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Buying carpet...will speaker cables laid on artificial fiber rugs degrade the sound? Myth? What to do?


garyrc

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We are about to lay new carpet.
The speaker cable must be laid over the carpet or,
perhaps laid directly on the floor, in channels cut in the rug pad (or double
rug pad, if necessary). This part of the room gets zero foot
traffic. Little tripods or overhead strings to hold the cable off of the
floor are out of the question. We hear from MapleShade (and others in the
grapevine) that "laying speaker cables, interconnects, and AC power cords
on an artificial fiber carpet will immediately
dull the sound of your stereo
." Apparently, they think that there is some kind
of electrical effect brought about by the artificial fiber … even though I tend
to doubt this, if there is some subtle audible effect, we might as well avoid it since we are laying new rug.
So, if the effect is real, does this mean:



a) A wool rug with a latex pad (natural
rubber) would not dull the sound?



B) A wool rug with a jute pad would not dull
the sound?



How can the carpet affect what is happening
in the speaker cable?





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We hear from MapleShade (and others in the
grapevine) that "laying speaker cables, interconnects, and AC power
cords
on an artificial fiber carpet will immediately
dull
the sound of your stereo
." Apparently, they
think that there is some kind
of electrical effect brought about by the artificial fiber … even though
I tend
to doubt this, if there is some subtle audible effect, we might as well
avoid it since we are laying new rug.

Will MapleShade or
"others in the grapevine" provide you with a true technical explanation
backed by data? The reason I ask is because I checked out their website
and noticed that some of their marketing material on speaker cables
doesn't agree with well established electrical theory. I'll give them
benefit of the doubt that their marketing team has run wild, but I would
fine it surprising for an engineer or scientist to claim that carpet
would exhibit appreciable electrical impact on the signal traveling
through a speaker wire.

Just for kicks, let's run a few
numbers....

The output impedance of your amplifier should be well
under 10 ohms...it's usually in the 0.1 ohm range, or even lower, but
let's just call it 10 ohms because that makes the analogy worst case.
The impedance of your speaker cable jacket should be on the order of
100,000,000 ohms at typical speaker voltages. The electrical impedance
of carpet is also going to be on the order of 100,000,000 ohms.

So
at DC, we have a fairly straightforward voltage divider where the
electrical impedance of the speaker cable jacket and the carpet are
going to present a 0.000005% reduction in the output of the signal,
which comes out to about a 0.0000004dB reduction in output. A 1dB change
in output is supposed to be the smallest discernable step-size, and
we're talking artifacts on the order of over one million times
smaller...even using an absolute worst case scenario.

Even if you
were using ESD Carpet, its impedance is still in the 1,000,000 ohm
range, but the 100,000,000 ohm resistance of your cable insulation is
still going to swamp that out.

The electrical impedance of the
human body is on the order of 500,000 ohms, so if you want to do a quick
experiment for yourself, have someone sitting by your speaker wires and
see if you can hear when they touch and let go of the speaker wire.

Granted,
these quick numbers are only back of hand DC calculations, but I see
absolutely no data to support that the impedance of carpet is lower at
higher frequencies...and even if it was capacitive at higher
frequencies, it still has to work against the ESR of the speaker wire
insulation. There's also no field to be generated on the other side of
the carpet, so there really can't be any energy storage.

So
all that to say, I really wouldn't worry about the sonic effects of
your carpet. I would, however, recommend purchasing a plenum rated cable
since it'll be a permanent install under the rug. Belden makes some
great low-inductance twisted pair speaker cable with a plenum jacket for
very reasonable prices. But given your application, I might also
recommend looking into flat cable so that the carpet can lay perfectly
flat.

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The electrical impedance of the human body is on the order of 500,000 ohms, so if you want to do a quick experiment for yourself, have someone sitting by your speaker wires and see if you can hear when they touch and let go of the speaker wire.

Love it!!!

Mike, That's absolutely one of the greatest rebuttals to snake oil marketing I've ever seen!!! [Y][Y][Y]

But then again.... what happens if a fat chick sits on the cable? Adipose tissue has a higher conductivity rate as it's the rough equivalent of "salt pork"? [6]

[H]

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But then again.... what happens if a fat chick sits on the cable? Adipose tissue has a higher conductivity rate as it's the rough equivalent of "salt pork"? Devil

Wow, now there's an image! Haha. Well I can certainly say it won't sound as good, but not for reasons of electrical behavior in the wire... [;)]

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It woud probably cost less to buy a "real" rug than expensive cables. My personal opinion is that the hypothesis is complete BS. Do a test. Lay one speaker wire on the artificial rug and arrange the other so it is not on the rug and see if you can hear a difference.

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Thanks everyone!

I'll run some tests, but it almost must be BS.

Mike: great answer!

Mark1101: Nylon is synthetic... i think it was the first! In the '40s they marketed "nylon needles" the "miracle synthetic" for one's phonograph. My old Webster Chicago (Webcor) I had when about 4 years old had one. They lasted about a month.

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Gary, this is certainly BS.

Let me tell a story.

Many years ago the office had some interns vising for a summer. Very intelligent people and educated in many ways, but not educated in the sciences. Let me say: they were willing to believe in new age notions which have the subtext that ancient truths have been unjustly suppressed by modern science, or that the new age notions are advances over present knowledge.

One of the interns got an ear ache. So they went out and tried and ear candle. http://en.wikipedia.org/wiki/Ear_candle Of course it did no good.

But then they asked me what I thought about ear candles. This was before Wikipedia..

What I thought was, "Don't you people have the sense that God Gave a Goose?" I e-mailed that back to them. No response and I suppose they were a little insulted.

That is what I think about the carpet question -- or better stated, anyone who would propose the effect to marks.

I hope you're not insulted. Smile.

Edit.

We all have to be a bit careful. Some of us here have been fooling around with wires and electonics for decades and thus have a good feel for BS. OTOH, there are hucksters out there who make authoritarian statements which are transparent fabrications. Newcomes can't always detect it.

Wm McD

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By the way.........what's the difference between artificial fiber and real fiber when it comes to rugs? Is nylon a real or artificial fiber?

And, perhaps more importantly, if a carpet is both real AND oxygen-free will the sound improve?

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  • 1 year later...

You don't need to cut channels in the pad. If the carpet pad is installed properly it will be on the inside edge of the tack strip that will grip the carpet and that won't be up against the wall either. After the tack strip and pad (go with the heaviest rebond you can afford) are installed you should be able to keep your wires just to the inside of the tack strip and have them notch the strip to allow the cable to come up tight against the base board. I would secure the wire in a couple of locations with small cable clamps that won't stick up any higher than the tack strip to make sure that the wire doesn't get over the tacks. Remember you don't walk around your house on the edge.

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