Programmable 16 stage phaser

Several months ago I built the MFOS 8 stage phaser and expanded it by 8 stages to 16, available in 4, 8, 12 or 16 stages. I didn’t really pay much attention to it and other things got in the way.

A few days ago I was running the strings from my Crumar Trilogy through it and I considered building it into the Trilogy by using the 8 front panel buttons as the locations for pots and buttons etc as I don’t really need them as I can select all my programs through the encoder.

So I got to work on conversion of the phaser to be CV controlled, I decided to replace the LFO section completely and replace it with a Taplfo3 which is easily controlled with 0-5v CVs for speed, depth, wave, multiplier, level etc. And then I added a VCA to control feedback and finally an 8 way mux to select the 4 output stages.

I then thought that this is a lot of hassle to add to the Trilogy, just the hardware alone was off-putting. So I decided to go with a standalone rack unit, but I though I can make this programmable too. After trying 3 different processors I settled on this Teensy 2++ as it had more memory than the Teensy 2 that I started with and I didn’t want to waste a T3.6 on such a small programmer. Of course it has no SD card or DAC outputs so I added these too and now I have a working programmer to add to the phaser board.

128 memories
Full midi control by CC and program changes
External or MIDI clock options


This is where I got upto by this evening, nearly all the hardware completed.


Built a new power supply and added and extra inverter to the feedback stage, that seems to have improved the sound quality, here is a demo with sample and hold for the lfo wave and then a triangular sweep.


Managed to box it up today, not too bad but needs a bezel for the display printed.