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Post-manufacturing cable treatments & double-blind subjective tests

[1 2 3, easy as a b c, oh which cable will it be?]
[Italian version]

Goodness Gracious, Great Balls of Wire

Product: post-manufacturing cable treatments & double-blind subjective tests
Price: N/A
Author: Mark Wheeler - TNT UK
Reviewers: Many & Various
Reviewed: 2006-2007

This is it. I put my reputation where my keyboard is, even if that phrase is slightly clumsier than putting one's money where one's mouth is! My article proposing that cable reviews are probably mostly useless provoked more reaction than anything I have ever written for TNT-audio. Many of those responses seemed to have resulted from the phenomenology of the reader's encounters with parts of the text, a deeply postmodern response, rather than with the totality of what I was rather clumsily trying to say.

I maintain that cable reviews are usually useless. Thorough cable reviewers try the bits of wire in various high-quality and revealing system contexts, while some of the more hyperbolous members of the press-pack only try the cables in their resident reference system, but in either case, unless you, dear reader happen to own and use the same 2 components on each end of the cable, you may not expect a similar experience.

I have tried experiments with otherwise identical sets (same length, same plugs, same loose twisted pairs) of cable in various conductor materials and insulators to come to this conclusion:

  • Multistrand copper
  • Single-strand copper
  • Multistrand silver-plated copper
  • Single-strand silver-plated copper
  • Multistrand nickel
  • Single-strand nickel
  • Multistrand silver
  • Single-strand silver

all at identical levels of purity for each metal type. The upshot was that I found that whatever the metal type, the construction type preference would remain the same between any given metal type for a given pair of components. For example a Croft Micro pre-amp was always preferred with single-strand than multi-strand, while a Naim 42.5 was always preferred with multistrand rather than single strand. Each preference was unanimous with whatever component was tried, by all listeners who were present at any encounter.

The point I am labouring rather heavily is that, when other factors are equal, system matching may contradict other quality level parameters. The above list is in order of preference by material in those same tests. A single-strand silver cable outperformed a single-strand silver-plated copper cable in the Croft system. A multistrand nickel cable outperformed a multistrand copper cable in the Naim system. To compare multistrand silver with single-strand nickel in the croft system would be as useful as trying to compare a Decca London Maroon with a Shure V15iii, two ancient cartridges with cult followings, but neither would work well in the same pickup arm as the other.

To compare the multistrand silver-plated copper to the single strand nickel using the Naim system would be like trying to compare the early Linn Kans to 15 ohm BBC LS3/5a, both bandwidth limited little sealed boxes with Kef B110 bass units and cult followings too; they'd never both give of their best on the end of the same system. That exercise merely compared different materials with simple constructions; there are many different insulations, each with unique behaviour and advocates. Some cables have compensating networks, some make a virtue out of spacing conductors, some out of twisting them tightly, some out of braiding them, some out of strands of particular cross-sections or combinations of cross-sections and the output characteristics of the source component will react via the cable with the input characteristics of the receiving component, wherever they are in the system. Some commentators have found that raising cables off the floor or preventing them from touching shelves or racks improves the sound.

I have tried the above experiment many times over, when optimising systems for people, with choices of same construction but different materials, and different construction same materials. It is always the case that the source or pre-amplifier component that favours unshielded single-strand copper over shielded multistrand copper, will also be better with unshielded single-strand silver than shielded multistrand silver. The same applied with nickel conductors, silver-plated copper conductors, etc. Likewise, sources that favour multistrand over single-strand will do so whatever are the materials, provided both under test use the same materials. Likewise, plaited conductors, woven conductors, separated conductors, etc.

Every time a component arrives for review I go through my cable stable until I try the best match for it and the same rule applies now as did with those early tests with the Croft and Naim pre-amps. Curiously, modifications may affect the preferred cable type. My Shanling CDT100c now favours a loosely twisted pair, whereas it previously favoured a tightly twisted quad. Speaker cables are very different from interconnects, being completely dependent on the speaker load and more subtly affected by the power amplifier.

Some of the more complicated constructions, like woven conductors spaced from a central earth, presumably work really well with components from the same stable, but my own experience of novelty constructions is that they are temperamental divas, when it comes to working with other equipment. I did make a prototype using a pair of ptfe insulated thick nickel single-strand, a pair of thinner silver single-strand (I don't recall the insulation material) of equal DC resistance, connected as a symmetrical twisted-quad construction, that drove a bus through the multistrand vs single-strand hegemony, thus proving that nothing is straightforward where cable is concerned.

I also took a loosely twisted quad (unshielded) of ptfe insulated nickel solid cores of 2 diameters that had served well in that form and twisted it tightly together (using an electric drill). On resoldering the original plugs with the same silver loaded solder from the same reel as before and plugged it in. In order to try to identify the expected improvements from tightly twisting, that I had anticipated from reading both manufacturers' blurb and DIY accounts, I had made notes of an A-B comparison with my usual reference. On hearing the new version of the cable I was astonished. It sounded obviously inferior. This ran counter to my expectations from everyone else's accounts. I undertook another A-B comparison with my reference, which had been stronger in some areas and weaker in others compared to the prototype. Now the prototype was consistently inferior. There was no comparison to the mk1 version. Dynamics were reduced, soundstage shrunk, bass lighter, yet on paper this cable was identical to before except for the tight twist. Perhaps capacitance changed due to the close more equal proximity, or microphony increased due to triboelectric effect as a consequence of such a capacitance increase. It is a salutory lesson to me never to take anything for granted with respect to cables.

A possibly related experience is that I have sometimes found cable dressing to have as significant an effect as differences between two superficially similar cables from different manufacturers. There are many audiophiles, and numerous manufacturers offering products to feed their paranoia, lifting speaker cables from the floor or carefully dressing interconnects away from shelves. I am one of the paranoid interconnect dressers, I'm sorry to admit, after noticing these differences.

[direction clear from red & blue labels at each end]

So, how can any reader expect to emulate the same conditions as the writer?

I hope I have found a way to test an increasingly popular cable feature, a feature that is offered by several manufacturers and suppliers with various of their range. Thus this would be a test solely of that feature, that uses a method that arguably eliminates listener bias, expectation bias and test set-up bias. Equally I hope that this exercise may cast some light on subjective evaluation technique, and the role expectation plays in influencing results.

  • This test can be genuinely double blind!
  • This test completely avoids group psychology bias!
  • This test elegantly swerves around the phenomenology of equipment encounters!
  • This test could make this reviewer look foolish!

Given that it is my experience that cable reviews are almost useless, because the construction of each cable affects its relationship with the equipment it is connecting, identical construction must be used for every feature except that under test. Thus the difference should be apparent in a well matched system, and equally might in a poorly matched system. An interconnect is chosen, because these are often those with the most elaborate treatments and constructions and also where this treatment is most commonly offered. More particularly, it is my experience, shared with may others I have asked, that the 'sending' or 'source' component has a profound effect on the success, or failure, of any component-cable combination, so as diverse a range of source components as possible will be tried.

So, to establish whether a particular material or process is effective in itself, one would need to have a cable of identical construction but different materials.

And the tester should not know which is which.

However, the tester still knows that one is different from the other, so will be seeking to hear a difference, rather than answer "Is there a difference at all?". If the tester were presented with 3 samples that look identical, apart from being marked (X, Y and Z for example), the tester has no idea which are supposed to be different. So that is what we will undertake.

Graham Nalty, designer of the very successful Sonic Link range, made some of the original experimental cables I investigated in the late 1980s so I approached him for this experiment. Graham is now now designer and proprietor of Black Rhodium cables, a 1992 name change he hopes draws attention to the considerable advances he believes have been made in cables in 20 years. On hearing my proposed experiment, Graham, was immediately enthusiastic. As a scientist and engineer by training Graham is sceptical about cable claims, and by whether theoretical improvements will be borne out in audible practice. Graham has a constant stream of prototypes arising from his blue-sky thinking, many of which I've been able to audition over 20 years. Often a conductor material that Graham thought theoretically promising will prove disappointing in use and be dismissed, or one that sounds good prove to be impossible to manufacture economically. Equally, an unexpected success might arise from innovation elsewhere; the use of silicone rubber insulation arose from a conversation we had about a friends research into the behaviour of high-voltage pulses in hostile environments, which proved a step up from ptfe in speaker cables.

Graham immediately knows what he'd like to put to the test. The most popular and controversial cable feature or treatment at the moment is invisible, costly, difficult to explain by conventional physics and easy to demolish by rational argument. You've probably guessed we're talking about cryogenic cable treatment. The idea that freezing and unfreezing a cable down to nearly absolute zero (0 Kelvin or -273°C) will affect its conductivity is not new. Physicists and engineers have been investigating superconductivity for years. However, the idea that freezing there will be any vestige of superconductivity, or any conductivity improvement if cable returns to room temperature (293 Kelvin or 20°C) seems les likely. Furthermore, if there are any effects on molecular or crystalline structures by this process, surely they would be negated as soon as the wire is heated by soldering or deformed by crimping connectors?

Black Rhodium are treating their cables after manufacture to overcome these potential problems. There seem to be several different approaches to cryogenic treatment, fast cool or slow cool, fast thaw or slow thaw, stepped cooling or thawing, how long cold. Cryogenic treatment is already used in specialist metals applications (and some curious ones including Formula 1 brake components that surely get exceedingly hot and therefore demonstrate an effect not destroyed by extreme reheating) but I can't state which cryogenic treatment regime we are testing here as it is obviously information expensively gained by Graham and not for sharing with rivals.

Graham believes his Concerto cable, near the top of his interconnect range, will demonstrate most effectively whether cryogenic treatment has any effect on interconnect cable. It is a symmetrical construction of solid nickel +&- conductors in ptfe low-loss dielectric insulation screened in a silver-plated-copper braid. I still use a much earlier version of a similar cable as one of my cable armory.

[abc or bac or cba or bca or call me a cab]

The cables are marked clearly A & B & C. It is obvious which end is which on each one, shown by a red band round the stereo pair at one end and a red band at the other. Each is used in the same direction so that we can eliminate cable directionality as a variable. One of the cables will be treated cryogenically. One of the cables will be untreated. A pair of cables like this would constitute a blind test, if the person auditioning is not the person making the connections. The listener would not know which was which, but they would know that there is a difference between the samples A & B and so would be psychologically preconditioned to notice and identify differences.

This test introduces a third cable, which may be treated cryogenically or it may be untreated. This is what makes this test matter. This is a genuinely double blind test. I do not know whether I have been supplied with two cryogenically treated cables and one untreated cable. I do not know if I have been supplied with two untreated cables and one cryogenically treated cable. Equally, I do not know if Graham has supplied me with three identical cables to check whether I'm suffering from reviewer auditory hallucination syndrome!

Three sample cables

  1. Black Rhodium Concerto cable A
    may be cryogenically treated or may be untreated
  2. Black Rhodium Concerto cable B
    may be cryogenically treated or may be untreated
  3. Black Rhodium Concerto cable C
    may be cryogenically treated or may be untreated

Graham made the cables up within a couple of weeks and I collected them with eager anticipation. I remind Graham that I will publish the results before I know the identity of the cables, and that I will correlate the results of many listeners to increase the statistical validity of the results. Shortly afterwards Graham Nalty tells me that Martin Colloms, doyen of UK hifi journalism in HiFi News, formerly HiFi Choice and most recently HiFi Critic, likes the idea of a double blind cable test so much that he requests an identical test set.

If I hear no difference it means one of three things:

  1. That there is no audible benefit from cryogenic treatment of this cable in the context of my system
  2. That my system resolution is not good enough to demonstrate the difference
  3. That my ears are not good enough to hear the difference between treated and untreated cables

If a significant proportion (more than 50%) of people do hear a difference between these cables it means one of two things:

  1. That Cryogenic treatment of cables somehow alters their transmission/conduction of audio band AC
  2. That more than 50% of hifi listeners can be deluded, and share the same delusion, even if they are not told the effect of the delusion

Unlikely as it seems, the latter condition is possible in group behaviour.

I began my own listening, and note what I hear. My two sons (12 and 14) listen and report hearing similar. I pass the three cables on to another listener.

[abc or bac or cba or bca or call me a cab]


My views on the lack of universal applicability of reviewing bits of wire are already well documented. Undertaking this test challenges my own prejudices against cable reviews, as its results effectively review just one variable in the cable domain.

This test also challenges established custom & practice (aka habit) in that it tests the cables in numerous combinations of equipment. The identical basic construction renders compatibility questions null. Only the cryogenic treatment is under test.

Finally, if a majority of the panel of listeners reliably hear clear differences that I do not hear, you really will have to reassess the reliability of my reviews, as I will have been demonstrably cloth-eared.

[Go to Part II]

Music enjoyed during writing this proposal

  • Sly & Robbie: Make 'em move, compilation of some their 80s Island productions, including the superb Bass & Trouble
  • Neil Young: Live at Massey Hall 1971, newly released cd in a cardboard sleeve, theoretically superior to those nasty fragile jewel cases, but so tight the cd may eventually suffer dust abrasion; sometimes you just can't win. Great concert disc of one of my favourite artists, buy it now.
  • Muse: Black Holes and Revelations, in a splendid gatefold sleeve of mostly cardboard, with a well-made plastic holder for the cd. All cd cases should be this good.

The Neil Young was bought from the splendidly named independent record shop Morning After Music in Machyntlleth in North Wales, where despite being only a passing through visitor I enjoyed a long and knowledgeable conversation with the proprietor who told me about gigs and festivals I might enjoy. This is a proper record shop and such places deserve your custom; they're the nodal points of networks of real musical enthusiasm, without which we'd be force-fed a diet of bland corporate AOR, not so much an opiate of the masses as a barbiturate of the imagination.

© Copyright 2007 Mark Wheeler - www.tnt-audio.com

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