In a special feature, respected electronic composer and performer Ian Boddy gives a personal overview of one of the few modular synthesisers currently available. He tells us how some of the principles introduced in Steve Howell's Modular Synthesis series work out in practice, and proves also that such designs don't necessarily have to be as big as a wall to yield impressive results.

The System 100M is not a new synthesiser by any means but at present is the only such system readily available from retailers in the UK (although Korg do produce the semi-modular MS system). This lack of choice is very frustrating but the fault may very well lie in our own laps. The biggest disadvantage of modular synthesis is that it takes time, sometimes hours to produce sounds of great subtlety and it impractical for live work as a solo instrument and so many people buy preset synths, and this lack of demand may well have forged the lack of choice already mentioned.

However, modular synthesis offers the great advantage of versatility, because as each component of the synthesiser is broken down into modules the user is not restricted by the manufacturer's signal path and also has complete control of how to patch-up the synth. This, together with the fact that you have functions not normally found on other synths, means that you can produce sounds of great subtlety and interest and it is possible even after years to come up with new sounds on your modular synthesiser. These synths can be very useful for live work as they can perform several functions simultaneously; the system described here, for example, which I have used in concert several times, can generate a voice to be driven by a sequencer, produce a sound effect and treat an external polysynth through one of its filters all at the same time.

Roland produce a large number of modules but I will only describe the six that would be most useful for a small set-up together with the polyphonic keyboard produced specifically for operating this system.

Dual VCO Module

Each identical oscillator has a rotary knob for switching between 32, 16, 8, 4 or 2 feet and a fine-frequency tuning knob.

Unfortunately, no sub-oscillator is provided which on most synths can get you down to 64 feet, useful for earth-rumbling bass drones! The waveforms available are also fairly limited, being switchable between triangle, ramp and square waves and only one waveform is available at any one time. The PWM facility however is very good, having two sliders for manual amount and external amount (a mini-jack input is provided). Both strong and weak sync modes are available for phase-locking of the VCOs, and mini-jacks are provided on each VCO for sync in and out. There are two inputs and three modulation inputs (one of which is prepatched to the keyboard CV input).

Dual VCF Module

These are standard - 24dB/oct low-pass filters with sliders for cutoff frequency and resonance. However, there is also a built-in high-pass filter with a switch for turning the HPF off or selecting one of three cutoff points (1, 2 and 5kHz). Two LEDs are also provided, green for signal level and red for distort condition. There are two signal outputs and three inputs, plus three modulation inputs, one of which is pre-patched to follow the keyboard CV input.

Dual VCA Module

Each VCA has three signal inputs and three modulation inputs. There are two outputs (low and high levels) as well as a rotary knob providing overall gain. There are green and red LEDs performing the same functions as on the VCF, and finally the VCAs are switchable between linear and exponential outputs.

LFO & Dual Envelope Generator Module

Each identical envelope generator has four sliders for attack (1.5ms - 7.5s), decay (4ms - 15s), sustain (0 - +/-10v) and release (4ms - 15s). There are four triggering modes, internally by gate; gate and trigger; externally (mini-jack input provided); or manually via a red pushbutton. Each ADSR has two normal outputs as well as an inverted one.

The LFO is very comprehensive, having a rotary knob to switch between the five waveforms (sine, triangle, square and rising or falling ramps). Two outputs are provided with switchable output levels of x1/10 or x1. Two sliders cater for frequency and delay time (0 - 7s) and a three-way switch for low, medium and high-frequency ranges which in conjunction with the frequency slider gives a frequency range of 0.05 - 30Hz. A frequency CV input is provided which is extremely useful: if the keyboard CV is used the LFO can then track the keyboard, and rates of vibrato can be faster at the top of the keyboard than at the bottom. Finally a keyboard trigger switch (on/off) allows phase-locking of the LFO output to the keyboard trigger pulse and a red LED gives a visual indication of the clock-rate.

Ring-Modulator/Noise Generator/Sample & Hold LFO Module

It's amazing how much is crammed into this module. The LFO is identical to the one described above so I'll start with perhaps the most interesting section of all those described in this review, the sample and hold function. Many synths have these modules but are in no way as comprehensive as the one provided here. Sliders cater for the clock-rate (0.2 - 25Hz) and lag-time (this smooths out the CV changes). There are outputs for the S&H and the clock-rate and an input for an external clock. This latter is very useful as a trigger pulse from a sequencer or drum-machine can then be used to control the rate of the S&H. The sample can be taken from an external source or from the LFO or noise sections of this module, the latter of course providing the random source (if you happen to want to sound like a space-invader!).

The noise generator consists simply of two outputs each for pink and white noise, and note that like the other sections such as the VCO, VCF and LFO no output level control is provided, so that levels are controlled instead at the input stage of each module.

The ring-modulator has two inputs, X being pre-patched to the noise generator and Y to the LFO, and a single output.

Basic Synthesiser Module

This module was obviously designed initially for budget systems and by squeezing a VCO, VCF and VCA into one module many of the features which make the individual modules so attractive are omitted and as one would primarily wish to buy a modular system for its flexibility, purchasing this module would seem to be rather counter-productive. I shall therefore describe briefly the features which have been omitted from the modules described above.

VCO: Only one VCO out and two modulation inputs are provided, the sync facility being omitted. The PWM has also been reduced to one slider making it less flexible.

VCF: Only two signal inputs and two modulation inputs are provided. No HPF or LEDs are available, the omission of the former greatly reducing the versatility of this section.

VCA: Again, the signal and modulation inputs have been reduced from three to two each, and there is no switch to choose between linear and exponential modes.

The Rack

The racks to hold the modules have to be bought separately and can hold either three or five modules. They consist of a black metal base housing the power supply and patch-panel, two wooden end-blocks and a dark grey metal top. It takes just a few seconds to assemble the rack and each of the modules slide into place, secured by two small screws at the front.

On the back of each rack are DIN plugs which connect up to the modules to supply power and prepatched keyboard CV, gate and trigger signals. There is one other DIN socket for connecting to another rack of modules. The advantage of this rack and modular system of course is that you buy as much as you can afford at any one time, adding to it at intervals as the time goes by.

On the front of the rack is the patch-panel, which is very useful for complex patches and interfacing with other equipment. Starting at the left-hand side there is a DIN-plug and three pairs of mini-jacks which are the prepatched inputs for keyboard CV, gate and trigger signals. Then there are nine multiple jacks; three have one ordinary jack input with three mini-jack outputs while the other six are all mini-jack sockets. To the right of these are output-jacks which convert from mini-jack to ordinary jack to phono-plug (on the back). Finally the power on/off button is on the extreme right.

The five-module rack only measures 558(W) x 314(H) x 192(D)mm and with five modules the total weight is just 15kg, so all in all it is an extremely compact package, much of this being achieved by the use of mini-jacks. The System 100M is designed primarily as a studio instrument, so if you do want to take it on the road, be very careful because the sliders are fairly delicate and can bend easily. A flightcase is therefore essential unless you want the hassle of continually assembling/disassembling the system. I don't know of any commercially available flightcases for the system so you'll have to search for somebody who is good at metalwork!

Polyphonic Keyboard

This is the most recent of the three keyboards produced by Roland for this system and by far the most useful. Although it is not essential - any synth with 1V/oct CV and positive-going gate outputs can drive the module - it is very useful since it can drive up to four independent voices.

The keyboard has four octaves (C-to-C), the action is similar to all the newer Roland keyboards and is quite pleasant to use. To the left of the keyboard is the control panel which provides some useful functions. There is the standard Roland spring-loaded bender which has a rotary knob for pitch-bend sensitivity - note that if the bender is used for anything other than pitch-bend, this knob must be set to zero. Above the bender are a row of eight push-buttons. The four white buttons on the left provide the arpeggiator modes of Up/Down/Up & Down/Random, but one annoying omission is the lack of a facility for setting the octave-span of the arpeggiator. The four blue buttons on the right are the keyboard trigger modes, two Unison and two Poly modes being provided.

Above these are rotary knobs for overall tune, arpeggio-rate, pitch-bend sensitivity and portamento amount as well as two switches for normal/one-octave-down and portamento on/off.

On the sloped back of the keyboard is the power button as well as all the inputs and outputs. From left to right these are arpeggio clock in; bender CV out; keyboard CV outputs 1-4; gate outputs 1-4; and total gate output. Each socket has both mini-jack and normal jack connectors. This keyboard can produce some startling effects. For example, if you have enough modules you can have a completely different sound for each voice, all triggered from the same keyboard. If you only have enough modules for two voices as described here, other synthesisers can produce the other voices. For example, I have linked up the System 100M with a Roland SH2 and SH09 to produce four voices. The gate outputs are very useful when used with the arpeggiator, as it will step through them in turn and you can use them to trigger up to four independent synth voices. As a socket is provided for arpeggio clock-in which can be controlled by a trigger pulse from a drum-machine, some unusual and interesting rhythm patterns can be produced.

Other Modules

Some of the other modules available are as follows:

Phase Shifter/Audio-Delay/Simple LFO/Gate Delay.
Analogue Sequencer (2-channel, eight steps in each).
Output Mixer for mixing four voices.
Dual CV/Audio Mixer and Voltage Processor.

As far as I know Roland have recently introduced some new modules including a portamento controller for up to four voices, and I hope they will continue to introduce new modules in the future.

Conclusion

The Roland System 100M is an almost ideal introduction to the world of modular synthesis. It can be hard work at times, not to mention a little frustrating, but your reward will be sounds that are far more complex and satisfying than your average mono-synth can produce, and some of these sounds may indeed be unique to you. It will also teach you a lot about synthesis (Roland publish two books called Practical Synthesis for Electronic Music, Volumes 1 & 2, which describe the various modules and their functions and provide plenty of fascinating patches) as for any voice you have to patch together the various modules using mini-jack leads. As with all Roland equipment, the interfaceability to other machines is excellent and the overall sound quality of the system is extremely high.

So although the world seems to have been flooded by polysynths offering sounds at the blink of an eyelid, if you take your synthesis seriously, make room for a modular synth such as this system and you'll have an instrument capable of producing sounds of tremendous individual character. It's also great fun to use!