The Hitchhiker's Synth to the Galaxy

Meet Deep Thought, an Oakley Based Analog Modular currently up for auction. Title link takes you to the shots. More on the synth pulled from the auction below. Via this post on VSE.



"I designed and built this Synthesiser myself, with Oakley Sound System modules and a lot of ear-bending with Tony Allgood (Oakley).

It has taken me an absolute age to build, and the Schaffer Front panel cost me 450 Euros alone. I also designed that. The patch panel uses the same principle as the Synthi AKS patch bay, in that voltages are summed on the rows, with patch pins having resistors in, with summing amplifiers on each row. This means that (say) the outputs of two LFOs can effectively be mixed on the bay and output to one of the pre-routed destinations. The Synth, which I called DEEP THOUGHT, (after Hitch hikers Guide to the Galaxy and took nearly as long to build as finding the ultimate answer- Oh and I was 42 when I started this thing!), was designed to have a fixed internal routing, but I got frustrated by those limitations, so I built a jack-panel into DEEP THOUGHT's top, where the internal routing came out to. This means it is not hard wired on the inside anymore, so you have to route it on the top for the synth to work. This gives much greater flexibility. I think I should have kept the internal hard-wiring and used the jacks as by-pass switches, but anyone with any savvy can do that.

Every module works. I have used screened cable for audio inside too. The power supply is well beefy enough to power the synth without it breaking into a sweat. In fact the supply is bolted to a huge piece of car-panel sheet metal, so you can have DEEP THOUGHT on all day, and it barely gets warm.

The synth is basically configured as a Stereo Pair of twin VCO/ twin LFO synths, but since the wiring is now so open, it can be whatever you like, within the limits of the wiring.

Each of the VCOs (4 of them) are Moog style Oscillators, with Oakleys proprietary tuning stability. Terrifically stable, and you don't need them to warm up for hours before they are useable. Really powerful sound, especially in unison! Wow. The pulse width is continuously variable and I have used a dedicated LFO for each pulse width modulation on each oscillator, which gives this synth a total of 8 LFOs. the PWM LFOs do not output to the patch-panel, though, since they are dedicated. The waveforms are Pulse, Saw, Triangle and Sine.

The two filters on the synth are a juicy Moog style ladder filter (left) and a precise State Variable filter (right). Control voltages for each are accessible from the patch-panel.

The patch panel has an led on each row output to indicate the activity on that row, and it's a great way of keeping tabs on what is going on in a complex patch-and the patches can get preettty complex!

The sample-hold clock is controlled from the patch-panel, as is its' sample signal. The output of it comes back to patch panel, and can be routed to, say, filters cvs etc

There are two PHASERS, one for each output, if you configure the synth in STEREO mode, of you can stack them or put them in serial. They have varible Q and a built in LFO for sweeping, as indicated by a cute bi-colour LED. DEEP THOUGHT is scattered with bi-colour LEDs, actually, and it's great in the dark (but get the patch done first!)

There are four VCA/EG combinations at the bottom of the synth. Two are hard-wired to the outputs, the other two are accessible from the patch panel. Each filter has its' own ADSR type envelope, hard wired internally, and dedicated to each filter.

The midi interface is configured for channel one, and also has the master tune facility, so once your VCOs are where you want them, you can just shift all four to match your others synths, and they keep there relative pitch tracking perfectly. There is also a cool retrigger/glide function.

The Noise unit features White and pink noise and an exceptionally useful INFRA RED output, which is a very low frequency random CV which outputs separately to the patch-panel.

If you use a Sequencer like Logic, you can control DEEP THOUGHT (via the midi interface) by use of HYPERDRAW in LOGIC so you can use modulation sweeps, velocity contours, and CC102, which can be assigned by you in LOGIC (or CUBASE, I'm sure) for any use. In fact, since the outputs of each of those HYPERDRAW curves manifest themselves as variable control voltages at the patch panel, you can assign them to whatever you like! Programmable filter sweeps are the obvious 1st choice!

The patch-pins are new genuine EMS ones, with a few non-resistance pins-just shorting type.

All the boards were built from the ground up by me, using quality components from RS and Rapid. It has cost me thousands of pounds and too many hours to count.

There's such a lot of meat on this synth that it's almost impossible to be sure I've remembered to mention everything, but anyone seriously intending to buy it, will know from the pictures just what it can do. Any (sensible) questions I will attempt to answer.

Mechanically, the big steel backplate just screws off, and it and the power supply just unplugs from the internal wiring (via coded suitable sturdy plugs), so the internal wiring is easily accessible for maintanance or modification.

So, to the niggles-:

1) I didn't wire the LEDs so they all shine red for positive voltages! So they vary from RED to GREEN, on positive (or negative) voltages and a couple of the patch LEDs glow with nothing plugged into the row, (which is the earthing issue I spoke of elsewhere), but those rows DO sum correctly anyway, and the LEDS do reflect what's on those rows when plugged into, so it isn't a serious issue.

2) The bypass switch on the right hand PHASER is wired wrong and doesn't bypass, and I just don't have the time to sort it. Should be a brainless fix, though.

3) The patch-panel had to be mounted so that the end collumn (EXTERNAL OUT) is shorted and doesn't work. This could easily be sorted by finding a different mounting for the patch-panel on the Schaffer panel. The patch-panel on that collumn works in itself-it's just the mounting screw! However, there is a spare socket on the top which could be wired for EXTERNAL OUT if you want.

4) a couple of pots are starting to sound a bit scratchy and could do with spraying, but still perfectly functional.

5) This thing is HEAVEY, 25Kg. The steel backplate is the big culprit, but those lovely FRENCH POLISHED (by me!) side cheeks are REAL solid HARDWOOD MAHOGANY!! So THEY weigh too. "