Mix anti-phase - load on amps

Jun 07, 2011 3 Replies

Quick question please.



If I have two audio signals from two amps, one swinging entirely above DC and the other entirely below what happens if the active sides are mixed without any earth connection? Both signals are identical and with the same DC offset, but 180 degress out of phase.



I am assuming the net voltage will be zero, but how does this affect the load seen by the amp?



Martin Kane


You forgot to say what you mean by 'mix.' The answers vary depending on that.

NT

"Mix" in RF means multiply. "Mix" in audio means arithmetic add. Note one cannot "wire or" low impedance outputs like amp outputs. You use a "buildout resistor". probably not a good idea on the output of an amp. Need hi wattage resistors that get real hot. Inefficient. In general, out of phase sine waves will cancel.

Given the nature of the question I couldnt rule that out. Who knows whether the OP meant amp outputs hardwired in parallel, hooked up in series, common ground or separate, speaker between the 2 signal outputs, could be anything.

In general, yes. But in some cases it can get different. If the OP were parallelling the outputs of 2 amps, and one provided much more power than the other, likely the smaller one would cut out and leave the big one to drive the load.

... who knows.

NT

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