This repository will hold my analog voice modules.
The plan is to design and build a cheap analog (mainly subtractive) voice that can be built very cheaply or even ordered via the Chinese PCB Assembly services.
Please read below for the status of these designs. Some are works in progress and some are completed.
I made a 3d-printed case with a dc-dc converter (£7.50) to test them:
8hp.
3340-based oscillator with hard and soft sync, linear and exponential fm (with fm cv attenuverter), pulse width (knob and cv with attenuator). Reverse polarity protection. Uses an as3340 chip.
The 3340 soft sync only works on a falling edge so a ramp waveform is ideal eg /| (and not |\ ). Hard sync works on rise and fall. The sync switch is an on-off-on switch (centre position turns off sync) The 3340 fm knob is an attenuverter. The fm switch selects between exp fm (dc coupled) and lin fm (ac coupled). It's an on-off-on switch so the centre position turns off fm (handy for wiggling). The lin fm is ideal for audio rate modulation. The 3340 pwm input takes 0-5v for min to max effect. The pwm pot is an attenuator, pwm is added to the pw pot. The outputs of the 3340 are all normalised to just below 10v p-p, all outputs are bipolar. Calibration is as per the cem3340 datasheet. ie set v/oct scaling, then do the hi-osc adjustment if necessary. Mine tracks within one cent over 6 octaves.
4hp.
4-pole (24db/oct lpf) with fm cv attenuverter, can self oscillate. Reverse polarity protection. Uses an as3320 chip.
The fm knob is an attenuverter The 3320 has quite an aggressive resonance which kicks in at about 1/3 of the turn of the pot. You can easily adjust this by using different values for r25. One technique to find what you like could be to wire a 100k pot to the two pads, play with the module and set the resonance how you want, then desolder, read the resistance and solder a resistor of that value. You can refer to the resonance curve in the datasheet as well to see the response curve. I like it quite aggressive and have chosen about a 50k (ie 49.9k) resistor to get full range of resonance. Calibration - turn resonance up to self-oscillation and adjust the tracking to get the best you can. It's not temperature corrected or perfect but is pretty reasonable. Before you calibrate, let it warm up for a few minutes ideally. It will track within 1 cent over two octaves.
4hp
NJM4556 based headphone amp. This is essentially the power section from the nwavguy o2 headphone amp. It has a very low output impedance (~1 ohm) so can drive even low impedance headphones. It can deliver a high power (utilising two sections of the njm4556 per channel) so can drive 600 ohm impedance headphones with no problem. There is a high pass filter on the input to block dc.
4hp
Buchla-esque lpg. Uses an analog switch ic to select between filter / lpg / vca so that a mechanicaly simple spdt on-off-on switch can be used instead of a 3pdt mechanical switch. Filter has added resonance control.
4hp
4-pole (24db/oct hpf) with fm cv attenuverter, can self oscillate. Reverse polarity protection. Uses an as3320 chip. Very similar to the lpf (above) with a simpler set of components around the 3320 but has similar features (apart from, obviously, being a high pass filter!)
4hp
Dual ASR (Attack/Sustain/Release) in 4hp. Gate A normalled to Gate B. Reverse polarity protection. Uses two as3310 chips.
4hp
Dual VCA in 4hp. (Derived from two sections of Mutable Instruments Veils). Can chain an unlimited number together to make a huge multi-channel VCA or VC-mixer. Uses a 2164 chip.
4hp
Wasp filter in 4hp.
4hp
a100m ADSR in 4hp.
4hp
ssi2144-based filter in 4hp with attenuverter on FM input.
SMT module tester module with four added precision voltage outputs (set with trimmers). Note: The above image shows the prototype panel! The one in the repository has the correct sized window.
4hp buffered mult (three sections from MI Links)
4hp triple S+H/noise
0603 version of Rob Hordijk's Benjolin (with kind permission from Rob)
Strictly for non-commercial use:
- matrix mixer - 14hp, 4x4, uni-/bipolar selectable per column (ie all pots in column are attenuators or attenuverters). Switch to select whether inputs are normalled to a precision voltage (either 5v or 10v, selectable with a jumper on the back of the module).
- vca (3360)
- vcadsr (3310)
- tzfm 3340 vco (currently being breadboarded)
- 2-sections of blinds in 4hp
- Wavefolder
- Distortion module
- envelope generator (dusg)
- quad adsr (3310)
- Either lfo or looping envelope generator (unsure which yet)
Licence: CC-BY-NC-SA 4.0, unless otherwise stated in the individual repositories
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