Recording Techniques (Part 8)
Part 8: David Mellor explains several techniques for taming that most difficult of instruments to record - the drum kit.
If you like a challenge, then you will probably enjoy recording drums more than any other instrument. It's human nature to respond to a challenge, and when it comes to this supremely complex collection of sound producing apparatus, several top class engineers have responded by achieving results so amazingly good that it would take years of experience even to come close - assuming that you have the good acoustics and first class equipment that are also necessary. Despite this, a little knowledge can go a long way. As long as you don't expect a drum sound that will rip the diaphragm out of your abdomen at the first attempt, a few well tried and tested techniques and concepts will help you achieve a good professional sound.
Of all the instruments, the engineer needs to know most about the drum kit and will have the most influence over the way it is set up and played. Try telling a guitarist or a bassist how they should plug in their instrument and how they should play, and they will probably think that you are getting too big for your boots! - unless you already have a good working relationship. But whatever the drummer thinks about your involvement with his kit and the way he is playing, it is extremely important to the end result. Here are three rules of thumb:
You can't get a good recording of...
1) a bad drum kit.
2) a good kit, badly set up.
3) a good kit, well set up but played badly (or inappropriately for the song).
Unless the drummer is experienced in studio work, most of his effort will have gone towards achieving a good live sound. Now is the time to persuade him that you want things done differently. First of all, let's look at the drums that make up the kit individually and see what we can do with them...
Americans call this the 'kick drum', because once upon a time it was played by simply giving it a good hard thwack with a size 10 boot. Evolution has made matters somewhat more sophisticated, and in fact if you are into hi-tech heavy engineering, take a look at some of the fancy bass drum pedals that are around these days!
The bass drum itself is just a large drum placed on its side, with a head (the drum skin) at either end. If that's how it comes into the studio - ie. with two heads -then you will need to do something because, in this case, two heads are not better than one. A double headed bass drum is a great instrument for a Salvation Army band, and it does suit many styles of music well, but for music in the modern idiom it is just too 'boomy'. Or to be more precise, the sound isn't sharp enough and goes on too long. The remedy is to remove the front head and put a blanket inside. This will produce the currently fashionable short sharp thud that we are aiming for most of the time. An alternative to this, which many drummers will have done already, is to cut a hole in the front head. This is a very acceptable solution. The hole allows access for the damping material - the blanket - and for the microphone.
Around the working end of the drum you will find the pedal and beater. It's always worth taking a look at the beater, as it may be hard or soft - giving hard or soft sounds, naturally - or may have one hard and one soft surface, which can be rotated. If you check this out before recording starts, you will at least know something more about the kit, and maybe have a valuable option if the bass drum sound needs changing for any reason.
Opinions differ on whether the snare or the bass is the most important drum in the kit, but it's for certain that they are both more important than any other. The snare drum always has two heads. The lower head has, tensioned against it, a number of snare wires, which gives the drum its 'snappy' sound. It's worth spending some time working on the tuning of this drum, because the sound is so vital in its contribution to the whole arrangement.
The drummer will have a key for adjusting the tensioners around the rim of the drum. Thoughtful recording engineers have their own drum key, too - just in case the drummer forgets. Drum tuning is a bit of an art, so you should let the drummer apply the motive force while you comment on the sound he is obtaining. Usually, the snare is tensioned evenly all round. The choice is between a higher or lower pitch, always aiming at a sound with which the drum itself sounds comfortable (because of the dimensions of the shell), and which hopefully will suit the arrangement of the music.
Just like bass drums, snare drums need to be damped. Many snare drums have internal damping mechanisms, which are good for absolutely nothing! The way to damp a snare drum, in order to produce a shorter, snappier sound, is to gaffer tape a piece of cotton wool to the top head. The sound will be affected by the quantity of damping material used and its positioning, so work out with the drummer what sounds best. Sometimes the snare wires also need a bit of damping, to prevent them from rattling too loudly in sympathy with the other drums in the kit.
(Useless fact for the day, number 1: Did you know that you can create a glissando on a snare drum if the drummer plays a roll while you blow into the air vent on the side? Useless fact number 2: It makes you look really stupid!)
Toms fall into two categories: double headed and single headed (sometimes called concert toms), and usually all the toms in any one kit will be of the same type. Unlike the situation with the bass drum, there isn't so much preference from the recording point of view. A good tom is a good tom, the only point being that concert toms give you an extra option when it comes to miking - you can mic them from below.
Usually, the function of the toms is to give the drummer the opportunity to play a thundering roll across all of them at a particularly dramatic point in the music, so you want the sound to be powerful. Once again, the tuning key comes out - either the drummer's or yours. There are two tuning requirements for toms, apart from the essential point that whatever pitch the head is tuned to, it should suit the size of the shell. Listening to all the toms, there should be an equal musical interval between each drum. You don't need an electronic tuner to judge this, nor do you have to tune them to any other instrument of the band, as long as a roll around the toms sounds good. The other point about tom tuning is that if the head is unevenly tensioned, the pitch will fall during the duration of the note, and this is what actually gives the tom its characteristic sound. Hopefully the drummer will know how to do this for best effect, but even if he doesn't, at least you will have given him something to think about and experiment with before the next session.
Arrgh! The curse of the recording engineer strikes again! If it wasn't for the cymbals, it would be so much easier to get a good drum sound, but those drummers got in first on the act, before recording was invented, so we have to cope with them as best we can. [Unless you do what Peter Gabriel did on his pioneering third album, and don't use any cymbals whatsoever! - Ed.]
A typical drum kit will have a minimum of four cymbals: crash, ride, and a pair of hi-hats. Crash and ride cymbals perform different functions for the drummer (one accentuates, the other supports the sound) but they are not usually treated any differently when it comes to recording.
As I said earlier, you are on to a loser if the drum kit isn't up to much. With cymbals, the problem is even greater. It seems that less than perfect drums can be tweaked up with appropriate mic positioning and EQ into something half-decent, if not wonderful. But bad quality cymbals always sound like dustbin lids!
The hi-hat is especially important, since it is the third most important component of the drum kit after the bass and snare drums. My own solution to drummers with poor cymbals was to buy my own pair of hi-hat cymbals (Paiste 2002 Sound Edge 14"), which I can't play to save my life, although I keep them on a stand to amuse visitors to my flat.
In my trip around the drum kit I have missed out one thing - that the drums will rattle like crazy until you liberally apply gaffer tape to the fixtures and fittings. After that, you are ready to put up some microphones. But where, and how many?
There are, to my mind, two ways to mic up drums. One is to use as few microphones as possible, the other is to use as many as you can think of positions for. In-between stages can only result in compromises on some of the instruments of the kit. Let me explain...
Obviously the smallest number of mics you can use on any instrument is two, if you want a stereo recording. Two isn't quite enough for drums, and Figures 1a and 1b show why. The best place for two of the mics has to be above the kit, but this leaves the bass drum rather too far away from any mic and isolated - so you need one more. The two overhead mics are placed behind the kit so that they don't pick up too much cymbal sound (although they'll still get plenty). Cymbals are directional and radiate most sound from their flat surfaces, so if the mics are positioned as nearly as possible in line with the edges, they won't pick up so much. Rest assured that with this arrangement, there is never any shortage of cymbal sound. When positioning the mics, don't go below the drummers shoulder level or he will screen off part of the kit.
The positioning of the bass drum mic gives the engineer a few options: the closer it is to the beater, the harder the sound will be; the further away it is, the more sound of the shell of the drum it will pick up. Experiment!
Perhaps you are now thinking, 'If three mics are good, won't four be better?'. The answer is yes, but problems arise. The obvious place for a fourth mic would be on the snare - but then the toms will be at a disadvantage. So you put mics on the toms, and pretty soon you have got a mic on every drum on the kit. In fact, it really is the only other way to go - one mic per drum plus one on the hi-hat and a pair of overheads, as in Figure 2.
I probably don't need to say that it is difficult to balance the levels from all these mics, and it is impossible to learn how to do it apart from by experience, but I can offer some guidelines:
Method 1: Get a sound on the overheads and bass drum mic. Then fade up each mic in turn until it fits in with the general sound. Use headphones to pan each mic precisely to the same position as it appears to be in the stereo image of the overheads.
Method 2: Start with the bass drum only, then bring in the snare, then the other mics in turn. When the individual mics are balanced, bring up the overheads to fill in the cymbals.
With these two methods, you will tend to get different results. The first will give a fairly natural sound, but stronger than the three mic setup. The second will be more powerful, but is harder to deal with and requires careful mic positioning. There is a third method, however...
Method 3: Bring up the faders to random levels and work it out from there! This may seem haphazard, but believe it or not, it is a valuable mixing technique, and works when you are mixing down the complete track to stereo, too. I wouldn't use it as a first option, though.
So far, everything is going smoothly. But that's because you are reading a magazine article and not doing it for real! As you know, there can be a world of difference between theory and practice. What will happen in real life is that a selection of problems will crop up at each stage. Here are a few:
• The drums don't sound very crisp.
For crispness, you need to use a capacitor microphone. The Neumann U87 is very good, for instance, as are some other expensive models.
• The toms sound weak, even when I push the faders right up.
For powerful toms, dynamic mics are best. Capacitor mics can give a very accurate sound, but do you want an accurate representation of what it's like to have your ear an inch from a drum head? Dynamic mics round off the fastest transients, which you can hardly hear anyway, and allow the real power to come through.
• The more mics I bring up on the faders, the more it seems to muddy the sound.
This is because every microphone you put out picks up every drum in the kit. It is bound to create a bit of a muddle. The best thing to do is to follow the 10:1 rule, which states that the second closest mic to any drum must be at least 10 times as far away as the closest.
• When I bring up the high tom mic, the snare sound goes all funny.
Aha! Sounds like the mics are picking up an out-of-phase signal on the snare. This happens by chance because of the relationship between the distances from the snare to the snare mic and from the snare to the tom mic, and the fundamental frequency produced by the snare drum. Press the Phase button on your mixer for one of the mics and it should cure the problem (but be aware that the same problem may have now moved elsewhere).
Recording drums and getting them to sound like a real kit being played by a real drummer isn't easy. As I have indicated, it takes a lot of experience to get the feel of whether a certain microphone can be placed an inch higher or lower, whether you should ask the drummer to tune a drum differently, or even play it differently, etc. There are, however, tricks of the trade to help you achieve better results, providing that they don't work to the detriment of the music, and also providing that the drummer is willing and able.
If you want to get a better drum sound, by which I mean clearer and more powerful, and with better dynamics, then the number one thing to do is to get rid of the dustbin lids - sorry, I mean cymbals. If we can do that, we get rid of a sound that is leaking into all our drum mics, and we will also be able to lower the overhead mics and pick up the individual drums more clearly. Even a simple three mic arrangement can give a really good clear sound if there are no cymbals in the way. Obviously, if the musical arrangement calls for a lot of subtle interplay between drums and cymbals, then you can't do it like this. But very often it is possible to record the cymbal crashes as overdubs, later. You might even find that the drummer likes working this way.
One step further along the same path is to get rid of the hi-hat, too, and overdub that. Most drummers have their hi-hat located very close to the snare, and inevitably a lot of its sound will leak into the snare mic - in fact, you may not need to use a hi-hat mic at all. It cleans up the sound even more to do away with the hi-hat, but the problem is that it may be impossible for the drummer to play the hi-hat as an overdub and get the rhythm precise enough. Even if it might be possible, the drummer may not be cooperative because he sees it as 'cheating' and a devaluation of his role. Of course, it's up to you, the engineer, to obtain the best possible sound by using appropriate techniques and being as persuasive as you can.
Once the drums, mics, and mixing console are set up to your satisfaction, it's all systems go - but remember that the drum kit is the foundation of the arrangement. Listen closely to the sounds the kit is making and to the accuracy of the drummer's rhythm. Don't hesitate to speak up if you think that something can be improved, or if the rhythm sags even momentarily. And while you are listening to the throbbing sound of the drums going down onto tape, just remember that you won't have this much fun again in the studio until you do the vocals... next month!
Feature by David Mellor
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