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From: sjc@mordor.UUCP (Steve Correll)
Newsgroups: net.audio
Subject: Re: Why do cables make a difference?
Message-ID: <5317@mordor.UUCP>
Date: Tue, 14-Aug-84 05:14:27 EDT
Article-I.D.: mordor.5317
Posted: Tue Aug 14 05:14:27 1984
Date-Received: Thu, 16-Aug-84 01:30:41 EDT
Organization: S-1 Project, LLNL
Lines: 48

I honestly do not know why cables are reported to affect the sound of
audio systems, but I will offer some hypotheses which one might test:

1. Many phonograph cartridges are quite sensitive to load
capacitance.  I have seen graphs in Audio magazine suggesting that
cables and preamp inputs vary enough in capacitance to affect the
high-frequency response of a cartridge by several dB, whereas people
seem able to discern variations of less than 1 dB.

Since the optimum value of capacitance varies with the cartridge in
question, simply minimizing capacitance may make some perform better
and others perform worse.

If high-end audio manufacturers were really interested in improving
turntables, they would stop touting pads, platters, and bases made out
of esoteric substances, and they would start putting a few FETs inside
the cartridge itself to isolate its coils from the load of the cables
and preamp. With current technology, the circuitry would increase the
mass of the cartridge/arm combination very little. (In fact, the tiny
additional wire required to bring a few milliamps from a power supply
in the base of the turntable up through the arm to the cartridge would
probably weigh more!)

2. A few preamps are overly sensitive to load capacitance. Studios
insist that line outputs be able to drive low-impedance but reactive
loads without straining, and the IHF/EIA specs define a reactive load
to be used in testing preamps. But one trend in high-end audio is to
minimize both the amount of active circuitry and the amount of feedback
used in amplifiers, and the tradeoff for this is often to make the whole
system more sensitive to loading.

3. Contact corrosion can subtantially affect audio signals whose
amplitude is less than a few dozen millivolts during quiet music.

4. A cable which admits RFI might cause active circuitry to saturate
or slew even though the interference frequencies are too high to hear.

5. Double-blind tests are fairly rare in this field. While I like to
consider myself objective, if I were at a wine-tasting party and I
liked a Gallo wine better than a Chateau St. Jean, I certainly wouldn't
admit it. If you hid the labels, however, there's no telling what
embarrassing judgements you might elicit from me.

                                                           --Steve Correll
sjc@s1-c.ARPA, ...!decvax!decwrl!mordor!sjc, or ...!ucbvax!dual!mordor!sjc
-- 
                                                           --Steve Correll
sjc@s1-c.ARPA, ...!decvax!decwrl!mordor!sjc, or ...!ucbvax!dual!mordor!sjc