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Boss Dr Rhythm DR550

Drum Machine

Article from Music Technology, May 1990

The latest in Boss' Dr Rhythm series drum machines sees affordability crossed with the sort of quality reserved for Roland's R8 flagship. Simon Trask asks if you can beat it.

The DR550 combines quality samples and programming sophistication into its compact frame, yet is easy to use and attractively priced. The ideal budget drum machine?

ROLAND'S BOSS DIVISION have a fine tradition of producing dinky little drum machines. From the DR55 through the DR110 to the DR220A and DR220E, the emphasis has been on compact, lightweight machines which avoid burning a hole in your pocket - if anything, they're more likely to fit in it. Measuring a modest 7 3/8" (W) x 6 3/16" (D) x 1 5/8" (H) and weighing a mere 1lb 2oz including batteries, the DR550 - the latest offspring of the Boss division - does its predecessors proud. It also preserves the Dr Rhythm tradition of being kind to your wallet by weighing in, so to speak, at a healthy £199.

However, proving that beauty is more than skin deep and size isn't everything, the most attractive aspect of the DR550 is that it earns its extra nought by packing a fair amount of sophistication into its compact frame. Most importantly, the new DR's drum and percussion samples match those of Roland's R5, R8 and R8M in quality - in fact, a number of them have their origins in the R-series' library. At the same time, Boss have kept the 550's complement of sounds to a very creditable 48 (the R machines have 64 each), which is a good deal more than have appeared on previous Boss drum machines (for instance, the DR55 had four sounds and the DR110 six). However, before your ardour gets too aroused, I should point out that, unlike the R8 and R8M (but like the R5), the 550 can't play further sounds via plug-in PCM sample cards. Quite sensibly, Boss have opted for a solid collection of standard kit sounds leavened by a workable if not extensive selection of Latin percussion instruments. The 550 is 12-voice polyphonic, which means that up to 12 instruments can sound at the same time.

The latest Dr Rhythm has 64 preset and 64 programmable one-bar pattern memories, and allows you to construct up to eight songs, each of up to 160 bars, by chaining these patterns together (longer songs can be created by linking DR550 Songs together, up to a maximum of 1280 bars for one "composite" song). Being limited to one-bar patterns does seem a bit of a relic from an earlier age, and doesn't exactly encourage musicians to think in terms of longer "phrases". This one-bar limit seems to be a consequence of the way the 550 records rhythm patterns into its memory (see below), so given this limitation it would perhaps have been useful to be able to record "across" several consecutive one-bar patterns (say, specify a record range of patterns 51-54).

The 550 brings the DR range into the MIDI age belatedly if not wholeheartedly: equipped only with a MIDI In, it can be slaved to a MIDI sequencer and have its sounds played from a MIDI keyboard or percussion controller, but obviously you can't transfer pattern and song data via MIDI SysEx for remote storage. However, you can bulk dump the 550's pattern and song data, along with pad assignments, MIDI settings and even the metronome click level, to cassette tape via the Tape Save/Load mini-jack connection on the drum machine's rear panel. Time to dust down the trusty Elftone Compucorder and press it into service once again...

Once you've selected Tape mode, Save, Verify and Load functions can be activated by pressing the Start button; the Tempo LED flashes for the duration of the operation, and Verify and Load operations are concluded with a message telling you whether or not they've been successful - which in practice they were every time I used them. Each operation takes a little under 90 seconds, which is bearable, I suppose.

The latest DR can be powered from an optional Boss PSA Series power supply unit or from six AA-type batteries; the latter give a quoted lifespan, under continuous use, of nine hours for manganese batteries and 23 hours for the alkaline type (the type you'd typically use in a Walkman). These batteries also preserve the contents of the 550's memory when the drum machine is switched off, so you need to beware running them down. Also, to avoid losing your patterns and songs while changing batteries you need to maintain power to the 550 via a psu.


THE DR550's 48 samples are organised into eight categories: kick, snare, side stick, tom, hi-hat, cymbal, percussion, effect. There are five bass drums - room, dry, solid, face and techno - which between them provide a good range of acoustic and electronic kick sounds. The six snares are similarly varied in character, from the massive reverb snare through the ringing, rattling rimshot to the snappy TR808 snare. The toms category provides low, mid and high room toms along with the more resonant low, mid and high attack toms, and low and high electronic toms.

TR808 samples crop up again in the hi-hats, which include the 808's electronic-sounding open and closed hi-hats along with open, closed and pedal closed hi-hats of acoustic origin. More splashy sounds are provided by crash cymbal, ride cymbal and ride cymbal bell samples which, like the R-series samples, capture the character of the sounds well, avoiding dissolving into undifferentiated high-frequency hiss (in fact, I think these are R-series samples). Here the fact that sample memory is at a premium on the 550 is most obvious, with these longer samples ending before you expect them to. In fact, many of the samples seem to have been kept as "tight" as possible, without shortening them to the point where they lose their character.

Percussion offers the 808 handclap and cowbell along with a "real" cowbell, claves, three congas (open low, slap high and mute high), low and high bongos, low and high timbales, low and high agogos, shaker, cabasa, a rather anaemic tambourine and a suitably piercing whistle.

Of the three effects, High Q is a highly concussive electronic click, the sort of sound much used by Kraftwerk, which sounds like it's been sampled from an old analogue synth with a very sharp filter attack. Scratch Low and Scratch High appear to be sampled record scratches (as in DJ scratching rather than knackered records), but they're better used as abstract rather than imitative sounds.

It's worth emphasising at this point that, while the DR550's sound quality might be on a par with that of the Roland R-series drum machines, it loses out in sonic versatility compared to those machines through not allowing you to pitch-shift its samples up and down. I found this quite frustrating, but sacrifices have to be made somewhere in pursuit of the budget price tag. I suppose.

"The new DR's drum and percussion samples match those of Roland's R5, R8 and R8M in quality - in fact, a number of them have their origins in the R-series' library."


PERHAPS NOW IS a good time to start a campaign for more colourful instrument front panels. Anyone who remembers (and who perhaps still has the pleasure of looking at) the multi-coloured front panels of old Roland instruments like the JP8, Juno 106 and TR808 will know that in the past Roland could hardly be accused of producing dour-looking instruments. Yet what do we get nowadays? Endless variations on sombre charcoal grey. What's wrong with a splash of colour, eh?

The DR550 is a case in point. To be more specific, it's a sombre charcoal grey case in point, with only marginally less gloomy grey buttons. This glum appearance isn't helped by the fact that the otherwise generous LCD window is - perhaps inevitably on a budget instrument such as this - not backlit. What it does do is display in its upper half the currently-selected Pad Bank, the Scale of the current pattern (its quantisation) and the Accent rhythm or the rhythm of any one of the instruments assigned to the drum machine's pads. In this respect it's less well specified than the old Boss DR110, which can display (in grid format) the rhythms of up to four of its six instruments together with the accent rhythm. However, you can very easily select a different instrument or Accent for the 550's display by holding down the Voice button and tapping the relevant instrument pad.

The lower half of the LCD, meanwhile, divides into three boxes which variously display such information as the current and next pattern numbers, the current song and song step number, and the current edit parameter and its value.

Below the LCD are the inevitable Start and Stop/Continue buttons together with the numeric keypad and mode buttons which are the operational heart of the 550. Although they're of the squidgy rubber variety, they seem to be operationally reliable. The 550 also has 12 rubber playing pads, which stood up well to the bashing they received during this review (with fingertips rather than drumsticks, I hasten to add). These pads aren't velocity sensitive, but then I'd have been pleasantly surprised if they were. The 550's sounds are velocity-responsive via MIDI, but although you can record patterns into the drum machine's memory from an external MIDI source - an Octapad, for instance - disappointingly, MIDI velocity information isn't recorded.

The DR550 adopts the Pad Bank concept of the R5 and R8 whereby you can program four "drumkits" on the machine's pads. This effectively gives you equal access to not 12 but 48 sounds from the 550's instrument pads, all of which can be used within a single pattern. Successive presses of the dedicated Pad Bank button rotate around the four Banks (A-D).

To understand how the DR550 functions, it's important to grasp that when you record a pattern the drum machine is storing pad hits only. If you record a cowbell part using pad three in Pad Bank four, say, and then assign a cabasa to that pad instead, your cowbell part will become a cabasa part. This way of working makes it easy to try out different sounds for an already recorded rhythm, plus it's easy to delete a part from a rhythm because you can quickly find the pad that it's assigned to. The down side is that any alterations you make to a Pad Bank to suit a new pattern that you're recording will affect any already-recorded patterns which use that Pad Bank. It's the perennial swings and roundabouts situation.

The DR550 adopts the "fixed memory" approach to recording rhythm patterns. If you imagine that each pattern is represented by a 16 x 49 grid in memory, with each "box" in the grid representing a 16th-note hit for one of the 48 instrument pads or Accent, then you can see that a fixed amount of memory is used for each pattern regardless of the actual rhythm being played. The advantage of this approach is that when the DR550's manual says you can record 64 one-bar patterns it means 64 one-bar patterns regardless of how dense or sparse the rhythms are.

Most of the operational buttons and instrument pads have a second function which is selected by holding down the Shift button and then pressing the relevant button or pad. The most difficult thing about using these functions is reading the labelling which identifies them - more shades of grey on grey. In practice the DR550 is a straightforward and fairly intuitive instrument which presents no real operational or conceptual problems for anyone already familiar with the way drum machines work. The beginner should find the 550 a reasonably friendly machine to get to grips with, especially as the accompanying manual is clearly written and well laid out, and includes what is now becoming (for Roland instruments, anyway) the customary index to help you get straight to the information on anything you don't understand.


EACH INSTRUMENT PAD within a Pad Bank can be assigned not only one of the 48 instruments but values for level, tone colour, decay, assign type, accent follow and pan parameters. Level setting is accessed via a dedicated Level button, and as the name suggests, allows you to set a volume level for each pad. Not only does this allow you to balance the levels of the instruments in your "composite kit", but by assigning one instrument to two or more pads you can simulate a limited velocity sensitivity for internal recording purposes.

Tone colour (0-7) provides a means of subtly varying the timbre of an instrument when it's assigned to a pad. This is a "static" alteration, but by assigning the same sound to two or more pads and giving each pad a different tone colour value you can introduce subtle inflections of a sound into a rhythm. A neat feature.

"Of the three effects, High Q is a concussive electronic click - the sort of sound much used by Kraftwerk - which sounds like it's been sampled from an old analogue synth."

The default decay time of an instrument can be changed by assigning its pad a different decay value (-32 to +32), though with short sounds this won't necessarily have any effect.

You can record an Accent rhythm in the same way as you'd record a rhythm using any of the instruments. Accent is either on or off, and applies to all instruments sounding at a particular step. However, by setting a different accent follow value (-7 to +7) for each pad, you can tailor the response of individual instruments. A value of zero means that the instrument won't respond to accents, while a negative value results in the instrument playing more quietly on an accented step.

This approach does allow for a fair amount of flexibility, though should two instruments with the same accent follow value both sound on an accented step, both will have the same response even if you only want one of them to be accented. Again, assigning the same instrument to more than one pad and giving each pad a different accent follow value can help you get around any problems.

Assign type allows you to set an instrument pad to Mono, Poly or Exclusive 1 or 2. If a pad is set to Mono, new pad hits cut short the instrument if it's still sounding from a previous pad hit, while Poly allows the instrument to play for its full duration, so that the sounds overlap. Setting two or more pads to the same Exclusive number effectively means that the instruments assigned to those pads can't be layered, which also means that you can use one instrument to cut short another. A traditional choice here would be open and closed hi-hats, but you can choose whatever combination of instruments you want.

Finally, the DR550 allows you to select one of seven pan values for each pad in each Pad Bank, so that if you're taking advantage of the drum machine's stereo audio outs you can position up to 48 instruments in the stereo image. You can also experiment with auto-panning effects by assigning an instrument to two or more pads and giving each pad a different pan value, but as with the other pad parameters this is at the expense of the variety of instruments you can use for your patterns.


THE DR550 ALLOWS you to record in real time and step time. Once you've selected Pattern Record mode, both methods are equally available to you: when the pattern is playing you're in real-time record, when it's stopped you're in step-time record.

Real-time recording is in familiar drum machine-style fashion of continuously looping the pattern while you add parts on e«ch pass. You get a quarter-note metronome click (with settable level 0-15) and a flashing red pinpoint LED to play along to. With Delete selected you can erase any sequence of notes within an individual instrument part by holding down the relevant pad at the relevant time during real-time record, while whole patterns or individual instruments/pads within a pattern can be erased with the Clear function.

In step-time recording, the DR550 records what pads you play at each step in the bar (while playing back whatever instruments, if any, you've already recorded for that step), and automatically advances to the next step after each hit and loops back to the first step when it reaches the end of the bar. As in real-time recording, the DR550 is permanently in overdub mode for step-time recording.

Alternatively you can use the instrument pads in conjunction with the Voice button to select the current instrument/pad in the LCD display "grid" and then enter your rhythms graphically rather than physically.

Usefully, during both real- and step-time recording, you can temporarily drop in and out of play mode by pressing the Voice button, which allows you to quickly locate the pad that a particular instrument is assigned to or try out an instrument part before recording it.

"The new Dr Rhythm has instant appeal - from the moment you see it to the moment you hear its high-quality sounds to the moment you discover that it's easy to use."

The 550 doesn't limit you to 4/4 time. By setting a Last Step value of less than the maximum of 16 you can create, for instance, 3/4, 5/8 or 7/8 time signatures. Scale, meanwhile, allows you to alter the quantisation of a pattern. This defaults to 16th notes, but alternatively you can select 32nd notes, triplet 16ths or triplet 8ths. There is a catch, however: because you're still limited to a maximum of 16 steps, selecting 32nd-note quantisation effectively reduces your pattern length to 2/4, so a 4/4 pattern has to be recorded over two 550 patterns. In similar fashion, selecting triplet 8ths allows you to use 5/4 time, while selecting triplet 16ths limits you to 2/4 or at most 5/8. So if you want to record a go go rhythm or a swingbeat rhythm, both of which use triplet 16ths to create their feel, you'll have to record a single 4/4 bar using two DR550 patterns.

Another possible limitation of the 550's approach, depending on what sort of rhythms you want to create, is that you can't combine triplet and non-triplet values (triplet 8ths and straight 8ths, for example).

Creating a DR550 Song is easy. You just scroll through the Song steps entering the required pattern number for each step. If you hit Start or Continue in Song Edit mode, the 550 repeatedly plays the pattern you've entered at the current step, which quickly allows you to see if you've chosen the right pattern. You can also start playing a Song from any step while in Song Play mode by scrolling to that step and then hitting Continue.

You can insert and delete occurrences of patterns within a Song, use the Song Chain function to link songs together in continuous play (giving you, as I mentioned earlier, fewer but longer "composite" songs), and set repeat on/off for each Song. You can also set an Initial Tempo value (40-250bpm) for each of the eight Songs - which, of course, only applies when the 550 is set to internal sync. The drum machine has a global tempo value which defaults to 120bpm each time you switch the machine on, but as soon as you select a Song that value changes to the Song's initial tempo value. Consequently, if you're working to and fro between Pattern and Song modes. Pattern mode automatically assumes whatever initial tempo value the Song is set to.


THE DR550 CAN be set to internal sync or slaved to incoming MIDI clocks. For the purposes of playing the drum machine's sounds from an external MIDI source you can set it to Omni receive (all channels), or to one of the 16 MIDI channels (it defaults to channel 10, the channel which Roland have ordained as the rhythm channel on their instruments).

For MIDI performance purposes you assign instrument pads rather than the actual instruments themselves to MIDI note numbers, which means that if a DR550 instrument isn't assigned to one of the 48 possible pads then you can't play it via MIDI. The 550 comes with a default set of pad-to-note assignments, but you can alter these to suit your own preferences. One thing you can't do is play more than one instrument/pad from a single MIDI note. The 550 allows you to set up such an assignment, but in practice the drum machine only plays the sound which is assigned to the lowest-numbered pad in or closest to Pad Bank A.

The 550 can respond to MIDI Song Select messages, allowing you to remotely select its internal Songs. However, one MIDI message it won't respond to is Song Position Pointer, the message, which tells a sequencer or drum machine where to start playing from in a song. Consequently, if you're slaving it off a sequencer and you've stopped the sequencer mid-song, and fast forwarded or rewound it to a different position, the 550 won't be able to tell where to play from. Which is rather a disappointment in this day and age, and one good reason to use the 550 purely as a sound source, putting together all your rhythm parts in your sequencer rather than using the 550's onboard pattern and song facilities.


THE NEW DR Rhythm has instant appeal - from the moment you see it to the moment you hear its high-quality sounds to the moment you discover that it's easy to use. Boss have concentrated on providing a solid collection of standard kit and Latin instruments rather than dazzling you with a diverse collection of more exotic instruments, and have ensured a good balance of acoustic and electronic sounds with an overall clean, upfront quality. The 550 is far more versatile sonically and far more sophisticated functionally than its predecessors, and benefits from the introduction of MIDI, at last, to the Dr Rhythm series. I have a few reservations about its rhythm programming flexibility, but what it loses in flexibility it gains in simplicity.

If you want sonic expandability and greater programming sophistication then it might be worth hanging on for Cheetah's forthcoming 16-bit drum machine, the MD16. But then you're talking half as much again on the price, which can be a lot to find if you're on a tight budget. The point is that Boss have packed a lot into the DR550 for its price and for its size, and have made it all easy to use in a way which should be attractive not only to the first-time buyer but also to anyone who likes their hi-tech instruments to be accessible. You can always wish for more of everything on a budget instrument, but overall Boss have come up with a balance of sounds, facilities, and accessibility on the DR550 which is well suited to its very attractive asking price, and I expect it will be a big success for them. Now, which pocket did I put it in?

Price £199 including VAT

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Publisher: Music Technology - Music Maker Publications (UK), Future Publishing.

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Music Technology - May 1990

Gear in this article:

Drum Machine > Boss > DR550

Gear Tags:

Digital Drums

Review by Simon Trask

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