wjm (03/16/83)
Frankly, I agree with Mark Terriblile that the use of Litz wire in the
outer conductor of a coaxial patch cord is overkill. However, the connecting
cables may be the weakest link in a high quality audio system, and in a
high - end system, the use of premium cables (running about $25-30/meter)
is probably worth it. Certainly gold plated phono plugs are worthwhile
since the conventional ones can add considerable noise through rectification
of RF due to poor contact caused by corrosion. Also, the lower capacitance
of these cables (generally due to their increased dielectric diameter)
can improve the frequency response f
some components (especially moving magnet phono cartridges). In addition,
they generally have better shielding which will reduce noise, and RF
pickup (and make your system less susceptable to CB, etc interference).
I've dissected some "standard" cables and found that the shielding was not
anywhere near 100% of the cable area.
They also have lower losses than conventional cables, due to the use of
higher conductivity (and heavier gauge) copper for the conductors.
While in theory, the use of Litz wire should improve performance by
reducing skin effect, I'd have to be convinced that it provides significant
effects at 20KHz.
While wer
While we're on the subject of patch cords, I'd like to flame about the
use of light gauge cables for speaker wire. In order to maintain the high
damping factor of a good power amp, one should use adequately heavy speaker
wire. Certainly nothing smaller than 18 gauge should ever be used, and
for runs of more than 6 or 8 feet with a high power (> 100 W/ch) amp or
4 ohm loads, 16 or 14 gauge is preferable. I don't think one has to use
these "special configuration" speaker wires, and some of them have been
known to do nasty things to finicky power amps - so if your amp has
a reputation for having problems with "difficult" loads (like electrostatic
speakers), beware. Personally, I use 14/2 SJ cord (the standard heavy-duty
black extension cord) which I bought at my friendly neighborhood hardware
store for speaker leads (even though a Hafler DH-220 can drive almost any load),
and I use the Audio Interface "Missing Link" cables (about $40/meter) for
interconnecting cables.
As for where high quality interconnections are most important, it depends on
the signal level - here is my priority list:
Most Critical - phono to preamp
preamp to any signal processors (EQ, etc)
preamp to power amp
tape deck to/from preamp
Least Critical - tuner to preamp
I put the most stress on the low level phono circuit, then circuits which
all signals must pass through, and put the tuner last due to the relatively
poor quality of most FM stations to begin with (I won't even talk about AM).
Bill Mitchell
Bell Labs - Whippany
(whuxk!wjm)emrath (03/18/83)
#R:whuxk:-15600:uiucdcs:22700009:000:902 uiucdcs!emrath Mar 17 07:26:00 1983 I also would like to flame about heavy gauge wire and special cables for power amp to speaker connections. I did some reading at the engineering library and all the technical literature that I found said a damping factor of 4 was adequate. My equipment isn't super and my ears aren't golden, but what I tried was to slap some 8 ohm power resisters in series with my speakers in order to artificially lower the damping factor. I could hear no difference in sound quality. A bigger effect was the 6dB drop in the noise floor (the speakers are 8 ohms), although this isn't important either, considering the noise levels of today's source devices (disc, tape, fm). I believe the colorations of microphones, studios, equalization and compression (provided by the recording engineer), recording/playback equipment, and especially speakers are far more significant than those caused by poor damping factor.
medin (03/25/83)
Thank goodness for Mr. Freeman's article setting straight the record on interconnection cables! Some of my Physics buddies and I were about to formulate our own response. Gold-on-tin can be somewhat corrosive (more than a gas tight tin-tin contact). Gold-on-gold is, of course, the desirable contact. As to the damping factor and speaker wires--consider this: The back-emf from the speaker is typically low-voltage but high current (.15 volts, 7 amps across a .02 ohm lab load for my Advents-- exciting signal frequency of 30 Hz---1cm excursion). The ideal amplifier output stage should exhibit a very small impedance to low-level signals (within the current ranges of the output stage). Now, resistance impedes the flow of current, not the voltage, and with the scales involved, .1 ohms of resistance in the speaker cables will have a significant effect. (I forgot to mention that the output impedance of my amp is in the range of .02 ohm for small signals of about 30Hz) I would be glad to discuss this with anyone and not take up more space. From deep in the midwest, Dave Medin
bill (03/27/83)
Speaking of rectification due to contact corrosion, does anyone have experience with Cramolin contact conditioner? There was a good article in Audio Amateur a year or two ago, but I have some unanswered questions. (Cramolin is a two part cleaner/conditioner; applied VERY lightly [a few molecules thickness] it stops contact corrosion/oxidation. One good way of applying it is dilution with TeflonTF, an industrial solvent now readily available from Radio Shack as tape head cleaner. SEE THE AUDIO AMATEUR ARTICLE AND THE CAUTIONS IN THE FOLLOWING ISSUE BEFORE MESSING WITH IT) (1) Is Cramolin useful/necessary for gold contacts? I have heard suggestions that while gold will not oxidize, other pollutants can cause a surface film with similar problems. (2) Are conventional (tinned) contacts, well-cleaned and with Cramolin applied, superior to gold? I have heard that the tinned connection is a better one if you can keep it oxidation/corrosion-free. Any information/answers/well-founded opinions will be greatly appreciated. Bill Cox bill@uwisc ...seismo!uwvax!bill
wjm@whuxl.UUCP (MITCHELL) (08/02/84)
<gulp> I agree with Phil's comments about using high quality connecting cables. They do make an audible difference in the sound (I'm using Monster Cable Interlinks (about $50/meter)). I was surprised at the improvement in sound quality when I replaced my Radio Shack "high grade (sic)" cables with the Interlinks. If you can't afford to cable your entire system this way, start with the most critical cables, namely phono to receiver or preamp, and then replace a few at a time. Regards, Bill Mitchell (whuxl!wjm)
dcm@drux3.UUCP (MengesDC) (08/03/84)
<is this line here?> I suspect that those with trained ears and a significant percentage of the rest of us can here the difference between "high" quality and "standard" connecting cables. However, I question how much is gained by their use with high end but not exotic components. The weakest link syndrome.... For example, once the connection is made to the component, what kind of wire is used inside it? Is it just vanilla shielded cable or is it OFHC (oxygen free, high conductivity - seems kinda redundant for copper) wire? For that matter, the phono jack you connected to, is it just tin plated? I have experienced problems with improper grounding at the phono jack/plug interface due to corosion of the tin plating. I suspect that the greatest benefit derived from the high end cables comes from the connectors. But, if your components have tin plated jacks (I've seen them on "highly regarded" Hafler? equipment) one must still take precautions to insure that corosion has not created a high impedance ground. I'm sure that climatic conditions are a factor in the rate of corosion (Do you folks on the east coast have more problems of this nature than those of us in say Colorado?). Would a connector with greater mechnical integrity such as a BNC provide even more improvement? How many manufacturers use high quality connectors on there equipment? High quality wire? Larry Cler ihnp4!drux2!ljc AT&T ISL Denver, Colorado
peters@cubsvax.UUCP (08/05/84)
Again, I'd like someone out there to explain to me why super-duper
connect cables should make a diff for audio applications. It would
seem as if the main thing one is doing when going from cheap to expensive
cables is lowering the resistance, both within the cable and at the
connections (if one is using gold-plated connections). I don't see
why this miniscule change in resistance should make any difference.
(This refers to line-level signals in coax cable, as did previous news
articles.)
Enough people I know have made the claim that expensive cables *do*
make a difference -- sometimes a dramatic difference is claimed -- that
I guess I believe it (though I've never tried this in my own system);
it's just that I have no idea *why* it should be so. Does anyone out
there know?
{philabs,cmcl2!rocky2}!cubsvax!peters Dr. Peter S. Shenkin
Dept of Biol. Sci.; Columbia Univ.; New York, N. Y. 10027; 212-280-5517