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Yamaha RX11 & RX15

Programmable Rhythm Machines

Yamaha's first-ever self-contained programmable drum machines have PCM-encoded voices and MIDI. Kendall Wrightson gives his verdict.

Yamaha's first-ever programmable drum machines are beginning to filter into music shops' displays. They're not as revolutionary as the DX synths, but they are excellent value. Kendall Wrightson

To say that Yamaha's digital drum machines have been eagerly awaited is something of an under-statement. Some three years have elapsed since Linn started the digital drum revolution with their LM1, while it's now seven months since Yamaha announced their entry into the field with the RX11 and 15 reviewed here. The wait has not been in vain, since Yamaha have spent the last three years carrying out intensive research and development, and that time has resulted in a pair of machines that are simply stunning in terms of both facilities and price - the RX15 is under one sixth of the cost of the original Linn... The long wait has also ensured that the RXs are supplied with a useful implementation of MIDI as standard, MIDI having been around for only 18 months - though it seems much longer!


The RXs are styled to match Yamaha's DX range of synthesisers, not only in appearance but also in operating procedures - hence the data entry controls and Function button. Once you've become familiar with the layout and operation of the controls, the units are very simple to use.

The RXs are light (about 3kg), the innards being held together by two pieces of moulded black plastic. Inside there are two PCBs, one attached to the base and one to the front panel moulding. Care has to be taken when opening an RX because the PCBs are connected together by short ribbon cables. The only IC given its own socket is the 27128 16K EPROM that contains the operating system. The drum sounds are stored on four (RX15) or six (RX11) Yamaha ROMs. It's clear from these observations that Yamaha do not intend for users to change the sounds in their drum machines.


Programming the RXs is eased considerably by the inclusion of a 16-character liquid crystal display, though unfortunately this is not back-illuminated. The LCD guides the user through the programming procedure, and control parameters may be displayed instantly: the RX11 also boasts a two-digit LED display to indicate song or pattern number.

The instrument keys are firm enough to inspire confidence, yet require only the lightest touch to trigger a sound. The Quantize (time correct) facility can be set from 1/4 to 1/192, the latter setting programming flam effects in real time, and four levels of Swing make life even more interesting.

In Step Write mode, the bar is divided up into beats depending on the Quantize value. Beats are advanced by pressing the +1 key (which programs a rest), or by pressing one of the instrument keys. In general, step time is most useful for fast, intricate patterns or for locating an offending drum beat.

Patterns may be edited either by Clearing instruments from a pattern when the machine is stopped, or by holding Clear and pressing the appropriate instrument button while in real time Write mode.

Up to ten Songs can be constructed from as many as 255 different patterns. Full editing is possible, and Songs may also contain repeats (to save memory), and Tempo changes, ie. the initial tempo of a song is set up by the user and a tempo change value is entered as part of the song memory. If the tempo change is part of a repeat loop, then the tempo will increase/decrease every time the repeat loop is executed. The initial tempo can be set accurately using the +1/-1 buttons.

The RX11 can store up to 2000 'events', the RX15 1500. This is significantly lower than the figure achieved by most of the RXs' rivals: in practice I found that the RXs could hold two or three reasonably complex songs, but that may not be enough for some users. Pity. Both machines are fitted with a tape dump facility for program storage, but the RX11 is also equipped with a cartridge slot for Yamaha RAM packs, and so is well suited to live use as cartridge data loads in only a few seconds.


DX synth owners will be pleased to hear that buying an RX drum machine will also get them a mini-sequencer! This is because each drum sound can be allocated a note value which it will transmit via MIDI Out. A note value of 36 is bottom C on a DX7, for example. Each instrument can also be allocated its own MIDI channel, but the fact that this feature works only on DXs is somewhat annoying, and I hope Yamaha update the RX software to cure this problem.

The RXs generate the 24 pulses-per-quarter-note MIDI clock signal, and can also be set to run from an external clock (via the Tape In socket) at 24 (Roland), 48 (Linn) and 96 (Oberheim) pulses-per-quarter-note. Drum voices may be played by an external MIDI keyboard or from pads with full velocity information, but not programmed in the same way. Unfortunately the RXs will not sync to tape directly, but this can be overcome either by using a sequencer which does, such as the Roland MSQ700, or by amplifying the sync signal coming back off tape and cleaning it up at the mixing desk.


Yamaha make a big thing about the drum sounds in their advertising for the RXs, and rightly so. (Just as well, bearing in mind my earlier comment about changing sounds!) The bass and snare drums are Linn-like but warmer, the toms are slightly reminiscent of those on the Drumulator, and the claps are Roland-ish. The remainder of the sounds are bright and powerful, the only slightly weak sound being the open hi-hat, which takes a bit of getting used to. The toms can sound together on the same beat (which I think is a world first in the digital drum machine market) and the Accent, which is per instrument rather than overall, makes life generally more dynamic.

The following is a list of the sounds available on each machine:

RX15 (15 sounds)RX11 (29 sounds)
Bass DrumBass Drum x 3
Snare Drum x 2Snare Drum x 8 (Medium, Hi Tune)
RimshotRimshot x 2
Hi-Hat OpenHi-Hat Open x 2
Hi-Hat ClosedHi-Hat Closed x 2
Hi-Hat PedalHi-Hat Pedal
Tom Tom x 3Tom Tom x 4
Cymbal RideCymbal Ride
Cymbal CrashCymbal Crash
Hand ClapsHand Claps x 2
CowbellCowbell x 2

Both RXs have stereo mix outputs rather than sockets for individual voices or groups of voices: the instrument levels, accent levels and pan settings are set up by the user via the data entry controls. These levels (together with MIDI status) are retained in memory even if the machine is turned off, thanks to good old battery back-up.


There's no escaping the fact that Yamaha's first-ever programmable drum machines are excellent products indeed. Cheap-sounding rhythm machines and poorly-recorded acoustic drums are the ruination of many an otherwise competent demo tape, but now that digital percussion technology is becoming more readily accessible, those problems could soon be a thing of the past.

The RXs' PCM-encoded sounds are all usable, and some of them are very impressive indeed, which helps make up for the lack of user-tunability or separate instrument outputs. Most important of all, both machines (and especially the RX15) are good value, and when you consider both devices' aesthetic elegance and ease of programming, there can be no dispute over the final verdict. Go out and hear them. Now.

The RX11 and 15 carry RRPs of £799 and £449 respectively including VAT.

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Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - Oct 1984

Donated & scanned by: Stewart Lawler

Gear in this article:

Drum Machine > Yamaha > RX11

Drum Machine > Yamaha > RX15

Gear Tags:

Digital Drums

Previous article in this issue:

> DDrums

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> 360 Systems Digital Keyboard...

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