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recording techniques, sessions

Mic Starting Points – Drum Overheads

So, I record live performances at a radio station. While on tour, many artists do their radio interviews and other press during the day, then play a show at night. While this may seem manageable enough, schedules can easily be delayed by traffic, last minute engagements and a host of other factors. We usually don’t have a whole lot of time to play with mic selection or placement once the artist arrives, so it became necessary to develop solid starting points for micing up various sources. Here’s how I approach overheads; I’ll use a recent recording of “Still Life” by The Horrors as an example.

For drums,  I go with the symmetrical spaced pair approach because it offers good rejection of other sources in our room while allowing for wide or narrow stereo imaging. I like to approach overheads as mics for the kit as a whole – each component adds to the collective, creating one source. In the control room, I want to hear kick and snare in the center, and cymbals and toms across the stereo field. When used properly, this technique accomplishes that.

The poorly-drawn red line with arrows represents the center of the stereo image I want to create. It splits the snare and kick drum straight through the middle. The yellow balls represent approximate overhead positions (I’d actually put them a bit farther apart). The blue balls (hah) represent the center of the kit. Physics (and common sense) tell us that, all else being equal, if I place my overheads symmetrically perpendicular to that axis equidistant from the center, and I pan the channels hard left/right, the kick and snare should be heard dead center in our overheads. Here’s why:

  • Since the distance to each mic is the same, the time of arrival at each mic would also be the same.
  • Due to the reason above, the acoustic pressure seen at each capsule would also be the same, resulting in waveforms of equal amplitude.
I’m making the assumption that we’re using a matched pair of microphones. In practice, I’ll generally set up the mics facing straight down, about 6 feet high, and around 4 feet from each capsule to the center of the snare. Obviously, these distances may change depending on the drummer and his particular set up, but its a place to start.

Some may wonder why I don’t use a coincident pair technique instead, such as X-Y or ORTF. After all, if one were to set up an X-Y pair on the depicted blue balls, she would be assured of negligible phase cancellation and a firmly centered kick and snare.  There’s nothing wrong with doing so. But what you gain in technical accuracy, you lose in depth and character. Since every piece of the kit arrives at both capsules at the same time, we’d sacrifice in the three characteristics which allow us to detect stereo information:

  • Energy: differences in amplitude would be provided only by the orientation of one capsule compared to the other, the mic’s pickup pattern, and it’s sensitivity at a given angle. (Ex: one of the mics would likely be pointing straight towards the hi-hat, so it would pick up less floor tom.)
  • Frequency: subtle though it may be, using a coincident pair removes high frequency decay from the equation.
  • Time: this is the big one. With capsules coincident, we lose out on all the subtle delays and time-of-arrival differences that allow our ears to perceive space and depth.

As an aside, overheads are not “cymbal mics!” Here’s a sample of our session with The Horrors, mixed live. The drums come in around 0:20. The kit was a 6-piece Pearl Reference with fresh heads. I forget what sort of cymbals.

Micing was as follows:

1 Kick In: Sennheiser e901
2 Kick Out: RE-20
3 Snare Top: Sennheiser 441
4 Snare Btm: SM 57
5 Rack Toms: AKG 535 (x2)
6 Floor Tom: Sennheiser 421
7 Overhead L: AKG 414
8 Overhead R: AKG 414
9 Hi Hat: AMT B811

The overheads were amplified with N72 preamps designed by Seventh Circle Audio. No compression was applied to individual sources, but channels 2 – 8 were compressed in parallel.

There are a million ways to mic drums, but for what we do, and in the space we do it within, this initial setup works well for me.

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