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Pear Cable Redux: How to Combat Scam with Science

by May 10, 2008

A Case Study in Applying an Audioholics A/V Education to Identify Marketing Drivel

In our first article, we looked at the saga of Pear Cables and the challenge by the James Randi Education Foundation to prove that some seriously overpriced Pear Anjou speaker cables made any difference in controlled testing conditions compared to common Monster Cable. Much smack talk ensued from both sides of the challenge, but ultimately, Head Pear Adam Blake turned tail and ran.

In this follow-up piece, we will look at Pear Cable as a case study in evaluating exaggerated marketing claims about the audio performance improvements attributed to cables. We will use known science, established engineering principles, and the educated opinions of well known audio engineering practitioners to look for contradictory statements, mistakes and misuse of engineering knowledge, and exaggeration of the audible significance to certain aspects of audio performance.

Pear Cable was chosen for this case study not to specifically single the company out, but because they are currently a high profile example of just what Audioholics has spoken out against when dealing with unfounded advertising claims based on sciency sounding jargon without any real root in science. The same analysis can be applied to any other cable manufacturer who uses exaggerated or fictitious claims to sell product. Pick a favorite overpriced audio cable manufacturer, strip the words Pear Cable out of the article, and insert the other manufacturer’s name. Yes, the particulars will vary, but the over-hyped claims and misuse of scientific principles always leads to the same end.

The controversy surrounding the claim to audible improvements due to cabling are widely known and the effects of wire are generally reported as insignificant by many sources outside of subjectivist audiophile circles. Numerous engineering experts in various fields of electrical, audio, and loudspeaker engineering have also stated this opinion. Such experts include Dr. Howard Johnson of Signal Consulting Inc., John Dunlavy most recently of Dunlay Audio Labs, and Roger Russell formerly Director of Acoustic Research for McIntosh Laboratory. Each of these gentlemen has spoken out against exaggerated claims of cable effects on audio reproduction in various venues; Mr. Russell, the man behind the McIntosh Loudspeaker Division from its inception in 1967 until 1992, goes as far as actively criticize exotic cable performance claims on the web site he maintains.

Several important questions must be answered when evaluating marketing claims for scientific validity about the effects of cable design on audio performance:

  • What established scientific knowledge supports the purported design issues?
  • How is established science applied to provide an engineering solution to these issues?
  • Do these issues produce significant audible effects that warrant design effort and cost?

We will take an extensive look into just these questions.

I will start by referring readers to Audioholics’ extensive library of documentation debunking nonsense cable design based on published research, mathematical calculations, and well known engineering principles that are supported with opinions from academics, practitioners, and other cable manufacturers who do not push over priced, high profit margin exotic cables. Several overview articles are linked here and many others are linked with specific topics:

We will find that every topic Pear claims is important to cable design has been debunked as nonexistent, inaudible, or insignificant at audio frequencies. Coupled with the fact that exotic cable designs are not used by the professional broadcast and recording studios that produce the recordings in the first place, this non-issue of cables is further diminished in significance.

Measurements: A Wealth of Scientific Information, and Expert Opinion

In the email correspondence reproduced on Gizmodo, Mr. Blake took umbrage at James Randi for calling Pear’s cable science junk. In between bouts of disparaging Mr. Randi for a high school education, Mr. Blake stated that Pear Cable’s performance claims are backed by all sorts of measurements, a wealth of scientific information, and expert opinion.

What measurements, scientific information, and expert opinion back Pear Cables, one might ask?

Let’s examine this claim of substantiated proof that cables make an audible improvement to sound quality based on the cited references.

Measurements: a single frequency response plot of some unnamed Pear cable on the web site.

Scientific information: an unsourced statement about RFI effects on speaker cables from the American Radio Relay League, an amateur radio association:

Although this high frequency noise cannot be heard directly, it has been well documented by professional organizations such as the American Radio Relay League that RFI can still be a problem in audio applications.

Pear Cable: Anjou Speaker Cable

Expert opinion: testimonial by some guy named Richard from the Bay Area Audiophile Society supposedly based on blind testing:

The Comice Silver Interconnects kick some audio butt.

- Richard, Some Guy

The ARRL is not a professional organization, it is an amateurs or ham radio organization.  While the ARRL does provide an extensive array of educational and general technical information about radio broadcasting for its members, as an amateur organization, it is not a suitable to support professional opinions or conclusions as an engineering reference.

Furthermore, without any particular source cited for the statement there is no way to evaluate the applicability of what the ARRL might have said regarding RFI and audio to this particular audio application.  A group like the ARRL is much more likely to be discussing the problems of parking several thousand watts of RF broadcast amplification next to the neighbor's consumer audio gear than to be discussing the need for very expensive audio cables to solve the problem of random stray radio interference on someone's hi-fi.

As to the other two components of proof that Pear Cables is addressing legitimate cable engineering issues, well...

The testing conditions of the provided measurement are poorly documented at best and really are completely out of context making them worthless.

Finally there is some guy named Richard who really likes his stereo so much he joined the Bay Area Audiophile Society, a group of people who also really like their stereos.  I think the scientific validity of this one speaks for itself.

A Summary from the One Legitimate Reference

There was one reference provided in Pear’s response to the challenge that seems a more reputable source for engineering information, an article on Audio DesignLine, Loudspeakers: Effects of amplifiers and cables, a reprint of excerpts from the book Loudspeakers for Music Recording and Reproduction, authored by Philip Newell, acoustics consultant and Keith Holland Ph.D., Institute of Sound and Vibration Research, University of Southampton. The article, in six parts, concerns the effects of speaker cables on both audio recording and reproduction. After some introductory information on amplifiers in the earlier sections, part 4 and part 5 gets into the question at hand.

On the surface, this article does seem to support Mr. Blake’s claims about audio cables; that is until one actually reads it. According to the article, cables can sound different but not exactly for the reasons typically espoused by cable manufacturers to support buying overpriced cables; a view head Audioholic Gene DellaSala shares and espouses regularly on this site.

The general electrical behavior of speaker cables and amplifier/cable/loudspeaker circuit can be summarized:

  • Low impedance is important to speaker cable
  • Impedance is dominated by resistance at low frequencies
  • Impedance is dominated by inductance at higher frequencies
  • Capacitive reactance is insignificant compared overall circuit impedance and will only affect signals that are well over the +100 kHz range

The article discusses test results obtained from various combinations of amplifier, loudspeaker, and cable types over different cable lengths. I will summarize (note the trend in cable length):

  • Cable properties can be shown to affect the impedance interaction of certain amplifier/cable/loudspeaker circuits with 6 meter (19.5 ft) cable lengths
  • Esoteric geometries (Litz, bi-metal plating, etc.) only seem to show any significant reduction of skin effect for long cables, over 10 meters (32.8 ft)
  • EMI interference is negligible for various 5 meter (16.4 ft) cable designs but become pronounced and varied at 50 meters (164.0 ft)
  • Various amplifier class topologies showed different susceptibility to interference on various 28 meter (91.9 ft) cable designs
  • High sensitivity speaker drivers are more susceptible to interference
  • Different cable construction will behave differently in impedance and noise rejection

Summarizing what these fellows are saying about cable affects on audio performance:

  • Unstable esoteric audiophile amplifiers that are overly sensitive to cable properties are the real culprits
  • Any effects from cable properties are so system specific that there is no general solution to improve sound quality with cables
  • There will be no difference in properly designed cables below 2 meters (6.7 ft) length irregardless of amplifier/loudspeaker combination
  • Using the shortest, lowest impedance cables possible is the only universal way to minimize effects of cable electrical properties

Any perceived difference in performance due to cables has more to do with esoteric audiophile amplifiers used in home audio, amplifiers that do not have robust, stable designs. The types of overly sensitive amplifiers, beloved by audiophiles, can be knocked out of kilter by cable properties that are not complimentary to their idiosyncrasies when coupled to a particular loudspeaker. As the authors clearly state:

An idiosyncratic, 8 watts per channel valve amplifier has rarely found a home in a professional recording studio, and especially not if it cost 5000 euros or more.

It is therefore worth re-emphasizing that the innumerable stories about either input or output cables magically changing the sound of domestic equipment (whilst a giant and highly respected organization such as the BBC has 'no policy' on esoteric cables) are more a testament to the sensitivity of much domestic equipment to minor changes in termination than to the general importance of esoteric cable design or materials of construction. However, that is not to say that cables are cables, and that any cable will suffice for connecting a loudspeaker as long as it manages not to catch fire at full volume.

Loudspeakers: Effects of amplifiers and cables

If one owns an amplifier that gets squirrelly with certain cables or is even bothered by cables at all, it is best to consider a better, not necessarily more expensive, amplifier that is not so touchy because using cables in this way does not solve the fundamental problem that still exists with the amplifier. It is this engineer’s opinion that any properly designed amplifier, one with low output impedance, proper usage of negative feedback, and a good power supply, is the best way to solve cable problems, and it would seem to be the solution favored by the authors as well.

One great problem about generalising about many, or most, of the effects of the performance of loudspeaker cables (once the basic properties of resistance and inductance have been adequately specified) is that their effects can be so system-specific. In other words, what occurs with one combination of amplifier, loudspeaker and location may have very little in common with what occurs with a different combination.

Loudspeakers: Effects of amplifiers and cables

Ideally, cables should have no effect on audio quality whatsoever; they should be a transparent transmission medium. Any movement towards this ideal due to cable interaction with other system components only reduces detrimental effects to sound quality, a subtle but important distinction from the idea of improvement that is bandied about. Because of the massive number of possible permutations in available amplifier/loudspeaker combinations, it is essentially a random phenomenon. This means that there is no single cable design that could work with every possible combination to minimize deleterious effects to sound quality through complimentary properties. It far more likely that a particular cable design will not have any effect on audio quality at all and, although a remote possibility either way, at least as likely that the cable properties are not complimentary to a particular system as it is likely that they are complimentary. This is most certainly not what high priced cable manufacturers are claiming when they try to sell their wares.

This leads back to the Audioholics stance that any properly designed cable is as good as any other. The basis of the statement is supported in probability.

Best of all, following publication of Mr. Blake’s cited reference on Audio DesignLine, Managing Editor Rich Pell, BS Electrical Engineering, had the following to say concerning the aforementioned article on audio cable differences:

So what's the most reasonable presumption concerning audio cables? Technically, there's little or no reason to believe they should sound different under most normal circumstances, and there's every reason to be skeptical about claims to the contrary. Also, trying to prove a negative - in this case that audio cables don't sound different - is difficult, to say the least.

In court, it isn't up to the defendant to prove him/herself not guilty - it's up to the prosecutor to prove that they are. Likewise, the onus is on those who claim that audible differences commonly exist among cables to prove their case - that cables are "guilty" of sonic differences.

Have they? Not as far as this juror is concerned, which leaves only one possible verdict: Not guilty.

Case dismissed.

Rich Pell: Are audio cables guilty of sonic differences?

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About the author:

Professionally, David engineers building structures. He is also a musician and audio enthusiast. David gives his perspective about loudspeakers and complex audio topics from his mechanical engineering and HAA Certified Level I training.

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Recent Forum Posts:

Clint DeBoer posts on May 13, 2008 14:52
Never let is be said that our reviewers can't take a hit. lol
AdrianMills posts on May 13, 2008 12:23
David Waratuke, post: 411992
Nope, just clearing up some misinformation suggested in one of the posts.

Appearantly I was unaware of how touchy a subject ham radio is for the operators. There were a lot more unhappy feelings in some of the posts than I would have expected for such a minor mention of the topic for a percieved slighting that was certainly not intentional.

David

Welcome to the WWW.
DavidW posts on May 13, 2008 12:19
Clint DeBoer, post: 411867
Oh my gosh, David - give it a rest will you. Last time I checked, the point of the article wasn't to insult Ham Radio operators.

Please send me some recommended changes and go find something else to defend your honor on.

Nope, just clearing up some misinformation suggested in one of the posts.

Appearantly I was unaware of how touchy a subject ham radio is for the operators. There were a lot more unhappy feelings in some of the posts than I would have expected for such a minor mention of the topic for a percieved slighting that was certainly not intentional.

David
Clint DeBoer posts on May 13, 2008 11:54
Article updated with submission from David… Red chicklets given to David, lol
gene posts on May 13, 2008 09:48
Oh my gosh, David - give it a rest will you. Last time I checked, the point of the article wasn't to insult Ham Radio operators.

Please send me some recommended changes and go find something else to defend your honor on.

Agreed this is simply ridiculous. Make the necessary corrections ASAP. thanks.
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