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Old 10-30-2009, 06:28 PM
O.G. Killa's Avatar
O.G. Killa O.G. Killa is offline
Join Date: Oct 2002
Location: Los Angeles
Posts: 2,152
Default Re: Overhead mic technique - what works for you?

A friend of mine and I have some instruction videos coming out on Hudson Music's website that touch on this topic. We cover Rock, Funk and Jazz. Slightly different mic'ing technique for each. While the videos are geared towards drummers (not sound engineerS) and the "engineering" aspect is watered down, you'll at least be able to see and hear what's going on. The series is called "Seeing Sounds". it should be up in a few weeks if not sooner...

But... to go in depth a little... First thing I'd like to address is people mentioning the 3:1 rule in regards to Overheads... this is a little pet peeve of mine. The 3:1 rule absolutely, in no way-shape-form, applies to ANY stereo mic'ing techniques. doesn't matter if it's spaced pair, XY, MS, ORTF, whatever. If it's a stereo mic'ing technique, 3:1 has no bearing. The 3:1 rule ONLY applies when mic'ing two DIFFERENT instruments/sound sources and aren't meant to be used in stereo. An example of where the 3:1 rule would apply on a drumset is the stereo overheads in conjunction with the close mics. If the tom mic or snare mic isn't at least 3 times closer than the overhead is to the drum, you'll get phase interference. Likewise, Tom mic 1 has to be 3 times closer to tom 1 than to tom 2 and tom mic 2. But from left to right in a stereo mic'ing technique, the 3:1 rule doesn't apply.

Why? Sound propagates as an ever-expanding sphere unless acted upon by an outside force. Because of that, so long as the mics are the same distance from the source, and they are panned left and right, you will get absolutely no problems. The varying distance of one part of the instrument to the two mics creates stereo image, not phase interference. Secondly, there is absolutely no way to get two mics 3 times the distance apart as they are from a single audio source. Try it, it's physically impossible. setup a snare drum in the room by itself. Measure 3 pieces of string, two at 1 yard/meter and one at 3 yards/meters in length. There is absolutely no way to get both mics to be exactly 1 yard/meter away from the snare while also being 3 yards/meters away from each other!!! Even if they are on either side of the drum, they are still only 2 yards/meters away from each other!!!!

Anyway... The point of a stereo mic'ing technique is to get those timing differences between the two mics. Pick one part of the drumset you want to be "in the center" and make sure both mics are equidistant to that and to each other. So for example, if you want the snare drum to be centered between the speakers and everything else to pan in relation to the snare. Make sure the overheads are, let's say, 5 feet from the snare and also 5 feet from one another. Also known as an equilateral triangle...

OK... so back to setting up the overheads in a small room. If the room is 12' x12' x 8', don't even bother trying to get a good overall "drum" sound in the overheads since the room itself is never going to yield a good drum sound on it's own. Instead, focus on using the overheads as cymbal spot mics.

I've found a combination spaced pair meets ORTF usually works best since you can't put the mics up that high. With ORTF the mics are supposed to be cardioid, be 17cm apart and be at a 110 degree angle to each other... OK... but you don't have to be exact with the distance or the angle for an overhead mic'ing technique... What I've found works pretty well is to spread them out a little more (this varies depending on the cymbal setup) and change the angle based on how much snare bleed you are getting. You are always going to get snare bleed, but the more horizontal facing the mics are, the more cymbal to snare drum ratio you get. And at that point they don't have to be perfectly symmetrical either, since you are no longer trying to use them as a "stereo drumset" mic and are using them more as a "cymbal spot mic". So the mic over the drummers left should be positioned to try and pick up all the cymbals and high hat on the left while minimizing snare drum bleed. Same goes for the mic over the drummer's right. Pay close attention to the ride cymbal. Usually the ride cymbal gets lost in the wash of drums and crashes, so don't be afraid to move the right overhead a little closer to the ride or put a third mic on the ride (now here the 3:1 rule applies since the spot mic and the right side overhead are not being used together as a stereo pair but will most likely be panned to the same side) Turn the ride mic way down and just bring it up a little bit for reinforcement if you need it.

Again, check the levels of the snare and kick in the overheads. Even though you aren't using them as a stereo mic'ing technique anymore, if the snare is 10dB louder in one mic than the other it will pull the whole stereo image of the kit to that side. Move the mic around to try and minimize the bleed.

One other thing with overheads, listen to make sure you can't hear the cymbals "sway". If the mics are too low, as the cymbal rocks up and down it will create a slight doppler/flanging effect in the mic (even when solo'd). If you hear that you need to move the mic.

Other than that, look into some serious bass trapping for the corners to help tame standing waves, and then look at some diffusors to help keep the drums "singing" without any flutter/slap echo. And also put some High frequency absorption above the drumset to keep the cymbals from "splattering" on the ceiling right above the kit.

Another thing to play around with is the Glyn John's iscoceles triangle technique. You put one mic overhead the other over the floor tom. Both mics have to be the same distance from the snare, but don't have to be that same distance to each other. pan the overhead left and the tom side mic right. Sometimes panning to "11 and 3" works better than hard left/right with this technique. Ideally the mic's should be the same make/model and there is supposed to be a third mic out front. But if you are close mic'ing the drums, you can forgo the the third mic and try just the overhead/tom side pair and see how it sounds for you. I have a couple pics of this setup on my myspace page if you want to see what it looks like.
Derek Jones
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