End of cable debate - snake oil

Murray, I guess that 'a' is 'Litz' or some fabrication from Cat5 style, 'b' is NACA5 and 'c' is two bits of ordinary copper wire laid side by side.

You can expect audible differences with these cables dependent on what you connect them to. Sometimes the smoke will come out of the amplifier and that is guaranteed audible.

But this is completely irrelevant. The cable makers and believers claims are nothing to do with the well known effects of cable geometry. It would hardly be possible to charge $8000 or more otherwise.

Paul

 

So you accept that there might be some audible differences between these 3?

I'm glad you agree with that. It's what I (and others) found when listening to them and other cables in a published blind test. (no smoke appeared when using any of the cables)

NACA5 is indeed one of them but amusingly was not the one you guessed at!

 

I do not want it “both ways” – I can hear and accurately identify differences between some cables, but not others. I have never equated price with performance, nor do I buy into the absurdist waffle that is written both by manufacturers and audio “journalists”. I have neither the equipment nor the technical knowledge to scientifically measure cables, but I’m prepared to bet that the ones I can accurately tell apart in a blind test environment measure differently too.

Tony.

 

Until somebody can say what optimal values L C and R a cable should have and then what tolerance is allowable for each, the issue of the electrical equivalence of different cables is unresolved. If we can't establish what electrical equivalence actually requires then saying all electrically equivalent cables sound alike 'may' be true but isn't terribly helpful.

The 3 examples of speaker cables given above don't appear to be electrically equivalent. Which ones are?

 

So it's 'c' and 'b' is completely unsuitable as a speaker cable? 0.5Ohms is extreme.

Well done for hearing differences. But it says nothing about the 'cable debate'. Did you measure the cables in situ?

Paul

 

The whole basis of the Randi challenge is that the cables don't measure differently.

To make it clear to Murray, we don't care what the actual LCR values are, only what the effect of the cable is on the system. The amount of inductance or resistance that will generate audible aberrations is obviously system dependent.

The reason for specifying 'electrically equivalent' is to avoid a situation where you listen to Litz and Naim, which are different, hear they're different, and suggest this says something about cable 'sound' rather than electricity. It's obfuscatory and not really very helpful.

Paul

 

well yeah , if there wasnt something measurably different about the different cables then they would have to all sound the same.

I dont think it's just down to LCR though

 

Aha, we're getting somewhere. Well spotted Paul.
So what would you say was an acceptable upper limit for series resistance? And what of the L & C components?

Paul Miller did the measurements. It was a blind test but also included a full set of measurements of each type of cable. (more than just the L, C & R too) You'd have to ask him where exactly he did the measurements. He was/is pretty well equipped for this.

How the test was done.

In practice the electrical termination of a speaker cable is anything but predictable. Consequently, past subjective observations of cable performance have hinged as much on the choice of speaker and amp as anything else. However for the tests conducted here we made an effort to sidestep 'system dependency' and adopted a novel yet proven technique for our auditioning.

This technique relied on the Deltec DPA-100S power amp which utilises a special double pole/zero-phase compensation scheme that extends out to, and includes, the very ends of the integral speaker leads. Therefore, by inserting a 5 metre length of test cable between the loudspeaker and notional feedback point we were able to perform direct A/B comparisons between the sound of 'no cable' and 'some cable'.
Our subjective observations could then be drawn against a nominal absolute rather than some arbitrary amp-cable-speaker reference. Once again, the technique is not perfect but does bring us one step closer to isolating the register of the cable itself.

The results were published in August 92 in HF Choice as a supplement.

 

I remember that amp well, a friend blew up several into very early AE1s. ISTR one needed to use the stiff black Deltec cable with it’s additional sensing wire or the magic smoke from within the amp escaped pretty damn fast

Tony.

 

That cable test did include Deltec's own IS19 cable which, apart from being a litz type, doesn't seem to show any unusual characteristics L,C and R wise.

 

This isn't an answerable question. It depends. It's much simpler to put it in terms of in situ aberration.

Your test would have been much more interesting if it was between cables that should be the same according to basic electrical theory. That's the question that is really being asked. Interconnects are simpler for this, it's really quite hard to screw an interconnect up, although care is required with MM carts and on the output of passive attenuators.

Paul

 

As the 3 commercially available cables given as examples show, they often aren't the same electrically and possibly this may account for the differences people hear.

There were two conclusions to that test which were interesting (to me anyway). Bear in mind that perhaps 8 different people listened unsighted over 4 or 5 days.


1. none of the cables was inaudible
2. The cable preferred by the blind listeners over all of the others in the group was the only pure silver cable in that group.

 

murray thats an interesting result, not that they favoured silver, but were all agreed on one cable.

what was the interaction between subjects, were they allowed to discuss their thoughts.

 

I've run a simple measurement on some interconnects I had to hand to try an illustrate the order of error introduced.



The cables are 1m Linn standard 'black', then about 10m of nasty thin coax from Maplin, and then 20m of the same. Measurement done with an M-Audio MobilePre USB and 'RightMark'. I think 0.1dB at 10kHz is probably audible, so these cables are not 'electrically equivalent'.

Paul

 

What is your test Paul? If it's a FR sweep of some kind then I'd expect the difference in HF to be audible in a good system (the Linn no doubt being the brightest!). I'd be interested to see your test with a cable of noticeably different construction, i.e. the Linn Analogue vs. say some Kimber KCAG, i.e. copper coax vs. some kind of silver solid-core weave. I am sure you would find them markedly dissimilar.

Tony.

 

It would be interesting to see the difference between cables of 1m length (rather than 1m, 10m, 20m)... if there is a difference to be seen of course.

 

True, and by my unbelievably crude understanding cable length effects capacitance doesn't it, and the more of that stuff one has the duller things sound (at least that's what happens to MM carts), i.e. the graph is predictable and explainable assuming the three cables are from the brightest to the dullest Linn Analogue, Maplin 10m, Maplin 20m.

Tony.

Not a scientist, obviously.

 

Would 'b' be DNM Reson by any chance?

 

It is precisely because of these factors that they are most appropriate for randis test - that being the point

Neither does the fact threat cable manufacturers charge $8K mean that they must believe it is worth it - they simply believe that the market wil bear that cost regardless of whether it has value or not

 

One control test should include two actually identical cables.