Originally Posted by destropaul
Off the multi-zone of a Pioneer Elite receiver, powered by the Elite M10X amplifier (4ohms/100Watts/2ch), we have two-pair, eight-ohm outdoor speakers ran in parallel.
Two speakers are about 400' away from the amplifier, the other two are about 150' away. The closer of the pair is ran through an impedance volume control. All wired with 14-gauge speaker-wire.
If you want top fidelity, you screwed up when you laid that too-thin wire.
This is a problem that is most economically and easily addressed by upgrading the wire to one with heavier gauge.
You lept before you thought. You didn't do your homework. You went cheap when the proper solution would not be that costly to implement, provided it was done up front. You have created a problem that will be costly to address, no matter how you address it.
Rewiring is not a possibility,
It's the best answer.
my multi-meter reads about 3ohms back to the amplifier,
14 gauge wire has .00297 ohms per foot. A 400 foot pair has 800 feet of wire in it. The actual expected resistance would be 2.376 ohms. This is way too much. You'd like the resistance of a speaker cable to be between 10 and 100 times less than the lowest impedance at any audio frequency of the speaker load. If you have 4 ohm speakers, you might want to have the cable resistance no more than 0.4 ohms, and preferably much less than that.
You really need something like number 8 or better wire for this application.
The resistance of copper wire is well-known. Why didn't you think about this before you laid the wire? Do you think that 400' runs of speaker cable are every-day occasions and you can just do what feels good and is cheap?
any suggestions how to improve this setup without spending a great deal of $$?
My first thought is repurpose the existing wire as a 120 volt power line and move the electronics out to the speakers. Or, if there is 120 volt power out there, put another amplifier or receiver out there and repurpose the existing wires as signal links using audio baluns.http://www.tristateu.com/itemdesc.asp?ic=MAE-P115-01Q
My second thought would be to use a professional-engineered approach called a "70 volt" system, which involves putting speaker-level audio transformers at the beginning and end of the long lines. They will raise the voltage but reduce the voltage on your under-sized cables. This reduces losses due to the resitance of the wire. These transformers will have to be exceptionally high quality and therefore expensive.
4 of these could fix you up:http://www.qscstore.com/ot300a.html
Most 70 volt systems inuse are voice grade, and reduce sound quality. You'll need something that is very heavy duty and over-built if you want good sound quality.
Should I have an impedance strip? Impedance Volume knob for the long pair?
Neither approach will work. They are going backwards.