Exploring Drum Overhead Microphone Techniques

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This article was written by renown front of house engineer Tim Lawrence. Tim has toured with some of the biggest acts in the world including Poison, Moody Blues, Linda Ronstadt, Josh Groban, and The Cult. Tim is an excellent front of house guy. Take a moment to read this article for some great tips!

This article is reproduced, with permission from Equation Audio. The original article can be found here.

Exploring Drum Overhead Microphone Techniques

The drum mix can make or break a rock, pop, or jazz recording. In fact, engineers are often judged by their ability to properly capture and mix a live drum sound. Over the years, drum recording techniques have ranged from simple mono room miking, to complex close miking with gated effect chains, to complete replacement of individual drum sounds via triggers or in pro-tools. Fads in drum mixing come and go, and often it is easy to date a recording within seconds of hearing the style of the drum mix.

Although there is a growing trend to create drum recordings synthetically via midi or by editing “canned” beats, acoustic drums played by a living breathing performer still rule in the studio, and the ambient miking techniques used to capture that sound are critical…more–>

Here at Equation Audio, we get questions regarding good miking techniques using our popular and affordable line of Alpha Series drum mics, as well as our premier line of recording microphones. The scope of variables in play with ambient miking are vast, and this article will limit the discussion to placement of your overheads in your mix.

Overheads are not just cymbal mics!

With the popularity of close miking all the skins on your kit, it is a common misconception that the overheads are there only to pick up the cymbals. While the Equation Audio CI.103 condenser microphone features a low rolloff filter useful for live applications where separation from other sound sources is a challenge and the volume of the overheads is reduced, in the studio, full range overheads are the foundation of the overall drum sound, with close mics used to add isolated detail to certain frequencies of each drum. It is possible to achieve an outstanding drum sound with ONLY three ambient room microphones. Classic recordings by Led Zeppelin and countless 70’s rock bands were done this way, and artists such as Lenny Kravitz or indie rock groups still prefer such natural sounds despite technological advances of unlimited multi-tracking. Jazz recordings that preserve the natural ambiance of the drum kit use such minimalist techniques extensively.

A Good Room Sound Means A Good Sounding Room

Real estate is the deciding factor with ambient miking. Assuming you don’t have access to a drum booth designed by an acoustical engineer, the rule of thumb is: “bigger is better.” Small rooms, or rooms with low ceilings cause unpleasant reflections and phasing that ruin a drum mix. A good room should have at least 12′ of ceiling clearance to allow the sound to “breathe.” Lower ceilings can be treated with acoustic insulation to yield a dry sound that can be augmented with outboard reverb to achieve a big room effect, but nothing beats a tall room. Acoustic insulation of larger rooms is also advisable, depending on the dimensions and problematic areas.

Overhead Microphone Placement

There are many different ideas on good mic placement, and while this is subjective, a few techniques have proven the test of time.

There are three ways that the ears and brain can make a stereo illusion: differences in loudness from one ear to the other, differences in time of arrival of the sound waves, and differences in frequency response. While there are fairly narrow ranges of timing and frequency response that the ears can detect, the brain is extremely powerful in detecting minute differences in level and timing between the two ears’ signals, and this contributes to precision in imaging.

Coincident stereo techniques such as M-S or X-Y use only loudness or intensity differences (this is often called intensity stereo between left and right, created by using two directional mics in nearly the same place but pointed in different directions. You probably have seen this configuration often, with two overheads crossed in an “X” pattern, the diaphrams facing opposite directions of the kit.

Semi-coincident stereo techniques use at least two mics, spaced up to about 50 cm (18 inches) apart. The mics are generally directional, and may be angled apart as well. Both intensity and time of arrival cues are used to produce the stereo image.

Spaced techniques primarily use time of arrival differences to produce a wide, spread-out stereo image.

Getting a Good Stereo Image

The limitation with the MS or X-Y techniques is that the stereo image has less separation. The tendency is to make up for this loss during the mixdown phase by panning other mics. However, with a simple tri-mic configuration this isn’t an option. This was well noted by legendary engineers such as Glynn Johns (The Kinks, The Rolling Stones) and Geoff Martin, and they used a different approach to achieving a wider, more musical image.

The natural instinct is often to “see” the stereo image of a kit by standing directly in front of the kick drum, as the audience might hear it. However, a better way is to sit behind the kit, facing the midpoint between your floor tom and the hi-hat (assuming these elements are the extremes of the stereo image). In this case, the snare is slightly to the left, and the middle rack tom is dead center.

* Place your first overhead microphone about 2-3 feet above the kit, facing between the snare and your hi-tom (not directly over the snare and drummer, but positioned more toward the end of the “stage” or the audience).

* Your second overhead microphone should be further to your right, even behind your shoulder when playing the hat and snare, placed about 2-3 feet over the floor tom.

* Snare Microphone (DMI.102S)

* Kick Microphone (DMI.104.SLF)

The Glynn Johns Technique

While the above placement provides a better stereo image, there may be some problems with phasing on the snare, especially if close miked. This is because the overheads are not an equal distance away from the snare, and the sound is reaching them at different times. The legendary Glynn Johns devised a brilliant and simple miking technique to avoid this issue. This scheme requires only 4 microphones, and with a good drummer and room will achieve a natural sound that will be hard to beat, even with unlimited mics!

* First Overhead should be a cardioid such as the Equation Audio CMI.103, or a large diaphragm model such as the F.20 (recommended) about 4-6 inches above Floor Tom facing the Hi-Hat across Snare. This signal should be panned.

* Second Overhead (F.20 or CMI.103) about 2′-3′ above the kit facing between the toms and snare. This signal should be panned.

* Snare Microphone (DMI.102S)

* Kick Microphone (DMI.104.SLF)

The final step is to measure the difference between the center point of your snare drum and both overheads, adjusting the mics and kit so that both are at an equal distance. A piece of string works well for this.

Large diaphragm overheads are strongly recommended to maximize the fullness of the entire kit, however, the CMI.103 also highly effective with the low filter disengaged. Experiment with these overhead techniques, you will be amazed at what is possible with such a fast and minimalistic setup. It could come in handy when time is limited, or when out in the field.