Analogue Solutions Concussor

Designing analogue circuitry to recreate drum sounds is nothing new, but Analogue Solutions have gone one stage further with their Concussor system — it's modular, making it probably the world's first commercially available dedicated modular percussion synth. Gordon Reid can scarcely control his voltages...

It's increasingly rare in this industry to come across anything that looks even remotely innovative, but the Concussor modular system is definitely a 'first' for me. While no modular system can be considered novel — we've had modular synths and even modular effects systems for more than three decades, after all — a modular analogue drum machine is something else. This could be interesting...

Back To The Beginning

Concussor bass drum snare, and percussion modules (l‑r): BD78 (CR78 bass drum), BD88 (TR808 bass drum) (x2), SD78 (CR78 snare), SD88 (TR808 snare) (x2), RC88 (TR808 rimshot/clave), CB88 (TR808 cowbell), MX61 mixer.

Cast your mind back to 1978, when Roland launched the first of its 'serious' drum machines. Called the CR78, this was a squat wooden cube that used analogue circuitry to produce a range of drum sounds that sounded... well, nothing like real drums. Nevertheless, the CR78 was very popular, and was the precursor of one of the greatest successes of the electronic music era: the TR808. This also used purely analogue circuitry to create all its sounds, but the individual timbres proved to be very different from those of the CR78. The final stage in this success story came in 1984 when Roland released the TR909, the last of its revered drum machines. This had a distinctive character all its own, and it too has since become part of the staple diet of the music industry.

With the exception of the TR909's sampled hi‑hats and cymbals, all the sounds on the CR78, TR808 and TR909 were generated by analogue circuits similar to those found in simple analogue monosynths. Indeed, it's not difficult to imitate these sounds using a basic synth such as the Roland SH101. But to do so ties up a keyboard that you could probably use more profitably elsewhere. So maybe it's not surprising that, 15 years later, a company (Black Country‑based vintage synth enthusiasts Analogue Solutions, to be precise) has analysed Roland's analogue percussion circuits and created new ones — based on the older designs, but not precisely alike — for inclusion in a modern drum machine. What's much more surprising is the nature of the machine itself; rather than being a self‑contained instrument with a comprehensive range of sounds and sequencing capabilities, it's designed like a modular synthesizer, with individual modules for each of the sounds accessed via control voltage inputs, and freely interconnectable and patchable in the time‑honoured tradition of modular synths.

Common Facilities

Assorted Concussor percussion modules (l‑r): TC88 (TR808 tom/conga) (x3), CP88 (TR808 clap), HH88 (TR808 hi‑hat), SY01 ('synth minus oscillator' module), SR01 (spring reverb), MX61 mixer.

All Concussor modules have a brushed‑aluminium finish, similar to that of the modules made by Cornish company Analogue Systems (unrelated companies, despite the similarity in name) and German company Doepfer. In fact, all the Concussor modules are designed to fit into the cases made by the other two manufacturers, and have power connectors that make them electrically compatible with both (see the 'Cases & Compatability' box elsewhere in this article for more on this). The Concussor modules' CV and trigger inputs are all 3.5mm sockets, and there is consistency in the choice of LED colours (red for triggers, green for gates, yellow for CV steps) and knob colours (blue for drum voices, yellow for synthesizer functions and so on).

The trigger input on each module accepts voltage triggers in the range 5V to 12V and, although the manual suggests pulse durations of around 1 millisecond (to ensure the correct sound) I found no difficulty using widely varying sources such as clocks, audio oscillators, and LFOs, so you shouldn't find too many limitations here. Each module's LED lets you know when it receives a trigger, so you'll know when to start looking for dodgy cables.

Most modules offer dual outputs with 3.5mm and quarter‑inch sockets. The former are useful for connecting to the Concussor's mixer and synth modules, as well as for interconnecting with other synths with 3.5mm sockets such as the Roland System 100M and the Analogue Systems RS Integrator. The latter are invaluable when using the Concussor in a serious studio, where you can connect every module to its own strip on your mixing desk. The HH88 hi‑hat and SY01 Synth modules (of which more shortly) are the exception to this: their front panels are so busy that there is no room for the quarter‑inch sockets. Shame!

You'll find that many of the Concussor's modules have similar controls. For example, Decay determines (as you would expect) the decay time of the sound. Similarly, all the Tune controls affect the pitches of the sounds. And, of course, each module has a Level control that determines the loudness of the sound.

There are two ways of accenting a sound (ie. making it louder). The first is obvious — apply a voltage to the 'ACC' CV input socket found on all but the SD78 snare module (more on the individual modules in a moment). But in the absence of the extra CV needed for this, you can also control the volume by increasing or decreasing the voltage of the trigger.

Sound Generators & Modifiers

Concussor CV8 8‑step CV sequencers (x4), plus MC01 master clock module.

• BASS DRUMS

There are three bass drum modules in the range. The BD78 emulates the bass drum of Roland's CR78, the BD88 does the same for the TR808, and the forthcoming BD99 will do so for the TR909. The BD78 is a strange beast... before I opened the manual I thought that it must be faulty, because some Tune and Decay settings caused it to emit a loud howl. It turns out that this is a consequence of the circuit originally employed by Roland and used as a design starting point by Analogue Solutions. Apparently, removing this would have affected the sound too much, and this was not considered acceptable. The BD88 lacks this side‑effect, but has an 'extra' facility: a Tone control that adds a user‑definable amount of the trigger signal into the audio signal. In principle this adds a fast click to the beginning of the sound, but this depends (of course) upon the nature of the trigger you use, and may not always yield the expected result. Both modules have wide‑ranging Tune controls that allow you to use them for tom, conga, and bongo‑type sounds. This is particularly appropriate for the BD78 because (as anybody with a CR78 and a sampler will have discovered) the CR78 used the same circuit for each of these sounds.

• SNARES

There will eventually be three snare modules, again emulating the sounds from the CR78, TR808 and TR909. And, as before, the SD99 is still 'in the works'. Of the two existing units, the SD78 is by far the simplest. It has just two controls: pitch and 'Snappy', the latter of which adds a user‑defined amount of noise to the sound. The SD88 is more involved. Like the TR808, it uses two oscillators plus noise to generate the basic sound, and you can balance the levels of these using the Tone and Snappy controls. You then have control over the noise decay, plus a high‑pass filter that allows you to create a wider variety of sounds than the module's name would suggest.

• HI‑HATS & CYMBALS

The only emulation of Roland's 'metallic' percussion sounds comes in the form of the HH88 module, which, among other things, recreates the TR808's hi‑hats. This is the most complex of the sound modules in the Concussor. The open hi‑hat sound has its own Decay control and a Decay CV input, as well as an Accent input. This is particularly welcome because it allows you to create 'ringing' sounds akin to cymbals. In the absence of any dedicated Crash or Ride modules this is the closest you will get to these sounds, and I would find the Concussor very limited without them. The closed hi‑hat also has a Decay control (but no CV input) and Accent input. Both sounds are tuned using a common Tune control, and you have the option of using a single output, or independent outputs for each sound.

• ASSORTED PERCUSSION

The next bunch of modules include all the other percussion sounds from the TR808. These are the TC88 (toms and congas), the RC88 (rimshots and claves), the CB88 (cowbells), and the CP88 (handclaps).

The TC88 has a switch that selects between its tom sound (with added noise) and conga sound (which has no noise present). The only other controls then determine the amount of noise present in the tom sound, and the pitch of the sounds. The Tune control has a fairly wide range, so that you can create a full range of toms, congas, and even bass drums. Similarly, the RC88 has a switch that selects between the rimshot and clave sounds. This time (in addition to the Tune control) the other control is a high‑pass filter (incorrectly described as a band‑pass filter in the manual) that modifies the tone of the rimshot.

The cowbell is an oddity. Rather than simply recreating the preset detuned dual‑oscillator sound of the TR808, it allows you to tune its two oscillators for a wide range of tonal and atonal synth sounds. I like this, and it would be delightful if a pitch CV input was present to allow you to play the module conventionally from a keyboard. Oh well, you can't have everything.

The CP88, too, incorporates a filter, and this time it is a band‑pass filter. There are also controls for Decay, and the now‑familiar 'Snappy'.

• SYNTFACILITIES

Besides the nine percussion modules supplied, the review Concussor also incorporates an SY01 'synthesizer'. In fact, this is a complete synthesizer minus oscillators (Analogue Solutions are already developing the VCO2, an oscillator module with cross‑mod, sync and PWM, to complement this). I could devote a complete review to the SY01, filling a couple of pages with its Moog‑style resonant low‑pass filter, filter cross‑modulation capabilities, AD/ASR envelope generator, VCA, dual signal inputs, dual filter CV inputs, resonance CV input (hooray!), trigger input, amplifier CV input, and patchable envelope generator output. Indeed, thousands of words have been devoted to analysing the sounds and idiosyncrasies of synthesizers with fewer controls and facilities than this. The thought has probably occurred to you that Analogue Solutions could release a dedicated synthesizer with a pair of these and a couple of its forthcoming oscillator modules, but they're way ahead of you — such a unit is already well into the planning stages.

• EFFECTS

Finally, as far as sound generation is concerned, the SR01 Spring Reverb is a short (6‑inch) dual‑spring affair with a CV for the wet mix (amount of reverb in the final signal). Analogue Solutions recognise the deficiencies in this and is planning a 12‑inch triple‑spring unit for the future. But in the meantime, if you're looking for a high‑quality reverb effect... the SR01 is going to be a severe disappointment. Nevertheless, its hissy, clangorous tone is an effect in its own right. It imparts a characteristic metallic 'boinggg' to everything passed through it and, used creatively, it can be fun. As long as you don't expect it to handle your main reverb duties, you'll be fine.

Sequencing Modules & Mixers

Four CT8 8‑step gate sequencers, plus the versatile FS01 quad switcher module.

If you're going to run your Concussor in isolation, the first thing you'll need is an MC01 Master Clock. This provides three outputs at clock tempo, plus four divided outputs at half, quarter, eighth and sixteenth tempos. The range of basic clock tempos is fairly limited so, if you want to stray into the audio range, you should use the Ext Clock input and drive the MC01 from an external LFO or oscillator.

The CV8 is an 8‑step CV sequencer with a preset range of just 0V to +5V. If this range is not sufficient, you can void your warranty by modifying it to +10V yourself, or Analogue Solutions will, on request, extend the range to +12V. I would advise every user with multiple CV8s to have at least one modified, because it significantly extends the usefulness of the module. There are two sets of outputs. The Step outs are +5V gates that go high on each appropriate step, while the dual CV outs reflect the positions of the eight CV knobs. This arrangement makes it possible to trigger and accent sound modules using just a single CV8, and also allows you to trigger and 'pitch' external synths and sequencers in time with the Concussor. There is also a Reset input that allows you to control the length of the sequence (if you want hip‑hop in a 5/8 time signature, this is how it's done) and a manual Step button.

The CV8 is complemented by the GT8 Dual Gate Sequencer. This parallels the CV8 in almost every way but, instead of CV knobs, has eight 3‑position switches that, on each step, send a Gate pulse to either the Gate1 output, the Gate2 output, or neither. This makes it straightforward to create complex ornaments within the sequence, or add fills and rolls using another module, the FS01, which is a very curious device. In essence, it is is a switcher that allows you to switch between two inputs (A and B) and direct the result to a single output (X) ... or... switch a single input (X) between two outputs (A and B). These signals can be CVs, Gates or audio, making the FS01 very powerful indeed. Moreover, the unit has four such devices operating bi‑directionally, simultaneously. Are you confused? Don't worry, so was I for quite some time, and I had the thing in front of me! And that's not all... the FS01 also has a Bar counter that, when correctly driven, will output Gate pulses of one bar's duration every 2, 4, 8 and 16 bars. Amongst other uses, this will help you to select the 'fill‑in' patterns I mentioned, whether after 1, 3, 7 or 15 bars. With enough modules you could even program different fills in different positions — it wouldn't be easy to configure, but it might be fun to try.

Finally, you're going to need at least one MX61 mixer. This is a unity‑gain device that combines up to six 0‑10V audio, CV, or Gate signals, and despatches them through standard or inverted outputs. Although its obvious use is as a simple audio mixer, you'll find it a far more interesting device if you experiment with mixing CVs and Gates.

In Use

So, does the Concussor sound exactly like a vintage Roland drum machine? Simple answer: No. OK, let's ask another question. Does it allow you to do the things that the vintage Rolands would? Answer: Yes, and a whole load more.

Let's clarify this. Some of the Concussor's sounds are quite close to the sounds on which they are based. For example, the BD88 can get very close to the TR808's bass drum sounds, but the additional click and tuning range make it more flexible when you want it to be. In contrast, the SD88 has the wrong basic pitch for the TR808 snare sound, and I couldn't get it even close to the original. Likewise, the RC88 rimshot is not quite 'right', and the clave is too clicky and not 'woody' enough. The toms in the TC88 suffer (or benefit, depending on your point of view) from the same clickiness, and, together with the conga in the same module, lack the body of the Roland sounds. I can't comment on the CP88 in my Concussor (it's a dummy module) but the CB88 is a good reproduction of the TR808 cowbell and, courtesy of its twin tuning controls, can offer a variety other sounds. Finally, I couldn't get the closed hi‑hats in the HH88 to sound like a TR808, but that didn't bother me — I prefer the sounds of the Concussor. The open hi‑hat, though, is not as satisfying — the Roland had a characteristic tonal quality that the HH88 lacks.

But to concentrate on the fine details is to miss the point. The Concussor modules are not a slavish imitation of the original Rolands — they are the bases of a fully configurable rhythm system that shares many of the attributes of its forebears, but with enhanced flexibility. Who cares whether the SD88 sounds exactly like a TR808? Some people might, but personally, I'm more interested in what you can do with it, and how it works in a musical context. Having said that, only you can decide how complex — and therefore how expensive — your sound palette needs to be. Remember that some of the modules have dual functions, so that (for example) you'll need more than one SD88 if you want to incorporate TR808 bongo and conga sounds in the same sequence as a TR808 snare drum. Similarly, you'll need two RC88s for rimshots and claves, and I would suggest at least a couple of HH88s (treated by independent EQs and reverbs) for hi‑hats and cymbals. The review system only offered one RC88 and one HH88, but at least it had three TC88s, so it was possible to configure these into a conventional 'kit'.

If you're going to get the best out of the Concussor you'll also have to become intimately acquainted with the sequencers, switch sequencers, and clocks that it offers. This is no easy matter, and a complete understanding of all their possible actions and interactions is not going to come in even a few weeks. But once you have set up your sounds, creating simple sequences is relatively... well, simple. For example, you can direct the MC01's clock output to the hi‑hat's trigger, the half‑speed output to a snare's, and the quarter‑speed output to the bass drum. Voilá... you have a basic but perfectly usable 4/4 sequence. Adding a Gate Sequencer allows you to start messing with time signatures, and adding an FS01 (maybe clocked by the sixteenth‑speed output) lets you jump between sequences.

If all this sounds fun, it's still fairly unmusical because the sounds themselves are too static. Furthermore, you can't expect all your sounds to mesh well without careful adjustment of their parameters. So, you'll need to work on the sounds themselves, and then add movement in the form of Accents using combinations of the CV sequencers. Once you have mastered this, you'll be able to make some instruments jump in and out of the mix, extend others' envelopes, and even change the tuning of others while the sequence is playing. Moving on, you could add the SY01 as a sound modifier or — which is far more fun — set it up to create various Syndrum‑style effects and incorporate these into your sequence. Then you could add cross‑modulation to the SY01 sound, and use one of the CV sequencers to alter the amount of Emphasis on a bar‑by‑bar basis...

If you've followed me this far, you'll have gathered that the Concussor is like any other modular synthesizer, in that I can no more tell you everything that it can do than I can describe every sound in a big Moog. It's a device that offers possibilities rather than simple answers. Fortunately, the manual is unusually informative, with a huge appendix called 'Electronic Music Techniques' that will lead nervous novices into the weird world of analogue synthesis and sequencing.

Sweetness And Light?

There are a number of difficulties that you'll need to consider if you're going to buy a Concussor. Most importantly, you'll have to decide how you're going to use and connect it. If you intend to drive it using only analogue sequencers (and mix the sounds to just a couple of outputs), you'll have no problems. But when you start thinking in MIDI terms, you have to wonder how you're going to trigger each of the modules. You may, with a sophisticated MIDI‑to‑CV converter, be able to configure enough key splits, but it's unlikely that this approach will cater for all the sounds and CVs that you'll want to use. Perhaps the only sensible solution is a MIDI‑to‑trigger converter plus a second converter for CVs. Analogue Solutions is offering a modified Kenton Pro‑KADI for exactly this purpose, but this will add £120 (for the Kenton box) and upwards of £200 (for a conventional multi‑output MIDI‑CV box) to the cost of your system. Furthermore, neither of these will be Concussor modules, so they won't fit into the system's cases.

Another (albeit minor) problem is the lack of quarter‑inch outputs on the HH88 and SY01. Personally, I would always choose to configure a Concussor system such that each module is directed to an independent channel on my mixer, so that I could EQ, pan, and effect every sound individually. The other modules' quarter‑inch outputs encourage this, but not the HH88 and SY01 — and I don't like 3.5mm‑to‑quarter‑inch adaptors.

There are also some anomalies within the modules themselves. The most obvious of these (it made itself apparent within minutes of switching the Concussor on) was the different voltage produced by each of the MC01's outputs. Since the Accent is controlled by trigger voltage, this made some modules quieter and less 'punchy' than others. In the same vein, the BD78 and SD78 are noticeably quieter than the TR808‑type modules, which, I suppose, is another reason for mixing each sound individually. In fairness, though, Analogue Solutions has confirmed that they are aware of this low‑output problem, and will be correcting it in the next revision of the two modules.

Conclusions

Most readers will find the Concussor amazingly 'Heath Robinson' in its approach to reproducing a range of basic percussion sounds. After all, samples of Roland drum machines now abound in every sample library, as well as in the ROMs of every new digital synth. But I still have a lot of time for the concept of a modular sequencer, and the Concussor might be the first ever example of this. Think of it like this: all the sections comprising a big (and expensive) analogue sequencer such as Analogue Systems' TH48 are available separately, thus allowing you to develop your own configuration as and when required, or as funds permit. At any time, you can add extra clocks, more CV and Gate sequencers, and add complexity with more of the weird and wonderful Quad Switchers, with each addition being affordable for most players. If you eventually build a large sequencer in this way, you can then have different clocks on different parts, with different sequence lengths, and complex switching between all manner of otherwise impossible configurations. In the end it will not be cheap, but it will certainly be flexible.

Similarly, we should applaud the Concussor as perhaps the first attempt to provide a user‑configurable analogue drum machine. Whereas I can't see a large Concussor rack replacing a genuine CR78, TR808 or TR909 (price alone should see to that) I think you'll find one far more useful than any of these, with a far greater range of sounds and facilities. The MIDI difficulties shouldn't provide an insuperable obstacle, and enthusiasts will revel in the system's combination of sequencers, electronic switches, external CV inputs, and grabbable knobs. Indeed, I suspect that, with a large enough system and enough time, you could generate complete tracks in real time using nothing more than the Concussor, a mixer, and a good selection of outboard effects.