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Vermona Perfourmer

Four-voice Analogue Rack Synth By Paul Nagle
Published March 2003

Formerly the East German state synth company (a great concept in itself), Vermona re-emerged last year with the MARS monophonic analogue synth. Clearly determined to win back their reputation, they've returned with the four-voice Perfourmer...

Vermona Perfourmer rack synth.Photo: Mike CameronJust when you think you've seen every slant on modern analogue synth design, somebody tosses in an unexpected variation on the theme. Vermona previously impressed me with the power of their MARS monophonic analogue rack synthesiser (reviewed in SOS October 2002 issue) and now they've released a quite different analogue rack synth.

This beautifully constructed silver module physically resembles an earlier product constructed by Vermona's parent company HDB Audio, the DRM1 analogue drum synth (reviewed in SOS April 2000, when it was being sold under the Touched By Sound brand name — it's now available in a MkII version). The Perfourmer has no less than 74 smooth-action controls that acquit themselves like Eddie Izzard in a working man's club (ie. they're a quality turn). The only downside to this generous array of knobs is that they are laid out in such a uniform fashion: it takes some concentration to confidently grab the one you want from amongst the throng. Indeed, even when in a legal state of mind, I occasionally snagged a Tune knob when I really intended to adjust an envelope's decay time.

Vermona Perfourmer £649
  • Sounds, looks and feels great.
  • Freely configurable, highly versatile.
  • Can be four analogue synths in one or a four-way audio processor.
  • Neither a fully featured polyphonic or monophonic synth but something in-between.
  • Oscillator waveform and octave selection bound together.
One of the more difficult synths to assess in words alone. The Perfourmer can't do everything, nor does it try, yet it possesses a certain magic that might make you approach music from a new angle. Perhaps it will help dispel the popular myth that a modern instrument must have zillions of features to be musically useful.


Wipe-clean overlays supplied with the Perfourmer, on which you mark the front-panel knob positions, are the only way to 'store' patch memories.Wipe-clean overlays supplied with the Perfourmer, on which you mark the front-panel knob positions, are the only way to 'store' patch memories.Included with the Perfourmer are a series of cardboard overlays. As the synth has no patch memories, you can mark your favourite settings on them — in much the same way as we old-timers used to record our patches back in the days before synths with memories. I took one of the overlays and marked the various sections in different fluorescent colours. In this way, I found it easier to find my way around — each section stood out clearly in both daylight and the UV light that fills my (rather psychedelic) little studio.

The Perfourmer occupies five rack spaces. Alternatively, it could, at a pinch, be used for sloping, table-top operation. Power is courtesy of an internal supply, and the On-Off switch is positioned for ease of access on the front panel, along with the MIDI channel selector, master volume control and headphone socket. The rear panel has MIDI In and Thru sockets plus stereo audio inputs and outputs (more on these later).

Four Play

Stripped down to its bare essentials, the Perfourmer consists of four separate (but identically specified) monophonic analogue synths. Each of these is remarkably uncomplicated, consisting of a single VCO, an ADSR envelope generator, a low-pass filter, an LFO and a VCA (for convenience, I'll use the term 'part' throughout the review to refer to an individual internal Perfourmer synth). Now please don't lose interest here, because this is far from the whole story. After all, there would be little point in merely packaging together four monosynths, would there? What Vermona have done is design an instrument whose individual parts can be freely configured. Each synthesizer can be played on its own MIDI channel (see box above), or, in one of its other operational modes, can work in conjunction with the others. There are three modes available: monophonic, duophonic or polyphonic and, using a combination of channel and mode, you can switch between many different configurations, such as a one-oscillator-per-voice polysynth, a four-oscillator layered monosynth and various interim combinations.

Additional interaction between the internal synths is available in the form of FM; each one is able to frequency-modulate the oscillator and/or filter of the next synth part downwards (ie. Part 1 serves as the FM source for Part 2, which is itself the source for Part 3, and so on). As the four parts are identical, let's take a look at one of them in detail.

One True Voice

Each Part's VCO features a Glide control for those smooth Roland TB303-type slides. I would personally have preferred this calibrated so that the longest (and rarely used) glide times didn't occupy quite so much of the knob's travel, but nevertheless this produces the required results well enough. Not so straightforward, however, is Vermona's quirky and frankly irritating single control that binds together oscillator waveform selection and pitch. This is an eight-stage switch offering the following audio sources: a 32' sawtooth wave, a 32' square, three 8' pulse waves of differing width, an 8' sawtooth, the external audio input and white noise. Additionally, a Tune control varies the pitch smoothly within a range of ±13 semitones. The result of these design choices is that searching for that popular 16' setting becomes a pain in the arse — you're braver than me if you dare to do it live. With no fine-tune available either, pitch adjustment is something you always have to perform with the utmost care. As on Vermona's MARS, the pulse waveforms are fixed, with no means to vary the pulse-width either manually or via an LFO. Happily, though (and as on the MARS), the Perfourmer's oscillators sound wonderfully rich and full, and for this you can forgive much.

The low-pass filter is a no-messing 24dB-per-octave monster, equally at home producing deep, classy filter sweeps, Moog-y solos or powerful, warm basses. In character I'd say it sits somewhere between a Minimoog and a Roland TB303, with a rather shrill resonance and a bite that won't be lost in any mix. The VCF controls are pared down to the bare minimum, with knobs for cutoff frequency, keyboard tracking (positive only) and resonance, but you can set the filter to self-oscillation if you crank up the resonance. Then, if you track the cutoff frequency with keyboard position, you have a sine wave that is playable, with reasonable accuracy, over a two- or three-octave span.

A single ADSR envelope per Part is provided, plus a VCF amount control for setting the depth at which it modulates the filter. This depth may be either positive or negative; the envelope has no effect on the filter in its 12 o'clock (zero) position. The envelope is fast and snappy; the shortest attack time is quoted at 1ms with an impressive 40 seconds as the longest release time. The synth uses single triggering only; legato playing doesn't retrigger the envelopes.

The envelope is shared between the VCF and VCA, and to help you overcome this limitation, a four-position switch is located within the VCA section. This switch offers 'Envelope', 'Gate', 'LFO' or 'On' modes, and if you set the mode to 'Gate', you switch in a preset on/off-type envelope, freeing up the ADSR for exclusive control of the filter. Setting the switch to 'LFO' can add variation to multi-part sequences or polyphonic pads, fading each voice in and out at a rate determined by its own LFO speed. The final setting — 'On' — is ideal if you are running an external signal through the Perfourmer's filter and it means you needn't trigger the envelope before hearing the results of your processing. The remaining (self-explanatory) VCA controls are Pan and Volume.

With 18 rotary knobs for each of the four internal synths controlling various sound-generating parameters on its front panel (including envelope, filter, keyboard tracking, glide and pan controls), the Perfourmer's not short on real-time tweakability.With 18 rotary knobs for each of the four internal synths controlling various sound-generating parameters on its front panel (including envelope, filter, keyboard tracking, glide and pan controls), the Perfourmer's not short on real-time tweakability.The LFO has four waveforms: triangle, square and positive and negative sawtooth. The manual claims that the minimum LFO speed is about 15 seconds, but on the review model, each LFO averaged closer to 10 seconds when I timed them. Two LFO depth knobs set the modulation level of VCO and VCF respectively, and these knobs take on a very different function when FM is activated.


Although now popularly associated with Yamaha's DX range of synths, frequency-modulation techniques have existed within analogue instruments since the earliest days of synthesis. With the advent of precise digital oscillators, FM was reborn as a vibrant source of electric piano, brass, and log drum sounds (as well as others). It is rather harder to control and predict within the analogue domain, and, as a result, is more often used to generate strange noises, including complex bell tones.

As mentioned earlier, FM is implemented here so that each synth Part may be the modulating source (or Modulator, as it is known) for the next Part in turn (which becomes the so-called Carrier). This means that the first part can be an FM source only. Once activated via dedicated buttons (with associated blue LEDs), controls that otherwise set LFO amount (of VCO and VCF) switch to their other roles governing FM intensity.

With FM such an integral part of the Perfourmer, it's a real surprise that the oscillators don't include sine waves. The manual suggests heavily filtering a square wave instead, but this is a poor substitute for providing the most appropriate waveforms in the first place. As anyone who's ever programmed a Yamaha TX81Z (for example) will tell you, FM becomes (even) less intuitive if you start off with complex waveforms. FM routing is performed before each Part's volume control, so a Part can serve as a modulator even when it is inaudible.

I experimented at length with FM on the Perfourmer. Activating FM on several Parts at once yielded some highly complex tones and cranking up the intensity produced a progressively wild succession of clangs, boings, metallic percussion and raspy filter shrieks. Despite spending some time trying to achieve a cutting FM bass and a (reasonably) realistic electric piano voice, I can't honestly say I found it worth the effort. Of far greater interest was my discovery that an external signal could serve as an FM modulator instead — this seemed to offer more extreme audio-mangling potential.

MIDI Control

You can read later how easy it is to set MIDI channels, but I expect you're still curious about the extent of MIDI control on offer. In fact, MIDI implementation is very basic, encompassing notes (but not their velocity), pitch-bend (fixed at ±3 semitones) and modulation wheel (mapped to filter cutoff frequency). Amazingly, that's pretty much it in terms of performance! However, eight additional MIDI controllers are defined, serving to activate or deactivate response to pitch-bend and mod wheel for each synthesizer part. A further five controllers duplicate the actions of mode and MIDI channel selection that you would otherwise program via the front panel. By using these controllers, you can reconfigure the synth from your sequencer without any button-pushing. The only action you need to do prior to using this technique is set a 'base' MIDI channel for receipt of these messages — a simple procedure done just once and, for a change, described adequately in the manual. I discovered that some of the control changes needed to be separated by a few seconds to allow the synth time to change modes accurately, but the ability to do this remotely was a welcome inclusion all the same.

It is a little strange to find a modern synth that doesn't respond to velocity or aftertouch, and which doesn't let you introduce vibrato with the mod wheel. In many ways, the Perfourmer is not so far removed from a traditional (pre-MIDI) analogue, with the same level of control an external MIDI/CV converter would offer.

Modes & MIDI Channels

Each synthesizer part has a trigger button that produces either a note or a short sequence. There are 16 variations, and they are selected via the control that otherwise sets the MIDI channel (when the trigger button is not being pressed). These notes and sequences are helpful when tuning the synth or programming it as a stand-alone device.

MIDI channel selection couldn't be much simpler: push the MIDI button (at the left-hand side of the Perfourmer) and release it. Any of the Parts active on the channel indicated by the selector knob's current position are shown by a lit red LED. Select a new channel, push the trigger button adjacent to each Part you wish to operate on that channel, and then push the MIDI button again to return to normal playing.

The MIDI button also sets the Perfourmer's three operational modes. Pushing it and keeping it held down lights one of three mode LEDs showing the current status. The LED that resides next to Part 2 denotes monophonic operation, the one underneath it signifies duophonic operation, and the lowest one of all represents polyphonic mode. If you make a change to the mode, the synth is instantly ready to play when you release the button. If you make no changes, releasing the button takes you into MIDI channel selection as before. This method of choosing mode and channel is quick, intuitive and highly flexible; by just pushing a few buttons, you can change the Perfourmer's fundamental nature. One minute it can be a collection of simplistic single-VCO monophonic synths, the next it is transformed into a quite different animal.

One of the first things you'll be tempted to try is the gratuitous layering of four monophonic Parts on the same channel, which can lead to the creation of the kind of sounds that belong on Celebrity Fat Club. Switching to polyphonic mode, however, is where the fun really begins. Naturally, you can play chords of up to four notes, and if you program each voice to sound similar, you might hear hints of the organic richness previously associated with the Oberheim 4 Voice, or four EDP Wasps and a Caterpillar (am I showing my budget roots here?). Alternatively, you could configure a three-note polysynth for chords, and use the fourth Part on its own channel for bass or solo duties.

For each note you play, the Perfourmer steps through the available voices in order — up to the maximum number allocated to the same MIDI channel. Anyone who's used a Korg MonoPoly will know at once why this is so cool, and I hope anyone who hasn't will forgive a slight digression here. The MonoPoly, when in its polyphonic mode, can cycle through four voices with its arpeggiator. By setting different tunings, levels and waveforms for each oscillator, you can create some of the funkiest patterns ever triggered by a simple arpeggiator. The Perfourmer goes one better than this by having not just four oscillators, but also separate filters, envelopes, panning and LFOs. Duly enthused, I generated a simple arpeggio from my Korg Prophecy, routed it to the Perfourmer, and tweaked each synthesizer voice in turn. It wasn't long before I was generating some of the most intricate, evolving sequences I'd ever achieved — with practically zero effort. I felt I should have been consumed by guilt!

Duophonic mode allows a maximum of two notes to be held simultaneously, and is unique in that the MIDI channel of individual parts has no meaning. In this mode, only the channel of the first part is used; the rest are ignored. Parts 1 and 2 are allocated as one voice, and Parts 3 and 4 become the second, with playback alternating between the two.

In and Out

The rear panel offers left and right outputs, and a MIDI In and Thru only (no MIDI output is possible). However, there is a stereo audio input, plus the top-panel jacks.The rear panel offers left and right outputs, and a MIDI In and Thru only (no MIDI output is possible). However, there is a stereo audio input, plus the top-panel jacks.The Perfourmer offers no less than six audio inputs — two on the rear panel and one for each individual internal synth, courtesy of front-panel sockets. The rear-panel inputs are summed internally. Thus, a signal can be processed by all four available filters at once, providing you set each oscillator source to 'External'. This presents a host of options for processing the usual candidates: drum machines, samples, suitably boosted vocals, other synths, and so on. There is no input-level control, nor is there any visual means to recognise whether the signal is clipping, so it's a little hit and miss, but great fun anyway.

In conjunction with the rear connections, each synthesizer Part may be addressed separately via easily accessed twin stereo jacks. This aspect of the Perfourmer is badly neglected in the manual, with no signal-flow diagram, description of the sockets' connections or, well, anything much. Fortunately, trial and error is my favourite way to work when it comes to connecting things — as my wife would confirm if the story didn't bring tears to her eyes. By using an insert lead, I was able to suss out what was happening quickly enough: the uppermost socket for each Part is both an audio input to the filter and the raw, unfiltered VCO output, while the lower socket is a direct output for the full synth voice and an insert point. In contrast to the rear inputs, any signal patched into a front-panel input remains audible along with that Part's oscillator — unless the oscillator is deliberately silenced by setting it to 'External'. The insert point is used to plug a signal into the Part at the panning stage, completely bypassing the filter, volume control or oscillator selection. When you make an insert connection, that Part's oscillator is removed from the main output and is then only available via the front-panel sockets.

Having separate inputs to each channel means you can use the Perfourmer as four mono or even dual stereo filter banks. As I've suggested elsewhere, things can become quite extreme if you use external signals as FM modulators instead of the onboard oscillators; you could, for example, draft in another synth or drum machine to frequency-modulate the Perfourmer's oscillators or filter.

As you can see, the interconnection possibilities deserve exploration. For example, if you take the raw VCO signal from one Part and connect it to the input of another, the two VCOs are mixed together, enabling you to process both via a single filter. Or, you could take the output of one complete synth Part and patch it into the input of another, gaining a new voice processed by two filters in series — the effective equivalent of a 48dB-per-octave slope.


If you choose your kit based on spec alone, you might not have even read this far. Certainly you won't hear many new sounds from such a basic synthesis engine and yes, I would have liked a few more spicy options to have been included, such as oscillator sync or pulse-width modulation (PWM). The latter would greatly boost the Perfourmer's capabilities for producing lush pads since, with just one oscillator per voice, it can't really cut the mustard in the creation of string ensemble sounds and the like [You might want to have a look at this month's Synth Secrets, which reveals a way of creating PWM effects on synths like the Perfourmer — Ed]. A more extensive MIDI implementation would have been welcome too. My number-one gripe, though, is much more elementary than all these, and relates to Vermona's single control for oscillator-waveform and pitch selection. For live use, especially, I find it pretty vital to be able to quickly and reliably shift each oscillator's pitch in octave intervals.

However, despite all this, I found Vermona's Perfourmer refreshingly 'out there'; it seems to have been created to be unlike anything else currently around. Exactly how you configure it, whether as a filter bank, as a series of individual monophonic synthesizers, or as a polyphonic or duophonic synth, is up to you. Unlike many instruments I have received for review over the years, understanding dawned in only a matter of moments — after which I hardly left it alone. And I obtained some great results, which it would not have been practical to tease from other gear — even my beloved MonoPoly.

The price is not ultra-budget compared with some recent synths, but then analogue technology is never going to be as cheap as a chunk of DSP, especially not when housed in a construction of this quality. The Perfourmer looks splendid but, better than that, it sounds fantastic. I suppose, in theory, its simplicity and general quirkiness should suggest a role as a 'sequencing machine' or 'basic polyphonic synth' but, somehow, it added up to far more than that for me. The pleasure of using it has remained constant over many weeks, and I find it a welcome departure from over-engineered, feature-packed instruments that invariably sound less impressive. If you get a chance to try one out, I think you'll see what I mean. It's more addictive than chocolate and just as fattening.

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Published March 2003