Polarity Conundrum


I recently bought an Audio Research LS-15 preamp and an Accuphase P-450 power amp from other Audiogoners. They will be connected via the balanced XLR ins/outs, but the polarity scheme is the opposite in each piece. The LS-15 is Ground/Positive/Negative, the P-450 is Ground/Negative Positive. Someone(s) on another thread suggested that the simple way to address this polarity inversion is by swapping the speaker leads to the amp to the opposite connectors.
Instead of positive to positive, you go positive to negative/negative to positive on the amp's output terminals. Can it be that simple? The Audio Research manual says to contact them when this situation is encountered, but if this simple fix will work, I'm all for it. What say you guys?
discnik

Showing 1 response by almarg

Yes, it’s that simple, assuming two things:

1) Most importantly, this assumes that the speakers are passive, e.g. they do not include built-in amplification, and that powered subwoofers are not connected to the amp outputs. In either of those cases it might not be safe to connect the + output of the amp to the - input terminal of the speaker or sub.

2) It assumes that the polarities of your source components conform to the usual USA convention of pin 2 positive and pin 3 negative in the case of XLR outputs, or that the source components are not polarity inverting in the case of RCA outputs. Otherwise interchanging + and - at the amp outputs would be introducing a polarity inversion, rather than correcting for one, since having two polarity inversions in the signal path results in correct overall polarity.

Finally, some will argue that whether or not you interchange the + and - connections at the amp outputs is unlikely to have much if any audible significance. And IMO they would be correct in the case of many and probably most recordings, but not all recordings.

Regards,
-- Al