Re: Sending audio signals through phone cables?
You will have no problems at all doing this.
Analysis from an electrical engineer with 25 years experience and a penchant for doing things that others say are impossible:
Issue 1: Impedence
Since you are dealing with audio frequencies any impedence mismatch will not be noticeable. Regular speaker wire is not 8 ohm impedence. Only at radio frequencies and higher is this an issue. NOT A PROBLEM
Issue 2: 28 guage wire.
28 guage wire has a resistance of about 6 ohms per 100 feet. So, assume that your longest run will be approx 50 feet, that's 6 ohms total for the trip out and back... what this means is that you will lose almost half of your power in the wire. (6 ohms in wire vs 8 ohm speaker) So what? It takes TEN times the power to DOUBLE the volume that you hear. So half the power lost will be barely noticable.
The inductance of 28 guage wire does make the 3dB cutoff frequency for 100 feet driving an 8 ohm speaker somewhere around 100kHz. So there should be no noticable high frequency loss in the audio, but certainly none that turning up the treble control slightly won't take care of.
Issue 3: Niose
As long as you are using the phone wires to send power to speakers, not as a low level signal transport to drive another amplifier, no problem. The 8 ohm impedence at the load end is low enough that the millivolts of noise that is coupled into the phone wires will be unhearable.
Issue 4: Disconnecting from the phone company
If your house has been built in the last 40 years, the phone company attaches to you home wiring with the same kind of plug that is on your phone, usually at the cable's entrance into your garage. Simply unplug this rj-45 plug, and you are free to do whatever you wish with your home's wiring.
The only issue is one of power. 26 guage wire is rated at 2.2 amps (this is for continuous current and is very conservative). This equates to approximately 32 watts at the speaker. However, this wire should have no real problem handling twice to four times that current intermittently (and a very, very small portion of audio signals are at full power). Since power is a function of current squared, at 4 amps you would be able to provide about 130W max at the speaker. This should be plenty for most applications, and short bursts of 8 amps would provide ~500W briefly, WAY more than necessary. This is the only issue, however, that may be seen as a detractor for using the phone wires. I don't really see it as a problem.
The discussion above was in reference to driving speakers directly through the phone wires. However, just about all of these arguments work the same for driving the phone lines with your iPod. The headphone impedence (and therefore the maximum output impedence of the iPod) is usually a little higher, 32 ohms or so, but this doesn't change much. The higher you turn the iPod's volume, the less likely you will have noise problems creeping into the other end. I would suggest using audio isolation transformers at each amplifiers input (available at radio shack for a few bucks each). Some stereo chassis have hot grounds, and you don't want to create a huge ground loop across multiple rooms and a hundred feet of wire. The 60Hz pickup could be huge, but the isolation transformers will eliminate this issue.
In reference to the 7dB loss due to multiple connections - only true if the load impedence matches the driver's impedence. The typical input impedence of a low level amplifier is, i believe, 10k ohm. Since the iPod's driver is no higher than 30 ohms or so, it would have to see a whole lot of amplifier's inputs before any loss is noticeable.
I realize now that this original post was several months ago... I hope it does somebody some good.
By all means try it. It should work quite well.
Good luck!
<br /><br />On to my question. I have no land line, only a cell phone, which leaves an unused jack in every room with a 4 conductor cable already wired to each one. Would it be possible to disconnect any wiring from the phone company, and then make an adapter that would plug my ipod into a phone jack? Or would the wires be too long/small gauge? I don't know much about how audio signals work...<br /><br />If this doesn't work I'm probably going to get an FM transmitter to do this, but the good ones are over $100, and as you guys know, I'm a cheap *******. 
