Axiom Home Page Forums General Discussion Technical Questions Speaker Wire - Dumb Question

Time to make myself some enemies on this one...

I'm of the "wire is wire is wire" camp - except with one caveat - gauge.

Consulting a nomograph - you should be looking at about 10ga. wire for your run.

For a:
RL (load resistance) of 8 ohms
40ft run of 2 conductor copper
----
14ga. will give you a damping factor (RL DIV RS) of 40 which is low for home theatre (but fine for performance arena).
10ga. will give you a damping factor of 100.

What is damping factor? Here's what Marantz has to say about it.

Having said that... the driver size of the QS4s and their duty in the HT setup mean they don't need to be as responsive as your mains, but this is something to consider.

Bren R.

In reply to:

---

Consulting a nomograph - you should be looking at about 10ga. wire for your run.

---

Yes, but 10 gauge wire is awfully thick and hard to pull through walls. Best of both worlds would then be 12 gauge, right? I think the 14 would still be adequate for most of us.

Damping factor can be significant in system performance, but sometimes is over-emphasized. Some time ago sushi pointed out the falsity of the claim of "tighter bass" supposedly provided by some solid state amps with very high damping factors. I concurred and referenced speaker designer Dick Pierce's findings on the point. That article now appears in expanded form here in Audioholics. Note the insignificant effect on damping at bass resonance shown in the first table until damping factor is in the low single digits. The separate matter of response fluctuations due to speaker impedance fluctuations is shown in the second table(columns 3 and 4 reversed)and is of more significance than damping at bass resonance, but wouldn't appear to be of audible significance at the frequency points involved until at least a damping factor under 20.

The conclusion is that Mr. Russell's suggestion of speaker wire resistance of not more than 5% of nominal speaker impedance(i.e. equivalent to a damping factor of 20 if receiver output impedance was zero)is reasonable and allows sufficient damping factor when combined with typical solid state amps having output impedance of less than 0.1 ohm. Of course in some worst-case situations involving high amp output impedances of several ohms(e.g. many tube amps), that in itself is sufficient to cause audible inaccuracies.

For runs of about 30 feet to my QS8s, I initially used Carol 12-ga. UL wire. It was probably overkill, but was only $19.30 per 100 feet. There were no problems with flexibility or routing. http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=100-740 I planned on running the cable in-wall, but just tacked it around the baseboard since I had other changes planned. Later when the room was recarpeted I used Radio Shack 14-ga flat under carpet wires. It worked great, can't feel it under the carpet, and no detectible sound difference from the 12-ga wire. http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F010%5F006%5F000&product%5Fid=278%2D1273

10 gauge speaker wire is multi stranded and not the same as 10 gauge electrical wire which is very difficult to pull through walls.

I back up Bren on the wire gauge - just think of the electrons as water through a pipe. The bigger the pipe the better the flow. The longer the run, the more your signal attenuates (weakens) and if you start with a small gauge wire, it may reduce your sound quality or put an extra load on your amp.

In reply to:

---

I back up Bren on the wire gauge - just think of the electrons as water through a pipe. The bigger the pipe the better the flow. The longer the run, the more your signal attenuates (weakens) and if you start with a small gauge wire, it may reduce your sound quality or put an extra load on your amp.

---

Umm... I'm glad you agree with me... but I didn't necessarily make any of those points. Again, the mantra is inductance, capacitance and resistance.

I appreciate JohnK's link to the explanation of the practical effects of damping factor... I've been hoisted by my own petard, I guess the more correct wording should have been "less than optimal" rather than "low" in my original message.

Bren R.

I had no idea what a petard was, until just now when I looked it up. Here's a pic:



It's an explosive used to destroy walls. How does the saying "hoisted by my own petard" make any sense?

The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.

petard

SYLLABICATION: pe·tard

NOUN: 1. A small bell-shaped bomb used to breach a gate or wall. 2. A loud firecracker.

ETYMOLOGY: French pétard, from Old French, from peter, to break wind, from pet, a breaking of wind, from Latin pditum, from neuter past participle of pdere, to break wind. See pezd- in Appendix I.

WORD HISTORY: The French used pétard, “a loud discharge of intestinal gas,” for a kind of infernal engine for blasting through the gates of a city. “To be hoist by one's own petard,” a now proverbial phrase apparently originating with Shakespeare's Hamlet (around 1604) not long after the word entered English (around 1598), means “to blow oneself up with one's own bomb, be undone by one's own devices.” The French noun pet, “fart,” developed regularly from the Latin noun pditum, from the Indo-European root *pezd–, “fart.”

Ah, thanks for the clarification. Makes much more sense to me now. I though it had something to do with a flagpole.

Well, If you were sitting on a flagpole and there was “a loud discharge of intestinal gas,” and you fell off the flagpole you would be "hoist by your own petard."