Analogue Synthesizer
Reviews : Keyboard
The reputation of Sequential Circuits is
up there with the likes of Moog and ARP, but is the first Prophet in 20
years a worthy addition to that heritage or a cash-in on former glories?
Photos: Mike Cameron
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It's possible that some readers have heard the names
'Sequential Circuits' and 'Prophet' but don't know what the fuss is all
about. But for those of us old enough to have been playing keyboards
since the 1970s, or who have contracted the vintage synth bug more
recently, the names of both the company and its most famous line of
products are magical. In part, this is technological: the original
Prophet (released in 1977, and now known universally as the 'Prophet 5')
was the first polyphonic synthesizer that could store the value of
every parameter in its voicing and control structure. This made it a
marvel; the first polysynth on which you could punch in a patch number,
and recall the actual sound that you had stored. If you weren't
performing in the '70s, you can barely imagine the impact that this had.
But, more significantly, the response to the Prophet name is an
emotional one. The synth sounded fantastic, with a rich, warm and — at
the time — instantly recognisable character that was a million miles
from the larger and more temperamental polysynths (the Oberheim 4-Voice
and Yamaha CS80) that had preceded it.
In many ways, the Prophet set the standard by which
subsequent polysynths would be judged and, even after competitors
brought similar instruments to the market, a mystique still surrounded
the name. This was enhanced by its professionals-with-a-contract-only
price tag. A fellow Sound On Sound writer, on a world tour and
playing at Madison Square Garden that evening, was refused service in a
well-known New York store because he 'didn't look like he could afford
one'. But those who could afford them (and who could get served)
eulogised and, for a while, you couldn't avoid the Prophet. Whether your
taste ran to Phil Collins' 'In The Air Tonight', all of Peter Gabriel's
early solo albums, Paul Hardcastle's '19', Japan's Tin Drum, or even the bass lines on Madonna's Like A Virgin... you were listening to Prophets.
For six years, Sequential Circuits flourished (see
'The History Of The Prophets' box) and the company and its founder and
chief designer, Dave Smith, enjoyed an enviable reputation. But the
world changed in 1983 when Yamaha released the DX7, and manufacturers of
big, heavy analogue polysynths found themselves in deep trouble. ARP
had already folded, and within a few years, Oberheim, Moog and
Sequential Circuits followed. By 1987, the era of the analogue polysynth
seemed forever over.
The Resurrection
As we now know, reports of the death of analogue
synthesis were exaggerated, and although Smith spent the best part of
two decades working in the digital arena with Yamaha, Korg and Seer
Systems, he moved closer to his roots again when he established Dave
Smith Instruments (DSI) and released the hybrid analogue/digital Evolver
and Poly Evolver synthesizers. These carved significant niches for
themselves, so it might have seemed likely that he would continue
developing this brand. But then, out of the blue, Smith announced that
his next keyboard would have an analogue signal path, and would be the
first keyboard to bear the Prophet name in 20 years. You can imagine the
questions this raised among aficionados. Would this be a cynical naming
exercise designed to lure musicians into buying something that it was
not? Or would players again be able to walk into a shop and buy a new,
reliable, synth that looked like a real Prophet, played like a real
Prophet and sounded like a real Prophet?
The Prophet 08's rear panel, with dual outputs and extra 'poly chain' MIDI out.
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So I asked Smith why he had chosen 2007 to step away
from the Evolver and to resurrect the Prophet name. He responded: "It's
true, the Prophet 08 design started as an alternative to the Evolver
with two targets: a reasonably-priced eight-voice synth, and an
all-analogue signal path. I had received many requests for both of
these, but I hesitated because I love the Evolver signal chain, and I
was worried that a traditional analogue, eight-voice synth would be too
simple and not as interesting in comparison.
Nevertheless, I decided to
give it a go and, as the instrument came together and I started playing
it, I was pleased to hear how good it sounded. It was only then, late
into the project, that I thought of calling it a Prophet, since it
really does have a sound worthy of the name. While it cannot match the
Evolver's range of tonal variations, it delivers that magical analogue
punch and depth."
So, 20 years after Sequential closed their doors for
the last time, a Prophet lives again. But is it real, or a marketing
stunt? Read on...
Overview
For many years, there has been no opportunity to buy
an affordable, fully integrated, keyboard-based polysynth with an
all-analogue signal path. Perhaps the closest would be the Alesis A6
Andromeda (Sound On Sound, April 2001). This shares much of the
Prophet 08's hybrid architecture, and its digital effects are even
placed in a side-chain so that you can retain a pure analogue
DCO/VCF/VCA signal path, as in the 08. But the Andromeda is a much more
complex and expensive beastie, and it sports a very un-vintage look and
feel. Consequently, laying hands on the Prophet 08 for the first time is
like greeting a long-missed friend. With its responsive, five-octave,
semi-weighted keyboard, traditional pitch-bend and modulation wheels,
sturdy chassis, wooden end-cheeks and good-quality hardware, it feels
like a vintage analogue synth, while the layout of the controls looks as
you always imagined a modern Prophet would.
So the 08 is still similar in look and feel to a
vintage Prophet, but it's not the Prophet 5 that it recalls, it's the
Prophet 600, to which it bears a remarkable resemblance that turns out
to be far more than skin deep. The 600 was one of the first 'hybrid'
synthesizers to embrace the concept of an all-analogue signal path
coupled to digitally generated modulators, and this is a very good
description of the 08. Eschewing the samples, DSP-driven
virtual-analogue synthesis and gazillion digital effects of the past
couple of decades, the 08 is a traditional analogue/digital hybrid in
which each voice comprises an all-analogue signal path of a couple of
oscillators, a low-pass filter and an amplifier, plus a goodly
complement of digitally-generated LFOs and contour generators. Indeed,
the similarities run even deeper that that, because the analogue chips
on which parts of the 08 are based were developed from the original
Curtis (CEM) chips found at the heart of many vintage synths.
But will the 08 appeal if you have never played one
of its ancestors and don't enjoy (or suffer from) this perspective?
Happily, yes. Unlike the many virtual analogue synths that are too
feature-laden to be intuitive, but in common with many revered vintage
synths from the late 1970s, everything on the 08 falls to hand, in large
part because most of the knobs are single function and don't rely on
menus and screens to tell you what they will do. OK, the knobs are
rotary encoders rather than potentiometers, so you can't look at the
panel to 'see' the sound. What's more, they are a little lightweight and
wobbly, and even brushing against one will bring it into focus. But
when you move one, its value — both before and after editing — is
displayed on the small LCD screen, and when you turn it, the parameter
value picks up from its existing value, so there's no glitch, which was
not always the case on some vintage synths. There are other nice
touches, too. For example, you can press '+' and '' simultaneously to
return a parameter to a default, and you can press Program and '+'
simultaneously to place the current Program into a 'basic' form from
which you can build a new sound. Touches like this raise a synth above
the merely useable and, while a handful of menus are necessary, there
are no sub-sub-sub-sub-menus to confound and annoy. The only thing that I
missed was a way to type values directly into parameters, or to select
patches at opposite ends of the memory without scrolling. A keypad would
have satisfied both needs but, unfortunately, there isn't one.
Despite the similarities, the Prophet 08 is no
slavish recreation of an original Prophet; there's too much that is new
for that to be the case, including velocity and pressure sensitivity
(which was only introduced on the T8) a four-channel analogue-style
sequencer, an arpeggiator, a modulation matrix, and even an optional
software editor/librarian. Furthermore, a peek around the back shows
that there must be some significant differences in the sonic
architecture itself because — in addition to a headphone output — there
are two pairs of signal outputs. This is because each of (what appear to
be) its two banks of 128 patches is in fact a Program containing two
patches that can be played independently, layered, or placed either side
of a user-defined split point. If you insert a pair of cables into the
'A' outputs alone, both patches appear here, but if you insert a second
pair into the 'B' outputs, the two patches can be treated and mixed
individually. So what we have here is the equivalent of two, stereo
Prophets, which suggests all manner of exciting possibilities. What's
more (and unlike some vintage analogue synths) the Prophet 08 does not
use a central repository of patches to build its Programs. This is a
cursed architecture, wherein changing a patch in one Program will often
wreck another. In the Prophet 08, there are 512 distinct patches
comprising the 256 Programs.
Staying around at the back for a moment, the 08
offers inputs for an assignable CV and a sustain pedal, plus the usual
three MIDI sockets, but there's another socket that might cause a
double-take: a fourth MIDI socket, called Poly Chain Out. This is an
idea that has been around since the earliest days of MIDI but is
implemented far too rarely: it allows you to connect a second instrument
to double the polyphony. This is not the same as chaining two 08s using
a conventional MIDI connection, because the voice assignment is
intelligent, and if you save a Program on the Master it's automatically
saved to the Slave.
The final hole accepts the input from a wall-wart.
Divorcing the power supply from the instrument contributes to the
lightness and compactness of the synth and makes it easier to satisfy
various electrical and safety regulations but, let's be honest, a DC
input feels less professional than an IEC socket.
The History Of The Prophets
Dave Smith produced his first synthesizer in 1977.
He designed this while building a Minimoog programmer and an early
digital sequencer and, whether by luck or craft, he hit upon a classic.
Based on SSM chips, it looked and sounded like the instrument we now
call a Rev 1 Prophet 5, except that there were two versions: one that
could play five notes and one that could play 10. Unfortunately, the
expanded version was unreliable and the only solution was a radical one:
most were converted back to the five-voice synths that we now know as
the Rev 1 Prophet 5.
This Prophet remained unreliable, but its second
incarnation (of which there were to be three revisions) was a more
robust beast. Then, in 1980, the company reworked the synth around
Curtis chips, which entailed a thorough redesign, so it's remarkable
that its sound remained almost unchanged.
Sequential's next product was the twin-manual
Prophet 10. More than two Prophets in a box, this monster could allocate
its voices in several modes, ranging from a two-oscillator-per-note
10-voice synth, to a monosynth with 20 oscillators under a single key.
In 1983, the Prophet 600 appeared. This was the
world's first MIDI synthesizer, and one of the first to use hybrid
(analogue/digital) technology. Unfortunately, its digitally generated
envelopes responded more slowly than analogue circuits, and its controls
were audibly quantised. Later that year, Sequential released the
Prophet T8, a close relative of the 600 that boasted a piano-weighted
keyboard with polyphonic aftertouch. Unfortunately, this was the year
that the Yamaha DX7 swept all before it, and Sequential lost its place
at the head of the market.
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The Oscillators & Filters
Perhaps surprisingly, the pitches of the 08's
oscillators are digitally controlled rather than voltage controlled. I
asked Smith whether he felt that he was taking a risk implementing DCOs
rather than VCOs. "DCOs picked up a bad reputation long ago because they
were sorely lacking in resolution, and they sounded too stiff," he
explained. "Now, with very high-speed frequency control, the oscillators
in the Prophet 08 can be exact and lock up (which can be useful
sometimes), or they can be precisely detuned, or you can add what we've
called oscillator 'slop', which is a slowly varying random frequency
change, independent on every oscillator. This is a subtle effect, but it
does a great job of mimicking VCOs when you want that characteristic
VCO sound."
A digital clock will lock an analogue oscillator to
its chosen frequency to a high degree of accuracy, which may not be what
you want for a given sound. Smith's 'slop' introduces a recognisable
thickness, so many will leave it permanently switched on. However, being
able to defeat it has its uses; you'll never find that the
concert-hall-shattering-note you expected comes out as an apologetic
squeak because the two oscillators are out of phase with respect to one
another!
Given the two instruments' similarities, I decided
to compare — as much as one can in an integrated polysynth — the sound
of the Prophet 08's DCOs against the VCOs of my Prophet 600. I started
with the sawtooth wave... and was stunned. The difference between the 08
and the 600 were no greater than the differences between Prophet 600
voices! However, the 08 soon began to reveal its individuality. The
triangle waves were not identical, with the older instrument revealing
mild distortion somewhere in the signal path, and the newer being
rounder and woodier. Likewise, the 600's pulse waves were slightly
brighter than the 08's. Even greater differences were revealed when I
applied hard sync. Since the vintage instrument uses VCOs and the new
one uses DCOs, the sync mechanism has changed, and sync'ed sounds are
not the same on the two. I'm not sure that either is better or worse;
they are just different.
There are differences in implementation, too. On the
'plus' side, the 08's oscillators score by being able to produce pulse
waves that are narrower than the 600's, thus increasing the range of
timbres, and they have a wider tuning range. On the 'minus' side, the 08
does not allow you to mix sawtooth, triangle and pulse waves (as the
600 does) but instead offers a sawtooth+triangle mixed wave, and a noise
generator.
Knowing that the traditional CEM chips used in the
early Prophets no longer exist in significant quantities, I asked Smith
how the Prophet '08 came to have Curtis filters. He told me: "We're
using a customised part that Doug Curtis designed a few years back for
the Evolver. As you may know, Doug passed away recently, but his
company, OnChip Systems, are still manufacturing the chips for us. The
part is similar to the one that Tom Oberheim used in his 'Marion' series
of synths a few years back, which in turn was a variation of an older
CEM part. In my opinion, this filter has a ballsier sound — I usually
avoid using descriptors like that, but everyone knows what it means —
than the CEM3320s we used in the later Prophet 5s, the Prophet 10, and
the Pro One, and I think that this is noticeable if you compare the
Prophet 08 to the older synths."
Almost all of the Prophet 08's controls can be found on the panel of the instrument.
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I decided to check this, but was surprised to find
that filtered sounds on the 08 sounded very different from (ostensibly)
identical patches created on my original Prophets. This was most
noticeable when I turned up the resonance to invoke filter
self-oscillation; sounds that use this can be played in tune across the
whole keyboard on many vintage synths, whereas the oscillation generated
by the 08's filters in 24dB/oct mode was not. I mentioned this to
Smith, and he suggested that I invoke the calibration routine. What a
difference! The filters in the 08 now sounded consistent and tracked
almost perfectly.
There are two filter modes; a self-oscillating
24dB/octave (four-pole) mode, which recalls the original Prophets, and a
non-self-oscillating 12dB/octave (two-pole) mode, as used on the
Oberheim OB series and the Yamaha CS series. Programming the filters in
12dB/octave mode created a different palette of sounds that some
commentators have already compared to the OB family. This is a knee-jerk
reaction that occurs whenever people see a two-pole filter, and is no
more accurate than saying that every polysynth with a four-pole filter
sounds like a Memorymoog. In truth, the 12dB/oct mode on the 08 has its
own pleasing and flexible character, and in some ways I prefer this to
the rather distinctive sound of the OBs.
Inevitably, the 08 offers facilities in the filter
section that the original Prophets did not, including such things as
fully variable keyboard tracking and inverted contour control. I also
found that the amount by which the filter could be swept was far greater
on the 08 than on previous models. In contrast, the amount of audio
frequency modulation that you can apply to the filter is not as great as
I had expected, and whereas vintage Prophets can use any combination of
their oscillators' waveforms as modulators, the 08 is limited to a
single waveform. This means that filter modulation on the older synths
tends to stray deeper into sci-fi territory, whereas the 08 is more
cultured and musical, especially when the frequency of the modulating
oscillator is swept or the depth of modulation is varied. Yet, despite
all of these differences, no Prophet aficionado will feel ill at ease
with the 08's filter architecture or sound. It is still recognisably a
Prophet.
EGs, LFOs, VCAs & More
The Prophet 600 was the first Prophet to use
digitally generated ADSR contour generators, and while these were
remarkable technology for 1983, they were famously sluggish. "Digital
envelopes got a bad rap (deservedly) in the 1980s, due to their slow
update rate," Smith admitted to me. "In contrast, the Prophet 08 update
rate is super fast, so you get the best of all worlds: nice, snappy
envelopes, but at much lower cost than a true analogue eight-voice with
analogue envelope generators." He's right, and as well as being fast and
offering an extra stage, the 08's three sets of HADSR contour
generators offer a huge range of routing possibilities, with — in the
case of Envelope 3 — looping for non-standard LFO shapes.
The difference that 24 years of progress can make is
even more apparent when you look at the LFOs. Or, rather, at the single
LFO that many vintage polysynths offered for all their voices. The
Prophet 08 sports no fewer than 32 digitally generated LFOs (four per
voice), all of which offer a wide frequency range — from approximately
0.03Hz at the lower end to 150Hz at the upper — and five waveforms,
including random for S&H effects. They can be independently sync'ed
to the keyboard (or not) and can receive MIDI clock, all with a wide
range of sync options. Sure, they share a single set of controls, but
programming them is simple and, to help you, the LEDs next to each of
the LFO selector buttons flash at the appropriate frequency and with the
appropriate waveform. This makes it possible to spot which LFO is doing
what in a complex patch. In addition to all this modulation power, a
small (four by four) matrix allows you to direct any of 20 sources to 42
destinations. Programming is again via a single set of controls, but
it's still quick and intuitive.
This is all a far cry from the Poly-Mod and LFO-Mod
(or Mono-Mod) sections on the early Prophets, and you may feel that it
isn't true to the spirit of the originals. But the Prophet 5 and its
siblings weren't simple because of an underlying philosophy: it was a
consequence of cost and practicality. Smith explained, "With 32 LFOs and
24 envelopes, the Prophet 08 would have cost more than $10,000 to
implement in hardware! Not only do you need the LFOs and envelope
generators themselves, but for each destination you need a VCA for
modulation routing. That's why the Prophet 5 had just one LFO and such
simple modulation routing. Digital envelopes and LFOs are not only more
cost-effective, they are more accurate from voice to voice. This is
because they don't have to go through VCAs where they would pick up gain
and offset errors."
An analogue VCA stage lies at the end of each
voice's signal path. This offers variable panning, which allows you to
create a stereo field for both the 'A' and 'B' output pairs, and the
amplifiers clip mildly if you overdrive them. Also, like the ARP 2600
and many virtual analogue synths, the 08 offers an Initial Level control
that allows you to create drones and other effects, but it has no
external signal input, so you can't use it to filter external signals.
That's a shame.
The 08 offers a four-mode arpeggiator that can be
driven by the internal clock or sync'ed to MIDI Clock. This can be
latched (which is good) but there is no way to play an arpeggio over
multiple octaves, and no random mode. I would urge DSI to add these
features if there are to be any further software revisions. There's also
a sequencer, but lest you fear that the 08 has been compromised by its
inclusion, fear not. This is no umpteen-channel workstation sequencer
with plug-in effects and whatnot: it's a four-channel, 16-step,
analogue-style sequencer similar in philosophy to, say, an ARP 1601 or
Analogue Systems TH48. All the usual facilities are included, as well as
nice touches such as being able to synchronise the voice LFOs to the
sequence to create filter sweeps in time with the music. The fly in the
ointment is that there are no dedicated sequencer controls; this is the
first place on the Prophet 08 where multi-functionality has reared its
head, with orange silk-screening alongside some of the knobs
differentiating the sequencer functions from the voicing functions. The
panel would need to be significantly larger and more expensive had
another 16 (or 64!) knobs been added, so this is forgivable, but there's
another decision that I admit to disliking; the sequencer is gated,
which means that it only plays when a key is depressed or a MIDI Note On
is received.
True to the philosophy of the early Prophets, there
are no effects built into the 08. To have added modern effects
processors would have entailed the use of ADCs and DACs in the audio
signal path, but I feel that the 08 would have benefited from an
analogue chorus, as on the Prophet VS. Sure, it doesn't need one to
sound lush and involving, but it would have added another flavour. At
one point, I played the review unit through a Roland Dimension D and...
wow!
Edit Your Prophet
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In Use
I am often complimentary about developments in DSP,
and about the quality of modern emulations of vintage synths.
Nonetheless, the 08 demonstrates (even to me) that there remains
something special about a really good analogue synthesizer. And have no
doubt, the Prophet 08 is a really good analogue synthesizer. It produces
superb strings, pads, brasses, leads, basses and all manner of special
effects, effortlessly. I even managed to recreate a haunting pad from my
Prophet 600 that has eluded me since I stopped using it on stage in
1991. Bliss!
I also programmed a 'Hammond' patch that is a
particularly stern test of any dual-oscillator analogue synth. Osc 1
provides the 16' signal, Osc 2 provides the 8' signal, and the
self-oscillating filter provides the 52/3' signal. When I tuned the 08's
filter very carefully, shaped the amplitude envelope for a bit of
click, and added some panning LFO for a basic rotating speaker effect
the result was... mmmmm! Patching took just moments, but the result was
delicious, far better than I could obtain from my vintage Prophets.
Now, let's talk about layering. Many years ago, Tony
Banks and I discussed how he used 'Dual' sounds on his Prophet 10 to
imitate the first four drawbars of his Hammond, eventually dispensing
with the organ altogether. The Prophet 08 emulated this effortlessly,
and I soon found myself deep into Genesis territory, circa 1980. It also
proved more than adequate for recreating the massive Prophet 10 drones
of tracks like 'Mama'. Next, I found a new palette of sounds awaiting
discovery if I layered a patch using a 24dB/oct filter with another
using a 12dB/oct filter. I created sounds with 'hard' transients
followed by 'softer' sustained stages, as well as patches (which I
obtained by using the envelopes to cross-fade a patch in one mode to a
patch in the other) that evolved tonally. But, if you're into grooves,
you'll probably find it more fun to use the split and layering
capabilities to combine rhythmic patches. There's no end of trance and
techno lurking within the 08's spaghetti of sync'able sequencers,
arpeggios and sync'd LFOs, and this synth will scream, tear and belch
with the best of them.
I can't move on without discussing soloing on the
Prophet 08. If you want to super-size your sounds, there are three modes
of unison; a single dual-oscillator voice for most of your favourite
monosynth imitations; all 16 oscillators stacked; and all available
oscillators stacked with detune. What's more, you can decide how the
keyboard responds in these modes, with low-, high- and last-note
priorities, and single- or multi-triggering. If you want to widdle at
100mph, choose one of the four velocity curves and one of the four
pressure-sensitivity curves to taste, and the 08 is ideal for the task.
There are also four modes of portamento, namely fixed rate and fixed
time, applied on every new note or just when you play legato, and the 08
even offers independent slew generators for each oscillator. Solo
sounds created using different slew rates can sound wonderful, because
the two rates of portamento produce one of the most subtle yet
interesting musical effects that is available.
Inevitably, the 08 isn't perfect but, apart from the
handful of points already made above, you have to look hard for things
to criticise about it. I suppose that some people may take issue with
the positions of the pitch-bend and mod wheels (which are behind the
keyboard rather than alongside it) but I found them to be perfectly
useable, and I appreciated the fact that this makes the 08 even more
manageable and compact than it would otherwise be. Others might complain
about the quantisation of the controls, but this is a consequence of
adding memories to any analogue synthesizer, and the 08 is less
quantised than many vintage synths.
So what of imperfections in the signal path? Sure,
there's a tiny amount of bleed in the oscillator mixer and through the
filter, and a faint halo of noise that's apparent on some sounds. So
what? There was a lot more on some revered vintage synths and, if
anything, these minor blemishes only prove again that the 08 is a real
analogue synth. Finally, I've heard comments that bemoan the lack of
high-pass and/or band-pass filter modes. These would have increased the
synth's sonic palette considerably, but I suspect that it would no
longer have felt like a Prophet, so I think that DSI made the right
decision. You may feel otherwise.
Conclusions
At the start of this review I asked whether the 08
is a real Prophet, and whether it can satisfy our nostalgia for all
things big, heavy and analogue. In both cases, the answer is 'yes'. The
08 deserves to bear the Prophet name, because it looks, feels and sounds
as a Prophet should. Please be clear; I'm too old to be beguiled by an
analogue signal path, nor (I hope) am I susceptible to the appeal of the
word 'Prophet' silk-screened onto a control panel. When I say that the
08 appears to be the real deal it's because nearly 30 years of
experience with Prophets tells me that this is so. That it's so pleasant
to use and sounds as warm and involving as its predecessors means that I
can see no reason not to buy one if that's the sound you're seeking.
There's no immediate competition and, with ageing Prophet 5s and Roland
Jupiter 8s now costing around £1500, Oberheim OBXs not far behind, and
Yamaha CS80s heading into deep space at £5000 or more, the Prophet 08 is
also excellent value.
To finish, I'd like to quote something that Smith
wrote to me a few days before I submitted this review: "It's been nice
to rescue the Prophet name from all the simulations that have multiplied
over the years!" To paraphrase Emerson Lake & Palmer, I can only
add, 'Welcome Back My Friends, To The Synth That Never Ends'.
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