My father used to say, “Son, opinions are like drum miking techniques. Everyone has one.” Or something like that…
Truthfully, there’s an overwhelming amount of information already out there on this topic, so rather than rehash it here, let’s explore a less conventional approach. I’ll admit that it’s a unique method, as it’s a hybrid of studio techniques and some ideas “begged, borrowed and stolen” from engineers I admire.
Picture a snare drum. Let’s mike the top and bottom heads. Remember that in a properly wired system, a positive pressure on the mic’s diaphragm creates a positive voltage on XLR pin 2, which pushes the loudspeaker cone forward.
OK, now hit the drum. Bang. The stick pushes down on the drum head, which moves away from the top mic (negative pressure) and towards the bottom mic (positive pressure). This means our bottom mic’s initial transient is a positive voltage, while the top mic’s is negative. (If you doubt this, make a recording and use DAW software to zoom way in on the waveform.)
We send both signals to the PA and create a tug of war at the loudspeaker cone, which is being told to move in and out at the same time. This creates a partial cancellation that’s very audible, typically as a loss of low-end “body” in the snare sound. Luckily we have a polarity inversion switch on the input channel, which “flips over” the waveform (by swapping XLR pins 2 and 3 at the preamp), so both transients are headed the same direction.
I don’t intend to enter the fray regarding whether absolute polarity is audible (most research suggests that it is not). Rather, let’s focus on keeping as many of our drum inputs as possible in polarity with each other. Convention and AES Standard both say positive pressure = positive voltage = outward (toward the audience) loudspeaker movement, so let’s go with that.
Start with Input 1, the kick drum mic. The beater (the part of the pedal that strikes the drum) will push the drum head forward (away from the drummer), which is toward the kick mic. It’s pretty common to mike both inside and outside kick, but they’ll both generate a positive transient.
It’s conceivable that the kick and snare would be played at the same time, so shouldn’t they be in polarity with each other. If we follow standard practice of inverting polarity on the snare bottom, our kick transient is positive-going, while both snare channels are negative-going. For this reason, I advocate flipping polarity on snare top instead – now kick and snare are all positive transients coming through the PA.
Basically, any part of the kit miked on the same side it’s hit is going to generate a negative initial transient, so let’s flip the polarity on all of the tom mics. I occasionally use a bottom mic on floor tom, so that can stay positive.
And now we come to the cymbals. I have a confession to make: I have overhead drum mics. In the studio, they’re great – studios spend a lot of money creating a pleasing acoustic environment, so overheads, room mics, and ambient mics can yield good results.
However, there isn’t a huge sound system blasting that room sound back into the room. I’ve always thought it a bit odd that we strive for maximum isolation on every other input, then hang super-sensitive condenser mics several feet above the stage. Solo overheads in your headphones some time and listen to how much “room sound” they’re leaking into your mix.
So instead, I utilize underheads. There are a variety of “clips and claws” that can be used to mount mics straight to the stands underneath the cymbals. This does a number of good things:
—No additional mic stands needed
—It’s low-profile, in nobody’s way, and there aren’t mics bouncing around above the drummer’s head, which I always find distracting
—Isolation is much improved; there’s less bleed from the other parts of the kit (hold that thought) because the mics are pointed away from the drums. Further, this rejection can be fine-tuned with hyper or supercardioid mics to reject the snare, which is the worst offender
—Set up is really fast
—To me, it sounds better – tighter and cleaner, which to my ears has much more clarity
—It preserves the polarity of the drum kit