Crowminius DIY MINIMOOG Synth Build

This is a very faithful reproduction of the Classic Model D Moog Minimoog from the 1970's

This build was only possible due to the excellent work by The Old Crow. His PCB made it possible, as I would not have had the ability to duplicate the Mini's circuitry otherwise.

It's a 3 OScillator mono synth with full filter control, CV gate and MIDI

It has a build in sequencer and 2x18 display. Quick demo of the type of sound possible

 

PANELS and COSMETICS

I got the panel made for me in Argentina by sintetizadores, he's got a shop online. It's a basic model D panel, but very well made. I then used a panel design program to build the other panels. I really should have just manufactured one panel rather than two but I forgot about a couple of extra switches, that were included in the Crowminius design, and wanted to include them. The new panels were a different finish than the matt power coat of the Model D panel, but it looks not too bad. I made a thin stainless steel under frame to hold all the pots in place rather than mount them to the panel directly. There's build pictures on the Crowminius thread in Muffwiggler. Also some on my website at mind burner dot co dot uk. A 19 inch qtr inch rack panel was used to hold the input and output sockets at the rear of the synth. I added the sequencer after I had the panels down, hence the sequencer controls being placed in a space blank space on the original Model D panel. Fitting the rocker switches was a right pain in the arse. They are new version of the old Moog type switch which are almost impossible to get hold of in any quantity. The new ones are smaller than the panel holes. I mounted them in the sub plate and drilled holes on this plate rather than the top panel. I filled in the gap with matt paint and some black fabric. This was a labour of love but worked ok. I built the case from some old mexican pine I had lying around. I used a table saw with a very fine blade to cut the wood to give a good finish. It's a little tight to be honest, so if you make one, make it a little bigger to allow for cables etc. It was my first cabinet build and came out pretty good, but not as good as say a joiner would make. The wood was treated with a nice light wood oil.

ELECTRONICS

This was a standard Crowminius board with through hole components. All were ordered from Mouser and Digikey. I used some bits and pieces from my spares box. Knobs from Thonk and others. I used multicore cable to attach the various pots and switches. The Power supply is a 18v (IIRC) torodial transformer, fused at the rear of the synth. I place the resistors first, then diodes, then capacitors I think.

ISSUES

Well I had one resistor which was actually the wrong one sent from Digikey which cause no end of hassle, with distortion. I ended up having to manually check all the resistors on board. I also had a weird problem getting OSC1 to tune up. This seems to be due to a bad op amp which checked out when tested but was an issue when installed on the Crowminius. My advice is to check the resistor codes as you install them, just to be sure. Make sure a 1k is not a 10k for example. Sounds obvious but can be a bitch to spot later on. Socket all IC's it's much easier to remove them if you have to. Use quality shielded cable for the pots etc and especially audio routes. Use decent multi turn trimmers from Bournes etc, makes life much easier when tuning up.

MODS

The only real mod was a sequencer module added, which does give added functionality. Its from midigals and is just inline with the MIDI flow. Rather than use the LCD for the Crowminius display, I used it for he midigals. I also did the old Jan Hammer trick of sending the audio out to the external audio input, can give some nice distortion.

 

some build pictures

interior

main panel and sub panel

 

SMD temp resistor

rats nest