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I am contemplating a new design for speaker cable stand-offs. I am unable to find support, only opinions, about static electricity produced by carpet affecting AC current between amplifiers and speakers. Does it affect sound quality or does it endanger electronics used in speaker crossovers?

SamGibson
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Mark Morris
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    Have you ever seen this done? Have you ever heard of static causing a speaker cross over to fail? Have you got any evidence that anything needs to be done? – Andy aka Nov 11 '20 at 15:27
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    This is entirely irrelevant. – Chris Stratton Nov 11 '20 at 15:33
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    Audiophiles seem to do that. There is no electrical function to it though. Surely the amplifiers are rated to withstand standard static electricity tests or they would not be able to sell those to people with cables snaking over carpets. Speakers have extremely low impedance and rarely an ESD surge would pass in and out of speaker terminals anyway. – Justme Nov 11 '20 at 15:33
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    If static could travel through your carpet across the room to your speakers then walking your carpet wouldn't produce static. The whole reason static develops is because the electrons gets trapped and are unable to move a great distance after being rubbed away. You can transfer this trapped charge to a conductor which then easily carry it away, but this isn't your carpet either. – DKNguyen Nov 11 '20 at 15:45
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    I have never heard of convincing evidence of any such problem and half my career has been at the higher quality end of audio. –  Nov 11 '20 at 15:45
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    @BrianDrummond Maybe your ears just aren't good enough :P – DKNguyen Nov 11 '20 at 15:46
  • Static is hazardous to IC's because they have a ludicrously thin glass layer internally, made to resist about 5V, and an ESD zap can be in the thousands of volts. Punch through that layer and kill it immediately. A crossover does not generally contain such fragile components. Further it usually has big capacitors, resistors and inductors, that would 'absorb' the ESD zap long before it could deliver any significant voltage to anything. EE's who buy into audiophile claims are few and far between. 99% of us know it's almost all BS. – Kyle B Nov 11 '20 at 16:45
  • @Justme - I spell it 'audiophools'. – Michael Harvey Nov 11 '20 at 22:50
  • If you're talking about standard passive speakers, the impedance is low (8-16 ohms) and hence the current level is relatively high. "Normal" static electricity will have no effect. – Hot Licks Nov 12 '20 at 01:05

2 Answers2

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Beware the "audiophile" hi-fi market, there is a lot of very dubious product sold, often at crazy prices, to exploit and generally befuddle the innocent.

In this category, we might include items such as:

  • speaker cables that claim to have almost magical properties, including but not limited to, directionality. The function of a speaker cable is to make a reliable connection of lowest possible resistance from amplifier to speaker. A few 100pF of capacitance and similarly low inductance is of little concern in any normal living room environment. A piece of heavy duty mains flex, available for a few cents/pence per metre is fine.
  • equally, line level interconnects which are attributed similar magical properties.
  • just about anything labelled as "cryogenically treated".
  • ditto anything that mentions quantum effects for no good reason (and there really is no good reason in audio engineering).
  • other odd things, like little wooden blocks for keeping cables off carpets.

I hope that helps.

EDIT : I guess some technical explanation might support the argument. So let's consider what happens when you walk around, wearing rubber soled shoes on a carpet, then touch (say) the metal radiator, resulting in a loud "crack" of static discharge.

What is going on here is that your body, which is more or less conductive, is very highly insulated from earth by the shoes (we are talking probably hundreds of megohms, maybe more). There is no current path from your body back to earth as you walk. In addition, the carpet and rubber are conspiring to build up an imbalance of charge between you an earth, because of friction. When you touch the radiator, your body is some significant voltage (I have no idea how much) away from the metal, which is very well connected to earth. You discharge very suddenly, possibly dropping your glass of expensive single malt and uttering a loud expletive in the process.

Now let's take the case of the speaker cable trailing across carpet. There are a number of key differences:

  1. The cable doesn't walk around. There is no significant friction. (It also doesn't drink whiskey or swear.)
  2. The cable has a rubber or plastic jacket, but the internal wires connect to the amplifier, which ought to be connected to earth by a fairly low impedance path. The wires are NOT isolated. There is really no possibility for significant charge to build up.

So we see where the idea comes from, but, as usual with this kind of thing, it lacks any form of foundation in reality. If there WERE a problem (there isn't) the logical thing would be to create a good low resistance path to earth - NOT to increase the isolation by using little wooden supports.

It's really a very silly myth designed to part the ignorant from their cash in an efficient manner.

danmcb
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  • I guess if you shuffle on the carpet enough to charge *yourself* up to a few thousand volts while the speaker leads remain actively held at ground potential, and then you touch the speaker leads? A bit of stretch, I know, and cable standoffs would do absolutely nothing for or against it. Then there's the passive output filter components of a switching (class-D) amp, or the always-on transistors of a linear one. Seems like either of those should absorb a few pC just fine. – AaronD Nov 11 '20 at 23:54
  • So you're saying you don't have speaker cables with 6 cores of mono-crystalline silver, insulated with a double layer of Kapton and PolyEtherEtherKetone, shielded with a dense braid made of mono-crystalline copper silver plated wires with an extra shield made of mono-crystalline gold-plated silver wires hanging well off the floor on antistatic wires? – ocrdu Nov 17 '20 at 15:38
  • @aarond the biggest danger in that case would be static damage to the output stage, but unlikely to affect anything other than mosfets, and modern ones are pretty rugged, also the designer ought to protect against such events. – danmcb Nov 20 '20 at 17:05
  • @danmcb I'm not sure it would even need much protection. At first glance, the L-C output filter of a switching amp would both absorb a static arc (C) and then impede what remains (L) from hitting the fets so hard. For a linear output stage, they're always on to some extent, behaving more like resistors than switches, and so the packet of charge flows nicely through them to the power rails. I guess a slow "error amp" and fast output devices might get it into a state where an output device sees a voltage spike and turns off before the charge is all gone. *That* I can see as a problem. – AaronD Nov 20 '20 at 18:00
  • Indeed it's not an issue I've ever seen arise – danmcb Nov 22 '20 at 06:15
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For years I struggled with sound that was too bright. I have a medium quality tube amplifier and horn speakers. Accidentally I discovered that nicely separating interlinks from current cables and lifting my mainsblock and cables from the floor on small wooden stands made the sound smoother. Isolating the plugs of interlinks and speaker cable with a bit of foam tube also works. Actually, there's nothing better than grounding your amplifier and cd-player. Putting wraps from Entreq over your plugs also works the treat. It's expensive, but my ears are too sensitive for bad sound (hard hearing and tinnitus). Sceptics beware, hold your jokes and comments, because in my case shielding cables works. I'm a happy audiophile now.

Charlie Dix
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