Inverted Phase Preamplifiers with REL Subwoofers

It is not necessary to do anything. Absolute phase is one of those things that is a whole lot more theoretical than actual. Technically there is an absolute phase. In reality every step in the chain- microphone, mixer, tape, etc- can and often times does invert the original phase. Most recordings are a random mix. You can drive yourself crazy trying to decipher absolute phase. Or stay sane. The sane solution is either do nothing (what I do) because it doesn’t matter (it doesn’t) or you can do the next best thing and listen, reverse polarity, and listen again. Only don’t be surprised if you do this and detect no difference. Or you can hear a difference, but then when you play a different recording you get a different result. Which is why the sane thing is to do nothing.

As for the sub you do of course want them in phase with your left and right channels. Except when you don't. It all depends on room and placement. Listen, and let your ears (or a meter) decide.

Thanks for clearing that up. 🙄

But, seriously, folks, so many recordings, esp. CDs, are in Reverse Polarity it might actually make more sense to keep the system in Reverse Absolute Polarity. Two wrongs make a right.

Whatever you do, don't reverse the sub connections such that the black (ground) wire from the sub is connected to a + output of the amp.  That can cause problems ranging from hum to damage, depending on the internal grounding configurations of the sub and the amp.

Regards,
-- Al 

I flip the polarity switch on my R305... using a c-j pre that inverts

Oddiofyl.  
REL claims that the correct switch position will yield a louder result whether it be a 0 or 180 when in correct phase with the rest of the set up.  Did you find that the sub was louder when you flipped the switch? Did you have the REL before you got the C-J?

If a sub is 180 degrees out of phase with the main speakers wouldn't there be a suck-out of those bass frequencies where there is a crossover overlap?

If a sub is 180 degrees out of phase with the main speakers wouldn't there be a suck-out of those bass frequencies where there is a crossover overlap?

Out of phase could be beneficial if the sub's woofer is not in the same plane as the main speakers.  On higher end subs, you often see a 180 degree phase switch to help integrate the sub with the mains

The absolute phase or polarity of the preamp has nothing to do with how the sub is operating- the latter has everything to do with your main amplifier.

use the high level inputs on your subwoofer.  

subwoofers seeing the same signal as your amplifier sounds best in my many trials and systems.