In article , Peter Scott
wrote:


I'm not in a position to give any results yet, but I am experimenting
along the lines of Wally's ideas. For me they were a necessity because
of the need to fill a larger room. I was not able to get the power I
needed from a single twin amp so decided to try out using three.

I have doubts that bi or even tri amping should usually make a big
difference to the sound levels you can obtain. This assumes, though, that:

1) Your initial amp wasn't current limiting due to the parallel loads of
the speakers.

2) You aren't using the active xover to avoid large losses in the initial
passive xover arrangements in the speakers.

If either of the above were the case, then the following comments may not
apply...

For getting the biggest possible increase in peak power you'd have to get a
situation where the vectors (voltages) of the bandsplit signals were all in
phase and of the same sign and amplitude. In this extreme case you might
get a peak improvement of x9 in power. i.e. less than 10dB, which in terms
of audibility tends to be regarded as impying you would never get more than
an apparent doubling in peak level.

However in practice I suspect you will find that almost all the time the
vectors are neither in phase nor of equal size. Thus the increase in
available power is likely to be much less than the above.

FWIW I did some analysis of the peak levels of band-divided musical signals
from CD when looking at clipping and tweeters (some pages on this on the
'Scots Guide' site). Can't be sure, but I'd be surprised if in general you
got much more than a few dB of sound level increase before occasional
clipping. i.e. not much more than the smallest change that is clearly
noticable.

You may, however, get an apparent increase if the frequency response
changes as that may affect the audibility and the audible impression
conveyed. However as with Wally's experiments, if this is the case, then
similar results might be obtained more easily.

Slainte,

Jim

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