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Recording Acoustic Drums

September 6, 2006

BUT FIRST, SOME PROBLEMS

Recording acoustic drums defines the meaning of “give and take.” A common technique is miking each drum, so all the mics will pick up leakage from each drum/cymbal but with a slight time delay. This delay can cause “comb filtering” (phase cancellation and addition), which alters the miked signal’s tone. The less leakage the better, but it’s impractical to baffle other drums and cymbals within the set. A work-around to cut down on leakage is to use fewer mics, and try to capture the set with a couple mics on the set itself, and maybe some room mics.

Another problem is that the drum head tuning will likely change over a relatively short period of time, due to the constant hitting of the drums as well as temperature changes within the studio environment. Keep lighting and air conditioning consistent, as they’re the main causes of temperature variations. Remember to check tom and snare tuning throughout the session.

Also note miking the full set leads to lots of mics, booms, and cables running around your studio. This multiplies the chances of an accident, like the mic stand falling over and killing your oh-so-expensive vintage tube mic. We’ll address this topic as well.


ISOLATION AND AVOIDING REFLECTIONS

Isolate the mics from the floor as much as possible so that they don’t pick up any rumbling noises. If your studio was not built with a floating floor (a second foundation over the first supported by rubber and styrofoam, as used in most pro studios; see Figure 1), a drum riser will help isolate the mics. Even if the studio has a floating floor, a drum riser may still be helpful. (When constructing a drum riser, make sure that it is solid and includes some type of rubber on the bottom of all surfaces that rest on the floor. Cover the platform with rugged, indoor/outdoor carpet.)

If the drums will be set up on the floor itself, a carpeted floor cuts down on reflections; a hardwood floor will allow sound waves to bounce back up into the drums, possibly causing phase cancellations. Consider a floor tom mounted in a standard vertical orientation: With a hardwood floor, when the player hits the drum the bottom head vibrates sympathetically. This directs a waveform toward the floor, which bounces back up and interacts with the vibrating bottom head to cancel or emphasize certain frequencies.

To minimize this problem, angle the floor tom slightly by lowering the triangular height rod (the one nearest the drummer) to taste; see Figure 2. This causes the waves to scatter somewhat.

MIC CONSIDERATIONS

If the drums will be hit medium to hard, you’ll usually want to enable the mic’s built-in attenuation (“pad”) switch. This helps minimize the chance of distortion.

Some condenser mics offer pattern choices. With an omni response, the mic hears everything — the front and back as well as on the sides. The figure 8 response allows the front and back of the diaphragm to be active but not the sides. Cardioid is directional on one side only, and is typically used for drums. Other patterns include “super cardioid” (very directional), which may be useful if you want to tighten up the sonic picture.

Note that all of the following mic placement positions are my starting positions. When listening to the mics to dial in the sound, always move the mic around a bit to find the best sound.

Regarding mics, there are so many, and the landscape has changed so much in the past few years with the advent of budget mics, that we won’t even attempt to recommend possible mics; I’ll just mention a few personal favorites and deal in generalities. One strategy for getting pointers on mics is reading interviews with producers and engineers whose work you admire, as they will often mention which mics they use for specific applications.

INITIAL MIC SETUP: ONE OVERHEAD MIC

Once the drums are set up, start by using one mic only — preferably a large capsule, wide-range condenser mic. Otherwise, use your best-sounding dynamic or ribbon mic.

With the mic placed on a boom stand, position the mic about two feet above the drummer’s head, and point it straight down at the bass drum pedal’s inner edge. But positioning the mic is not enough: It has to be stable. Most mic stand bases can tip easily; if a mic hits the floor, it may be permanently damaged. The bigger the mic stand base, the better.

Anchor the mic stand with sand bags or any stable, heavy object that will not slip or rattle (three sand bags in a triangular position works for me). The best weights have a handle in the middle for carrying.

Now that the stand is solid, while positioning the mic, wrap the mic cable around the boom stand arm a few times and leave a little slack at the back of the mic so the cord doesn’t pull at the mic and change its position. To keep the cord from moving, tie the cord to the stand using removable cable ties (available at most electronic supply stores). Put a few cable ties on the boom and a few on the main mic stand, all the way down to the base.

Avoid permanent cable ties, or you will have to cut the cable tie and throw it away when putting away the mic and stand. Velcro cable wraps, available from most pro and consumer recording supply companies, are costly but are also the best choice as they are easy to set up and remove. In a pinch, you can use something like Scotch tape.

Even though we’ve secured the mic stand and cable, someone could still trip over the mic cable and knock over the mic. But there is a solution.

With wood floors, use duct tape to tape down the mic cable on the floor, from the mic stand base to the mic panel or recording console. There should be a very little mic cable slack at the mic stand base.

If you are low on duct tape, cross the cable in one foot strips about every two or three feet. Artist tape or any thin tape will not do the job. Keep the tape down tight, with no slack between the tape strips. In areas where there will be foot traffic, cover the cable totally with duct tape.

With carpeted floors, avoid duct tape (which leaves glue residue) and put something like throw rugs over the cable. Bathroom rugs will work in a pinch. Get some carpet remnants, and cut them up to suit your needs. If you use carpet on a wood floor, make sure it won’t move (i.e., has a rubber underside) if someone walks across it.

Now that the mic stand and cable are secure, and the cable is taped down, plug the mic cable output into the appropriate mixer or audio interface channel. As there typically will be some cable slack at this end, “cable tie” after plugging in, then tape this down if someone could trip over the mic cable.

GENERAL TWEAKING WITH EQ

When you’re satisfied with the mic position, experiment with the EQ. For more “bottom end” with the bass drum, toms, and snare, try boosting the low frequencies (e.g., +2dB at 100Hz). Experiment with other frequencies (from 50 to 150Hz or so) to discover the best area for your particular mic setup. Typically, 50Hz will not do much with distant miking, but 150Hz may be better than 100Hz in this situation.

Experiment with the midrange EQ. 2kHz through 4kHz will make the snare “bite,” and the toms will have more of an attack sound. However, the cymbals may start to sound painful with this added EQ. As mentioned, recording drums involves tradeoffs.

For the high frequencies, start with a very slight shelving boost at 10kHz. You’ll notice an added sheen; the cymbals will get louder, and all drums will sound brighter and more open. Careful, though — your ears can get used to the extra high frequencies, which means you’ll want to add more, but your ears get used to that, so you add more . . . a little high frequency boost goes a long way.

A typical setting (Figure 3) for one drum overhead mic would be adding at least a few dB in the low end (100 to 150Hz) and a few dB at 10 to 12kHz.

KICK DRUM MIC/PLACEMENT

A dynamic mic, which can handle loud sound pressure levels, is the typical choice. The Sennheiser 421 is popular, but try all the dynamic mics at your disposal. Some people use the Neumann 47 FET (condenser) mic. If you use any condenser mic, it is crucial to realize that the sound pressure may hurt the fragile condenser diaphragm. The rule of thumb regarding condenser mics is “use it only if you can put your ear in front of the sound source you will be miking without hurting your hearing.” Because the kick drum sound pressure and transient is strong, I highly recommend a dynamic mic.

If the mic you choose has a bass rolloff switch (bass attenuation), don’t use it! The rolloff (low end filter) might have choices like “music” and “voice” or “M” for music and “V” for voice. There may be more than these two options, like Voice 1&2. The voice mode is surely a low frequency rolloff, so use the lowest number music mode. When dialing in the sound, experiment with any switches to make sure that you are getting the mic’s full frequency range.

Kick options fall into three categories:

-If there’s no front kick drum head, position the mic inside the bass drum about a foot back from the point where the beater hits. Now move left half way to the side, and angle at 45% towards the left rim.

-If the kick has two heads, with a hole for miking, place the mic about one foot in and angle slightly toward the left rim.

-If the kick has two heads and no hole for miking, place the mic about 6" back from the center, and slightly to the left.

All starting positions are just that. Finding the best mic position involves finding the best compromise between getting as much “natural bottom end” as possible without losing too much of the “point” (beater attack). Some like a boxy or boomy sound with or without “point.” For less point, move the mic farther away from the beater, meaning near the side of the shell and pointing away from the beater.

But also note that in these days of unlimited tracks, it’s very common to place more than one mic on the kick, and you’ll usually find a hole in the front head where you can stick a mic. Steve Sykes (a brilliant engineer) uses a dynamic mic inside the kick basically pointing at the beater. He also uses a Neumann U47 FET on the outside head a few inches back, and a Yamaha NS 10 woofer speaker as a mic! This adds the real lows (around the 60Hz range) in this era of home and car playback systems with extended low frequency response. He positions the woofer to taste on the outside head in which the low frequencies are thick — simply move around until you hear the most natural low frequencies.

When using multiple mics, though, slip the track for any mic set at some distance from the head so that its phase lines up with the dynamic mic inside the kick. This is important to maintain the fullest possible sound.

After experimenting with the kick drum mic placement, when you feel that it sounds good, reset the levels (if needed) and EQ to taste. Try adding around 60–100Hz to bring up the bottom end. If the sound is kind of “boxy,” try cutting the EQ response a bit at around 300–500Hz. To add more point, add a boost at 5kHz or so.

The kick drum may have a pillow resting up against the inside bass drum head. Typically, the pillow rests equally between the bottom of the bass drum and the inside head. This stops the bass drum from ringing (reverberating) like a tom. The amount of pressure of the pillow against the head defines the sound’s “dwell.” During the ’70s pop music era, the pillow was packed against the head but these days, there are no rules — the kick sound can go from a totally dead sound to wide open, with no pillow or padding. When using padding, anchor the pillow down with a sand bag or a non-reflecting heavy object so it doesn’t move.

Drum tuning is crucial. If using padding, pull back the padding and ask the drummer to get the tuning “even” and as low as possible without making the head too loose for the beater. This is a touchy area. The drummer needs to be comfortable with the feel of the beater hitting the head. The experienced drummer should know the sweet spot for the tuning. The room sound may help dictate the best tuning if you don’t use a pillow.

If the kick drum has one head, after getting the kick drum sound to taste acoustically, put a packing blanket or any thick blanket over the bass drum’s outer shell. This helps isolation. Tape the blanket on the drum near the center of the shell with duct tape or any strong tape, and let it hang on the floor over the outside of the kick. If you’re not using a pillow, and will be using room mics, you may not want to use the packing blanket.

SNARE DRUM MIC/PLACEMENT

Typically, a dynamic mic (like the “old standby” Shure SM 57) does the job. There are many options to explore, as most dynamics will sound anywhere from usable to great on a snare. Condensers are used sometimes, but watch out regarding mic placement. If the drummer accidentally hits an SM 57, this is a drag but the replacement cost is cheap in comparison.

My favorite condenser for snare is the Sony 37A tube condenser mic. Yes, this breaks the rule regarding sound levels with condenser diaphragms; but if this mic sounds best after trying many mics, I cross my fingers and hope it survives the session.

You’ll need a mic “boom stand” for the snare. As with all mic stands for the drum mics, a big base or triangular base (three legs) is best. Position the mic stand between the hi-hat and kick drum, with the boom extended to the nearest edge of the snare rim. Now move the boom in order to position the mic about 2" over the rim edge, and move in about 2" in toward the center of the snare head. Adjust the mic capsule to point at a 45º angle toward the drum head (Figure 4).

Ask the drummer if the mic is in the way, i.e., it would be possible to hit the mic when playing. If so, back it up until the drummer feels the mic is out of the way.

Moving the mic closer to the drum head picks up more low end. The ’80s-era mic placement was around 1" away from the head to get the “proximity effect.” Around 3" is typical these days but as always, move and experiment. If the mic has a bass rolloff, don’t use it — you can always trim the bottom later with the console EQ.

Some people mic the snare on top with something like an SM 57 and use another mic (typically a dynamic or small capsule condenser) on the bottom to pick up more of the “snare rattle.” Start by pointing the bottom mic up to the center of the snare drum bottom head, about 4" under. If the mic is a condenser with pattern selection, use super cardioid or cardioid.

This is a good place for a short mic stand, as fitting a boom stand in the area of the other stands will be tight. Small stands usually have a small base, so secure it with sand bags and maybe duct tape too. A gooseneck stand adapter may work — but the gooseneck will move easily if the mic cable pulls on it.

When using a top and bottom mic, note that when two mics face each other so the top mic diaphragm sees the air moving away when the snare is hit, while the bottom mic sees the air coming toward the diaphragm. This causes phase cancellation. The fix is to reverse the phase on one of the mics. In this case, reverse the top mic. (Note that you should also reverse the phase of all mics on drums that are miked from the top of the sound source — the only mic that sees correct phase is the kick — air moving towards the diaphragm at initial attack.)

HI-HAT MIC/PLACEMENT

Many condensers will work. Small diaphragm condenser mics are the usual choice. The AKG 451 or 452 are both fairly common. If the mic has a low end rolloff filter, you may want to use it as you do not want bottom end (low frequencies) from the hi-hat mic. If you will use something other than a condenser mic, use a mic that sounds “small,” “tight,” and bright.

Set the mic boom stand so the mic is directly above the shaft of the high pedal, then back away from the drummer half way to the outer edge of the hats. The mic should point straight down and about a foot above (Figure 5). As always, you will want to move this mic around while dialing in the sound.

TOM MICS/PLACEMENT

This is an area where dynamics and condensers are used about equally. With dynamic mics, use ones with a fair amount of low end response. The Sennheiser 421 is a good choice but watch out where you place it, as the mic is large and may get hit by a drum stick or wobbling cymbal. SM 57s are a possibility, as are many others. I like small capsule condensers (AKG 391 or 451/452) on rack toms, and large diaphragm condensers (AKG 414 EB) on the floor tom(s) for a smooth, big response. For the high and mid toms, it’s best to use the same model mic.

Set the boom stand for the high tom on the floor in front of the kick drum/tom; position the mic about 2" above the tom, and about 1" in from the rim away from the drummer. Same for the mid tom. Position the floor tom mic stand on the floor and set in the same manner. One reason for setting the mics fairly close is that the “proximity effect,” which accentuates the low end, will be a good friend if you want a full, deep tom sound.

If the drummer has the cymbals positioned low and close to the toms, grab each cymbal and move it on its axis to see if it will hit the mic or stand. If there’s no way to avoid the cymbal hitting the tom mic stand or mic, as a last resort you now have to ask something drummers usually don’t like to hear: “Please move the cymbals up a taste.” An experienced player will adapt if necessary.

CYMBAL (OVERHEADS) MICS/PLACEMENT

Condenser mics are the norm. I like AGK 414s, but most any good condenser pair will do the trick. Neuman, Telefunken, and AKG are typical brands of this era as well as past eras. Avoid mics with a built-in 2kHz bump (build up) like the SM 57; this is one application where this mic is not recommended. If you must use the SM 57, when “dialing in the sound,” use the EQ to roll out a few dB at 2kHz or so.

When positioning the two overhead mics, be very careful that they don’t fall down as the booms will generally be extended to full length. Secure the mic stands as soon as you’ve set the position.

As mentioned previously, I look at drums from the audience perspective (floor tom at the left, hi-hat on the right). In this case, position the left overhead boom mic between the center of the ride and crash cymbal about 2–3 feet above. Start by pointing the mic straight down.

Position the right overhead over the crash on the right side, with the same basic placement. If there’s more than one crash on this side, go between the cymbals as on the opposite side. Position the mic stand on the floor near the hi-hat mic stand.

If the drummer hits the crash cymbals hard, and they’re fairly loose on the cymbal stand, they will wobble and you will hear this wobble in the mics. A little wobble sounds natural, but extreme wobble will sound like the cymbal is almost canceling out during the travel when the cymbal edges get near 90º away from the mic. A possible fix is to angle the mics at about 45º in towards the center of the cymbals, but this may not totally fix the problem and is not a good position for the overheads in general. The best fix is to ask the drummer to tighten the cymbal nut to cut down on the wobble.

If the drummer uses more than four cymbals, and if the ride cymbal is used instead of the hi-hat as the constant time keeper, you might need to add another mic for the ride cymbal if it’s not loud enough in the overhead mic compared to the crash cymbals. Again, a small diaphragm condenser works well.

Position the mic above the center of the ride cymbal, looking straight down and about a foot above. Move in half way between the center and the inner edge of the ride if you want more “ping” (drum stick sound).

Which is the main overhead mic? Typically the one with the ride cymbal, so let’s say left overhead. Take a piece of string (or a mic cable, whatever) and hold it against the center of the main overhead mic diaphragm. Put the other end of the string in the center of the snare head. Now that you know the distance of the left overhead in relation to the center of the snare head, use that same measurement for the right overhead mic, meaning move the right overhead mic up/down, or slightly change where the cymbal is miked, to achieve the exact same length to the center of the snare head. This will minimize snare comb filtering/phase cancellation in the overhead mics.

ROOM MICS/PLACEMENT

This area is tricky. Room frequency “build-ups” and “suck outs” have a major influence. Condensers are the typical choice but each room sounds different, so try every mic that’s left over. It’s a good idea to use two of the same model with the overheads.

You might think an omni pickup pattern would work well, meaning the condenser mics would hear behind as well as the sides. Maybe, but I use cardioid most of the time. Start by placing the mics about 15 feet in front of the drums, about four feet above the floor. Spread apart the mics around eight feet or more, using the bass drum as center.

This is what works for me in my studio, but every studio will have “sweet spots” so experiment! Even a “semi-dead room” might like room mics.

It is possible to use more room mics, especially if the room is big with high ceilings. If this is the case, for high distant miking, try the Neumann M50 (nickel capsule is best) which is designed to be a room mic. This mic sounds bright even when distant from the sound source. It’s a hard mic to find, but it’s great for this application.

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