My new project

[Haible_Juergen#Tel2743]

Hi!

I have finally started to design voices for my new project that will
be called JH-4 PolySynth.
For each voice, I will stack three PCBs on top of each other,
each one sized 15cm x 20cm (double euro).
The 1st board (top) will carry the potentiometers and switches,
board 2 and 3 will carry the analogue electronics. All three
boards will be connected by a ribbon cable. If I should decide
to make the whole thing storable, I will just disconnect board
1 from boards 2 and 3 and put the programming stuff in between.
But for now, I will only make it with manual controls, but every
single parameter will be voltage controlled. (Hey, that needs
lots of 3080's, more than the synth kernel itself ...)
Whole voice is intended to have the following controls:
(Potentiometers, if not mentioned otherwise)

for both VCOs in common:
======================

* Frequency
* Tune
* Sync Switch (1->2)
* Beat LED

for VCO 1:
========

* Pulse width
* Modulation Dest/Amount (FM-0-PWM)
* Modulation Source (LFO-VCO2 switch)

for VCO 2:
=========

* Intervall
* Detune
* Pulse Width
* Modulation Dest/Amount (FM-0-PWM)
* Modulation Source (LFO-ENV2 switch)

for VCF:
=======

* Frequency
* Resonance
* Mode (LP ... NF ... HP ... BP ... 4pole-LP
   with a single potentiometer)
* Envelope amount (negative-0-positive)
* Envelope select (ENV1-ENV2 switch)
* Modulation Source/Amount (VCO2-0-LFO)
* VCO1 input (saw-0-pulse)
* VCO2 input (saw-0-pulse)

for LFO:
=======

* Manual Rate
* Rate LED
* Rate Modulation (ENV1-0-extCV)
* Full / CV amount switch
* Local LFO / External LFO switch

for VCA:
=======

* ENV1-Drone-ENV2 switch
* Panorama Modulation amount (Local LFO)

for ENV1:
========

* Attack
* Decay
* Sustain
* Release

for ENV2:
========

* Attack
* Decay
* Sustain
* Release

for whole voice:
=============

* Assign On-Off switch
* Gate LED
* Program/Manual/Save
  (to be ready for storage, some time (;->) )

A few words to the LFO: I chose to make a Sine LFO only,
but with FM and AM.
There will be an Overall LFO, however, for all voices in common,
which wil have every waveform one could wish. This way, I can
add S/H and other weird stuff globally, but still have the Local
Sine LFO for panning etc. IMO, this is the best compromise
regarding parts count vs. flexibility.

Implementation:

* Lots of CA3080's for amount / mixing / crossfading VCA's and
   for the 2-pole filter
* SSM 2040 for the 4pole filter
* SSM2056's for the envelopes
* discrete VCO's

Well now you know why I bought all these SSM chips (8-)) !

Meanwhile, I have made the layout for the 2pole filter, filter
mixer and VCA.
I'll keep you informed about the progress of the project, if you like.

JH.