Any time there’s more than one mic on a source, there’s a possibility for phase cancellation. Combining snare top and snare bottom mics often results in phase issues. Once you have the gain settings dialed in for these mics, listen to just the top mic. Slowly bring in the bottom snare mic and listen to the low-mids. If they get weaker, there’s a phase issue. Flip the polarity switch (Ø) on the input channel for the snare bottom mic and see if the low-mids come back.
Phase can also be an issue when overheads are combined with close tom or snare drum mics; whether or not this is an issue depends upon the manner in which you use the overheads. A good starting point is ensuring that each overhead mic is equidistant from the snare, which produces the same arrival time for the snare in each overhead mic. Whether or not those two overheads are in-phase with the snare top mic is another story, so you’ll have to check by solo’ing all three mics and flipping the polarity switch on the snare top channel….
The polarity switch is most effective when two signals are perfectly 180° out of phase and may be too coarse a tool in some situations, but there are other options. Digital consoles usually provide channel delay which can help if it permits adjustments in increments less than 1mS. You can also try a phase alignment plug-in or hardware device such as Radial Engineering’s Phazer (pictured here) or the Little Labs IBP — all of which provide far finer resolution in phase adjustment.
From “Common Mistakes to Avoid When Miking Drums” by Steve LaCerra, FOH, February 2024, page 34
