An edited version of this text also appears in
SOUND ON SOUND magazine Vol.16 No.7. May 2001

by Chris Carter


The late 70's were exciting times for analogue synthesis, MIDI was still a few years away and legendary names such as Moog, EMS, Serge, Oberheim and Prophet were releasing innovative and exciting gear.
But it was Roland that always had a special place in my affections and much of my early years were spent lusting over Roland catalogues... yeah, me and Roland go back years. Hanging out at Rod Argent's and Macari's music stores in London's West End, tinkering with the new Roland gear while trying to convince sales staff I was serious buyer. Little did they know I was on my lunch break with just a few bob in my pocket and only a couple of quid in the bank. Roland were on a roll, Bosa Nova stylee drum machines and weedy sounding keyboards were a thing of the past and seriously specified analogue synths and studio gear were appearing on a regular basis. Those were the days...

I bought my SPV355 on a bit of an expensive whim after seeing a very polished Roland demo involving a guitar and a saxophone (I think). Although not being either a saxophonist OR a guitarist I'm not sure what was going through my mind at the time. Within hours I had it hooked up to a tape deck, a microphone, a drum machine and a Roland 100M modular system. In fact anything with an audio output or CV/gate connections. The rest as they say is history.

The SPV355 Pitch-to-Voltage Synthesizer was launched in 1979 as part of the Roland Rack series of 19 inch studio quality effects units, amplifiers and specialist pre-amps. The most famous of these are probably the 'Vocoder' and the 'Dimension D' spacial chorus. For its time and also for such a compact unit the P/V Synthesizer was quite well specified with two VCOs, a sub-oscillator, VCF, VCA, Envelope generator, 2 audio mixers and a multitude of interface sockets.
As with other Roland Rack units the SPV355 is housed in a 2U steel case, which makes it a pretty hefty beast to lug around at nearly 6 kg. And as far as build quality, well... the word tank springs to mind and phrases like: 'heavy duty' and 'they don't make em' like that anymore'.

The P/V Synth is a bit of a curiosity because on the one hand it seems to have been released as a rack mounting analogue expander module but on the other hand as budget alternative to the Roland guitar synthesizers: the GR series. The GR Synths were quite expensive specialised instruments and the system consisted of a high quality specially adapted guitar connected via a 24-way cable to floor unit containing a rudimentary 6-note polyphonic synth engine.
However, the SPV355 scores brownie points as it doesn't need any special interface hardware (pick-ups etc.) and you could, in theory, use any old guitar to play the synth. The 1979 Roland catalogue reads: "The SPV355 P/V Synthesizer... specially designed for use with guitars", which is ironic as this is probably the P/V Synth's least effective and most problematic mode, more on this later.

The P of the P/V Synth title stands for pitch and the V stands for voltage but what is this scary pitch-to-voltage technology they speak of? Well nothing to do with Theramins or Tesla coils, its main function is to translate an audio signal, such as a guitar, voice or wind instrument into musically related control voltages and triggers capable of playing its own internal or an external CV/gate synthesizer.
There are a couple of points to consider when using a pitch detection system: they can't decipher chords and they have a hard time with harmonics. Unfortunately these are both features which the guitar excels at. Solo voice and some woodwind are translated quite well but guitars, even playing single notes and sounds containing complex tones can give rise to jumpy, unstable pitch tracking errors. Ultimately keep it basic, clean and monophonic, and you'll be surprised at how accurate the SPV355 can be.

The front end starts off with the Input (pitch detector) and a three way switch for selecting the type of input signal: Guitar (pick-up), Voice (microphone) or Brass (transducer). There are a couple of useful LEDs to indicate activity, green for Gate triggering and red for audio overloading, plus a Threshold control to adjust the Gate trigger sensitivity to the Envelope generator. Too high a setting will give spurious multiple triggering, too low and you'll end up with ignored or missed notes.

The dual (monophonic) VCOs are switchable over three pitch ranges (4', 8' and 16') and each VCO can generate Saw, Square and Pulse waves, unfortunately both VCOs share the same controls for Range, Waveform and Tune. However, VCO 2 also includes an additional foot switch controlled A/B tuning function which makes it possible to offset its tuning relative to VCO 1 by +/- 1 octave. VCO 1 also has a separate Square wave Sub-oscillator output (-1 octave) and all three outputs (VCO 1, 2 and sub) are fed into Audio Mixer 1, which allows for some interesting tones and textures to be created. A foot switch controlled variable Portamento function is available for the VCOs, but unfortunately this only works internally and not when under external CV control.

The SPV355 includes a well specified VCF. The filter is a 24dB/octave type with a range of 10 Hz to 20 kHz and with the ability to self oscillate, in which case it becomes a third VCO. It has the usual Frequency and Resonance controls but also includes sliders for Pitch Follow and Envelope modulation depth, usefully both work in positive and negative directions for inverted or reverse type effects. The VCF is one the P/V Synths jewels and give it a lot of its character. As with many Roland synths of the time sounds sweet and musical and very analogue, it's just a shame there isn't a way of feeding the external audio through it.

The VCA section is minimalist with just a single switch to select control via the Envelope Follower or the Envelope Generator. The Envelope Follower works by generating a control voltage that closely follows the amplitude of the input signal and its only control is some interactivity with the Input Threshold control. The Envelope Follower CV signal can modulate both the VCF and VCA and is also available via a jack socket on the rear interface panel. The Envelope Generator is an ADS type, without the usual Release function. In use this doesn't really make a great deal of difference to the kinds of sounds produced, and in fact is extremely good at shaping short, punchy bass or sequencer envelopes. If I were the cynical type I could suggest Roland omitted Release function because of the inherent pitch drift when using the Pitch Hold function, but hey! this WAS before digital.

Using the P/V Synth successfully with a guitar requires a lot of patience, plus a pretty unnatural style of playing. I have to admit I've rarely used it this way, the main reason being that I'm not a guitarist but even my partner (who is a guitarist) gave up on it years ago. However more satisfying results can be achieved working with voice and brass. Although I've used it live on a number of occasions I couldn't really recommend using this way unless you are playing experimental music, because of its tendency to unpredictability and instability.

Although its main purpose in life is usually going to be a Pitch-to-Voltage converter the SPV355 doubles as a very good and very hands-on analogue expander module. The relative simplicity of its operation and editing thankfully means no menus or multi-mode switches and with its versatile interfacing options it will integrate well into most old and new CV/gate based modular systems and set-ups. It is also ideally suited to partner something like an SH101 or even a Vocoder, for real-time synth pitch following. Admittedly it lacks a few useful features like independent waveform controls a Noise generator and an LFO (although many MIDI-to-CV converters have built-in LFOs) but with its dual VCOs, sub-oscillator, well specified VCF and logical layout the SPV355 is very good at quickly producing bass, lead and authentic analogue synth sounds with plenty of character and bite.

The SPV355 can also take on the role of a rudimentary MID-to-CV converter as the pitch-tracking function, understandably, works best when driven from a clean strong (monophonic) signal and feeding it the audio output of a keyboard or sound module will often give the most consistent results. Of course these could be manually played or MIDI driven and the SPV355 will respond surprisingly accurately to vibrato, pitch-bend and portamento contained in the audio signal, although the SPV's own portamento will probably work more effectively. Sounds that are rich in harmonics, below 70 Hz or in the very upper kHz range are best avoided as they will introduce noticeable tracking errors.

The 5 front panel performance control sockets are primarily meant for use with foot switches and pedals however, if you have access to a CV/gate modular system it is worth experimenting with controlling these functions automatically from the likes of sequencers, triggers, gates and LFOs.
Similarly the rear Pitch CV/Gate and Envelope Follower CV outputs can be used to control the functions of all kinds of other analogue controlled modules. Feeding audio signals (taped or otherwise) of dialogue into the SPV355 is also an interesting way of generating seemingly random pitches, gate triggers and envelope signals.

Voices are also fun to work with, off tape or live and I've often found that the cheaper the microphone the better the results. I use an old Coloursound dynamic mic through a pre-amp for the most accurate pitch and envelope-tracking. Singing a few lines of wordless 'doo whop whops' can be transformed into very effective bass lines or sequencer patterns, particularly after a few effects are added. Just make sure you are recording as you go along, this kind of 'on the fly' experimentation is hard to reproduce ad infinitum.
Connecting a drum machine to the audio inputs can also reap some interesting and strange results. Cymbals and snares don't translate too well but some bass drum, toms and short percussion sounds can be very useable.

If you are handy with a soldering iron take a bare jack plug and solder a small on/off toggle switch to the earth and tip tags. Make a couple of these 'jack switches' and they can be used instead of foot switches in the front panel sockets to directly select features such as A/B Tune for VCO 2, Portamento and the CV/Gate Hold and Mix/Direct functions.

Over the last 20 years the SPV355 (and my Dimension D) has become an integral part of my analogue modular system and apart from a few racking scratches is almost as good as the day I bought it, but then I've only used it live a couple of times. Ten years ago it was serviced, mainly to tighten up some excessive pitch-drift. This drifting effect is quite common in the SPV355 but thankfully is only apparent when using the CV/Gate Hold function in P/V mode. When controlled from an external CV/Gate control source I've always found it to be stable and accurate.

The SPV355 can be both frustrating and unpredictable, it lacks MIDI, memories and all too easily generates wibbly wobbly squeaks and squawks. On the other hand if used with care as either an expander or P/V Synth, and without much effort, it is eminently capable of producing a wide range of classic analogue synth sounds, in fact almost everything a good analogue synth should be.

Most Roland Rack series units such as P/V Synth, Dimension D, Vocoder and the Stereo Flanger and Phase Shifter have developed a kind of mythical status. This is due to a number of factors, foremost is probably their excellent sound quality and features, second must be the industrial strength build quality (they just keep on going and going) and lastly it is their scarcity. You hardly EVER see original Roland Rack units in classified ads. True you can sometimes find them in pro-dealer lists, at inflated prices but they rarely turn up elsewhere. Which in itself is strange as they were being manufactured by Roland for about 5 years, and by my reckoning there must be a few thousand out there, somewhere. I guess owners just hang on to them, I have.
A new P/V Synth SPV355 had a list price of around £500, I bought mine new in 1981 for about £450. By the late eighties second hand prices were almost double the original price but by the mid nineties prices had settled down around the £300 mark. Currently, as with much classic Roland analogue gear, prices are creeping up a little. As always second-hand prices will vary, a bashed up and gigged to death unit with bent (or broken) sliders could cost as little a £100-£150 but a clean and stable P/V Synth in good working order, with an instruction manual could probably command around £400 or more... if you are lucky enough to find one.

Versatile and fat sounding VCO/VCF combination.
Accurate, fast tracking (with the right type of signal).
Easy to edit and use.
CV/Gate/Env inputs and outputs.
Outstanding build quality.

No independent VCO controls.
No Envelope Release control.
No Sample & Hold.
No White Noise.
Pitch Hold drift.
Some functions only available in P/V mode.
Hard to find.

In all my years of gigging and traveling I've only seen a handful of P/V Synths and most of those were either in private or commercial studios. Some years ago I saw an uncredited picture of a gigging rack full of them but I have no idea how they were being used, or by who. No doubt there are probably many 80's band that used the P/V Synth but the following bands ARE documented as using it in one guise or another: Landscape, Tangerine Dream, Wings, Rick Wakeman, Groove Corporation, Throbbing Gristle, Chris & Cosey.

Variable Pitch and Trigger Detector.
Monophonic dual VCO.
24dB VCF.
Audio Mixer.
ASR Envelope Generator.
Envelope Follower.

482mm (W) 92mm (H) 350mm (D)

Rear CV/Gate Interfaces:-
CV IN/OUT: 1V/octave.
Effect Send.
Effect Return.

Front Panel Interface sockets:-
Portamento control.
VCO 2 A/B Tune.
CV/Gate Hold.
VCO/VCF Sensitivity.



Using the SPV355 with a Vocoder
To get any meaningful use out of a vocoder you need to play a keyboard or synth (into the vocoder Modulator input) in time with vocal phrases (feeding the vocoder Carrier input). If your keyboard skills aren't too good problems can arise with inteligability and phrases getting chopped up or truncated, although if you are happy to sound like a robot you could just use a constant drone. However, by using the same voice signal to feed the vocoder Carrier input AND the SPV355 audio input and then routing the SPV355 Synth output to the vocoder Modulator input you can get some unusual but effective vocoder effects.
When used this way the synth (if tuned correctly on the SPV355) and voice will track each other more faithfully than a keyboard because the P/V Synth isn't restricted to playing the 12-note divisions of a keyboard, using a slight touch of portamento will also make pitch transitions a little smoother. Timing isn't as important when used this way either as the P/V synth will only be triggered when it detects the voice signal, as will the vocoder.
Alternatively if you are willing to spend some time experimenting try hooking up the SPV355 CV/gate outputs to another analogue synth (or module) and feeding that audio output into the vocoder Modulator input. With the right kind of patch some pretty strange and unique vocoder effects not dissimilar to the current voice processor favourite the Roland VP9000 can be achieved.
Also using a vocoder in kind of arrangement means non-keyboard players, guitarists or brass players can have fun vocoding too.

The SPV355 CV/Gate Hold function (also called Pitch-Hold).
The foot switch triggered CV/Gate Hold feature should/could be great but in practical terms it doesn't deliver. The general idea is that while playing or signing you activate the Hold function on a particular note and the P/V Synth will hold that note indefinitely. Unfortunately it doesn't, never has done and probably never will. Instead the pitch just drifts away slowly but VERY noticeably and VERY unprofessionally. Of course we are talking (pre-digital) analogue technology and and I've been informed by a service engineer that the problem is attributable to a single capacitor. Every SPV355 owner I've spoken too suffers the same problem and I suppose you could call it 'a design flaw' but I just call it a pain in the a...

Copyright © 2001 Chris Carter / SOS Publications.
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