Update on the "Wire Challenge"

From Audio Basics, Volume Nine, Number Two, February 1990

As you readers should remember, I issued a challenge last month to the high fidelity cable and wire industry to prove to me that their premium speaker wires and interconnect cables can be a musically useful asset in my (and your) audio system.

We sent the letter to 19 different hi-fi wire and cable companies. The names and addresses were taken from the most recent Audio equipment directory and from Stereophile's display advertising and want-ads.

To be honest, I did not expect to get any response at all, but I was mistaken. So far I have had two things happen. One letter, to Clarity Audio Systems of San Francisco bounced back from the post office marked "Moved, Not Forwardable." If you are still out there Clarity, let me know where you are.

But, however, I did get one very nice telephone response from the president of a wire company. He says he is sending me samples of a couple grades of his speaker wires and of his interconnect cables. He informed me that he thinks that his company does have good engineering documentations as to why his cables and wires are musically useful, but also admitted that sometimes it is hard to explain just why things sound the way they do. (I don't disagree with this honest comment).

He wants me to thoroughly test the wire using our own standards before he will explain his own test methodology to me, to keep me open minded, he says. That is certainly fair and I am looking forward to the experience.

We have not yet received the samples as of this letter. As I promised in my challenge letter, I am not going to mention the name of the company unless and until I find that their products are of positive musical value or are of significantly detrimental mechanical value. The purpose is not to write "bad reviews" of any cable but to see if I can find any real value in extra cost cable that is worthwhile recommending to you.

The manufacturer did note that, "Sometimes they found amplifiers that just plowed right through the amplifier - cable - speaker interface such that the kind of cable used made nearly no difference." So he asked me to try the cables on mundane equipment as well as on our own amplifiers (which are designed to drive difficult loads as page one of this issue points out). We shall honor his request. We also can see where varying the load can change the sound.

The Great Wire Challenge Concluded

From Audio Basics, Volume Nine, Number Five, May 1990

I reported last month that we had actually received interconnect and speaker wire samples from one supplier and were promised samples from a second supplier. We waited as long as possible for the second samples to show up but they never did. Thus inasmuch as only one supplier has responded to our challenge issued herein in January, it is time to report on our findings. We regret we got so little response from the manufacturers. They all were certainly quick to sign that letter to Audio magazine.

Anyway, to make a long story very short, I am now using Kimber Kables in my own reference system. Why? Because I believe the system sounds slightly more musical with them than without them. The differences I think I hear are subtle. not at all day and night, and are not anything like the purple prose cable test write-ups in the underground magazines. I have real reservations about the cost-benefit ratio of the improvements (the retail price of all the cables I am using would nearly pay for a complete Fet-Valve 500 amplifier and that will make a really big improvement in your system - or if you have enough audio equipment already it would pay for a Sony 32HSR10 big screen TV (make your value judgements carefully). I also have reservations about the mechanical interface of the interconnect cables with the system. Finally, neither I nor the rest of my staff could pick out the cables on an A-B blind test (except for the marginally shielded KCAG types which we could pick out close to the woofer by noticing a bit more background hum). But, the bottom line is that when I put Kimber Kables everywhere in my system (from tuner to preamp, from my Fet-Valve CD player to its hybrid control box, from the control box to the preamp, from the preamp to the power amp, and finally from the power amp to my B&W and Acoustat loudspeakers) I think long term listening tells me the system is a tiny bit sweeter, a bit clearer, and a bit purer. Since I got these samples for free, I am going to use them. But since they would cost you over $1800.00 for all the cables I am now using I am not at all certain that they should be your first choice for an upgrade. But if you have everything else, then why not? They do seem to make a nice finishing touch to an already superior audio system.

It is possible that they are only sugar pills, but sometimes sugar pills taste pretty good. If you have the spare cash to play with, go ahead and experiment with cables - you may find something you like and I would recommend that you experiment with Kimber Kables first because they were the only company to respond to my challenge and because their cables certainly are built to high mechanical standards and because Ray Kimber, their president, is a really nice and rational person. I think you will be satisfied in doing business with his company because he is going to make sure that you are.

The First Evaluation Was at the Test Bench

We received two kinds of interconnect cables from Kimber. The interconnect cables are very well made with very sturdy RCA plugs. The outer barrels of the plugs are metal so you must take care to not let them touch together in some applications (such as at the inputs of a stock Dyna St-70 or at the chassis of Dyna 400 amplifiers) or possible hum causing ground loops could occur.

The lower cost ($101.35/pair) interconnect set was their model KC1-2M, a 2 meter long blue cable consisting of four heavy insulated stranded conductors braided together inside a shielded sheath. One of the conductors was hot, the other three were the signal ground, and at one end of the cable (marked the preamp end) the shield was connected too. This cable measured about 268 pF total capacitance.

The premium interconnects were their $650/pair KCAG 2 meter silver cables. These appeared to have the same physical construction as the others (with much more expensive materials of course), except there was no outer sheath or shield. This cable measured very low capacitance — 113 pF for 2 meters, but we could induct more hum into this cable than we could in either the blue Kimber Kables or Radio Shack cables by holding an AC power cord close to them — even with the cable ends shorted together. The increase in noise was not terrible, but it was observable. We would suggest you be very careful in using this cable in long runs near AC power lines. You may get lower noise with better shielded cables.

Our crusty old Radio Shack cables measured about 194 pF for 6 feet, halfway between the Kimbers. The capacitance readings tell us that you may induce an audible roll-off if you use the long versions of the blue Kimber Kables between a vacuum tube preamp and a power amp. The extra stray capacitance may roll off the highs and may also cause a vacuum tube preamp to current limit - increasing distortion. That could make a sound change you could hear, but that would not be very nice. The very low capacitance RCAG cables would be much more appropriate for the output of a vacuum tube preamp.

We noted that the Kimber Kable RCA plugs made very firm contact with our jacks (good) but that they may scrape into the finish layer on your jacks quicker if plugged in and unplugged many times (not so good but not likely to happen in a plug it in and forget it system). They did not deform the inner contacts in our RCA jacks as we have observed many "premium" cables to do. The blue cables were at the upper limits of stiffness that we are comfortable with. Cables this stiff can come loose if equipment is moved or adjusted on the shelf - but the very firm interface with the equipments' jacks make this unpleasant happening less likely.

We tested the cables dynamically with white noise and square waves feeding identical signals into one Kimber Kable and one Radio Shack cable and then setting the scope to invert and sum the two signals. If there was no difference at the output between the cables' ability to transmit an audio frequency signal, it should show up as a straight line on the scope. Any difference would generate an observable difference signal. We could not observe any difference signal on any of the interconnect cables within the resolution limits of our scope and within the band width limits of our square wave generator at any frequency close to audio. We did observe a slight high frequency roll-off on very high frequency (100 KHz and above) square waves on all the cables and that the roll-off was slightly less with the premium Kimber Kables. We saw no overshoot or ringing with any of the cables.

Kimber also supplied two kinds of speaker cable. The lower cost version was their $1.00 per foot braided 8 conductor 4PR wire. It consisted of four brown and four black insulated stranded conductors braided together and terminated in bare wire ends. It measured about 1150 pF total capacitance for the 20 foot runs supplied. The higher cost Kimber Kables was their $4.40 per foot braided 8 conductor 4TC wire. This has Teflon insulation and was supplied with dual stacking banana plugs - a very reliable and easy to use termination. The 4TC cables measured 1110 pF total capacitance for the same length. In comparison, our 18 gauge Radio Shack two conductor "zip cord" type speaker wire measures about 230 pF for 20 feet of cable - a figure we are more comfortable with for reasons discussed below.

We tested the cables dynamically as we had the interconnects, driving them from two channels of a Fet-Valve 500 amplifier carefully checked for identical channel performance (which all our amps have). We matched a Kimber Kable with a Radio Shack cable into an 8 ohm load and measured the difference signal at the load. Again, neither on white noise nor on square waves could we detect any difference between the cables. Note that because our amplifiers will drive very large capacitive loads without ringing or slowing down, the extra capacitive load caused by the Kimber Kables was negated. With some marginally stable amplifiers, the extra stray capacitance might cause overshoot and ringing (and a "brighter" sound) or as a worse case, an oscillating and damaged amplifier. With our amplifier there was no overshoot or ringing at all with either the high capacitance Kimber Kables or the low capacitance Radio Shack cables. The higher resistance of the Radio Shack cables had no effect on the signal bandwidth or amplitude because the slightly higher resistance of the Radio Shack cable was still negligible in comparison to the 8 ohm load. You really don't need a heavy speaker wire unless you are running hundreds of feet of cable into a low impedance loudspeaker.

A-B Listening Gave Us No "Better" Results

We made our formal listening tests by installing the Kimber Kables in one channel of the system and Radio Shack cables in the other channel (first with interconnects only, then with speaker cables only, and finally with both). We used CD test disc generated white noise into a pair of very carefully matched B&W Matrix Three Series Two speakers making sure we listened exactly on axis to both speakers in my very dead evaluation room. We compared one channel to the other attempting to hear any difference between the speakers. Nobody could detect any differences. In comparison, moving the mid-range coil of a B&W 801 Matrix a few inches makes a huge and instantly observable difference. We listened to mono records and CDs with Kimber Kable from input to output on one channel. Nobody could hear any worthwhile musical differences between the two channels or could tell which channel had the "good wires." We tried again with the Acoustat electrostatics with the same results. We substituted our lowest priced equipment for the all Fet-Valve system and there still was no difference between the channels we could hear under these test conditions (we could tell the Fet-Valve impact was missing though). All of the carefully conducted tests ended up telling us there was no useful difference between the Kimber Kables and the low cost cables we had been using.

Then Why Am I Using the Kimber Kable?

Because when all the formal tests were done I went ahead and installed the Kimber Kables from input to output of both channels of my reference system and went back to simply relax and listen to the music and that is when I started to "hear something" or more appropriately, "not hear something." Everything sounded the same, but everything sounded a tiny bit closer to live real music. Not all on my staff agree. Some think I am simply hearing the "sugar pill effect" of all those expensive cables being there. Others don't disagree with my very subjective evaluation. They remember that we designed some widely accepted audio equipment (the Dyna 416 and Double 400 for example) "by ear" long before we had full time electrical engineers on the staff and that the test bench and formal A-B testing doesn't give us all the answers (or always the right answer).

Maybe I am "hearing things" and certainly I would not want to pay as much for audio cables as these cost, but the Kimber Kables are staying in my system for now. They met my challenge fairly and surprised me by making my system seem to work that little bit better and in the quest for perfect music reproduction, each "little bit" counts.

Frank Van Alstine

Copyright, Audio by Van Alstine, Inc., 1990. No part of AUDIO BASICS may be reprinted or reproduced in any manner without the permission of the publisher.