SCI – Sequential Circuits Synthesizer

SCI – Sequential Circuits Synthesizer , DSI , dave smith instruments

Prophet 5 / P5 / T8 Drumtraks (drumtracks!) Mulititrak
Pro-One Sixtrak
Prophet 600 TOM
Studio 440
Max Prophet VS

SCI gear trigger: in/out 15V GROUND to positive.

SCI text images: click to see a larger image..
SCI SCI Synth overview / überblick..
Sequential Circuits
Prophet 5
there are basically 3 Revisions
the first one had SSM chips (78), rev2 (78 -80) still ssm and rev3 (from 80) had curtis chips.. there was also a chance in the VCA and DACs architecture due to the change from the (different) ssm chips.
rev 3 also divides into 3 sub-versions:

the first one (3.1) added the edit mode as we know it today (change parameter when turning the knobs) and the tape interface (compact cassette) and other little things
3.2 was minor changes
3.3 changed it to 120 presets to be saved instead of 40 but you can not store them in one go to tape without copy..

some are MIDI-retrofitted, some aren’t..

this synthesizer was the first “real” 5 voice synthesizer (after the 4voice from oberheim and others..)

interesting: the so called poly mod. for making the sound more interesting ;)

see the left section? this is the key to the prophets..

pic by/thx to Rob Schweizer

chips inside the Prophet 5 and all other models are listed here

SCI Prophet 5 Synthesizer
SCI Prophet Five Synthesizer

SCI Prophet5 Synthesizer
Prophet 5 image to enlarge..

SCI Prophet 5 Synthesizer
SCI Prophet 5 Synthesizer

Prophet 600

the “cheaper” version of the Prophet 5

the parameters were more “stepped” and some mod routings have been removed compared to the Prophet 5 but it was much cheaper and had to compete with the polysix and other poly synthesizers in the 80ies..

anyway it still sounds comparable..the difference:
it has no noise generator and pwm is missing in poly mod section.

the 1983 released Prophet 600 was the first midi equipped synth to talk to the jupiter 6 (same time) in omni mode and later ones in poly mode.. (very few)

the weak point on the Prophet 600 is the keypad like the sitraks keypad this is the weakest thing to check for before getting one..

Sequential Circuits Prophet 600
prophet 600 synthesizer

prophet600 synthesizer

one voice of the P5
(prophet 5)

the SCI ProOne (Pro1)

basically one voice of the p5,so it’s monophonic.

Powerful Oscillators but a quite low quality of the construction itself. very easy and a Sequencer and Arpeggiator is also on board. it was the post poly-synth era, so they did it to make a solo synth that normal people could afford..

chips inside the P5 and all other models are listed herefind more Pro One info on unease

SCI ProOne

sequential pro one
above pic by theo bloderer @
very large SCI
Pro One image click this one:
SCI ProOne
want to read the inscription? enlarge? vergrössern?.. alle beschriftung lesen?
pic by/thx to Rob Schweizer

another one by myself..
SCI Pro One Sequential Circuits

a double Prophet 5 (P5) with card slot..

it is simply a dual keyboard dual Prophet5 boards for 2×5 voices…

the PROPHET 10 is quite rare, possibly it was too much.. ;)

3 Versions of this were made..
since this is a P5 related synth but doubled it also reflects the P5‘s rev versions in another way..

the first one was a rev1 “doubled”, the 79 version of course was more close to a rev 2 p5 (doubled)..

perhaps the early one was only double voices but not “multi timbral” style..

(click to enlarge PROPHET 10)
SCI Prophet10 Synthesizer
SCI Prophet 10 Synthesizer
SCI Prophet 10 Synthesizer
power supply and some processors..
SCI Prophet 10 board
double boards with CEMs
SCI Prophet 10 board
SCI T8the top model
in fact they all said: hey, Dave you want poly pressure on the new (yes!) midi standard just for this synth! (no other synth exept the cs80 had poly pressure “Aftertouch” that time)

it is mainly a velocity equipped dual prophet 5. no more , no less. to my ears it is a bit thinner than a p10 or p5 but more expressive (velocity and pressure)

SCI T8 Synth
SCI T8 Synthesizer
SCI Programmerthis is basically for keeping parameters in memory, it is not made for a special synth, imagine your modular or any analog synth have some RAM to save your sound.. this is the one to do it.. strange, that there are not many of new programmers out there for newer modulars.. SCI Programmer
the SCI poly sequencer .. store your data to cassette recorder! ;)and the c64 interface. SCI poly sequencer
dave smith. head of SCI now makes the evolver under another name
has the prophet VS waves, lots of LFOs and ENVS, analogue filter, distortion, and (!!) a tunables trackable delay loop with feedback, so you can do noise “robotic” and karplus-strong like sounds.. also internal 16step sequencer..

more about evolver here

kleiner deutscher impressions-bericht zum evolver..

a keyboard EVOLVER with knobs 5oct. ist ready for NAMM 2005

all EVOLVERs use Curtis Chips which seem to be produced for Dave..!

Want to see the Evolver Keyboard Board?
find pics here:

thanks for board pics to Bluescreen/St.Trippler

more – go here: (DaveSmithInstruments)

some audio (my amazona review): it CAN sound soft, too (unlike the opinion of some..)

evo#02.mp3 (glitch warp sounds)

evo#05.mp3 (harder..)


strange dark pad


PEK (poly evolver keyboard)
DSI Evolver Keyboard Synthesizer

DSI evolver
there is also the 1U rack with 4 evolvers inside “poly evolver” to show up in 2004. it is controlled by … an evolver! yes! you need to use one to edit the rack or software, very BIG sound!.. so this is the 4 voice polyphonic EVOLVER!
polyvolver = Poly Evolver
monophonic keyboard MEK: (pic thx to docT /



a nice 8bit (!) sample playing drum machine.

it’s one of those that can be burned by the Oberheim Prommer

can be clocked and has midi (SCI were the first ones introducing midi those times..)24dB/oct. filters on board, 11 sounds, 6 voice polyphony.

listen to it:

SCI drumtraks - drummachine
SCI drumtraks - drummachine
thx viewermail studio for pic!
the DRUMTRAKS interna..

listen to it:

SCI drumtraks intern - drummachine
SCI drumtraks - drummachine intern
thx viewermail studio for pic!
DRUMTRAKS brochure.. (click the pics to see them enlarged..) SCI drumtraks - drummachine_SCI drumtraks - drummachine
_SCI drumtraks - drummachine
thx viewermail studio for pic!
upper pic – below: Studio 440, a 12bit with 512KB ram for own samples.. quite normal 1986..

Sequential TOM
fixed samples but can be played backwards and pitched, 1985 this added a lot to variety..

sequential studio 440
sequential circuits tom

one of the first mono mode midi synthesizers.
6 voices. and a very simple sequencer.

todays view: you can switch it to double mode and tune up the LFO for nice FM filtering..

it’s only one VCO per voice, thats why it’s better to go to dual mode.. stable but you need a nice info about the progging stuff (midi and stuff is progged by those numbers on the right side!.. the parameters are printed on the case.. but the midi stuff isn’t..)-eg: double mode is track rec & select 2

-midi clock input: speed full left

-prog change enable/disable: ctrl rec.+1

-local on: track rec.+7
-local off: track rec+8

-wheel/param.change: ctrl rec.+4

-dump to midi:ctrl rec+2
-dump all 100: ctrl rec+9

dump seq: ctrl rec+0

midi modes:
omni on: track rec+1
poly on: track rec+3
mono on:track r.+4
good to know, huh?

Sequential Circuits SIXTRAK
SCI sixtrak synthesizer
click to enlarge.. sixtrak
+ to read parameter list!

SCI sixtrak synthesizer
sixtrak: nice, but check if the buttons still work (number keys!)
SCI sixtrak synthesizer
specs see below.. quite like the multitrak..
SIXTRAK brochure..nice fast LFO btw.. sixtrak synthesizer_sixtrak synthesizer

sixtrak synthesizer

click the SIXTRAK pics to enlarge! sixtrak synthesizer_sixtrak synthesizer
6 voice synthesizer

the sequential TOM and MAX were also part of a “system”. the Commodore C64 as a sequencer was used at that time!

the max is more like an “expander” and it can beedited via software (c64: the SCI 920 software will do it.. or sounddiver from emagic today!) it’s (beside no real editing) the same as a sixtrak.

the 4time polyphinc TOM was a more advanced drumtraks (well, it also looks like a more coloured drumtraks,too) ;)
why? more parameters! (tuning per instrument)

the later (1986) studio 440 was the top model and sequencer and was more like the mpc60 then just a “drum machine”.. 12bit sampling (44.1khz max.) and filter (no reso)! max memory: 512KB RAM. 8 voices. and “swing”.

also pic from “fairlight”: viewermail studios
, so far.. also “for the home user”-mono mode synth..
SCI multitrak synthesizer
also 1 VCO (pwm,sqr,tri,saw,noise) per voice but also mono midi mode, so it was quite sophisticated for 1985! other synthesizers used to offer poly mode only.
2 ADSR envs for VCF and VCA
SCI multitrak SCI tom SCI max
SCI multitrak synthesizer
sci max synth
Split Eight lso midi brought to us this synth, quite like the max, sixtrak etc.

8 voices in here..

SCI split eight
Prophet VS

chips inside the P5 and all other models are listed herethis is THEEE SCI machine.. using vector synthesis (4 DCOs that can be controlled by env or/and joystick – advanced in the korg wavestation) has real analogue filters with resonance (unfortunately the wavestation had no resonance parameter at all)

the ENVs could be looped and the user had the chance to make some spectra (additive!) for use as one of the DCOs..
yes, this is a hybrid synth.. the evolver (above) has the same waves and hybridness, but is far more extended..

there is a rack and key version available.

SCI Prophet VS Vector Synthesizer
Prophet VS (and prelude preset synth under the table)
click to enlarge..
SCI prophet VS
SCI Prophet VS Vector Synthesizer

SCI Prophet VS Vector Synthesizer

Dave Smith and other things..the prophet 3000 sampler with remote display / control .. on top of the rack: the prophet3000 itself is in the rack on the bottom
analog filtered like on the prophet 2002 (topmost)

the strange rack stuff is the SCI FX systems which had CEM 3360 for phasing , delay etc.

not too many made… less then 10.

anyway, SCI started the prophet 3000 sampler series and soon went into bankrupcy..

SCI prophet3000 and FX rack
click pic to enlarge prophet 3000, prophet 2002 and FX

Dave was involved in the Korg Wavestation (see Korg Section) Project and some even more exiting projects, but in fact the wavestation was the final buyble “product to buy”..

Dave Smith started SEER SYSTEMS and did the “REALITY” software synthesizer. I did not sell well and was Win only.. Dave went back to hardware and presented the Evolver and Polyevelver after that.

SCI SCI Synth overview / überblick..

Comments are closed.