Dave Smith Instruments Prophet 12

A new Prophet is always an exciting prospect, but the name certainly carries a weight of expectation. Can the latest model live up to its illustrious ancestry?

Thirty-five years after it was first attached to a synthesizer, the Prophet name still invokes awe, and the day isn't long enough to list all of the musicians who have achieved great things using Prophet 5s, 10s, 600s and T8s. Consequently, there's always an air of expectation when a new Prophet is announced. But is it justified? Does a world replete with workstations offering multiple virtual analogue engines, gigabyte samplers, sequencers, terabyte hard disk recorders and gazillions of effects need another 12-voice hybrid polysynth?

The Prophet 12 comprises two six-voice synthesizers called Layer A and Layer B. These can be played individually, layered, or placed either side of a split point, so you can use the Prophet 12 as a single 12-voice polysynth, as a six-voice bi-timbral synth, or as two independent six-voice synths. Happily, it doesn't require dozens of hidden functions and tiers of menus to achieve all of this. Much of what it can do is immediately accessible from its control panel, so it gives of its best quickly, even to relative novices. Nonetheless, there's more here than meets a casual glance, so let's start by working through the voice structure and seeing what we can place into each of those Layers.

Oscillators

There has been much gossip among the chattering classes about the hybrid analogue/digital nature of the Prophet 12. Nowhere is this more relevant than the oscillators, which are generated by no fewer than six SHARC chips, each of which handles the digital elements of two voices. This is a non-trivial amount of processing power, but with four oscillators per voice, each with coarse and fine tuning, slop (tuning instability) and independent portamento, plus a sine wave sub-oscillator one octave below Osc 1, that's a total of up to 60 waveforms being generated at any given moment, which is not trivial if you're going to do it correctly.

Each oscillator offers the standard set of analogue-style waveforms, each with waveshaping options. The best-known form of waveshaping is pulse-width modulation, but there are other shapers for the sawtooth, triangle and sine waves, and even for the three noise colours.

There are also 12 additional waves, chosen to expand the initial palette in interesting ways. These have names such as Nasal, Ohhhh, Ahhh and Buzzz, which give you a rough idea of what they sound like, and of the uses to which they can be put. Instead of waveshaping, the additional waves allow you to select a base waveform, place one of the other shapes to its left and another to its right, and crossfade (or, in modern parlance, morph) between them, either to obtain new static waveshapes, or to create unusual dynamic waveforms.

As you would expect, the waveshaping and morphing of all of these sources can be controlled by the LFOs, the contours, and many other facilities available through the modulation matrix (which we'll address in a moment) and you can set this up independently for each of the oscillators in a voice, so the initial sound can become very detailed, very quickly.

You'll also find controls within the oscillator section for Amplitude Modulation, Frequency Modulation ('cross-mod') and a button for hard sync. The ring to the left of these shows which oscillators are active at any given time, and the preset routings of the AM, FM and sync sources and destinations: Osc 4 affects Osc 3; Osc 3 affects Osc 2, and so on. This is a powerful architecture. For example, you can have two sync'ed pairs in a single voice, or a sync'ed pair and a two-operator FM sound, or a three-op FM sound and an unmolested oscillator, or... well, you get the picture. Except that you don't, because you can also assign and route the oscillators within the modulation matrix. This fully vindicates DSI's decision to use digital oscillators, because even the smallest deviations between voices would result in excessive tonal differences between notes and render polyphonic patches unusable.

'Character', VCFs & VCA

Given the degree to which the initial waveforms and tunings can be modulated, and the myriad ways in which the AM and FM amounts can be modified within the Prophet 12, the tonal possibilities are enormous even without invoking filters and other effects, and careful programming generates sounds that would never be available on a pure analogue polysynth (or, for that matter, many digital ones). Nonetheless, whereas the filter section would immediately follow the oscillators on most synths, the Prophet 12 has an additional waveshaping section positioned prior to the filter. This is called Character, and it offers five ways to mangle the outputs of the oscillators on a 'per-voice' basis before passing the signal to the D-A converters that lie before the filters. The first two are called Girth and Air, and these accentuate the bottom and top ends of the sound, apparently adding a bit of harmonic excitation in addition to their low- and high-frequency boosts. Next, Hack reduces the word length down to a minimum of two bits per sample, and Decimation reduces the sample rate down to a minimum of a 16th of the initial frequency. So, if you have a penchant for the earliest digital synths, you can make the Prophet 12 sound as rough and grainy as you wish. (And worse!) Finally, there's the excellent Drive, which does what you would expect, and does it very nicely.

Passing through the D-A converters, we now come to the analogue signal path, starting with the CEM-derived low-pass filter that's been used in many other DSI synths in recent years. This can be switched between a resonant (but not self-oscillating) 12dB-per-octave mode and a resonant, self-oscillating 24dB/oct mode. Its architecture is otherwise straightforward, with cutoff frequency and resonance controls, variable key tracking (which tracks 1:1 if requested), a dedicated ADSR contour generator with variable amount (positive and negative polarity), and variable key velocity directed to the envelope amount. There are only two additional facilities available through the menus. The first is a short delay before the onset of the Attack (which makes the contour an HADSR), and the second is a Repeat function that loops the HAD stages for rhythmic effects.

The signal now passes to the resonant 12dB/oct high-pass filter, which is based upon the device found in the DSI Tempest. With physical controls for cutoff frequency, resonance and key tracking, this appears to be even simpler than the LPF, but appearances can be deceptive because you can route any of the modulators to affect the filters, and even push the HPF into self-oscillation to create a class of sounds that were never available on early Prophets. High-pass filters are often overlooked or treated as the poor relations of their low-pass cousins. Don't make that mistake on the Prophet 12.

The next stage in the signal path is the audio VCA. Again, its dedicated contour appears to be an ADSR but is in fact an HADSR whose amount can be controlled using velocity, and it offers the same HAD Repeat mode. An additional control allows you to determine the spread of voices across the stereo sound field to create expansive-sounding patches, and a menu item determines the overall volume of the patch so it can be matched to other sounds.

Feedback & Effects

We now come to a fork. One side of this passes the audio through an A-D stage before injecting it into a feedback loop that returns it to the input of the Character section. This loop will ring at high levels and has a delay element that tracks the keyboard accurately, thereby providing a consistent character to sounds that use it. At high levels, the loop will oscillate up to a maximum pitch of MIDI Note C4, and you can play the resulting sound in the conventional manner. With no signal injected, I obtained a rough, reedy tone with a slightly uncertain attack — the best synthesized bass accordion I have heard in years! Inverting the polarity of the loop produces different tones with a more restricted frequency range. Of course, this isn't what the loop is there for and, using it conventionally, I obtained all manner of fascinating sounds, from gnarly analogue torture to all manner of FM-like chimes and digital pianos.

The A-D also feeds the digital delay section, which offers four programmable taps (each with a maximum delay of one second), panning and variable feedback. You can create numerous modulation-based effects such as chorus/ensembles and flangers with this, and a wide range of echo effects that can be sync'ed to MIDI Clock, to the arpeggiators and to the modulators.

The other side of the fork passes the unmolested analogue signal directly to the output section, which comprises two analogue distortion units (one for each Layer) and a final volume control. This means that, in contrast to (say) DSI's PolyEvolver, the Prophet 12's signal path can remain analogue from the low-pass filter section onward.

The distortion units themselves can create super-aggressive sounds but, if you crank them up toward their maxima, you'll hear what sounds like leakage from the oscillator section. This is actually the tiny residual signal that floats around the inside of any analogue (or hybrid) synth, and it's being made audible by the huge amount of gain on offer. If you feel the need to distort the signal to this degree, you'll probably want to gate the synth externally, just as you would when overdriving a lead guitar in the same fashion.

More On Modulation

The Prophet 12 offers four assignable LFOs per voice, each offering seven cyclic waveforms plus Sample & Hold. Each can be sync'ed to the arpeggiator and/or delay, each can be reset at the start of each note and offset to any degree, and each has an integrated slew generator to smooth the existing waveshapes into new forms. In addition to these (and in addition to the two contour generators already discussed) there are also two Auxiliary Envelopes. These are bi-polar, with the same five stages, repeat mode and velocity sensitivity as the others.

This then brings us to the Modulation Matrix itself, which offers 16 slots into which you can insert your choice of 26 sources including, of course, performance controls such as velocity and aftertouch as well as the LFOs and contour generators, and no fewer than 97 destinations. It was while experimenting with this that I began to realise how 'modular' each Layer can be. You can even cascade controllers by using one slot to affect the depth of another, just as on a true modular synth with patchable VCAs. To aid setup, there's a neat method for determining routings: press and hold the Mod Source button and then turn or press (or whatever) the desired source, then do the same using the Mod Destination button. That's a nice touch.

Programming

Like the Prophet 08, the Prophet 12 doesn't use a central repository of patches from which to build its Programs; instead it provides 792 Programs containing 1584 distinct patches. Despite this generosity, I'm always a little bemused when synthesizers are shipped with factory sounds that can't be overwritten by the user; it seems a little egocentric to make them half of them permanent, as here. Fortunately, the 396 programmable memories (792 patches) on offer should be sufficient to satisfy most users. If it isn't, you can dump and recall sounds on a per-Program or per-Bank basis. Just be careful that you don't lose valuable new sounds when you recall old ones, because they are always reloaded into the locations from which they were dumped.

Creating sounds on the Prophet 12 proved to be a genuine pleasure. The panel offers control over the majority of functions, and those that lack a dedicated knob or button appear within the small but crisp OLED, which displays graphics where appropriate and offers more precise control. At first, I though that I would bemoan the Prophet 12's inability to accept parameter values from its numeric keypad, but it wasn't an issue: the 'soft knobs' above the screen are both quick and precise in action. There's also a Show button that allows you to jump to an appropriate page to see parameter values without changing them, and other neat tricks such as ability to edit all four oscillators simultaneously, all of which make editing quick and fun. I found just one bug; if you set no destination for an LFO on the control panel and then try to route it from within the modulation matrix, it remains off. I let Dave Smith know, and he undertook to look into it. In the meantime, I wouldn't worry about it.

By the way, you may have noticed from the photos that some of the knobs have lines that show their positions, while others do not. This is not an oversight. Those with lines are potentiometers that report their values in absolute terms; the others are rotary encoders that increase or decrease an existing value. To make editing as smooth as possible, the pots offer three modes: relative, pass-thru and jump. I set the Global parameter to pass-thru as soon as I received the synth, and everything worked as I had hoped.

Performance Facilities

When I received the Prophet 12, I discovered that it was way out of calibration, so I invoked the calibration and tuning routines. These took a few minutes — I made an espresso and consumed a rather nice piece of cake before they had finished — but calibrated everything perfectly, and I was ready to go.

Next, I experimented with the velocity and aftertouch response curves, and I was pleased to find that, unlike the Prophet 08, the illuminated pitch-bend and modulation wheels were in their usual and more natural positions. In addition to these, the Prophet 12 also offers two touch-sensitive ribbons that generate controllers according to the positions at which they're being touched and the pressures with which they're being pressed. The four control messages thus generated are then available as sources within the modulation matrix. Both sliders have rows of LEDs underneath the ribbon itself, and these show where you're touching it. This seems pointless until you realise that the values can be held after you remove your finger, at which point the indicators become useful, especially on stage. Talking of which, Play Lists are another nice touch for gigging musicians. These allow you to create sequential lists of Programs so that you can step through the patches that you need for any given gig without having to reorder them in the Program memories. I can assure you that, once you've used Play Lists, it's a right royal pain in the arse to go back to a synth without them. You can store 40 Programs as 10 sets of four in each of the four Lists, each of which is probably enough for a concert, although I would have preferred to see them arranged as single 40-sound sequences. The only caveat is to be careful not to edit and save a Program from within a List. The sounds are not saved separately, so any changes in one list will update the underlying Program and therefore change it in all other lists in which it's referenced. Oh yes… and if you want to sequence your performances, including any tweaks to the control panel settings, you can do so, because the Prophet 12 sends any changes in real-time as MIDI CCs or NRPNs, the latter of which are the method of choice because MIDI CC values are limited to the range zero to 127, and some of the Prophet 12's parameters extend beyond this.

Sounds

I have no idea how to try to encapsulate the sound and flexibility of the Prophet 12, simply because there's so much to it. For example, in addition to everything obvious that the oscillator section offers, its four oscillators allow you to emulate vector synthesis using the ribbons rather than a joystick, and as for all the possibilities offered by the simultaneous use of sync, FM and wave modulation, I can't begin to outline what's feasible. Also worthy of special mention is key-on sync, which DSI call 'wave reset'. This reinitialises the oscillators when you trigger a note and ensures that you don't obtain the tentative squeak that sometimes occurs when you play detuned sounds using free-running oscillators. That's a nice touch.

The Character section is equally worthy of praise. Take a simple oscillator setup and, with the filters wide open, experiment with the effects within it. Now sweep them using contour generators and modulate themThe Prophet 12's front panel: many will be glad to see that, unlike on the Prophet 08, the wheels are back where they belong at the side of the keyboard. using LFOs and other sources. I found that the best results were obtained using subtle changes, but you can add a lot of variation to the initial sounds if you prefer.

When I reviewed the Prophet 08, I suggested that DSI had been right to omit high-pass filtering from its specification because this might make the synth a little less Prophet-y than it would otherwise be. And, as I experimented with the dual low-pass modes on the Prophet 12 and learned how to invoke things such as variable Q and self-oscillation in the HPF, it began to generate sounds that could never be coaxed from its predecessors. Nonetheless, it didn't feel less of a Prophet, so maybe I was wrong. Just be aware that, given the limited number of programmable values for the filters' cutoff frequencies, you'll obtain steps if you sweep them manually, whereas sweeping them using contour generators and other modulators will generate the smoother changes that one would hope.

Other than that, there's little to criticise about the Prophet 12. I suspect that some people are going to wish that it were larger — it would be easier to be impressed by something the size of an OBX or, even better, a CS80 — but, being realistic, there isn't a lot to dislike. Sure, I found the aftertouch to be rather too eager for my tastes, and I think it's a shame that it lacks a dedicated analogue chorus/ensemble, but these are far from fatal flaws. Also, there's no editor/librarian as yet, although one may appear if we're patient. Other than that, plus the limitation of the headphone output (see the 'The Rear Panel' box) and the possible need for an external noise gate when driving the distortion units to their limits, I'm at a loss to find anything bad to say about it.

Conclusions

I have had the privilege to own and play every major Prophet synthesizer, and I still have a Rev1 Prophet 5, a Prophet 10, a Prophet 600 and a T8. The Prophet 5 sounds beautiful, but it's temperamental and prone to not working on weekends. To be honest, it's prone to not working on weekdays too. The Prophet 10 is a monster, but it's too big and heavy unless you have access to Genesis's road crew. I gigged with my Prophet 600 for more than a decade, and I still love it, but it lacks velocity or aftertouch sensitivity, which limits what I can do with it. Strangely, the T8 — which is often described as an enhanced Prophet 600 with velocity and aftertouch — doesn't sound as good. So how does the Prophet 12 compare?

To be fair, it lacks the sheer muscle of the Rev1 Prophet 5, but it's better in just about every other way. Likewise, it lacks the dual manuals and presence of the Prophet 10, but it's better in just about every other way. It also lacks the simplicity of the Prophet 600, but it's better in just about every other way. And it lacks the excellent weighted keyboard of the T8, but it's better in just about every other way. In short, DSI have taken the best from the heyday of analogue synthesis, and added a significant amount of new technology to create a modern classic. Dave Smith told me recently that, "I don't use the Prophet name lightly, but the Prophet 12 is clearly deserving of it, and a great new flagship instrument.” I agree.