ms (03/31/83)
Just to add more fuel to the fire...
The following information is taken from the 2/1980 issue
of Speaker Builder magazine, by Nelson Pass.
Following the comments I will give his reference list, so this may
be quite lengthy.
I like the way Mr. Pass starts out his article by saying that the
new cables are neither panacea nor placebo, but components whose
characteristics must be evaluated in the context of their usage.
Regardless of cable type, the effects of it are proportional to
its length, the shorter they are, the more intimate the connection
of the speaker to the amplifier, and as the length grows, subtle
differences become much more noticeable.
Mr. Pass used 10ft. lengths of the following cables for
testing: 24 ga. Zip, 18 ga. Zip, Lucas, Monster, Fulton, Polk,
Mogami, Audio Source Hi. Def., Audio Source Ultra-Hi. Def. He
measured performance in two frequency ranges, 0-100kHz and 100kHz-
40MHz. The cables were driven by a high source impedance and
the voltage across them measured, showing its series impedance.
For twin lead cables, inductive and "skin effect" components begin
to show up at 1kHz; they increase the impedance, causing high
frequency loss in addition to the cable's resistive losses.
Looking at his graph, it shows up to 10x resistive increase
PER FOOT between 1kHz and 10kHz.
The amplifier's source impedance and the loudspeaker's load
impedance must also be considered as part of the performance
context. The overall system performance will depend on the
sum of all the impedances involved:
Z_source + Z_connections + Z_cable + Z_load
Since speakers can have widely varying impedances, and amplifiers
can have varying inductances, their interactions with different
cable must be considered on a per system basis.
At first, one may wonder why Mr. Pass tested in the
100+kHz range. Well, consider that there are some amps on the
market which have ultra-wide bandwiths (up to 50MHz). He found
that some cables exhibited an apparent GAIN of 100, i.e. with a 50mV
input, amplitudes as high as 5V appeared on the other end of the
cable. Other instability problems occurred in actual system
testing, such as blown fuses. These problems seem to be limited
to the more esoteric cables with extremely low inductance.
In summary: One of the major problems with maintaining or
improving sound is the connecting surfaces of conductors. Loose,
dirty or oxidized surfaces deteriorate performance. Keep those
surfaces clean. Now, to quote Mr. Pass. "Frankly, I found it
difficult to assess the results except at the extremes of
performance. For 10 foot lengths with properly terminated
cables and speakers with inductive high frequency characteristics,
the differences between low inductance cable and twin conductor
are extremely subtle and subject to question. With a low output
inductance amplifier and a Heil tweeter (whose impedance is a
nearly perfect 6 ohm resistive) the difference was discernable as
a slightly but not unpleasant softening of the highest frequencies.
Fulton or Monster cable were a clear improvement over 24 or even
18 gauge, though a little less subtle than I would have expected,
leading me to believe that the effort associated with heavier
cables pays off in bass response and in apparent midrange
definition, especially at crossover frequencies. The worst case
load, the modified Dayton Wright electrostatics, presented some
interesting paradoxes: the extremely low impedance involved showed
the greatest differences between all the types of cables. However,
the best sound cables were not necessarily electrically the best
because several amplifiers preferred the highest resistance cable.
In one case, I had to use 24 gauge cable to prevent tripping
the amplifier's protection circuitry."
REFERENCES
1. Brochures/Pamphlets:
a. Fulton Speaker Cable. Fulton Musical Industries, 4428 Zane Ave.
North, Minneapolis, MN 55422.
b. Mogami Speaker Cable. (at press time, no locatable distributor)
c. Polk Audio Sound Cable. Polk Audio, 1205 S. Carey St.,
Baltimore, MD 21230.
d. Ultra High Definition Speaker Cable. Audio Source, 1185 Chess
Dr., Foster City, CA 94404.
2. Hiraga, Jean, "Can We Hear Connecting Wires?", Hi Fi News and
Record Review, August 1977.
3. Retsoff, Alexander, "Retsoff's Remedies", Stereo, Fall 1978.
4. Klipsch, Paul, "Speaker Wire", Dope From Hope, Sept. 13, 1978.
5. Pass, Nelson, "Loudspeaker Damping", Audio Magazine.
6. Gailus, Mark, "Speaker Wire: What Size is Sufficient?", Audio
Forum, Aug.-Sept.
7. Greinier, R.A., "Another Look At Speaker Cables", Speaker,
The Boston Audio Society, Dec. 1978.
8. Gross, T.A.G., "Multistrand Litz Wire Adds 'Skin' To Cut AC
Losses in Switching Power Supplies", Electronic Design,
Feb. 1, 1979.jj (04/01/83)
Well, I must admit that I am a bit annoyed at the article on speaker cables. Most of the comparisions made, while likely accurate, although I have some doubts about the "skin effect" problem, simply don't represent a comparison with a reasonable size of zip cord. The article gives some impressions regarding 18 and 22 gauge zip, both of which are too small for any but the shortest runs. <In fact, #22 isn't even big enough if the amplifier is sitting on top of both of the speakers.> I would be interested in a careful test that uses #14 and #16 zip as the conventional standards, and whatever is viewed appropriate as the "special" cables. It's quite discouraging that so much effort went into a test with samples chosen so badly. I must admit that, were I a manufacturer of "whizzo speaker cables" or whatever, I would like my cables, which undoubtedly have large cross sectional area, to be compared to #22 zip cord. Unfortunately, as a consumer, I can't credit a test that makes such a comparison. With resignation, rabbit!jj. (Who, as usual, will merely mail abuse to /dev/null)
jacoby@kpno.UUCP (09/29/83)
I'm not sure I understand all the fuss about speaker cables.
After all, why not use "expensive" cables when they only cost
about $25 for a set of Monster or Kimber cable.
Once you've spent $1000 for the speakers, you may as well spend
another 2 percent and not worry about the difference the heavier
cables probably make anyway.
george jacoby, kitt peak national observatory, 950 n. cherry ave, tucson, az
(602) 325-9292
{{{ucbvax|utah-cs|purdue|mcnc}!arizona}|unc|hao}!kpno!jacobyshauns@tekcad.UUCP (Shaun Simpkins) (10/03/83)
Yes! WHY all the fuss? However, the argument [since I've spent kilobucks on
speakers, $50 for cable is a trifle] misses the point entirely. If ordinary
line cord at 9 cents a foot cannot be distinguished from dollar a foot zillion
strand litz wire in carefully controlled tests, then it makes no practical
sense to buy the litz wire. Doing so only lines the manufacturer's pockets.
However, such cabling does fufill the first commandment of audio equipment
manufacture,
``Thou shalt make a product that is above all else sexy''.
Personally, I'd rather spend the $45 difference on new records.
--
Shaun Simpkins
uucp: {ucbvax,decvax,chico,pur-ee,cbosg,ihnss}!teklabs!tekcad!shauns
CSnet: shauns@tek
ARPAnet:shauns.tek@rand-relaydswankii@uok.UUCP (10/30/83)
#R:tekcad:-6400:uok:400002:000:411
uok!dswankii Oct 14 16:22:00 1983
One of the best things I have found for speaker cable is two
conductor outdoor do-it-yourself-extention-cord cable. With a
capacity of 1350 watts, it is in no danger of being burned by my
45 watt reciever. Plus it hold up well to hostile environments.
Teething puppies and power heads on electric brooms compose said
environment.
David Swank II
University of Oklahomajon@boulder.UUCP (Jon Corbet) (08/30/84)
[I bet no computer will eat this line.] Let me speculate on this subject, drawing on my EE degree at last... Any wire of significant length will have a certain amount of inductance. Inductance puts a sort of inertia onto an electrical system. You see, the voltage across an inductor is directly proportional to the derivative of the current through it. High frequencies involve rapid changes in current, meaning high voltages across the speaker line. Since the power required is proportional to the voltage SQUARED, most amplifiers will run out of power on the high frequencies especially quickly if the speaker cable is highly inductive. Now, when one says "high frequencies", one usually means megahertz at least, but to a small extent the inductive effect will apply to audio frequencies as well. Look at the cables used for high quality TV monitors, and you will see that they are heavy, coaxial cables; much like the fancy expensive audio cables. Personally, I do not own a pair, since I am quite happy with my 10-gauge power cord speaker wires... I would like to be a bit more coherent, but it was a long day... Jon Corbet (National Center for Atmospheric Research)