reversing phase in microphones

[frosty55]

When recording a snare drum with two microphones, one from underneath, one pointing down, how is the phasing reversed?
Do you swop the negative and positive over in one end of the cable on only one of the microphones?

[Enzo]

You swap + and - on any mic you want reversed. DOn't do it "just because." Do it if there is a sonic reason to. DOn't assume the top and bottom of the drum are "out of phase" and need correcting. The drum is a mechanical system and is not instantaneous. The signal in the top mic will not just be an out of phase copy of the bottom signal.

Better mixers have a phase reversal switch for each channel strip. You can also make up little male to female phase reversing adaptors. Insert one where needed.

[Steve Conner]

Those adaptors Enzo mentions are traditionally coloured pink so you won't get them mixed up with ordinary leads.

If you use Pro Tools, most of the plugins have phase reverse buttons. I don't know why they put them there, but they work.

[Don Moose]

Can you reverse phase on a condenser mic that's being phantom-powered?
(yes, a desk with phantom power would likely have a phase switch as well - just curious)

[Steve Conner]

Yes. Phantom power is a common-mode thing: it's +48V relative to ground on both the + and - pins.

[frosty55]

So i think i get this now...if the bottom snare mic was to be the one to have the phase reversed then you would swap the negative and positive pins over on that mic lead, on both ends of the lead, or just the end that was fitted into the mic?

[Luteman]

So i think i get this now...if the bottom snare mic was to be the one to have the phase reversed then you would swap the negative and positive pins over on that mic lead, on both ends of the lead, or just the end that was fitted into the mic?

Reverse either end, but not both (otherwise one end is undoing the reversing of the other end, if you see what I mean)

Good luck

[frosty55]

Thanks for the advice chaps.

[Enzo]

And really PLEASE just record with the mics as they are first. Try it. Drum sounds are not coherent on both sides of the things. You most likely won't have to reverse phases anyway.

[Regis]

I built an inline adapter using a Switchcraft S3FM that switches the phase.

I think Enzo is right tho, try it without phase shift first.

[Enzo]

Yes that M-F adaptor body is sturdy and simple. We have made a couple for phase reversal. We also make the little 6" XLR cable versions though for live use, since we didn;t want something sticking out 6" into the air..just itching to get knocked out. At least around our all-thumbs crew.