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Boss DR550 Dr. Rhythm

In 1980, the original boss DR55 Dr. Rhythm gave many people their first introduction to programmable drum machines. In 1990, the new DR550 is set to make musicians on a tight budget equally happy by providing their first taste of excellent 16-bit sampled drum sounds. Paul Ireson beats a path to his local music store's door.

It didn't take me very long to decide exactly how I felt about the new Boss Dr. Rhythm DR550 drum machine. A quick run through the demo songs stirred something in me, and once I'd spent a couple of minutes tapping away at the drum pads to audition the sounds, the feeling blossomed with full force: I was as mad as hell, and I still am. The thing's just too damn good! Ordinarily this wouldn't be a problem, but right now it is, because nobody in their right mind is going to spend hard cash on the two ageing beat boxes that I'm trying to sell when they can buy this for under £200. Given the choice, number and quality of the new Dr. Rhythm's sounds, and its facilities, that £200 is definitely peanuts. It sets a new standard for affordable drum machines, and if an 'affordable drum machine' is what you're after, you'd be totally crazy to buy anything else before hearing this one.


For those who aren't too clear about the relationship between Boss and Roland, it's basically this - Boss is a division of Roland, and Boss products are generally cheaper, good value, relatives of Roland goodies. Boss's original DR55 Dr. Rhythm represented many people's first introduction to programmable drum machines, and although there have been other rhythm boxes bearing the same name (but different numbers) since then, never has the distinction between 'professional' and 'budget' beat boxes been as blurred as with the new DR550.

The DR550 lacks refinements such as separate outputs, velocity sensitive pads, or even a very substantial case come to that, but in the crucial area of sounds it is outstanding. Its 48 internal 16-bit PCM drum and percussion samples appear to be drawn from the Roland R8/R5 sound library (internal and card), and the DR550 sounds every bit as good as those machines - I wasn't able to conduct a side-by-side comparison, but I doubt that in a blind test anyone would distinguish the R8 from the DR550 if they were playing the same sounds. Given the praise that was heaped on the R8 when it was launched, including not a little from my own review in SOS [February 1989], I am very impressed that Roland have made the same quality of sounds available on such a cheap machine.

The DR550, not surprisingly, concedes an awful lot to its bigger Roland brethren in terms of programming features, but it nevertheless offers more than its direct ancestors — it's the first Boss machine to allow real-time Pattern programming. There are 64 preset rhythm Patterns, plus 64 user Patterns, all of which can be used in eight Songs. Physically, it resembles the R8 and R5 in a matt black and grey, rounded-edges sort of way, but on a smaller scale. No power supply is provided, although the rear panel does include a 9 volt DC input. This is not an oversight, for the DR550 can be run either on batteries (hi-tech buskers take note) or mains power. If you're a cheapskate like me, you'll fill the machine up with six regular non-alkaline batteries, find that they only last about eight hours, then give up and use a suitable transformer - which is what you should have done in the first place anyway.

Similarly, whilst the LCD display on the DR550 is not as large and useful as those of many recent Roland drum machines, it's a good deal better than on previous Dr. Rhythms and adequate by anyone's standards. Amongst other things, it includes a 1 x 16 grid to aid programming in step-time, and gives a clear indication of which of the six modes of operation is selected at any time (Pattern Play, Pattern Write, Song Play, Song Write, Pad Edit, MIDI Setup). To the right of the LCD is a large volume knob. Most aspects of the DR550's operation are controlled with the buttons located on the bottom left of the front panel: Start, Stop/Continue, eight numeric buttons, Tempo, Level, Up/Down, Shift, Bank, Voice, Accent. Pressing Shift in conjunction with any of the numeric keys. Tempo, Level, Bank, Voice or Accent gives a set of related Pattern and Song programming functions.

The 12 instrument pads, located to the right of the control buttons, are perhaps a little too small - I can see some people hitting the wrong pads by mistake. Nine of the pads also have dual 'shifted' functions - six are used to select modes of operation, and the other three select tape save/load functions.

The rear panel is fairly basic - 'uncluttered' one might say, incorporating stereo output jacks, a single MIDI In (no Out or Thru), a stereo mini-jack headphones socket, a mini-jack tape interface socket, a power switch, and an input for a 9 volt DC feed from an external PSU. The tape interface socket allows data to be dumped to and retrieved from audio cassettes. This is probably a good thing, as the absence of a MIDI Out socket rules out System Exclusive storage for drum patterns and other data. The single mini-jack tape interface performs both input and output functions, so a certain amount of repatching is called for when saving, verifying, and loading data.


Given that the DR550 has 48 internal drum sounds, but only 12 pads, it follows that either you can only use 12 of the sounds (which would be a shame) or some neat trick is employed to let you use all 48 (which would be, well... neat). The neat trick is in fact the same as is used on the R8: the 12 physical pads become 48 virtual pads through the existence of four Pad Banks (A, B, C, D). When Bank A is selected, the 12 physical pads play one set of 12 sounds; when Bank B is selected, another set of 12 is available, and so on. Although you can only physically play one Bank at a time, all four are available for use in Patterns and Songs - so you can use all 48 sounds within any Pattern.

The pads are not velocity sensitive, so an Accent function is provided to allow you to inject a little expression into your Patterns. For those who've never had to use accents, you simply programme them into your Patterns in much the same way as an extra drum sound - the accents are silent 'flags', which boost the volume of any or all of the drum sounds that are played on the same beat by a fixed amount. Traditionally this meant that either all drum sounds would be boosted, which is rather indiscriminate, or only one or two would be, which left the parts played by non-accented instruments sounding comparatively flat and lifeless. However, the DR550 has a way around this, as I'll explain later.

In a simple but boring world, 48 pads and 48 drum sounds would mean a fixed assignment of one sound to each pad, but fortunately things are a little more complex than that, and the DR550 gives you several pad parameters to determine just what sound emerges when you trigger a given pad number: Assign, Level, Tone Colour, Decay, Assign Type, Accent Follow, Pan.

Assign lets you choose which of the internal sounds is assigned to the pad that you are editing. The main reason for having a means of assigning the same sound to several pads is that the other pad parameters allow several different versions of a basic sound to be created. Conversely, you might want to have the same open and closed hi-hat sounds on the same pads in all four Pad Banks, to facilitate Pattern programming.

Level sets a basic volume level (0-15) for the sound on that pad. Tone Colour (0-7) has a different, and always fairly subtle, effect from sound to sound. On some sounds it seems to control a low-pass filter, on others (notably snares) a notch filter. The variations that Tone Colour offers are never drastic, but worth experimenting with nonetheless.

Decay (-32 to +32) is pretty self-explanatory. The extent to which this parameter will affect the basic drum sound varies enormously, as some of the shorter samples (such as cowbell) just can't have their decay 'stretched' and are too short to be reduced significantly without actually disappearing. Likewise, the crash cymbal is already at full length at its nominal 'standard' decay time, so increasing the decay parameter makes no difference. It can be considerably shortened, however.

Assign Type (Mono, Poly, Exc 1/2) allows you to determine if and how drum sounds are played polyphonically. If any sound on a pad is set to play monophonically, then when you strike the pad twice in quick succession, the second note will cut short the decay of the first. In polyphonic playback mode, the decay of a drum sound will be unaffected by subsequently triggered notes. Note that the monophonic mode makes a pad, rather than a sound, monophonic, so that if the same snare sound is assigned to play monophonically on two different pads, the two pads can still be played at the same time. The use of Exc(lusive) assignment extends the concept of monophonic playback to encompass more than one sound; only one out of all of the pads that have the same Exclusive Assign number (1 or 2) can be played at a time. This means that playing a second sound will cut off a first, which is generally exactly what you want with open and closed hi-hat sounds, as the two cannot be played at the same time on a real hi-hat. (The Exclusive function can also be used to provide muting, if one pad's Level is set to zero.)

Accent Follow (—7 to +7) sets the amount by which each pad's level is affected by an accent in a Pattern. Negative values mean that accents will cut a pad's volume. The fact that several pads can play the same sound means that you can, to some extent, overcome the traditional limitations of the Accent function by setting up the same sound on several pads but with different Accent Follow values. A little laborious perhaps, but you may feel it's worth it to inject a little extra feel into your rhythms. Pan (seven positions) is self-explanatory, and very useful given that the DR550 has stereo output only.

As they stand, the parameters do allow the user to exercise a fair degree of control over the sound of the 48 pads, but it's a shame that equally basic but even more useful facilities, such as tuning, couldn't have been squeezed in as well. This wouldn't have been hard to implement, but I suspect that Roland simply didn't want to make the DR550 too powerful for fear of harming R5 sales.


The 48 sounds contained in the DR550 are surely its most attractive feature, both in terms of their sonic quality and the choice of samples. Roland always seem to be particularly good at choosing the right drum sounds, and those on the DR550 encompass very realistic acoustic sounds, aggressive processed 'modern' sounds, and 'effects' that are actually usable - which is quite a novel feature on a drum machine. The audio quality really is outstanding, as I've already made clear, and would be at any price.

The best test of how good sounds are is how much they are improved by a touch of quality reverb - or rather, how good they seem when you take it away again. The DR550 stood up to this test superbly and sounds fantastic when played 'dry', even allowing for the fact that several of its sounds have been recorded with some ambience. The samples are quiet, clear, and sizzling with life - the hi-hats, for example, are wonderfully crisp with a perfectly-defined high frequency content, and the sharper snare sounds have a superb 'snap' to them. Let's take a quick look at the range of sounds on offer.


Room kick
Dry kick
Solid kick
Face kick
Techno kick
Reverb snare
Real snare
Rimshot snare
Birch snare
TR808 snare
Bright snare
Side stick
Low room tom
Mid room tom
High room tom
Low attack tom
Mid attack tom
High attack tom
Low electronic tom
High electronic tom
Closed hi-hat
Open hi-hat
Pedal closed hi-hat
TR808 closed hi-hat
TR808 open hi-hat
Crash cymbal
Ride cymbal
Ride cymbal bell
TR808 hand clap
TR808 cowbell
Open low conga
Slap high conga
Mute high conga
Low bongo
High bongo
Low timbale
High timbale
Low agogo
High agogo
High Q
Scratch low
Scratch high

The five kicks are a good assortment: one powerful and solid with a touch of reverb; one 'slappy'; one 'snappy'; plus two electronic kicks. The six snares are similarly varied, including two quite deep, reverbed sounds, a good sharp rimshot, one 'real' snare, one 'birch', and the by-now-classic TR808 snare sound. The sidestick is a good sharp sample, with a very short reverb tail that can be trimmed with the Decay parameter.

There are three sets of toms - two acoustic and one electronic. All sets are comprised of different samples, rather than a single sample played back at different pitches. The first set of acoustic toms has a big, classic rock sound. The second has a better defined attack and pitch, but less 'oomph'. The electronic toms are a slight variation on the classic generic sound, and it's perhaps here that a tuning facility is most sorely missed.

There are two sets of hi-hats. The acoustic set - comprising closed, open, and pedal sounds - has an excellent presence, and you can hear the cymbals touching as the open hi-hat rings out. The electronic hi-hat is taken from the TR808 - it's interesting to reflect that this sound is perhaps a 'standard' almost as much as the acoustic model (that it rather poorly imitates) undoubtedly is.

The crash, ride, and ride bell cymbals are perhaps the only duplicated sounds that I remember being significantly better on the R8 - those of the DR550 seem shorter, with a decay that appears noticeably too abrupt, and they just don't quite jump out at you as I remember the R8 sounds doing. They're still excellent sounds, but not as excellent.

On the percussion front, the handclaps are the essential TR808 sample, and there are two cowbells: one real (a good solid 'clonk') and one TR808 sample. The claves, three congas, two bongos, two timbales, and two agogos are all very convincing, but they're somehow the kinds of sounds that defy easy description. The shaker and cabasa are both well defined yet subtle sounds, and most importantly, they don't sound too similar. The tambourine is a crisp, almost frosty, burst of restrained energy, and the whistle (a sound which I have never managed to find a use for) is good as these things go.

The surprisingly usable effects are High Q and two scratch sounds. High Q is the kind of sound you produce on an analogue synth by turning up the filter resonance to the point of self-oscillation, and then sweeping the cutoff frequency from very high to very low with a sharp percussive envelope. (Herbie Hancock's Rockit is a well-known example of the use of this sound.)


Rhythm Patterns are stored in two Banks of 64 Patterns each. Bank A contains user-programmable Patterns, and Bank B contains only presets. Patterns are only one bar in length and there's no way of chaining them together to form longer Patterns - that's strictly into the realms of Song creation. In Pattern Play mode, the number of the Pattern currently playing is displayed in the bottom left of the LCD display, and whichever Pattern is selected to play next (if any) is shown in the middle. You select Patterns with the eight numeric buttons, and control playback with the Start and Stop/Continue buttons. Playback tempo is set as a global parameter - press Tempo once to access the tempo change function, edit the parameter with the Up/Down buttons, and then press Tempo again to return to normal operation. Tempo can be changed in all of the six main modes of operation, even during real-time programming. It is variable from 40 to 250bpm, although the tempo resolution varies throughout the range: 1 bpm steps up to 100bpm; 2bpm steps from 100 to 154bpm; 4bpm steps from 154 to 220bpm, and 6bpm steps from 220bpm to 250bpm.

Programming your own Patterns is a simple matter, and is made easier by the provision of real-time recording for the first time on a Boss machine. You can mix step-time and real-time recording very easily - once you've selected Pattern Edit mode, you're all ready to begin step-time recording in the current Pattern. The Up/Down buttons move from beat to beat, and pressing a drum pad enters a drum beat. The current beat number is shown in the LCD window. Alternatively, if you press Start, then you initiate real-time recording, complete with metronome click - press Stop and you're back in step-time. Accents are recorded in exactly the same way as other instruments. Drum strikes can be erased in both real-time and step-time, and you can also delete an entire instrument from a Pattern whilst leaving everything else untouched.

You can switch between all four Pad Banks at any time, giving you full access to all 48 pads. The most logical way to proceed for most people is to record one drum at a time; if you work in this way, the facility to show any one pad's part on the 1 x 16 grid will be very helpful. You switch between pads for the display simply by tapping the desired pad while holding down the Voice key. It's important to realise that because of the DR550's pad programming system, each rhythm Pattern contains a record not of what sounds are to be played, but of what pads. As a result, if you edit the pad settings, you may find that Patterns that worked with the old 'kit' don't sound quite the same anymore.

Before you actually get down to placing your beats, however, you have to specify a resolution and time signature for your pattern. Like most drum machines, unless told otherwise, the DR550 will assume that every Pattern you write is going to be one bar of 4/4, with 16th note quantisation. The machine can only create one-bar Patterns, and only Patterns containing 16 or fewer quantisation intervals. However, quantisation can be set to 16th, 32nd, 8th note triplets or 16th note triplets, and the number of ticks (ie. quantisation intervals) set from 1 to 16. The limit of 16 ticks in a Pattern means that Patterns which employ 32nd note quantisation, for example, can only be up to half a 4/4 bar in length.


Writing and playing Songs is perhaps the highest level of operation of the DR550, but it's also probably the simplest. Once you've assembled a selection of Patterns that you like, creating a Song out of them - the DR550 can store eight Songs internally - is simply a matter of chaining them together in a sequence. Writing and editing Songs is made easier by Delete and Insert functions. Patterns from both Pattern Banks A and B can be freely mixed. You can specify an initial tempo for each song, or set this function to 'off', in which case playback will take place at the current system tempo.

There's not much to say about Song playback. You can start at any measure number, and jump straight to the start or end of Songs. A Song Chain facility is available, whereby when one Song has finished, its numerical successor will start playing immediately.


The DR550 is very unusual, in this day and age, in having a single MIDI In socket (no Out or Thru). This means that the DR550 cannot obviously be used as the master clock source for a MIDI system. A Thru at least would have been welcome, but if this is the price to pay for keeping this unit at under £200, I'm all for it.

The DR550 will sync to an external MIDI timing source (eg. from a sequencer) without any problems, and Song Select (but not Song Position) messages are recognised. An even more promising MIDI avenue to explore is that of using the DR550 essentially as a drum sound module, as most musicians will have sequencers whose composition facilities far outstrip those of the drum machine itself. Also, the DR550 recognises note velocity data, and so triggering the sounds via MIDI allows independent and full control over the dynamics of all 48 drum/percussion sounds - something the unit's own pads will not allow. (Nurse, mop my fevered brow!)

The MIDI Setup function allows you to determine how the DR550 will respond to incoming note data: Omni reception can be toggled on and off; a single MIDI channel can be set for reception; and a MIDI note number can be assigned to each of the 48 virtual pads. Assigning MIDI note numbers to pads rather than directly to sounds means that you can still use the pad parameters to tweak the sounds.


Competition? Frankly, there isn't any at the moment. The Boss DR550 is probably as good a sounding drum machine as money will buy, and if you don't want separate outputs, velocity sensitive pads, and advanced pattern and song programming features (ie. tempo changes, long patterns), then look no further for your ideal beat box - this is it, and it'll only set you back £199 (inc VAT!). Whilst separate outputs remains a problem, if you use a drum machine purely as a sound module, as many people do, then the lack of better pads and programming features is a total irrelevance - the DR550 is not only the ultimate budget drum machine, but also the ultimate budget drum sound expander.

Dr. Rhythm has certainly come a long way since he set up in practice, and it's a tribute to the march of technology that this new model offers so much more than its predecessors, for what is still relatively little money. It wouldn't be quite true to say that Boss's new baby has made other manufacturers look silly, but it makes a lot of their prices look pretty outrageous.

Many thanks to Future Music (Chelsea) for the loan of the review model.


£199 inc VAT.

Roland (UK) Ltd, (Contact Details).


Internal Sounds: 48.
Dynamic Range: 16-bit.
Polyphony: 12-note.
Pad Parameters: Sound Assign, Level, Decay, Pan, Assign Type, Tone Colour, Accent Follow.
Patterns: 64 preset, 64 programmable.
Songs: 8 (max of 160 measures), max of 1280 measures of successive play.
External Storage: dump to tape/cassette.
Max Resolution: 32nd notes.
Tempo Range: 40 to 250 bpm.
Display: LCD main display, LED beat indicator.
Outputs: stereo outs (L/R ¼" jacks), stereo headphones mini jack.
Battery Life: standard batteries 9 hours; alkaline batteries 23 hours.

Also featuring gear in this article

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Shape of Things to Come

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Sonic Images Sample CDs

Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - May 1990

Donated by: Bert Jansch / Adam Jansch


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Gear in this article:

Drum Machine > Boss > DR550

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Digital Drums

Review by Paul Ireson

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