FV-1 effects processor added to the Crumar Trilogy

The Trilogy sound was always a bit flat and needs effects to enhance it. So I added an FV-1 effects board with 16 core effects that can be programmed with the Trilogy controls and recalled for each patch. All 3 sections can be sent individually to the effects processor or bypassed.


Apart from adding hardware to achieve this, I take it you must have adapted the original software of the Crumar. Can you explain a bit how you got hold of it and went about making those changes?

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Yeah, it was my first idea for an Arduino/Teensy project, I owned a Trilogy from new back in the day and was severely disappointed by it’s lack of programming abilities. 7 pots and two switches could be saved in 7 presets with number 1 being the front panel.

Fast forward to about 5 years ago I picked up a cheap Trilogy and made plans to replace the programmer board with a Teensy based mux/demux, only problem was I didn’t know how. Took me a while to figure out how to create a demux and I set about building a board that could replace the existing 7 controls and the two switches, once working I expanded it to cover the oscillator buttons, LFO section and glide. This meant replacing some parts of the synth such as the LFO with more CV friendly designs such as electric druid Taplfo3 etc. All controls were read in by the mux. Then I did the organ section and volume controls, added VCAs and read the pots in again. Finally I tackled the string section with more VCAs etc. So the whole synth was made programmable, but I didn’t know about shift registers at the time so outputs were all demux and level converters which was quite messy, recently I added two shift registers to free up 8 demux outputs and add an extra 8 switched outputs. Once this was done I could add and control the FV-1 board. Sorry for the long explanation.


Oh no, I really like them and so do others I think.

Since you “only” adapted the controls, you managed to keep the original sound of the Crumar unchanged?

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That was the plan, keep the sound as unchanged as possible, easy enough on the synth and organ sections, strings was more tricky as it had a botch job of a filter on a pot which didn’t match the schematics, but I think I pulled it off. It sounds the same as pre modifications.


Nice one!

Any chance you could upload some sound bites?

There is one on my YouTube channel, obviously not with the effects, but I will add some more soon. It’s not impressive playing wise but it shows the fact that the LFO and glide can be programmed per patch whereas as previously they were static and affected every preset the same way. I have a lot more patches for it now including some mixes of each section etc.


So I’ve spent the day messing with the eeprom used to store FX for the FV-1 and found two banks of ensembles and rotary effects etc. but because they are hex files I cannot load them into the SpinCad designer software to create a custom eeprom.

I found a bit of code on GitHub that reads the eeprom and spits out 8 progmem banks, I can then take the effects I want out of these banks and build one complete bank of effects I like and construct a new eeprom with these effects in.

Works like a charm.


Trilogy effects board improvements, since fitting the effects board to the Trilogy I have been searching for some nice rotary or Leslie type effects, I have 3 loaded into the eeprom and the speed is controlled by pot3 to the FV-1, as I had no way of speeding up and slowing down the effects I thought why not add a foot switch option to the Teensy board and increase or decrease the CV to pot3 accordingly on a press of the pedal. I’m pretty pleased with the results, it will remember your speed settings if slow or fast and return to them on each press of the pedal, just need a pedal now.

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