This year's UK Music Trade Show saw the unveiling of two exciting new rhythm units from the Japanese Roland Corporation. Rhythm units have been going through a boom period over the past couple of years. Their attraction relies on their capability to give the musician that 'one man band' facility. The rhythm unit has become the focal point of many a home recording studio set-up as an erstwhile player can now do the lot, without having to get in other musicians, building drum booths, sound proofing etc. One little box will solve so many problems, and nowadays, not only can the rhythm unit be used to generate percussive patterns, but it can also be used, in conjunction with a sequencer, to provide the bass and accompaniment to almost any composition. No wonder Roland now have six different drum machines in their catalogue.

Microprocessors

Undeniably, the advances in digital technology led to the total transformation of the rhythm unit's design. If we forget about the voice generation circuitry (for the moment), it is clearly the case that a rhythm unit centres around a control device that provides trigger pulses at exact positions in order to assemble a rhythm pattern or track. Early rhythm machines had very simple ROM — like arrangements generating basic patterns which just cycled round. Now, with the processor controlled units far more complex paralleled pulse trains can be set up — and what's more, they can be user defined, i.e. the units are programmable.

Needless to say, these new Roland machines are processor controlled and both offer programmable facilities.

The CR 8000 at £399, is big brother to the CR 5000 (£299), so let's look first at the 8000, then examine the differences.

The CompuRhythm CR-8000 Microcomputer Controlled Rhythm Machine, to give it its full title, comes packaged in a comparatively small unit. The casework is made from high impact white plastic (injection moulded) with an angled front panel. The controls used consist of rotary knobs (knurled and of various sizes), rotary switches, and push button switches with LED indicators — all of high quality construction. So to look at, and to operate, a smart well designed and fairly intelligently laid out product.

In brief the CR 8000 offers 24 basic rhythm patterns (pre-programmed at the factory), seven preset Intro/Fills, as well as eight programmable rhythm locations, and four programmable Intro/Fills. The basic rhythm patterns are selected by an 8 x 3 matrix — 8 rhythm buttons, and three bank selector buttons. It is possible to combine two presets in any one bank together for a more complex pattern. There are eight programmable location buttons which can also be combined with one of the preset rhythms if required. The preset patterns include all the old favourites — Waltz, Swing (2), Slow Rock, Tango, Enka, Habanera (?), Rock (6 different ones), Disco, Foxtrot, 8 Latins, and an unusual one marked BD-4, which gives a straight 4/4 Bass Drum beat — yup! that's 24 in all.

In addition to these preset and programmable rhythms, Roland have come up with a new section known as the Arranger. It's really very simple; there are a series of eight push buttons that will either modify or introduce a preset instrumental pattern to the basic or programmed rhythm selected. Seven of these buttons will modify with a Cymbal-4 (a 4-beat cymbal), Cymbal-8, High Hat-4, High Hat-16, Open High Hat (an 8-beat off the beat), a Hand Clap, and a Conga (a mixture pattern of low, mid and high congas). For those that are counting, the eighth button, marked Shuffle, can be used to transform most preset patterns to a Shuffle beat. So this Arranger section is a handy little feature. I soon found that by combining the BD-4 preset with the Arranger's Hand Clap that it was possible to produce that awful rhythm track that accompanies those ghastly compilation singles that seem to have infiltrated the music charts recently (though I shouldn't let my musical preferences creep in here).

The Intro/Fill Section is indeed a useful tool, it can be used both manually and automatically to provide an introduction pattern or to break up the cycling basic pattern. If you have a unit that doesn't have any form of fill facility, then the overall effect can become very monotonous. With the CR 8000, it is possible, in manual mode to select how much of the fill you want, this is dependent on which part of the cycle the manual fill button is depressed. In automatic mode the complete fill rhythm comes in every 2, 4, 8, 12 or 16 bars.

Programming

As with all the rhythm patterns, there are two measures available, and each measure is divided up into 16 (or in the case of Waltz, Swing etc: 12) steps. For the programmable Intro/Fills, there is but one measure. To program a pattern is simplicity itself. The Program mode switch is moved from Play to Basic (or Fill In), and a percussion voice selected. Two buttons are then used to step through the 32, or 24 steps, one tells the unit to register a 'hit' for that step, the other indicates a rest. When one voice line is recorded, another instrument is selected and that line programmed. Any number of instrument tracks can be used, though for best effect I found it advisable to use just five or six, otherwise things become a bit cluttered. Figure 1 shows how a pattern can be programmed. I suppose that I should point out that there is a battery back up installed in the unit, so all the patterns are memorised when the unit is disconnected from the mains.

The Analogue Voices

There are 14 different percussive voices on the analogue voice card of the CR 8000, and the quality of these simulations is excellent. Roland have produced a masterly Hand Clap voicing, as well as some excellent cymbal/hi-hat sounds using, as I understand it several ring modulation circuits (though unfortunately diagrams of these units' circuitry are as yet unavailable). Roland pioneered the Open-Closed Hi-Hat effect, which is so important when trying to simulate an acoustic kit. There are six independent voice volume controls (some voices share a single control) thus enabling the 'kit' to be balanced as desired. In addition there is an independent Accent control which can be used to emphasise certain beats in the bar (as programmed or preset).

I should mention the extremely useful LED numeric readout included on this unit, which enables the number of beats per minute to be selected just by the turn of a knob.

On the rear panel are sockets providing: trigger outputs; the DIN interface connector common now to many Roland products, and carrying Start/Stop, and Clock information; and surprisingly, just a single mono audio output. I would have liked to have seen either a stereo output, or separate output jacks for certain percussive voices.

The CR 5000, which is a hundred pounds cheaper, doesn't offer any programmable features or an LED tempo readout, otherwise with the omission of the Hand Clap voicing, it is similar to the CR 8000.

It goes without saying that these units are beautifully made, both internally and externally, and that Roland will undoubtedly do well with them, though whether they can match the success of the earlier CR 78, only time will tell.