SynthGuy's Synthworld: Sequential Circuit's Forgotten Past...The Model 700 Programmer

Before they became world famous for creating the Prophet 5 synthesizer, Sequential Circuits built accessories for popular synths. An interesting and under-appreciated one is the Model 700 programmer. Designed to be hooked up to a Minimoog ( or other CV controlled synth) it's easy to see how this unit was the seed of the concept that eventually led to the creation of the P5.
Print ads from back in the 70's show the unit along with Sequential's other product at the time, the model 800 Digital Sequencer. Here's an early ad featuring no less than Undisputed Minimoog King Rick Wakeman, not too shabby of an endorsement for a fledgeling company that at this point appears to be based at yet another interim address in Silicon Valley, possibly one of Dave Smith's apartments.

Companies did a fair amount of wanderin' back in those days, it would seem.

These devices both offered an interesting alternative to what Oberheim was offering at the time. Oberheim had been building a digital/analog hybrid sequencer since 1974, and offered a rudimentary programmer as an addition to their four and eight voice polyphonic systems, but not as a stand alone device to control other synths.

The address for this ad shows yet another location for the early operations of the company before they settled into their main headquarters on North First Street in San Jose...

...After which, one assumes that they had a nice party to celebrate. The Digital Sequencer was apparently well-shielded against such real world hazards as cake frosting and delicious candies, while the Programmer appears somewhat less ready to deal with such tasty dangers.

The unit has 64 user definable presets to control various key aspects of the host synthesizer.
There are three quantized CVs that can control oscillator pitch, and two programmable envelope generators (including delay) that can control the filter and final VCA. Switches for each oscillator allowed the inclusion of an external CV source like a sequencer (perhaps the Model 800, eh?) and the filter envelope section included an offset control for initial filter tuning. Although there's no way to set various wave forms or mix or mute individual oscillators, this was still a big step forward for those Brave Souls grappling to successfully control a Minimoog or the like in the heat of a live performance.

Imagine the pressure...

"Tune Those Oscillators!"

"Trim That Filter!"

"Adjust Those Attack and Decay Times!"

"Flail Randomly at that Keyboard!"

"Dance, Monkey Boy, Dance!!!"

If you hold your head at the proper angle and squint your eyes at it just so you can sort of see some the control panel for the P5 lurking there, just under the surface.

I picked up my first Model 700 in Sacramento in the early 80's, where I found it sitting dusty and unloved in the corner of a store, for $75. I used it to give the Moog 55 some quick programmability, and got a fair amount of fun out of it over the years. It was easy to connect into the system in various ways since it was equipped with 1/4" jacks, and the programmable DADSR envelope generators were a nice addition, although the programmable steps (64 for each segment) were a little coarse. I couldn't resist customizing the preset selector switches with color coded ones, to match what I had done with my Prophet 5 (more on that in a future blog).

To get the maximum amount of control with a Minimoog required some modification of the instrument, and typically a multi pin connector was added to match the one provided on the back of the Model 700. This made connecting things quick and easy, but the hassle and expense to get this done probably discouraged some potential customers at the time (not to mention the units $1200 price tag).

Back then, for a few hundred dollars more, you could actually buy a Minimoog.

I remember reading that Howard Leese used one with Heart, and I can see him wailing on a Minimoog during "Magic Man" in my mind's eye as I look at this unit.

An interesting performance feature is a footswitch jack that lets you step through the presets, a great idea. There's a front panel knob that sets the number of steps (1-8) the unit will cycle through in a bank, so you could preprogram a manageable sized preset cluster to jump around through during a song if desired, without having to take your hands off the keys. It's Magic, Man!

Now, if you look at this feature set closely, it begins to look more and more familiar.

Hmmm....programmable voltages, switch steppable, selectable cycle length...

Hey, It's an (up to) 8 step sequencer!

Each step has 3 quantized pitch CVs, and two programmable envelope generators, as well as filter and VCA settings, making this this a pretty powerful sequencing tool. The footswitch input is even switch selectable to accept V or S triggers. What more could a young synthesist need?
Let the Sequencing begin! Yee-Haaa!

Well, in reality, the stock unit took a finite amount of time to update all the parameters when switched, which made running faster sequences tricky, as you could often hear the pitches slewing to reach the notes in time.

I got a schematic for the unit (mucho thanks again, Riley!) and noticed that the design was pretty straightforward...no microprocessors here! I found that by speeding up the system clock, I sped up the overall response time, which reduced the slewing effect at faster sequence speeds. I carefully adjusted the clock for the fastest performance possible without things going horribly awry during preset changes, and this boosted the usable sequencer speed considerably. Not as blazing fast as the Moog 960, but reasonably zippy nonetheless, and with the wealth of features available and some thought and planning, the sequences could be incredibly deep and detailed.

For those looking for even more control, a simple mod allows the internal Delay CVs to be routed to a set of jacks on the back, providing the user with two more programmable CVs per step. By using a normalled jack for this, the Delay function of the DADSR generators is available until you plug in a cable, which sets the delay to zero and makes the CV available for other nefarious purposes in your system. Push that pulse width? Bully a VCO? Totally programmable System Transposition per step?

Hey, WHY NOT?!!?

Besides, how often are ya gonna actually use that delay function, Chukko?

An interesting quirk of the unit is that the rotary selector switches have positions that are unused, and just labeled as OFF (maybe they got a good deal on the extra position switches). The step position selector was like this, so I decided to press these unused positions into service somehow.

After some tinkering around, I devised a circuit that could switch preset banks at the end of the 8 step sequence (much like using the sequential switch on the Moog 55) so now the unused rotary switch positions could be used to select a longer sequence by combining banks, making 16, 24, 32, up to full 64 step sequences possible.

Now this was starting to become a pretty formidable sequencing tool, as well as a super cool programmer.

Who knew?

There were two versions of this unit produced during its lifetime. My first unit was the later version, which had some improvements and used SSM voltage controlled envelope generator chips and VCAs to handle the programmable side of things.

Years later, I discovered that there was an earlier version, when I picked one up in a store in San Jose, also at a very reasonable price (thanks, Barney!). This one had engraved numbered preset selector buttons, and a discrete component envelope generator inside, probably predating the ready availability of the SSM chip.

As you can see, this is a pretty early example (SN15!!) almost certainly built in Dave Smith's apartment (you can almost see him at his kitchen table laboring deep into the night soldering the circuit boards by hand...) The board and component assembly looked much more, er, rustic with a more California handmade/organic quality to it.

The Waves sticker on the back is an interesting touch...I've never been able to find any info on them, but the thought of good Napa Valley wine and synthesizers is a very appealing combination. Any info out there, anyone?

This one I've left stock. Particularly interesting is the large number of CA3080 progammable OTA chips inside, being used as the many sample and hold cicuits and VCAs for the various CVs inside.

Dig all that OTA goodness, Bunkie!