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Compromising Position

Yamaha's RX21 Drum Machine offers a lot of sound for very little outlay.

Yamaha have used the technology developed for their RX11 and RX15 drum machines to produce the budget RX21, but at what cost in facilities?

Yamaha RX21.

It's a fact that technology is getting cheaper and what would have been very expensive only a few years ago now makes its appearance in the budget end of the market. A case in point is the digital drum machine. At one time it was a Linn or nothing and at a cost few could afford, but now you can get a reasonable sounding digital machine for less than the price of an old analogue unit.

Yamaha's latest drum machine, the RX21, is a perfect example. For around £250, you get a professional sounding drum machine but in order to keep the cost this low, some facilities have had to be omitted or at least amended.


Firstly let's look at the drum voices themselves. The RX21 offers none of the expansion possibilities that the Americans are so fond of (such as the Sequential Tom's plug-in cartridges). The voices you get are what you are stuck with.

What you do get are nine PCM-encoded voices comprising the familiar kit sounds, plus the ubiquitous handclaps. A year or two ago that would have seemed a decent enough selection, but now that Roland and Korg have started freeing impecunious musicians from the restrictions of acoustic sounding drums, it might have been possible for Yamaha to be a little more adventurous. However, we do know that a Latin version of the RX21 is on the cards.

In case you might bethinking that the RX21's budget price has resulted in a lowering in quality of the voices, I should stress they're actually the same sounds used by the RX15 drum machine, but there are fewer of them. If there's one thing that characterises all these sounds (bass, snare, three toms, open and closed hi-hats, crash cymbal and handclaps), it's presence. They're all crisp and punchy, and the bass drum and low tom in particular have plenty of kick behind them. Most of the voices can be sounded simultaneously but Yamaha have bowed to tradition in not allowing the open and closed hi-hats to sound on the same beat. It's possible to produce a very realistic sounding drum track with this machine and only the limited sample time used on the crash cymbal might give the game away if listened to in isolation.

Along with the overall volume level, it's possible to set individual levels for each voice, though these levels aren't programmable per pattern: more evidence of cost-cutting by comparison with the RX15, which does have this facility. Also retained, in a simplified form from Yamaha's more expensive machines, is the useful facility of being able to program an accent for any beat. Thus you can reinforce four to the bar (or the downbeat on some odd time signature like 7/16), turn a beat around, or give a sizzling syncopations some extra bottle. Accentuation is also useful for giving added interest to sustained ride cymbal or open hi-hat. However, unlike its more expensive counterparts, the accent facility in the RX21 means that all voices falling on an accented beat will be emphasised, you can't program the accent for individual voices. This system is similar to that used on Roland's drum machines and can still be used to great effect.

"Along with the overall volume level, it's possible to set individual levels for each voice."


So much for the voices, but what of the RX21's memory capabilities? At first sight the RX21's budget price doesn't seem to have affected its provision of patterns: a creditable 100. However, it transpires that 44 of these are preset rhythms, safely tucked away on ROM so that you can't get rid of them. This still leaves you with as many programmable patterns as you get on Roland's TR707, but the patterns Yamaha have provided on ROM are neither as varied nor as interesting as they could have been, and I kept finding myself wanting to get in there and muck about with them. Still, they form a good basis for copying and modifying if you're not too hot at writing drum parts.

Talking of changing things a bit brings us on to the actual operation of the RX21. Patterns can be recorded in real and step time and freely passed between one mode and the other. Thus you can record some parts of a pattern in step time and some in real time, or perform step time edits on parts recorded in real time: a nice degree of flexibility that's made possible by the fact that all input, whether in real or step time, is quantised to one of four values (only one of which can be active per pattern, of course). These are 12, 16, 24 and 32 (ie. triplet quavers, semiquavers, triplet semiquavers and demisemiquavers). You have to decide whether you want triplet (swing style) or 'straight' type quantisation before you start recording, because you can't change from one to the other once finger has been laid on pad. This is more of an irritation than a limitation, though.

The maximum length for a single pattern is 16/16, and this can be reduced to as little as 1/16. Real time recording gives you the usual metronome beat on each crotchet, accented on the first beat of the bar. In time honoured fashion, the pattern loops continuously until you exit record mode, so that you can add to it at whatever point and time you want. Any beat you don't like can be deleted by judicious application of the Clear button in conjunction with the appropriate voice pad, though if that beat is also an accent, you need to find a third finger for the Accent pad.

The 21's version of step-time writing allows you to enter one voice at a time on each quantisation step (rests are input by means of the all-purpose '+' key). As with real time recording, the steps keep looping until you exit record mode, so you can build up your pattern gradually. As you move through each step, the voices already recorded on that step are played back to you. (If only every step-time system did that.) As I mentioned earlier, you can move to real time writing at any time and carry on recording your pattern, should you wish.

However, Yamaha have done a bit more with the step time system. Specifically, you can view a step time representation of your patterns (one voice at a time, of course) in the LCD window, where a system of dashes and dots gives a clear indication of each step while small blobs (looking a bit like hand grenades) show where a beat has been placed. Not even Yamaha's costliest digital drum package, the RX11, has a visual display of this kind, and it's certainly a useful inclusion that's as educational as it is informative. In fact, my only major grouse is that, like so many LCDs, this one isn't backlit, so that unless you look at it straight on in decent light, you have to experience a degree of eye strain.

"In case you might be thinking that the RX21's budget price has resulted in a lowering in quality of the voices, I should stress they're actually the same sounds used by the RX15."

Song And Dance

Like any decent programmable drum machine, the RX21 allows you to combine patterns into songs. In all, the memory can hold four of these songs, each of which can be made up of as many as 512 patterns. My own feeling is that more songs with fewer steps would have been far more useful, both for live work, recording and for use in conjunction with a MIDI sequencer. To give the memory eight songs of 256 steps each, or even 16 songs of 128, would surely have cost very little extra in software terms.

In song mode, the RX21 gives you the basic editing facilities of inserting and deleting steps, but what you won't find are any of those useful facilities that give you real flexibility in song programming, such as tempo changes and pattern repeats. Again, you have to look to a more expensive instrument such as the RX15 for features like these.

On a more positive note, one area where Yamaha deserve much praise is in front panel design and for the ease with which you can find your way around the instrument. For any newcomers to the world of drum machines, the RX21 shouldn't foster any phobias; the control layout makes it simple to use, even if the scaled-down facilities must also be partly responsible for this.

As on the RX15 and RX11, Yamaha have provided a facility for copying a pattern from one position into another which is useful if you want to take a pattern and adjust it bit by bit for inclusion in a song, for instance. You can also clear both patterns and songs at a touch of the appropriate button. There's also a Repeat on/off function which affects patterns and songs alike, while tempo is continuously variable from crotchet = 40 to crotchet = 250.

When it comes to conversing with the outside world, the RX21 is strictly MIDI-compatible only, with one MIDI In and one MIDI Out socket on its rear panel. The machine can be set to read either its own internal clock or incoming MIDI timing bytes, allowing the RX21 to control or be controlled by a sequencer or another drum machine.

"Real time recording gives you the usual metronome beat on each crotchet, accented on the first beat of the bar..."

Yamaha RX21L; a latin version RX21 shortly to be released.

Yes, you can play the 21's voices from a MIDI keyboard, though not vice versa, it seems. The MIDI receive channel for this purpose can be any one of the 16, which gives you maximum flexibility if you want to run the RX21 off a MIDI sequencer.

One area of compromise which may be a serious limitation when the machine is used in a recording context is that there are no separate voice outputs, only a choice of mono or stereo. This is a problem if you want to add effects to say the snare drum but not the bass drum, and you can't even pan all the toms and snare to one side and the bass to the other as the pan positioning in the stereo mode is fixed. I know that this compromise has been made in order to minimise the cost, but in view of the fact that most drum machines in the UK are used for recording, perhaps fitting a separate bass drum output would have been a more acceptable compromise.

External storage of the 21's data can be to either cassette (with the familiar array of save, load and verify functions; a complete dump takes 15 seconds) or via System Exclusive MIDI dump, though this, of course, requires a computer and appropriate software at the receiving end.


The RX21 must be the best sounding digital drum machine currently available at the price, and as such it will find a place in many budget home studios where the more sophisticated RX15 or RX11 are just too expensive. It is however a serious limitation that there are only stereo outputs, particularly if you like to experiment with reverb, as you'll nearly always want to add a lot more reverb to a snare sound than to a bass drum.

The MIDI aspect of the machine is useful if you are syncing a sequencer to tape and using this to run a selection of MIDI bits and pieces because this approach saves tracks and also saves one generation of recording which improves the quality of the end product. Sadly though, MIDI is included to the exclusion of all other types of interface so you don't get any trigger outs to trigger your sampled car crash sounds and you can't sync the machine directly to tape. Even with these limitations though this machine represents excellent value for money, is easy to use and sounds most impressive.

The RX21 costs £249 and further details are available from: Yamaha Kemble, (Contact Details).

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Home & Studio Recording - Copyright: Music Maker Publications (UK), Future Publishing.


Home & Studio Recording - Feb 1986

Donated & scanned by: Mike Gorman

Gear in this article:

Drum Machine > Yamaha > RX21

Gear Tags:

Digital Drums

Review by Simon Trask

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