Home made analogue mono-synth from R.A.Penfold Book

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"Here for sale is a home made analogue mono-synth constructed from a book by R.A.Penfold called "Electronic Synthesiser Construction"... Link to the book is here [on Amazon]

The synthesiser was built by me in the early nineties and then forgotten about in a cupboard for many years, now during a studio clear out it's resurfaced and I thought it should get some use somewhere else in the world! :-)

The synth concept follows the classic layout of a single VCO with Square / Tri / Pulse waveforms, Mixer, multimode resonant 12db/oct VCF and finally VCA. There is also an LFO and ENV generator for modulation of the VCO, VCF and VCA..

The connections round the back are CV, Gate In, Audio In (routed to mixer and then on to the VCF) and the main Audio Out - all are on 1/4inch jack sockets.

It sounded great back in the day but now it has some faults so I'm listing it as For Parts Or Not Working.
I've tested it and established the following issues.
LFO is not working,
VCO tuning is prone to wander around,
Mutimode VCF seems to sometimes function as a lowpass and then wanders into bandpass mode,
VCF resonance control is dodgy.
VCF is easily over-driven by the levels in the mixer - perhaps this VCF behaviour is not exactly a fault but I thought it was a tad harsh but maybe that's just me..."

Update:

penfold1

YouTube Published on May 6, 2012 by monkeyb0y999

Home made analogue mono-synth from the R.A.Penfold book "Electronic Synthesiser Construction". Vid2

YouTube Published on May 6, 2012 by monkeyb0y999

"Demo of a home-brew synth I built in the nineties from the excellent R.A.Penfold book "Electronic Synthesiser Construction".

It's a single VCO affair with an OTA based 12db/oct state variable VCF.
The sequence is from a x0xb0x controlling the synth over CV/Gate.
I'm selling it on eBay and the video has been posted to highlight a number of faults the synth has like the fact the LFO no longer functions, the tuning wanders and some of the controls are a bit flaky. Will prob leave it up on youTube after the auction for historical interest."