100 vs 100M (clone) VCA and VCO
Prompted by a comment on my System 100 VCA stripboard post, for as much use as it is here’s a very quick comparison of the original System 100 VCA and a clone System 100M VCA, built on stripboard with a BA662 clone for the OTA.
No envelope tweaking, just a bit of VCF variation from CV2 on the MC-4, and then full-gas into whichever VCA.
Here’s the stripboard clone 100M VCA, behold:
This is the (non-clone) System 100-only demo:
And this is the System 100 played through the clone 100M VCA (set on linear response), using the System 100 envelope as a CV source.
The System 100 has a lower output envelope than the 100M, so the 100M VCA is super-quiet when triggered from the 100 when set to exponential response. Flipping the VCA to linear gives you a usable audio level to play with.
The VCOs in my 100M clone are a couple of Curetronic boards, both using a heated CA3046 in place of the ua726. I’m not convinced the scaling is totally right on either VCO, so try and ignore that. Here’s a quick test of the VCO waveforms played through the System 100 VCF and VCA. You’ll hear:
- System 100 square, low VCF, mid res
- 100M square, low VCF, mid res
- System 100 sawtooth, low VCF, mid res
- 100M sawtooth, low VCF, mid res
- System 100 PWM’d square, open VCF
- 100M square, open VCF
- System 100 sawtooth, open VCF
- 100M sawtooth, open VCF
and if you can take it, here are some sweeps, 100 then 100m, in the order
- PWM square
- triangle wave
That’s too much excitement for now, I’m going for a lie down.