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Max Holubitsky wrote:

Isn't paralleling the outputs dangerous?


The amplifier has output transformers, so it shouldn't be. The Dynaco ST-70
was intended to be operated in parallel, and my RCA theatre amps have
instructions to be operated in parallel. I can't really see what the problem
would be so long as they're in phase.


Do not put amplifier outputs in parallel. This has nothing
to do with O/P transformers. Any decent amplifier has a
very low Thevenin equivalent generator output impedance,
well below one ohm, likely around 0.1 ohm. BTW, this has
nothing to do with the nominal 8 ohm speaker rating which is
a measure of the ability of the amplifier to deliver
current. Thus, if the individual outputs are in any way
different the difference signal would see this load , i.e.
the other amplifier, and a huge current would flow that
could cause damage. Just being "in phase" is no guarantee
of no difference signal, e.g. the gains could be different.

The correct way to get double the power is to bridge them
(see elsewhere) or much better, IMO, use two speakers - they
can even be in the same box.

Cheers,

Roger

--
Roger Jones, P.Eng.
Thornhill, Ontario,
Canada.

"Friends don't let friends vote Liberal"