Re: Amplilfier wiring


"Stephen J. Rush" <sjrush@xxxxxxxxxxx> wrote in message
news:LOydnYXod_TpSAjanZ2dnUVZ_h3inZ2d@xxxxxxxxxxxxxx
On Mon, 21 Jan 2008 20:38:26 -0500, Dave C. wrote:

I don't know if this is the right NG to ask about the following:

I have a Sony DAV-FX500 5.1 home theater now installed which works very
well for our fairly medium sized room. I was surprised to see the wire
size to four of the speakers as small as it is. The wire size to the
two front speakers and the two rear speakers is #22 and to the woofer is
#16.

I am considering changing out the #22 wire to #18 wire. I am wondering
if the
benefit would be worth the trouble.

Amplifilier output specs are:

For each of the four speaker amplifier outputs: 84 watts, with 3 ohms
impedance each.

Woofer amplifier output: 160 watts, with 1.5 ohms impedance.

After thought: Just thinking, would the #22 wire resistance be there by
design because of the fairly low amplifier output of 3 ohms?

This isn't a transmisson-line problem. For speakers, the less resistance
between the amp and the speaker, the better. The use of 22-guage wire
was just to shave a few cents off the cost of production.

Your amp can safely drive 3-ohm loads, but its actual output impedance is
much lower, ideally zero. Your speakers are probably rated at 4 ohms.
40 watts (consumer audio amp ratings always exaggerate) in 4 ohms is Sqrt
(40 * 4) = 12.65 amps, a bit much for #22 wire if it were continuous.
Switching to #18, with more than twice the cross-sectional area, might
make an audible difference, especially if you listen at high volume.

There is a lot of bull*** slung around about speaker cables. If someone
tries to sell you expensive wire, claiming some esoteric technology, make
a rude gesture and go to a hardware store. Copper is copper (for this
application, at least), so thicker is better, period. For power levels
that you can tolerate in you living room, you can't beat lamp cord.

Thanks for the information. We are shortly getting an HDTV to replace our
ageing TV and I need to do some room and furniture revisions and is would be
easier to replace the speaker wire at th is time. We listen to surround
sound (right now via DVD) not at a theater level but a medium level to enjoy
the 5.1. No. 22 probably is probably OK as you say, but the better policy
would be using #18.

Regards,

Dave C.


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