I built 3 different VCOs since I started performing on stage with my DIY modular synth. These VCOs were inspired by Look Mum No Computer design who had CEM3340 on their core.
Each one has the same issues : it was very difficult to tune it and the tuning itself could change during a show.
Even if I am not a big fan of perfect tuning, it makes me think of solutions to get the perfect VCO which was always in tune.
I spent a lot of time working with Daisy Seed and when I discovered they released the Patch SM which is basically a Daisy seed with all the CV part prebuilt I couldn't wait : this is my solution for the perfect in-tune VCO.
So let's make it clear : this is a pure digital VCO, no analog here. And it's okay. It does not sound as cool as the CEM3340, but for my use, live on stage, without the stress of detune, I think it's lovely.
As a developer, it is even more easy to add some features : hard sync controls, smooth waveform change, different tuning between the two oscillators.
Each one has the same issues : it was very difficult to tune it and the tuning itself could change during a show.
Even if I am not a big fan of perfect tuning, it makes me think of solutions to get the perfect VCO which was always in tune.
I spent a lot of time working with Daisy Seed and when I discovered they released the Patch SM which is basically a Daisy seed with all the CV part prebuilt I couldn't wait : this is my solution for the perfect in-tune VCO.
So let's make it clear : this is a pure digital VCO, no analog here. And it's okay. It does not sound as cool as the CEM3340, but for my use, live on stage, without the stress of detune, I think it's lovely.
As a developer, it is even more easy to add some features : hard sync controls, smooth waveform change, different tuning between the two oscillators.
Component List
1× Daisy Patch SM7× 10kΩ potentiometer
2× 100kΩ potentiometer
1× 1kΩ resistor
1× LED
5× Jack socket
1× SPDT Switch
2× 10µF capacitor
This VCO contains 2 oscillators, each with its own output.
The second oscillator can have a different tuning, from -1 octave to +1 octave, with some detune.
There's a hard sync control which can affect the first or the second oscillator.
I also add a kind of "chord mode", it uses 4 oscillators instead of 2, and tune them with some detune, or with +3, +4 or +5 semitones.
As you can see, on electronic side, it's quite easy to do. Daisy patch SM does already all the job. That's why it's very handy for a developer like myself.
The second oscillator can have a different tuning, from -1 octave to +1 octave, with some detune.
There's a hard sync control which can affect the first or the second oscillator.
I also add a kind of "chord mode", it uses 4 oscillators instead of 2, and tune them with some detune, or with +3, +4 or +5 semitones.
As you can see, on electronic side, it's quite easy to do. Daisy patch SM does already all the job. That's why it's very handy for a developer like myself.
But there is one tricky thing, and it's called calibration. Even if it's digital, it's based on analog input. And they can't be perfect. I had to put some offsets on CV input to get a perfect 0 when there's no signal. I must admit at 5V, the result is also not what's expected, but it's OK.
You will have to tweak the code, maybe, to get something that's in tune. Check the github project, I explained it a little bit.
I recently spent more time on CEM3340 and I figured out how to optimize and stabilize my analog VCO ! So I might write an article about it someday !
You will have to tweak the code, maybe, to get something that's in tune. Check the github project, I explained it a little bit.
I recently spent more time on CEM3340 and I figured out how to optimize and stabilize my analog VCO ! So I might write an article about it someday !