Yesterday I saw a press release via the Premier Guitar Twitter feed announcing Dean Markley Blue Steel instrument cables. Promising all kinds of magical tonal benefits due to the cable receiving a brief blast of liquid nitrogen. I say it’s pseudo-scientific nonsense. Dean Markley say that’s just my opinion. Well, this is how I, a guitarist and physics PhD, arrived at my opinion…

First let me point you to their press release: https://www.premierguitar.com/articles/26249-dean-markley-releases-blue-steel-instrument-and-speaker-cables

Lets quote some of the claims Dean Markley make about these cables…

“…wider and more dynamic range with smoother, more refined highs and deeper and more articulate bass. Players will immediately notice the super brilliant tone…

 

They can be used with both analog and digital gear to produce organic, three-dimensional sound quality.

Sounds very impressive. Magical, even. How are they supposed to make this happen?

“…a quick blast of liquid nitrogen that tightens the cables’ molecular structure, removing transient material that produces harsh highs and muddy lows.

Sounds kinda like science! Oddly, if you take the time to play the video accompanying the press release, you’ll notice that any difference in sound between the cables is small, at best, and fails to support any claims they make. That’s because those claims are nonsense. Here’s why…

Now, if I am wrong in what appears below, I will happily put a retraction at the top of the page in bold text and announce it publically. But I challenge Dean Markley to publish justification for their claims with appropriate real data that can be verified. Dean Markley are making the claim here. The burden of proof is theirs, not mine.

Now, let’s first point out that we are talking about a very specific electronic situation: musical instruments with passive electromagnetic circuitry. Audio frequencies are LOW in the grand scheme of electronic things, no higher than 20 kHz, which is the generally accepted limit of human hearing. Most adults can’t hear much above 16 kHz, and that decreases with age. FM radio typically doesn’t broadcast above 12 kHz. The speakers in guitar and bass amplifiers generally don’t produce much above 8 kHz to 10 kHz. For electric guitar and bass guitar, anything over approx 2 kHz is regarded as high frequency, and below about 300 Hz is bass. Electrical engineers designing signal transmission lines deal with much higher frequencies, into the MHz (mega Hertz) range, where cable characteristics can be critical. But not for us; instrument cables are not rocket science. There are only three parameters we need to know how our guitar signal will be transmitted. They are; resistance, capacitance, and inductance. That’s it, that’s all. In principle if we know about the materials and cable dimensions we can calculate the resistance and capacitance and inductance. But it’s not necessary because with instrument cables we can simplify things greatly…

Our instrument cables typically plug into a very high resistance at one end: the amplifier or effects pedal, which may typically have in input impedance of 500 kΩ or 1 MΩ. At the other end of the cable is our instrument which may have 250 kΩ or 500 kΩ control potentiometers in parallel for volume and tone control and of course 6 kΩ-12 kΩ pickup coil resistance. The resistance of our cable is less than 1 ohm. Clearly, cable resistance is many thousands of times smaller than anything else in the circuit. We can ignore cable resistance completely.  A quick blast of liquid nitrogen could (briefly) reduce it further but we already don’t care.

The same is true of inductance. Our instruments contain a “pickup” coil which have an inductance usually in the 2 H – 6 H range (the ‘H’ is the unit of inductance called a “Henry”). But cable inductance is typically very tiny, measured in millionths of a henry. Again, we see the cable contribution of inductance to the circuit is so small that we can completely ignore it. No short blast of liquid nitrogen will make a significant change to the cable inductance.

So, for passive electric guitars and basses, capacitance is the ONLY relevant characteristic of the cable that relates to how our guitar sounds. And cable capacitance does make a difference. Like inductance, cable capacitance is a function of the insulator material and cable dimensions. Instrument cables typically have a capacitance around 30 pF/ft, sometimes higher, sometimes lower. I think it’s a reasonable guess that many guitarists and bassists, given a side-by-side comparison, can hear the difference between two cables with a 20 % difference in capacitance.

So, could a quick blast of liquid nitrogen could cause a permanent change in capacitance that large or larger? No, I don’t think it could. But for the sake of argument, let’s say it could. Our next question is whether it could it produce the claims that Dean Markley make? I say, no way, absolutely not. Here’s why…

In instruments with passive electronics, cable capacitance interacts with the pickup inductance, volume pot resistance, and amplifier input impedance to shape the frequency response of the guitar-cable-amp circuit. When we change cable capacitance we shift the resonant frequency of the circuit, which is typically in the range 2.5 kHz – 3 kHz. In addition we have strong low pass filtering (12 dB/octave) attenuating all frequencies higher than the resonant peak. In general, cable capacitance is not good thing for passive pickup electric guitars and basses, we usually want to avoid that high frequency loss that comes from our cables. We often call it “tone suck” and it gets worse as we as we turn down the volume pot on our instrument.

What’s important to note is that all frequencies below the resonant peak, what we call mids and bass in the guitar world, remain unchanged. This means that all cables perform identically below the resonant frequency no matter what what or how they made. This also means that all cables with the same total capacitance value sound exactly the same. (See here for a great explanation and demonstration of this at the Ovni Labs website.)

This means there is nothing you can do to get “deeper more articulate bass“. Note that “deeper” here implies “more at lower frequencies”, which is simply not possible from any passive device or circuit (which can only give you less of anything).

Could their cables have “smoother, more refined highs“? Well, first Dean Markley need to tell us what “more refined” means in terms of frequency content because until they do it’s meaningless. How about “smoother“? I think most sound engineers and guitarists would take that to mean reduced high frequency content relative to other frequencies. We know that’s possible; just increase the cable capacitance and hey presto, less highs and smoother tone (or darker or muddier, depending on your taste). But Dean Markley also claim “super brilliant tone“. Brilliance in music and audio generally refers to additional high frequencies compared to something else. That suggests a lower capacitance compared to other cables. Have Dean Markley contradicted themselves here? Sure seems like it to me.

And let’s not forget cable length. Cable capacitance (and thus the frequency response of our guitar to amp circuit) depends on the length of the cable. Double the cable length and you get double the capacitcance, which means loss of high frequencies. Two pieces of the same cable of different length will sound different. Dean Markley’s 30 ft long cable will sound very noticeably darker than their 10 ft cable. This alone is enough to negate Dean Markley’s claims – they can’t claim both cables have “super brilliant tone“.

If Dean Markley would tell us the capacitance per foot of their cables we’d know how they compare to some other cables on the market at different lengths. Sadly, they are one of too many instrument cable sellers that don’t offer that information. For me, all this magical verbiage in their press release tells me precisely nothing.

And then there is active electronics, as in instruments with active pickups, or using the cable to connect a non-true bypass effect pedal and an amplifier input. Active circuits have a low output impedance, a few tens or hundreds of ohms. Why? So that any high-frequency loss due to cable capacitance is avoided for cable lengths shorter than about 50 feet. As we saw with the Ovni labs webpage above, all cables perform identically under these conditions. Also see this excellent demonstration by Pete Thorn and Thomas Nordegg, and this longer discussion by Dave and Mick of “That Pedal Show”, of how cable length affects high frequency loss and how active buffer circuits cures it. Again, note that only the high frequencies change, not the lows or mids.

Remember this from the press release: “”…a quick blast of liquid nitrogen that tightens the cables’ molecular structure, removing transient material that produces harsh highs and muddy lows“? That sounds like impressive science to some but I need Dean Markley to explain it, because my scienctific background includes enough polymer science and metallurgy that my baloney detection alarm is ringing loudly. What is the “transient material” you refer to? What is “molecular tightening“, i.e. what phase change could occur in a polymer or pure metallic copper due to a “quick blast of liquid nitrogen” that won’t revert to its previous state when the cable returns to room temperature? How would this change the cable capacitance and produce the results you claim? If you can’t answer these questions with a plausible, testable explanation you can not make the claim.

So, you see now why I describe this marketing as pseudoscientific bullshit? Monster Cable Inc do this too; their “time correct windings” and “magnetic flux tube technology” are somewhat based in real science but applied in a situation where it makes not one iota of difference.

And this angers me because it takes advantage of people, who through no fault of their own, lack the specific technical knowledge to know that these are empty claims. People work hard to pay the costs of pursuing their musical hobby or profession and these companies will blatantly lie to them to get their money. Confirmation bias in audio is so ingrained in the human brain, so difficult to avoid, that “emperor’s new clothes” are a really easy sell: in the absence of an easily recognisable difference, we believe we hear what we expect to hear. This is a pervasive problem throughout the guitar industry, and pro audio, and has been for a very long time. But that doesn’t make it any less unethical or immoral.

OK. Time to give Dean Markley some “benefit of the doubt”.

Dean Markley may still be selling a really nice cable. All cables are not created equal: in addition to capacitance, shielding, handling noise, and durability count for a lot too. Maybe they’ve done a great cable design job here. Or maybe they’ve bought a quality cable from a big cable manufacturer, dressed it up and stuck their logo on it, which would be totally fine and what many companies do anyway. But I they should do something important when they sell it…

Stand by your product for what it really is!

Guitar and bass players care about their tone. We know cables make a small difference to our sound, one the audience won’t notice, but it is important to us. Don’t market to us a ton of bull. Tell us what we need to know. Tell us how the cable really compares to others on the market, in real meaningful terms. And don’t ever assume your customers are less smart than a marketing department with an ethical deficit.

Do that and you will win lasting brand loyalty and respect.

Updated 24 Nov 2017: Edited, one or two typos fixed, tightened up and shortened some paragraphs.