Making The Most Of...
Acoustic Drums 2
To continue the saga of recording acoustic drums, this month we look at ways of treating the recorded sound.
Last month we covered the recording of acoustic drums. This month we continue by looking at ways of treating the recorded sound.
By employing the methods outlined in last month's H&SR, you should be able to lay down a reasonable drum sound, but now, especially if you are limited by the number of available tracks, you'll have to think about bouncing down into stereo before proceeding further. If you do have tracks to spare, the following techniques still apply, it's just that you will then have the luxury of being able to leave all your artistic decisions until the last minute rather than having to commit yourself at an early stage.
When we looked at the recording stage, you'll remember that each drum was considered in isolation before the kit was finally appraised as a single instrument in it's own right, and the same approach may now be taken at the mixing stage. Depending on how many tracks you used, you'll probably have the bass and snare drums on tracks of their own with the toms spread in stereo over two tracks. Additionally, you may well have used another pair of tracks on a couple of ambience mics which should enable you to pull the cymbals out of the mix. You may even have opted for extra cymbal and hi-hat mics.
The bass drum sound, unless gated at the recording stage will inevitably contain a significant amount of spillage from other parts of the kit and so you now have to decide whether to tolerate this spillage and allow for it in the mix, or whether to try to tighten up the sound with a gate. The advantage of gating at this stage rather than the record stage is that you are not going to ruin a good take if the gate is inappropriately set up; you just have to run the tape again. Another advantage, and one that is particularly relevant if you are not using a noise reduction system, is that the gate will also remove tape noise between beats.
The first problem, and one which is common if the kit contains a deep, loud snare drum, is that spill from the snare drum will tend to trigger the gate. To get around this problem you really need a gate with frequency conscious keying and if you don't have a dedicated unit, you can usually patch an equaliser into the side chain access point of your gate to perform the filtering. This may be a graphic, parametric or basic sweep type of equaliser, and its quality is relatively unimportant as it will not affect the sound of the signal passing through the gate. It's convenient at this point to patch in some way of monitoring the output of the equaliser, as you can then optimise the settings to emphasise the bass drum as much as possible whilst rejecting sounds from the snare drum or the rest of the kit. This will give the gate the best chance of differentiating between the two drums. You won't of course be able to eliminate unwanted signals entirely, but it should be possible to attenuate them to such an extent that they do not cause any unwanted triggering of the gate.
Setting up the gate's parameters is an important part of this job and you'll need to use the fastest attack time so that you don't lose the percussive transient at the beginning of the sound. Release must also be fairly fast, but listen to the results as you make adjustments because if the release time is too fast, you may notice that the sound is unnaturally truncated.
If your gate has a hold control, this should generally be set to minimum. Great care, however, should be taken in setting up the threshold control and remember to check your chosen setting on both the loudest and quietest parts of the music. If the threshold is set too high, you'll lose quiet beats completely and if too low, the snare drum will start to break through on the loud passages.
Fortunately many of the treatments for the snare drum are similar to those used for the bass drum, except when you're setting up the noise gate, you now have to worry about keeping the bass drum out off the snare track rather than vice versa. Pay particular attention to setting a threshold that will not cut off light beats or grace notes, and beware of the dreaded hi-hat which will probably be so loud that it will take a lot of fiddling about to keep it from triggering even a frequency conscious gate. Also remember that unless you have used a dedicated hi-hat mic, you may be relying on the snare mic to pick up the hi-hat so then you're faced with exactly the opposite problem of trying to gate out the snare rattles without cutting off the decay on the hi-hats, which will probably entail setting a longer release time.
"...you can use slapback echo, digital delay or even reversed reverb to make things more interesting..."
If you just can't get a crisp sound, the old Scintillator brightens things up nicely and again you can use an Aphex or a Tantek to do the same job.
Reverb treatment is very popular on snare drums and as well as the gated and non-linear sounds described in the bass drum section. Conventional reverb is still the most widely used effect. This is often used with a little predelay for added depth and if you have the facility to vary the decay time, this can give you a useful choice ranging from a mild ambience to a full bodied hall sound. A simple spring unit can be given shorter decay times by routing the reverb output through a gate in the same way as described for creating gated and non-linear reverbs, the difference being that the attack and hold times are set to minimum and the release time used to control the decay time. Of course you can't set up decay times longer than the basic spring decay time but you can get some viable short decay effects with the added bonus that you gate out any noise produced in the reverb unit. Again you can use slapback echo, digital delay or even reversed reverb to make things more interesting, the latter effect being achieved by playing the tape in reverse and simultaneously recording a reverberated version of the snare track onto a spare track. When the tape is rethreaded the right way round, the reverb sound will build up before each beat in a totally unnatural almost surreal way.
Providing that you've got a good basic sound on tape, these shouldn't present too much of a problem, but if you're recording with ambience mics, do record the toms so that the stereo imaging on the close miked tracks approximates that of the ambience mics, otherwise the imaging might sound rather odd. A common mistake is to get the image totally reversed on one set of mics with respect to the other which won't do a lot for the finished result.
All the previously discussed reverb treatments apply equally well to toms as do the comments on the use of psychoacoustic enhancers which tend to emphasise the attack portion of the sound and give the illusion of separation and transparency. Compression, EQ compression and gating may also be applied if considered necessary, but remember, there will almost certainly be a significant amount of crash and ride cymbal on these tracks which might make gating difficult, so again a frequency conscious system is your best bet. Also, if you are relying entirely on the tom mics to pick up the cymbals, you will find it virtually impossible to use any form of gating without ruining the cymbal sound.
Close miked drum kits tend to sound a bit dull and lifeless, especially if you don't use extra mics on the cymbals, and this is where the addition of a couple of ambience mics can make a world of difference. Apart from picking up something of the colouration of the room, these mics also tend to emphasise the cymbals and, if you've used PZM mics, they will contain a lot of high frequency detail that may well be absent if you rely entirely on close miking. The actual balance between the close miked kit and the ambience mics is a matter of taste and depends on whether you want a clinical, dry sound or a more natural sound. In either event, you will probably want to mix in a little of the ambient sound to breathe some life into the cymbals.
Having got the gate organised, you are well on the way but you may decide that the sound needs more attention before you declare the result artistically acceptable. If you are lucky, a tweak of the EQ on the desk will be all that you need, but more often than not, the problem area will require a more sophisticated type of EQ such as a graphic or a parametric. It may be advantageous to place this before the gate so that any contribution it makes to the overall noise will be gated out between beats.
"If you just can't get a crisp sound, the old Scintillator brightens things up nicely and again you can use an Aphex or a Tantek to do the same job."
In the event of the playing being a bit on the uneven side, you might like to try a compressor to even things up a bit but, as these tend to bring up noise levels, you should again try patching it in before the gate but preferably after the point from which you are deriving the gate's control signal. The reason for this is that if you derive the control signal from a compressed source, there will be less level difference between the loudest and quietest sounds and so it will be more difficult to find a reliable threshold setting.
A compressor can of course be used to modify the sound as well as to control the dynamics, and by setting an attack time of a few tens of milliseconds, you effectively allow the leading edge of a sound to pass uncompressed which gives it a better defined attack. Again the release time should be fairly short, but if you listen whilst making adjustments, you'll instinctively home in on the right setting.
There's another treatment for limp bass drum sounds, which I discovered when confronted with a bass drum fitted with Evans heads that persisted in sounding like a wet suitcase despite all attempts to tune it. I just happened to have a Scintillator enhancer kicking around which I patched into the bass drum channel's insert point, though you could equally well use the Tantek Psychoacoustic Enhancer or an Aphex Type B Aural Exciter to achieve the same result. By setting the filter control on the Scintillator to it's lowest range, and adjusting the drive and effect controls, it became possible to transform this lifeless thud into something which would not have disgraced a Michael Jackson album; definitely a useful salvage tool!
Well that just about wraps up the basic sound so what about effects?
It used to be standard practice to keep bass drums fairly dry and this attitude still prevails to a large extent, the only noticeable exception being the application of gated reverb. This may be produced by feeding the effect send into a reverb unit, spring, plate or digital, and also feeding this signal into the control circuit of a noise gate. The reverb output is fed into the input of the gate and both the attack and decay settings should be at minimum. You need a gate with a hold function to do this trick, and this is set to give you the desired length of reverb burst following the sound. Because the reverb sound is cut off so sharply, a less than perfect spring reverb unit may be coaxed into giving artistically viable results. By introducing a little pre-delay before the reverb unit and setting a slow attack time in conjunction with a fast hold and release time, some convincing reverse envelope reverb sounds may be created which correspond to the non-linear settings on the more expensive digital reverberators. Of course if you have a digital reverb, it may well offer all these treatments without the need for a gate, but either way, the type of result is much the same though digitals don't twang on transients like springs do.
Other treatments are worth experimenting with, including slapback echo (single short delays in the order of a few tens of milliseconds) or flanged reverb. But now we're getting into the realms of production which we'll be exploring in future issues.
"...do record the toms so that the stereo imaging on the close miked tracks approximates that of the ambience mics..."
Another trick, which is particularly effective if you have a good live room with a bit of natural reverberation, is to gate the output from the ambience channels using a stereo linked gate, triggering it either from a single drum track, such as the snare drum, or from a mix of some or all of the drums depending on the effect that you want to create. Given the right type of room, you can create a really huge drum sound, the most famous exponent of this technique probably being Phil Collins.
In the way of effects, it is interesting to treat the ambience sound whilst keeping the close miked component fairly dry, and mild flanging or a Roland Dimension D can be quite dramatic if used tastefully.
If the ambient sound is particularly good, usually the case if you play a well tuned kit in a flattering room, you may well get away with using little or no close miking apart from a little reinforcement for the bass and possibly the snare drum.
Once you've optimised the sounds of all the individual parts of the kit, you'll need to listen to the kit as a whole to see if the sounds blend. If you've recorded a lot of spill between mics, this will affect the final sound and so some adjustments will have to be made while you're listening to the complete drum mix, (complete with any effects that you have chosen to use). Ideally you should listen to the drum mix in context with the rest of the track because what seems like a lot of reverb in isolation may well tend to get lost in the whole mix. Sadly, if you're bouncing tracks to make room for the rest of the instruments, you probably won't have the opportunity to do this and so will have to imagine how the drum part will sound in context. This takes a certain amount of experience to be able to judge properly (but if everything were easy, then everyone would be an expert wouldn't they)? If you find at the end of the day that you have miscalculated and the cymbals are getting lost, put the whole drum mix through a psychoacoustic enhancer and you will be pleasantly surprised to find that they re-appear. If you think that such devices are beyond your financial reach, check out the Tantek range; even ready built they're ridiculously cheap for the quality they offer.
A final few words on positioning drums within a mix: bass drums and snare drums tend to be panned near centre and this is not just in respect of artistic considerations. Because the bass drum provides the drive for a piece of music, it can be made louder if it's arranged to come out of both speakers rather than just one, and the same is true of the snare drum and the bass guitar or bass synth. A possible exception is in the case of a snare drum treated with slapback echo where the original sound may be contrived to appear at one side with the delayed version at the other.
For a natural kit sound, it is a good idea not to pan any of the drums to extremes as the mental image of a drum kit about forty feet wide does nothing to convince the brain that it's actually there at the gig; save such tricks for larger than life production extravaganzas.
That's it for the standard drum kit then, but we will get around to looking at other types of percussion in the not too distant future.
Feature by Paul White
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