
MOTM 300 VCO	CV Keyboard	Aries VCF	ADSR	VCA	LFO

MOTM 300 VCO

After looking and many available MOTM format VCOs as well as the MFOS VCO, we decided on the MOTM 300. It has all the features we were looking for, like sine, saw, ramp, and square on separate jacks, plus a reputation of being very accurate and reliable. We bought the PCB, front panel, and brackets from SynthCube.com. Other parts came from suppliers including Mouser, Digi-Key, Jameco, Small Bear, and eBay.

CV Keyboard

We really like the idea of an old-school analog synth, so we didn't want to use a MIDI to CV converter. We looked at a bunch of CV keyboards from PAIA, MFOS, and an interesting one from the old ETI magazine. I even have a set of schematics for the Oberheim Two-Voice, which I always wanted to try to build. And when researching, I ran into RichardC64s site, which just happens to have a modern update of the Oberheim 2-voice. I purchased a raw keyboard years ago that already has the scanning matrix diodes, so now we just need to build the rest of the circuit. We're going to go with the DAC0800 for the D/A, since it seems easier than matching resistors.

Aries VCF

This isn't really a SDIY, since I was given this filter by the good people at EML when I worked there while in college. But we are going to incorporate this into our modular synth.

ADSR

The ADSR we chose was the dual ADSR from Bareille. It has really cool lights for each step.

VCA

We want a VCA not just for the audio, but also for control voltages (i.e. run an LFO through a VCA to get a variable effect). The MFOS has been getting a lot of good reviews as well as the Thomas Henry from the 21 Century book.

LFO

Years ago I had a Korg MS-10 synth. I really liked the LFO on the MS-10 because it had a wave shape control for the triangle, so you could do ramp up, ramp down, or a triangle. It also had a square wave that you could change the pulse width on. It turns out that Oakley Sound makes a MOTM format version of this very LFO, only they put two in one module. This is the lfo we will use on our project.