Although polarity/phase adjustments at mixdown can radically affect the sound of a multimiked drum kit, they might make very little difference at all. The only way to find out is to check...
I’ve recently become interested in manipulating phase while mixing recorded drums to see what that would do, as I’ve not messed with that before! The drums in question were recorded onto seven channels with three non-matching mics: front, back and overhead, plus kick, snare and two tom mics. I downloaded the Sonalksis FreeG fader, which has a polarity reverse button, and also the UAD Little Labs IBP variable phase-manipulation plug-in. I tried about every variation I could come up with in terms of phase with the seven channels, starting with polarity flips and then slowly sweeping the 180-degree range with IBP. While there was some variation in sound as a result, it was minimal, and not necessarily better — just different. Certainly not dramatic and nothing that I ended up using. Is that unusual?
Tom Dyer, via email
SOS contributor Mike Senior replies: Not at all. Depending on the mic positions, spill levels, and balance between the drum mics (and whether they were gated during recording), phase can make anything from a massive to a miniscule difference. However, it’s very rare that it makes no discernible difference at all, so it’s always worth checking for the most appealing-sounding combination as a matter of course whenever you’re dealing with multi-miked recordings. Yes, the polarity/phase relationship you choose will be a subjective decision, but then subjective preferences are a lot of what mixing is about, after all!
I’d also add that a final mix is rarely constructed from a handful of huge ‘night and day’ sonic changes, but is almost always the result of hundreds of subtle little tweaks, so even when the effects of a single polarity/phase adjustment are fairly minimal, the cumulative effect of a such adjustments across multiple tracks may nonetheless add up to something more substantial.