Wave-D : a WaveTable Synthesiser
Get ready for another Cease and Desist letter...
The Wave-D was a PPG-clone long before cloning instruments became fashionable.
I've been a fan of PPG's synths from the days of the near legendary PPG Wave Computer. I especially loved the chiming, dissonant metalallic sounds which seemed completely beyond the capabilities of the analogue synths of the day. In addition, it seemed like the PPG tone could cut through a mix like a diamond-encrusted chainsaw, which was exactly what I wanted in terms of sonic clarity.
Skip forward to around 1992. Still keen to harness the power of the PPG, I managed to knock together a crude DDS oscillator using a 6502 microprocessor running at 2 MHz into an eight-bit DAC. The oscillator was usable but did not exactly sound pretty, aliasing being a major problem. I think the algorithm topped out at around 32 kHz even with major optimisation. I added a 18dB Butterworth filter to the output which improved matters enormously but it was still a long way from a full-on PPG.
A year or so later, I discovered the sound processing capabilities of the Silicon Graphics workstations - effectively a Fairlight in a box - and I found myself hopelessly lost down that rabbit hole for a very long time. I eventually managed to program a sixteen voice, sixteen bit polyphonic synthesiser with a graphical front end built around a salvaged SGI Personal IRIS I bought, second or third hand, for £150. It was good but it wasn't a PPG and neither was it a Fairlight.
In 2001, I was introduced to the Modulus Electronics Monowave, which had that PPG sound in abundance, essentially because Modulus had cloned the Wave 2.2 wavetables. Whether Modulus had permission to do that was aways vague and uncertain but we'll let that pass, shall we? The Monowave also featured a 24 dB/Oct Low Pass Moog-style Ladder filter and it sounded massive. A real window-rattler. I quickly became a beta-tester for the project and helped develop the firmware on and off for a couple of years.
I can't remember exactly when, probably around 2008 or thereabouts, but I copied the contents of the Monowave's EEPROMs and burned them into an Atmel micro running at 16 MHz. I then wrote a couple of basic oscillator algorithms that would make a sound via a very crude sixteen-bit resistor-ladder DAC. The final signal was a bit rough but it very definitely had that characteristic PPG tone. A bit more tweaking followed and you could walk through the wavetables one by one or use the modulation wheel to change the timbre. To simplify editing, I added a second microprocessor and a front panel, and that really did hit the nail on the head. At last, I had my very own monophonic PPG Wave 2.2 clone and I was happy.
I soon realised that the microprocessor had enough power to implement a crude low pass filter, an addition which really made the instrument sound pretty sweet. Envelope generators came next and the end result was a crude but workable monophonic synthesiser. I christened it the Wave-D and wondered if it had any potential as a finished product.
Using the Processing programming language, I added a waveform editor and then greatly extended the number of waveforms available. These changes pushed the synth down one or two very interesting sidestreets, with capabilities that bordered on Synclavier territory.
We demo’d the Wave-D at Maker Faire 2014 in Newcastle and the unit generated a lot of interest, perhaps too much interest. We were soon contacted by a person very close to PPG and Waldorf, and he suggested that Waldforf might not take too kindly to someone ripping off their wavetables.
With that gentlest of hints in mind, I decided not to take the Wave-D design any further but the instrument (and the not-quite-a-cease-and-desist letter) remains a career high.
Update 18-Feb-25 : I found a method of recreating PPG-style wavetables using a Fourier Transform tool. I've added a few of these wavetables to our Echo and Plasma synthesisers, and they sound really sweet. Expect more of the same in future projects.