prk@charm.UUCP (Paul Kolodner) (05/08/85)
The recent posting about Hitachi super-pure cable really gave me a laugh. The author raves about how the number of oxide inclusions has been miraculously reduced from 50,000 to only 19 per meter! Then he/she says, roughly, that it's gratifying that scientists can finally measure things that humans can hear. Well, a scientist who suspects that this new cable is hot stuff for hearing as well as purity would have done exactly what another netter suggested a few days ago: do a double-blind test with a lot of subjects to see if humans can perceive the changes in the cable associated by its breathtaking purity, rather than advertise its electrical properties. My guess, by the way, is that they can't - more on that later. The point of my message, however, is this: It's easy to make a lot of fancy electrical measurements on inanimate objects like cables and speakers. It's a lot harder to objectively quantify what meaning, if any, those measurements have, and it's irresponsible to run around quoting numbers if they're irrelevant or meaningless. A recent case in point in my life: I went to stereo store to by speakers and cables. The salesman told me enthusiatically that I should use gold-plated banana plugs rather than nickel because they have lower electrical resistivity. Think: what effect could the difference in resistance between a micron of gold and a micron of nickel have on a circuit with an impedance of many ohms? Answer: zero. Period. Salesmen are distinguished by their willingness to uncritically and enthusiastically repeat things they don't understand. Here on the vaulted *NET*, I hope we can do better. Don't tell us the number of inclusions per meter until you tell us how many inclusions per meter we can HEAR. Until then, it's less than useless to know. Now, let's talk a little about how many we CAN hear. First of all, a reply to the original posting asked about the analogy of these little inclusions with a string of little capacitors. If they act like a bunch of capacitors in series, the poster asked, how come they don't seem like a huge impedance at finite frequencies? Answer: because, whatever they are, they're also in parallel with the rest of the (purer) copper, which has low resistance. The analogy was incomplete. As for how many of the little buggers is too much, let me just remind you that the metallurgy of copper is not a new field. Even I know about it. Every low-temperature physicist knows that oxygen-free copper has much better transport properties at cryogenic temperatures than normal, impure copper, because, at low temperatures, the phonons, which do all the scattering at room temperature, are frozen out, leaving only the impurities to muck up the electrical properties. If cupric oxide inclusions were the dominant source of scattering of charge carriers at room temperature, then I would concede that reducing their density might have a strong effect on usefulness of speaker cable. But that's not the case. Phonons dominate, accompanied by scattering by the boundaries between microcrystals (grain boundaries) and by other impurities. 50,000 clumps of CuO (size 1 micron, shall we say?) per meter of wire of diameter of, say, 2mm, works out to reasonably high purity, and there are other things in there besides oxygen! So my guess is: you can't hear the oxygen in speaker wire unless your living room floor is covered with liquid helium. And, as I said above, the rebuttal to my speculations is not to refer the Net to Hitachi's memorandum no matter how reasonable it sounds, unless it documents that their improvements in puroty can be heard. DISCLAIMER: Many of the replies I see in the Net are nasty and personal; it seems that the authors use anonimity as an excuse for inhumanity. My comments are not meant in this vain - otherwise they'd be in private.
saf@clyde.UUCP (Steve Falco) (05/08/85)
I have never participated in any double-blind tests of any product - particularly not audio cables. Thus I feel eminently qualified to comment on a previous reply to a comment on Hitachi super-pure cable. (Let me toss a :-) in here to stifle the flames...) The comment that aroused my ire denounced gold connectors because a micron of gold has about the same resistance as a micron of nickel - namely zero. Yah but... the surface-to-surface resistance is what it's all about. Nickel oxidizes but gold doesn't (much). So gold connectors actually give you a nice zero-ish resistance while the nickel connectors can give you a bunch of ohms, assuming they have become sufficiently corroded (very). It is also known that metal oxides can act as rectifiers - in fact, oxidized copper plates were used as diodes - I believe they predate even selenium rectifiers - we're talking ancient here. But you really don't want rectifiers in your cables. So much for the technical discussion. Obviously (!) gold is "better". Is it sufficiently better? Is it audibly better? I don't know 'cause I haven't done any listening to substantiate a decision. Why not actually give it a fair test before deciding it's hype? Steve Falco
herbie@watdcsu.UUCP (Herb Chong [DCS]) (05/08/85)
In article <659@charm.UUCP> prk@charm.UUCP (Paul Kolodner) writes: >Well, a scientist who suspects that >this new cable is hot stuff for hearing as well as purity >would have done exactly what another netter suggested a >few days ago: do a double-blind test with a lot of subjects >to see if humans can perceive the changes in the cable >associated by its breathtaking purity, rather than advertise >its electrical properties. stereo review or high fidelity did this a few years ago with zip cord and expensive cables of various gauges. their conclusion was that, to the listening panel, perceived differences were not statistically significant. however, given their hardware setup, there could have been other factors which would have masked the results. specifically, no matter how thick your speaker cables are, if the ones inside the box are thin (22 Ga.), then there's not going to be a lot of difference for anything less than 18 Ga. if you run short lengths (10 ft.). i run a short length 10 Ga, but i also have 12 Ga cabling inside my speakers to replace the 22 Ga original. >The point of my >message, however, is this: It's easy to make a lot of >fancy electrical measurements on inanimate objects like >cables and speakers. It's a lot harder to objectively >quantify what meaning, if any, those measurements have, and >it's irresponsible to run around quoting numbers if they're >irrelevant or meaningless. this is true of all audio components to one degree or another. the transducers suffer from this problem the greatest. no-one is completely sure what the measurements mean audibly. to different people, different levels of flaws are acceptible. >A recent case in point in my >life: I went to stereo store to by speakers and cables. >The salesman told me enthusiatically that I should use >gold-plated banana plugs rather than nickel because they >have lower electrical resistivity. Think: what effect could the >difference in resistance between a micron of gold and a micron >of nickel have on a circuit with an impedance of many ohms? >Answer: zero. Period. Salesmen are distinguished by their >willingness to uncritically and enthusiastically repeat >things they don't understand. they *DO* reduce resistance, but not by reducing bulk resistance. contact resistance is reduced because the gold contacts are essentially corrosion proof. of course, if you have very thin gold-plate or it's too soft, it can scrape off on the first use. price is somewhat of a guide here. in phono circuits, there is also an appreciable contact capacitance which may or may not affect the frequency response of your cartridge depending upon the exact value and the sensitivity of the cartridge to changes in it's load. >If cupric oxide inclusions >were the dominant source of scattering of charge carriers at >room temperature, then I would concede that reducing their >density might have a strong effect on usefulness of speaker >cable. But that's not the case. Phonons dominate, accompanied >by scattering by the boundaries between microcrystals (grain >boundaries) and by other impurities. 50,000 clumps of CuO (size >1 micron, shall we say?) per meter of wire of diameter >of, say, 2mm, works out to reasonably high purity, and there are >other things in there besides oxygen! the limited amount of material science that i have taken shows that there is a lot of impurities at crystal boundaries. inclusions form at temperatures that are above the melting point of copper. they are the nuclei that the crystals of pure copper coalesce around. during the final stages of crystalization, more impurities come out of solution and tend to be at or near crystal boundaries. (at least ironhas these properities). i think Phil was slightly mistaken when he said "inclusions". the technical data i have seen talks about reducing the number of *crystals* in the cable. a 1m interconnect is claimed to consist of about 50 crystals of copper. a typical interconnect would be on the order of several hundred thousand to one million. what's a phonon? Herb Chong... I'm user-friendly -- I don't byte, I nybble.... UUCP: {decvax|utzoo|ihnp4|allegra|clyde}!watmath!water!watdcsu!herbie CSNET: herbie%watdcsu@waterloo.csnet ARPA: herbie%watdcsu%waterloo.csnet@csnet-relay.arpa NETNORTH, BITNET, EARN: herbie@watdcs, herbie@watdcsu
man@bocar.UUCP (M Nevar) (05/09/85)
>In article <659@charm.UUCP> prk@charm.UUCP (Paul Kolodner) writes: >>Well, a scientist who suspects that >>this new cable is hot stuff for hearing as well as purity >>would have done exactly what another netter suggested a >>few days ago: do a double-blind test with a lot of subjects >>to see if humans can perceive the changes in the cable >>associated by its breathtaking purity, rather than advertise >>its electrical properties. >stereo review or high fidelity did this a few years ago with zip cord >and expensive cables of various gauges. their conclusion was that, to >the listening panel, perceived differences were not statistically >significant. however, given their hardware setup, there could have The man who wrote this article (and performed the tests) was Larry Greenhil. It was for Stereo Review. He recieved a lot of nasty remarks from the hi-end press about this article. Stereophile then hired him and defended him in an issue last year. It seems that the editors at Stereo Review did a great butchering job on the article and actually rewrote Mr. Greenhil's conclusions!! If anyone wants, I'll summarize the editorial. Mark