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The Truth About Interconnects and Cables - page 2

By Rod Elliott

Preamble Part 2

A fairly well known person (rampant on certain forum pages) has claimed that I consider all conductors and insulators to be "perfect", and that "all engineers who design in the real world know this is not the case". Oh really! ... and where exactly did I say that all conductors and insulators are "perfect"? Where did I imply that they are perfect?

These questions remain unanswered (of course) because I have never claimed, assumed or implied that they are perfect.

No insulator or co nductor is perfect - in fact, no "anything" is perfect. The simple fact of the matter is that these imperfections are not significant at audio frequencies, except perhaps in "unusual" cable constructions (of the type often suggested by the lunatic fringe). This is one of the typical "red herrings" that raving psychotics will bring up time and time again, to bolster their unsubstantiated and flawed "reasoning". Claims like that are typical of delusional thinking, and the delusional only have to claim that I (or someone else) said that "all conductors and insulators are perfect" (for example), and it somehow makes it "true" that these words were in fact used.

Well, I have some news that may come as a shock - anyone can say anything they like, but the saying does not make it so! I have never claimed that all conductors or insulators are perfect, but I have challenged anyone who claims that the imperfections are audible to please do so. So far, there has not been one shred of evidence that indicates that Teflon TM (wonderful stuff that may well be) is audibly superior to PVC in a properly controlled double-blind (or ABX) test.

Differences are measurable (with the right equipment) but are not relevant to the audio range unless the "facts" or cable topology are manipulated to influence the test.

I have asked every person and/or company named in the Mad As Hell articles for any information they have that substantiates their outrageous claims, and not one, not a single one , has supplied anything more than some useless promotional material or "satisfied customer" e-mails. Why is "satisfied customer" in quotes? How do I, or anyone else, know that they are genuine? For all we know, they are fabricated (i.e. lies), without an iota of truth in any of them. Oh, but I am so negative !

Of course I am, these people are liars, charlatans and thieves, either by accident (they may actually think they are realistic because of mental illness [such as delusion or psychosis] or some other mitigating circumstance) or by design - they simply have one goal ... to separate people from their money. The actual "mechanism" is unimportant - the fact that they are wrong does not enter into their equation of life, so whether their claims are due to mental illness or greed makes no difference to the consumer, who is being ripped off and lied to either way.

I recently had an e-mail exchange on the topic of interconnects, and the "conversation" started out innocently enough. I was advised that by using the tape loop on a preamp, I could listen to the effects of different interconnect cables, simply by switching to/from tape monitor.

I firstly suggested the test methodology suggested was flawed, since any additional circuitry used to make up the tape loop circuit would have some influence. In addition, the feedback to the brain (knowing which switch setting was which) means that a genuinely objective (double blind) test was impossible. The test method does not even qualify as single blind - it is an open test, and the experimenter expectancy effect will confer non-existent attributes to the material being tested, based on preconceived ideas and expectations.

The e-mails went back and forth for a while, and eventually I was finding that it took up too much of my time, and the topic is not all that interesting anyway - after all, how excited can one get over ordinary signal leads.

This is doubly true when the other party invents reasons that ABX tests are "invalid" for audio - something about the signal complexity, and the psychological effects of the music was mentioned. This is exactly why we must use ABX or similar double blind tests - anything else will fail to properly eliminate feedback cues, and these will be used (albeit subconsciously) to determine whether the "standard" or "test" item is currently in circuit. Any test where there is any possibility of identifying the components under test is completely invalid.

It is interesting that in a relatively non-demanding application such as an interconnect, a material such as aluminium would likely be sneered at by any audiophile, yet this very same material is used regularly in loudspeaker voice coils. I am reasonably sure that sonic performance of an aluminium interconnect would be deemed to fall way short of excellence, yet I hear (or read) no highly critical comments about using it in a voice coil. This is an extremely demanding role, and the performance of aluminium is (or can be) audibly and measurably worse than copper. *

My (almost) final e-mail pointed out that no metallic conductor introduces distortion. Now, I must admit that I did not qualify this, but when I speak of distortion I refer almost invariably to non-linear distortion (i.e. the type introduced by all active components, that generates harmonics and intermodulation products not present in the original signal). A simple question would have cleared this up, but ...

The response I received astonished me - suddenly, my statement that "no metallic conductor introduces distortion" was utterly misconstrued, and became "all metals are perfect conductors"! It was inferred (of course) that this was the reason that my tests and experiences are simply invalid, while those of my correspondent were reasoned and obvious.

This is absolutely the sort of thinking that got everyone to this impasse in the first place. I never suggested that all metals are perfect conductors - I said that they don't generate (non-linear) distortion. By means of misinterpretation, the subjectivist camp will now think it has another "weapon" against the enemy - the fact that it is the result of a gross mangling of the original statement is of no consequence ... "Never let the facts get in the way of a good story".

The fact of the matter is that no metallic conductor causes (non-linear) distortion.

There are various resistances depending on the metal, but it's basic conductivity is completely linear. Check things like thermal coefficient of resistance for any metal - it is linear. There are no curves or "fudge factors" to be taken into account. While it may be possible to make an alloy that exhibits some degree of non-linearity, this would not be used as an electrical conductor, and would certainly not be suggested as an alternative to copper. Even then, within the very limited range of acceptable temperatures in the listening room, such non-linearities could easily be less than that of air - the medium that carries the sound from the speakers to our ears..

None of this has anything to do with skin effect, velocity factor or any of the other seemingly strange behaviours of all conductors at high frequencies (none of which are non-linear distortions), we are interested in the simple ability to conduct current from point A to point B without any form of rectification or other non-linear effect. All metallic conductors in common use will do this perfectly well, and will not add harmonics or change the waveshape in any non-linear way.

Harmonics can of course be removed - this is a filter effect (a completely passive linear function), and is caused by capacitance and inductance. All cables have these parameters as a fact of life - a silver wire and an aluminium wire of the same length and diameter have different resistance, but inductance and capacitance are the same.

The degree of hostility I experienced towards ABX testing was equally puzzling. I don't know of any designer who will claim that listening tests are invalid - only that they may not reveal the entire truth of the matter, and that additional "technical" evaluations may be needed to find out why the listening tests did (or did not) correlate with the measurements.

On the other hand, many subjectivists claim that anything other than a listening test is invalid, and commonly and even vigorously eschew ABX testing - possibly because they know in their hearts that they will be unable to find any difference. This is very confronting, and to have one's beliefs shattered is not a pleasant experience.

What is the most interesting to me is the "head in the sand" behaviour. I was automatically wrong in my thinking, and I suspect that anything that I said would have been twisted around to make sure that I stayed wrong. I could (of course) have simply agreed with the subjectivist's position, however to have done so would have been a lie on my part.

The issues at stake here are the crux of the on-going debate between the two "camps". While I will admit that not all designers will take any subjective opinion seriously, I do know from my own testing and from a huge amount of reader feedback that some of my designs sound better with different transistors or power supply configurations (for example). Most of these differences can be quantified, although some are elusive, and that is something that I live with, knowing that many of the further "tweaks" are assessed by purely subjective methods. There is every chance that ABX testing would reveal no audible difference.


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