On 6/16/2012 10:22 PM, Charles wrote:
http://www.rane.com/note136.html

What a long way to get to a place, when you can simply do the math
in your head. The third schematic won't work, because the drawing shows
both amps in phase. There will be 0 volts at the outputs of the amps,
as drawn. I've also seen a system with severe distortion and overheating
amps that were wired in parallel, but out of phase. I was doing this in
the early '60s, and owned a commercial sound business for a decade after
that.

Web pages like that are pure marketing, nothing more. 350 watts
loss in a 1 KW system is **** poor design. It was written by a
marketing dweeb, who thinks that they are a design engineer.


The amps or transformers are simple, and three formulas cover 25,
70.7 & 100 volt systems:

25*25 = 625 ohms per watt. A 100 watt amp would be 6.25 ohms.

70.7*70.7 = 5000 ohms per watt. A 100 watt amp would be 50.0 ohms.

100*100 = 10,000 ohms per watt. A 100 watt amp would be 100 ohms.

You use the ohms/watt over the desired watts and it gives you the
load impedance. Or just total all the loads and be within +/- 20% of
the amplifier's rated output. This has been done for almost 100 years
and it's still a valid method. I always preferred the error to be on
the +20% side so a few additional speakers could be added at a later date.

This is no more rocket science than wiring in any power distribution
system is.

KISS, so people don't clutter their minds with useless classroom
type crap. You could waste days doing that way, instead of minutes, and
that's a great way to price yourself out of business. Instead, know
what you have to work with, and carry everything you need to the job in
as few trips as possible. Have extra parts and hardware on hand.
Stopping work to go buy a couple screws or electrical box can cost you
several hours of lost productivity. Very few customers are foolish
enough to sign a T&M contract.