs aren't much different, Neither player, in my opinion, does as good a job at sound reproduction as a really good cassette deck running first generation master tapes, or my SOTA Sapphire turntable. Maybe the source of a lot of these "looks good on paper, sounds awful" sort of problems have a lot to do with the WAY these measurements are taken. For example, as I recall, turntable speed accuracy measurements are done by playing 1Khz test tones. Servo motor powered turntables cope with this type of material well, since tye stylus drag, and hence, the load imposed on the turntable's motor, is constant. Now get this same turntable, and try playing a real record, with it's varying degrees of modulation, on it. Hit a loud passage, and the stylus drag builds up. Platter slows down, servo tries (too late) to compensate. I had a turntable like this. With most types of top 40 music, it sounded OK. Couldn't figure out why piano music always sounded somehow off key. Naturally, the spec sheet told me that the turntable had nearly perfect speed accuracy, and it did, so long as I played 1Khz test tones. If nothing else, this incident taught me the value of trusting one's own ears. As a result, I'm not too proud to admit that my system is made up, among other things, of a Dyna PAS-3x (tube) preamp and Randall Research interconnects. Why? Simply because, tube noise and all, the system does a better job at reproducing music that most other systems I have listened to.
bks@unisoft.UUCP (Brian K. Shiratsuki) (10/05/87)
In article <899@uhccux.UUCP> cm450s02@uhccux.UUCP (jeff t. segawa) writes: >...Neither [cd ] player, in my opinion, does as good a job at sound reproduc- >tion as a really good cassette deck running first generation master tapes... what do you mean ``first generation master tapes'' on a cassette deck? who masters on cassettes, and where do you find these tapes? -- brian
rab@well.UUCP (Bob Bickford) (10/05/87)
jeff t. segawa writes:
+ Maybe the source of a lot of these
+ "looks good on paper, sounds awful" sort of problems have a lot to
+ do with the WAY these measurements are taken. For example, as I recall,
+ turntable speed accuracy measurements are done by playing 1Khz test
+ tones. Servo motor powered turntables cope with this type of material
+ well, since tye stylus drag, and hence, the load imposed on the
+ turntable's motor, is constant. Now get this same turntable, and try
+ playing a real record, with it's varying degrees of modulation, on it.
+ Hit a loud passage, and the stylus drag builds up. Platter slows down,
+ servo tries (too late) to compensate. I had a turntable like this.
+ With most types of top 40 music, it sounded OK. Couldn't figure out
+ why piano music always sounded somehow off key. Naturally, the spec
+ sheet told me that the turntable had nearly perfect speed accuracy,
+ and it did, so long as I played 1Khz test tones. If nothing else,
+ this incident taught me the value of trusting one's own ears.
<sigh> If you are able to detect *ANY* variation in the speed of *ANY*
turntable based on "stylus drag", then it's time to chuck the thing
in the trash. Run the calculations yourself if you don't believe me;
the effect of the stylus is *at least* three orders of magnitude below
normal frictional forces (bearings, etc.). Tell me you have a magnetically
levitated platter running in a vacuum chamber, and I *might* believe that
the effect of the "stylus drag" could be detected.
Try to think before you say things like that, okay? <sheesh>
Robert Bickford {hplabs, ucbvax, lll-lcc, ptsfa}!well!rabcm450s02@uhccux.UUCP (jeff t. segawa) (10/05/87)
In article <601@unisoft.UUCP> bks@unisoft.UUCP (Brian K. Shiratsuki) writes: >In article <899@uhccux.UUCP> cm450s02@uhccux.UUCP (jeff t. segawa) writes: >>...Neither [cd ] player, in my opinion, does as good a job at sound reproduc- >>tion as a really good cassette deck running first generation master tapes... > >what do you mean ``first generation master tapes'' on a cassette deck? who >masters on cassettes, and where do you find these tapes? >-- > > brian At the stereo store I use to work at, one of the guys there was into live recording, so when he had the chance, he would invite musician customers to perform (in the sound room). Recording equipment generall included a Nakamiche 550, Nakamichi BX300 and Sony SLHF900 Super Beta. (though not all at the same time). 2 or 3 Nakamichi mikes were also used (using the 550 as a simple mixing board). The advantage of having these tapes is that we knew just what the original performance was supposed to sound like so we had an idea what the recording/playback equipment was or was not reproducing faithfully. I have also done live recordings using a Nakamichi 500 and Sony SL5200 Beta Hi Fi. True, we probably would have been better off using 15 or 30 ips open reel tapes, but we didn't have access to one.
cm450s02@uhccux.UUCP (jeff t. segawa) (10/06/87)
In article <4139@well.UUCP> rab@well.UUCP (Bob Bickford) writes: ><sigh> If you are able to detect *ANY* variation in the speed of *ANY* >turntable based on "stylus drag", then it's time to chuck the thing >in the trash. Sure the stylus drag is probably small compared to other sources of friction, but aren't those other sources more or less constant, while the stylus drag is anything but? Considering how tiny some of those modulations in a typical record groove really are, I don't see why it should be so hard to belive that tiny speed variations or resonances could have an audible effect on the sound. It's a shame that I don't still have that turntable. I would've loved to let you hear it for yourself.
rees@apollo.uucp (Jim Rees) (10/06/87)
what do you mean ``first generation master tapes'' on a cassette deck? who
masters on cassettes, and where do you find these tapes?
[ I have removed sci.physics from the list ]
I have one at home. I have friends in the recording industry, and I
was at a local recording studio a few weeks ago while they were mixing
a new release. Standard practice these days seems to be recording on
a 24 (or so) track analog deck, then mixing down to digital via VCR.
The mixing board has a control track that sets up the mixer boards,
so it's very easy to replay a particular mix. You can even set up
several different mixes if you want to sacrifice the tracks.
I talked the engineer into doing a mix direct from the original tape
onto cassette for me. We used chrome tape with Dolby C. My home
cassette deck is an el-cheapo (~$120) Technics, but I have to say
that it sounds pretty good when playing this particular tape.
The point is that they had several cassette decks in the studio, and
I got the impression that they master onto cassette all the time.
Not to send the tape to the record presser, of course, but to give
the musician something to take home, or to make a demo tape, or
whatever.klm@munsell.UUCP (Kevin (my watch has a touch screen) McBride) (10/07/87)
In article <601@unisoft.UUCP> bks@unisoft.UUCP (Brian K. Shiratsuki) writes: > >what do you mean ``first generation master tapes'' on a cassette deck? who >masters on cassettes, and where do you find these tapes? > > brian Well, Bruce Springsteen recorded one of his albums in the living room of his home on a four track cassette recorder. (I think it was "The River", but don't quote me on that.) You know what? The whole album sounds like it was recorded in the living room of his home on a four track cassette recorder. Can you say "lousy dynamic range"? Can you say "tape hiss"? Can you say "It sounds like he's singing into a toilet bowl"? I thought you could. It was one of his less impressive works. (Not that ANY of his recent works could be labelled "impressive". I like the "Old" Boss.) (Donning my asbestos suit just in case.) -- Kevin McBride | "Is that a real | harvard -\ I/O Software Group | poncho, or is that | ll-xn ---adelie----> munsell!klm Eikonix - A Kodak Co. | a Sears poncho?" | decvax -v talcott -v | Billerica, MA | - Frank Zappa | allegra ------------encore
georgep@vice.TEK.COM (George Pell) (10/08/87)
Seems to me that using wire is the wrong way to go. What you need is a transmission line! Lets see... .062 dual clad G10 material, 2 oz copper, .367 wide traces. Where can I get a 1" by 15 foot pc board?????