Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!hao!boulder!sunybcs!rutgers!labrea!jade!ucbcad!eros!max From: max@eros.uucp (Max Hauser) Newsgroups: rec.audio,sci.physics,sci.electronics Subject: Re: Mercury Filled Speaker Wire Message-ID: <1854@ucbcad.berkeley.edu> Date: Mon, 14-Sep-87 01:46:42 EDT Article-I.D.: ucbcad.1854 Posted: Mon Sep 14 01:46:42 1987 Date-Received: Tue, 15-Sep-87 04:27:42 EDT References: <3816@watdcsu.waterloo.edu> <578@uthub.toronto.edu> <1700@crash.CTS.COM> Sender: news@ucbcad.berkeley.edu Reply-To: max@eros.UUCP (Max Hauser) Distribution: rec Organization: University of California, Berkeley Lines: 104 Xref: mnetor rec.audio:3224 sci.physics:2161 sci.electronics:1290 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.