Pursuit Of The Perfect Drum Sound

bass drum

The bass drum is one of the most important elements in a song. It works in partnership with the bass guitar to create a pulse for the music, drawing the listener into the listening experience. From a recording standpoint, the bass drum must be captured correctly or the mixing engineer will be at a serious disadvantage. Getting a good sound comes down to a combination of the drum and microphone. Just as the player’s technique plays a major role in how the drum is voiced, the microphone choice and placement are the recording engineer’s contribution to the sound. In this article we will cover some of the most commonly used microphones for bass drum recording, discuss placement techniques, and explain some of the strange tricks engineers use to capture the bass drum in the studio.

First Thing's First

Before anything else, you first need to determine the type of bass drum sound you want. What does the producer want? What is the drummer trying to achieve? From the clicking doom of a metal double kick to the inferred bloom of a 24" big band bass drum, the recording engineer has to know the goal for the song. We need to gauge how much beater articulation and how much low end from the shell will be needed come mixdown time.

Once the style is established, it’s time to examine the drum to determine its fundamental pitch. The best way to find out is by taking off the heads and – gulp – all the hardware. Stick one hand inside the drum and suspend it by a finger or two. Strike the outside of the shell with the meat of the bottom of your other hand (as if you were holding a hammer). You should hear a definitive “thump.” Record this sound, run it through a spectrum analyzer, or identify the note on a keyboard.

Each drum has a resonance where it will sing best. Some people determine the musical note of the drum. I find knowing the frequency much more important, as the 12 notes repeat across the audible spectrum. Most kick drums will fall in the G# range from 52—104Hz.

One revelation from this test is the discovery that drum dimensions don’t always indicate its pitch. The wood, the number of plies, and how the manufacturer fabricates the instrument are much more important factors. In fact, two drums of the same size can often have different fundamental tones. Knowing this frequency will help with tuning and choosing a good microphone for the recording.

Next, you need to consider the resonant head. Many engineers like to use two mikes to capture a bass drum – one inside for articulation and another in front to capture the low end. In order to place a microphone inside the bass drum, either the front head should have a vent port cut into it (Fig. 1) or it should be removed altogether. If it’s solid, it limits the engineer’s options to other types of placements.

Be warned: This can be a political hot button on stage and in the studio. I’ve seen shouting matches over making such changes. Usually the engineer wants to remove the front head against the drummer’s wishes. I take the view that I have a job because the drummer needs me – not the other way around.

So I will work with whatever situation I face. Some engineers love resonant heads; others hate them. Personally, I like having a port – it’s an extra option – but good sounds can be achieved both ways.

bass drum

Fig. 1 If the resonant head has a vent, that’s good news for getting a dynamic inside the shell. Of course, it has to fit in the port! Although large, this Telefunken M82 can make it if you are carfeul about the mount. Note the fraying on the port; that’s from rough removals of microphones.

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Tools Of The Trade

When people tour the studio one of the questions we always get is, “Why do you have so many microphones?” The short answer is we record many different things. No single mike is the best choice for every source, and a bass drum is no exception. Talking with producers and engineers reveals a short list of frequently used microphones, which range in price, type, and design. For discussion purposes, I’ve broken them into three categories: dedicated, conscripted, and inventive.

bass drum

Fig. 2

Born To Kick

Several manufacturers market microphones specifically dedicated as bass drum mikes. These are designed to be durable and handle high sound pressure levels (SPL). Additionally, dedicated kick mikes have diaphragms suited for low frequency reproduction, and have a cardioid or hypercardioid pattern to help reject bleed from other drums.

Internally, dedicated kick mikes usually possess a frequency response tailored for the instrument. Designers alter the mike through air porting and electronics to provide a more pleasing kick sound. Think of it as a built-in equalizer. Most have a low frequency boost at the bass drum’s fundamental, the boom of the midrange is often reduced, and a second boost at a higher frequency is added to capture the beater attack. The big three dynamic kick microphones include the AKG D112, Audix D6, and Shure Beta 52. Pulling manufacturers’ published specification and response curves reveals the profiles in Fig. 2.

Note the diverse approaches to optimal low frequency and optimal high attack frequency. Each microphone is different! Now, recall how each kick drum has a natural pitch. Knowing these facts, which mike is the best? Answer: it depends. (I’ll also give full credit for “all of them”). Given 100 random kick drums and these dynamic mikes, some microphones will sound better with some drums than with others. So, if you’re recording your kit at home, you may find one of these mikes best suited to your personal kick. But if you are a sound professional, you probably want to buy them all. Actually, if you record double bass you need two of each. (Don’t write in to yell at the editor. We’re just the messengers. Blame physics.)

Dynamic mikes are usually placed inside the kick drum. Their SPL tolerance ensures their survival, while their built-in equalization response helps cap- ture both the boom and the click. They’re also happy to be placed on the resonant head or just inside the port on a vented front head. If you can have only one kick mike, the oddsmakers suggest you pick one of these three.

bass drum

Fig. 3 Not all ribbons are equal. The Royer 121 can take the sound pressure of the front head, provided you angle the microphone. This allows the soundwaves to travel along the ribbon, thereby distributing the stress. If you’re unsure, moving a ribbon microphone away from the bass drum is a safer option, especially a vintage model like the RCA 44.

Conscripted Solutions

Recording engineers are a zany bunch. They rarely read directions or owner’s manuals. Consider the microphones they’ve borrowed from other fields to record bass drums. The Electro Voice RE 20, Sennheiser MD 421, and Telefunken M82 are more natural-sounding broad- cast mikes. It bears mention- ing that the Telefunken is dual purpose, with both vocal and kick drum-specific equalization circuit choices. The Crown PZM-30D is a pressure zone microphone, which is a small diaphragm condenser specifically paired with a hard surface to create a “sound grabbing field.” Although some companies make kick-drum labeled pressure zone microphones for internal use, the Crown PZM-30D is often used outside the kick for purposes of low-end augmentation. The Royer 121 (Fig. 3) is a modern ribbon mike that can be used to capture the resonant head. Neumann’s U47 FET, with its complex and wide-frequency responsiveness, is a staple external mike for those fortunate enough to own one.

Broadcast dynamics are used interchangeably with dedicated dynamic kick microphones. Stick them inside the drum and record. Their frequency response is flatter, or more natural, leaving equalization duties for mix time. You will need to scoop out the unneeded lows and mids to make room for the bass guitar, but otherwise, these make for fine options.

The Royer 121 can be a life-saver in some instances. Royer reports that the mike can be placed a few inches from the resonant head, provided you angle the mike at a 45-degree plane from the drum. Note that this is different than keeping the microphone perpendicular to the floor and rotating the axis. Imagine the mike bowing to the kick as if it were a martial arts contest; this angle distributes sound pressure down the ribbon as opposed to hitting the entire element at the same time. I pre- fer the 121 a few feet away from the bass drum, but about a foot off the ground. The Neumann U47 FET is glorious as a front head microphone. Most people choose to keep it off center and about 3—4" from the head. It can capture every nuance of the shell while picking up some of the initial hit of the beater. The U47 FET-plus-broadcast-dynamic combination is probably responsible for more modern kick drum recordings than we could count.

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Fig. 4 An old trick was to combine a small condenser and a dynamic by taping them together. Aligning the mike elements for phase coherence was an arduous and imperfect task. Fortunately Audio Technica created a dedicated combo that does the same thing, with the diaphragms aligned and fixed at the factory. If this sound appeals to you, stop the DIY method or buy a big bottle of aspirin.

Necessity, She’s A Mother

There are some other interesting mike-tools that come from dissatisfaction with store-bought solutions. The Earthworks Kick Pad is a short tube with XLR connections on each end. The passive device is attached in-line with a microphone and provides a pad (sound pressure attenuator) and a bass drum-tailored equalization curve. In effect, it lets you turn a standard dynamic microphone into a pre-purposed kick drum mike.

When the two-mike technique was first tried, some engineers used gaffer tape to bind a small diaphragm condenser mike to a large diaphragm dynamic (Fig. 4). The SDC gave the attack and the dynamic gave the fundamental. The problem with this solution was getting the microphone elements aligned for optimal phase response.

The Audio-Technica Artist Series ATM250DE takes the guesswork out of this method by including both mikes in a pre-set, pre-aligned package. A special dual mike cable splits into a Y, allowing each microphone to be connected to a different recording channel.

Finally, the Yamaha Subkick is one of the coolest inventions of the bunch. Microphones and speakers are both transducers. They turn sound into energy or energy into sound. One day some engineer decided to hook up his extra car stereo speaker to some XLR cables to see what it sounded like as a microphone. Before long so many people were using this homemade solution that Yamaha stepped up and created a sturdy industrial version. Although it looks like a popcorn snare mounted perpendicular to the floor, the Subkick (Fig. 5) is really a 6.5" monitor speaker doing duty as a dynamic microphone. At a fraction of the price of the Neumann U47 FET, the Subkick is a very popular outside microphone.

bass drum

Fig. 5 Hard to believe, but this is a great kick drum mike. The Yamaha Subkick is a much more convenient solution than trying to DIY this. Yamaha includes a protective mesh to protect the speaker (removed for photo), a hard protective shell, XLR port, and small snare stand for stability.

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Fig. 6 Sometimes you need to mike the beater side to get the attack you need. This is tough to do. I suggest a cardioid mike, which is nulled (pointed away from the snare) to reduce snare bleed. Your kick pedal needs to be in good working order, too. Otherwise you’ll be listening to squeak-smack-squeak-smack.

Application & Techniques

We’ve got good news and bad news about placing a microphone inside a bass drum. The good news is half the battle is won. You’re going to be able to get a clear attack sound. The bad news is that this can be difficult. Why? Other than a snare drum, no other drum mike placement is as sensitive to small changes than inside a bass drum. Once you’re inside that shell, even 1" changes in depth, height, or axis positioning can make an enormous difference to quality of the attack and the amount of low end captured by the microphone. There is more good news about being inside the kick drum, since the shell helps keep spill from other instruments to a minimum. Of course, any mechanical noise from the kick pedal will be obvious, but it’s a good trade off.

If there is no front head, you can place the mike just about anywhere inside. Avoid going straight in the middle or level with the bass drum beater. This is a blast zone of bad sound. Start with a place between the beater and the shell.

If the front head is ported, the port will by default choose your entry path. In general, how deeply the microphone enters the shell will affect the beater presence. You’ll capture more attack closer to the batter head and more tone as you move the microphone further away. If you find the optimal slap, but aren’t happy with the quality of the shell sound, you can adjust the timbre by adjusting the mike’s axis angle. Often you’ll end up placing the microphone either a third or two-thirds of the way in, especially if there is a ported front head. Having the mike smack in the middle can place it in a reflective node where the bounce-back from the resonant head collides with the attack of the next hit. This can lead to a warble and phase problems. Regardless of ultimate position, my main engineering secret is to take as much time as you need to find the best placement for the kick (and the snare). No preamp or post production will matter as much as a great setup. And having a great foundation from the bass drum makes all the difference. If you need to take a five minute break, grab a cup of coffee, or count to 100 – do it. This is not the time to hurry up to the finish line. This is one of the most important tasks you’ll do while recording drums.

Life On The Outside

A solid resonant head tends to provide the most sustained, round sound. However, miking at the front makes it difficult to pick up the beater, since it would be behind two drumheads, and external miking is subject to bleed from the rest of the kick. Some engineers place outside microphones lower to the ground – at least the rest of the front head blocks the other drums a bit.

Oddly enough, one way to get more articulation is to move the microphone further away from the drum. Of course, spill increases as you move back, which has led to a variety of contraptions and creations to give the distant mike a personal line to the kick. From extra kick drums to industrial fiber barrels to full-fledged pillow forts, this trick has been around forever. Done correctly, you can block much of the tom and cymbal spill while gathering a cannon-like explosion on every hit.

In rock circles, Butch Vig is famous for employing this technique on Dave Grohl’s kick on Nirvana’s Nevermind. A word of caution – make sure you’ve placed your close-mike or inside microphone where you want it.

Making adjustments is very difficult once the fort is constructed. I also suggest taking photos in case you want to recreate the effect for another project.

If you cannot achieve the slap sound you need, you may need to resort to miking the batter head (Fig. 6). I know – it sounds crazy, but it has been done. A small diaphragm condenser or sturdy dynamic mike (think Shure 57) with its rear pointing at the snare to reduce bleed can give you all the attack you need.

There are a couple limitations to using this technique. You need to find space to place the mike while keeping it out of the way, and the batter mike will pick up a slight amount of pedal noise and/ or squeak. Fortunately modern kick pedals are infinitely better than 1970s era models in this regard. Have some spray lubricant on hand if you try this route.

It’s common in drum recording to add one (or several) room mikes. Some engineers place this mike just about anywhere. They are trying to capture room ambience, not necessarily the kit. Let me suggest keeping the kick drum in mind as you place the room mike. Instead of going high or in a corner, walk as far as makes sense in your room, point the mike at the kick, and place it about 2' off the floor. A PZM mike, ribbon, or large diaphragm condenser are great choices for this application. This mike will get the shell, the room sound, and when combined with a closer mike, it can add to the impression of attack.

bass drum

Fig. 7 Hard to imagine the basic old kick drum is so complicated to record. But all of these microphones are legitimate candidates for the job. And there are many that could be added to this list.

Conclusion

Recording a kick drum well can be a difficult proposition. Many engineers continue to struggle using trial and error, only to be confused when the method that worked last time becomes a bad approach on the next session. As a drummer, the main issues deal with the shell fundamental and the resonant head options. From there you can choose a microphone to complement the particular drum in your session. By working with the producer and artist, you can determine how much shell sound and batter attack are needed for a project. This is also a time when you can be creative with the second mike. Whether you choose an inventive solution such as the Yamaha Subkick or building a 12' kick tube of the apocalypse, do what best serves the song and the drummer. And the next time you see an Internet forum fight over the best bass drum microphone, you’ll know the real answer.