Making the Most of...
Drum Machines and Electronic Percussion
Martin Sheehan looks at recording drum machines and electronic percussion
Drum machines are a convenient and socially acceptable alternative to 'real' drums — but you can do much more with them than just plug them in and let them loose.
Without electronic drums, how many home recordists would be able to have a drum track on their recorded works? In terms of space saving (and staying within the local noise pollution bylaws), electronic drums offer the biggest advantage over their acoustic counterparts to the musician working at home. Electronic drums do not provide a global panacea for recording percussion, however, and bring with them a few problems of their own. How often have you heard remarks similar to 'Oh my goodness, not another zarking rhythm box?' (Very rarely - Ed). No one complains about keyboards not sounding natural but a lot of people expect drums to sound like the real thing. These derogatory remarks concerning electronic drums may originally have been provoked, quite justifiably, by some early models whose sounds were more like a cement mixer full of light bulbs than a real drum kit. Models in current circulation however, generally present us with much better basic sounds and there are a number of treatments the home recordists can use to make the recorded sound more interesting.
One of the first things to watch when recording any percussion, not just the electronic variety, is the recording level. The VU type meters fitted to most budget recording systems, and some professional models, will not respond fast enough to give a true reading of the level of signal going on to tape. A VU meter showing -7dB peaks may in fact be responding (or rather not responding) to true peaks above 0dB. Advancing the record level so that the meter is actually showing around 0dB whilst monitoring from source, will result in an attack of sneezing and graunching when monitoring from tape. Optimum levels for recording percussion are best arrived at by trial and error until you get to know your own make of recorder, and you can then use the metering as a guide, knowing that a needle dodging around at -5dB may be as much level as your particular recorder can handle as regards percussion. Some VU meters have associated peak LED indicators which can be a great help and bar graph type meters using rows of LEDs are also frequently seen and can respond quite accurately to signal peaks.
A good way to find the optimum recording level on three head recorders is to monitor off tape from the playback head during recording whilst adjusting the record level. A good level can then be arrived at by increasing the record level until distortion is heard and then backing off.
Having given your electronic drum sound the best possible start in life level-wise, it can now be improved by wetting the inherent dryness of electronic drums and attempting to loosen things up generally.
"Electronic drums do not provide a global panacea for recording percussion."
When acoustic drums are recorded it's inevitable that a certain amount of ambient sound and spillage will be picked up by the microphones and consequently put down on tape. This 'extra' sound, other than that received directly, is what gives our ears and brain the information it searches for in order to ascertain the environment within which a sound is produced.
One very simple way of injecting some ambience into electronic drums is to put them through the monitors and then record them via a microphone. It is necessary to move the mic around to find the best recording position and to achieve a balance between the sound coming directly from the speakers and the indirect sound bouncing into the mic from walls and ceilings. A rather more easily controllable version of this technique is to record the directly injected drums whilst also mixing in some of the signal picked up from the monitor speakers by the microphone. The microphone placement becomes far less critical here as a fair amount of 'positioning' can be achieved by using the relevant fader and EQ controls on the mixer. Although this can be quite an effective way of overcoming the dryness of electronic drums it is limited by the acoustics of the room in which you are recording which is usually a deliberately dead area. Far more variety can be introduced by using echo and reverberation units or by putting the monitors in the bathroom.
A delay (or echo) unit can be used in a couple of basically different ways to inject some life into electronic drums. The first method involves the use of short delays of somewhere around 50 to 100 milliseconds to represent the sound reflections which would occur were a real kit being bashed in a fair sized room or hall. Using just a tiny bit of feedback or regeneration on the delay, its level should be brought up gradually until a distinct difference in sound is heard. At the longer end this may be heard as a discernible repeat but at the shorter end the sound will just appear thicker. Once this point has been reached the echo return level should be eased back a little to obtain what would be nearer a natural sounding level of ambience. The ears will quickly become accustomed to this slight ambient injection and if the echo return fader is whipped down the drum sound will suddenly appear very cold and stark. This is when you appreciate just how much depth a small amount of echo can add. If you have EQ available on your echo return, or you are bringing it back via an input channel, a further improvement can be made to this sound by rolling off some of the bottom end using the bass or low frequency controls. Low frequency sounds are less directional than high frequency ones, and this, combined with their generally longer decay time, obviates the need for so much wetting in this region. Indeed, too much low frequency delay can tend to muddle a sound rather than enhance it.
"Timed repeats from a delay line can add quite a degree of interest to a rhythm track."
This method of using short delays fulfills a similar roll to that of pre-delay used in conjunction with reverberation units, and if you can afford to use a separate track for the echoed sound, the extra sense of depth is worthwhile.
The second method of using echo on electronic drums can tend to add a degree of 'feel' to the rhythm. Various electronic kits on the market, probably best symbolised by the word Simmons, have a disadvantage against drum boxes in terms of size, but great advantages in terms of feel. The feel of a drum track is created by the irregularities and variations in timing and level. Many of the electronic kits will respond in the same way as a normal drum by producing a level of output proportional to the force with which the thing is hit; when it comes to programming rhythms into boxes, as opposed to playing them with sticks, a large degree of feel goes out of the window. In the case of the more sophisticated electronic drum units there are various levels of accent available and even some that have a facility whereby the timings within a bar can be tampered with in an attempt to mimic some human element, but at the lower end of the scale, only one level of accent may be available.
For those recordists with buttons instead of pads, timed repeats from a delay line can add quite a degree of interest to a rhythm track. The timing of the repeats is not limited to the clock pulses inside the rhythm unit and the level of the repeats is not limited to the available accent levels. Delays around the range of roughly 200-500mS are most valuable in this instance. Adjusting the timing of the repeats to land on the beat will reinforce some beats and fill in with little incidentals in other places. One of my favourites is to place the repeat either a third or two thirds of the way between beats or bars to give a triplet feel which can really push things along. Even if you only have one delay unit, it is quite practical to use both these delay based techniques by using the short delay when laying the drum track down, and the long delays on mixdown.
"...consider using a Sync Track box to lock the drum machine to one track of the tape machine."
The adding of reverberation to electronic drums can be a problem with some units where individual outputs for each drum sound are not available. The trend towards heavy gated reverb on some drums, especially the snare, can be difficult to achieve without creating a blanket of reverb as it ends up being triggered by anything within earshot. One way to avoid this without resorting to recording the snare separately onto a track of its own, is to use a noise gate on the reverb send as well as on the return. Providing the reverb is required on the loudest sounding drum, or that a side chain filter can be selectively keyed into the appropriate drum sound, the threshold can be set to allow a signal through to the reverb unit only at the time. This method does, however, mean that any other sound occurring at the same time as the gate is open will also receive the treatment. A more reliable method of which some recordists will be able to take advantage, is to sample a snare drum, either acoustic or electronic, and trigger it from the drum unit. It is then available as a separate signal to do with as you will. Although the price of this sort of technology may be out of reach of a lot of home recordists at the moment, it won't be too long before the prices start to look more affordable.
A few specific problems relating to the recording of electronic drums have to be brought to light and it is worth mentioning them here. One of these is noise level in some of the earlier budget models. It is clear that they were not designed specifically with recording in mind and whilst their noise levels are quite acceptable for live work, they are less than ideal for recording. One specific problem is the breakthrough of the clock pulse which can sound like a continuous ticking away in the background. (This was a problem on some early TR606 machines and was caused by bad soldered joints where the switch lugs pass through the PCB. Re-soldering these usually cures things but may be difficult as the lug plating doesn't solder easily and this is what caused the problem in the first place-Ed). Whilst it is masked on beats, it is pregnant during pauses. Using a noise gate can solve this problem but it needs to be quite a good one to act fast enough not to adversely affect the drum sounds. This noise problem is one which can easily be avoided simply by listening to the thing in the shop if you're thinking of buying one. The next couple of problems, however, would only come to light whilst actually recording.
"The adding of reverberation to electronic drums can be a problem where individual outputs are not available."
The Roland Drumatix, whilst being a very popular programmable rhythm unit, has a cymbal and hi-hat sound which can cause recording problems. The cymbal sound produces harmonics which are high enough to interfere with the bias frequency on some recorders. This can result in the crash which you heard on source turning into a sneeze on playback. H&SR are looking into this problem and it should be quite cheap and easy to remedy with a simple low pass filter circuit which will be published in a future issue. The Drumatix also has two trigger outputs which can be used to drive E&MM Syndroms to add a couple of digital voices.
To mention one more specific model: the Korg SuperDrums, whilst producing very good affordable digital drum sounds, could give vari-speed addicts a circuitry which puts all the digital goings on only just out of ears reach. Slowing down the tape on playback reveals a sort of 'ting' to the top of the snare in particular. Whilst excellent results are possible with the Korg SuperDrums at normal pitch, it is a point worth bearing in mind if you do a lot of messing about with tape speeds.
Electronic drums now come in a multitude of forms, from pre-programmed blips and pops to velocity sensitive pads triggering real drum sounds. Whatever principles they use, they all go down on the same sort of tape and the same sort of treatments can be applied. If you don't have enough tape tracks to do your drum machine justice, consider using a Sync Track box to lock the machine to one track of the tape machine so that you don't have to record it at all until the final mix. This means that any separate outputs can be individually treated at the mixdown stage and the individual outputs panned in stereo. Just because they are so much less trouble to record than an acoustic kit, it doesn't mean they should be given any less attention. Whether you play in step-time, real-time or out of time, don't just put them down dry on the first one or two tracks and forget about them - have a fiddle with your paradiddle.
Feature by Martin Sheehan
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