Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!cmcl2!rutgers!ames!sdcsvax!ucsdhub!hp-sdd!ncr-sd!crash!bblue
From: bblue@crash.CTS.COM (Bill Blue)
Newsgroups: rec.audio,sci.physics,sci.electronics
Subject: Re: Mercury Filled Speaker Wire
Message-ID: <1700@crash.CTS.COM>
Date: Sat, 12-Sep-87 15:48:04 EDT
Article-I.D.: crash.1700
Posted: Sat Sep 12 15:48:04 1987
Date-Received: Sun, 13-Sep-87 10:44:44 EDT
References: <3816@watdcsu.waterloo.edu> <578@uthub.toronto.edu>
Reply-To: bblue@crash.CTS.COM (Bill Blue)
Distribution: rec
Organization: Crash TS, El Cajon, CA
Lines: 120
Xref: mnetor rec.audio:3218 sci.physics:2158 sci.electronics:1286

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