My clone-ish 100M panels were from Schaeffer using their UV print process. Not as good as screen printing but still really good.
Shame about the “env 1 out” on the second envelope out, could’ve been worse though. Would have liked to have it in grey but couldn’t see that as an option, so strangely it looks a bit 700-ish. And pretty much as big, which I realised later, wasn’t really the point of the 100M.
Oh well – it’s built now, and it’s bloody massive.
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
That’s too much excitement for now, I’m going for a lie down.
Out of all the various dodgy looking stripboards in my 100M clone, this one turned out the best (let’s just not mention the LFOs, they were a pain in the arse).
Determined to get it going first time, I made sure I’d done all the cuts, checked for shorts between tracks, powered up the board without ICs – was generally super careful, and then only later found that I’d missed out a couple of capacitors. Silly.
I made a daft mistake with the hold in the sample and hold. It worked, but the held voltage was drifting downwards rather quickly. Compared it to my System 700 board and realised my mistake – I’d used a 2.2nF (222) capacitor rather than the specified 22nF (223).
(Actually I was tempted to use System 700 boards rather than faffing with stripboard, but they’re so lazily massive that they didn’t fit in the panel space I’d designed).
I compared the white noise to the pink, and the white noise just sounded really quiet. Which is weird because it’s coming out of the same place, it’s just being filtered differently. Here’s the relevant bit of the schematic.
I compared the outputs on the oscilloscope – didn’t take a photo, but the white noise was chopped off at 0V, whilst the pink danced around both sides of the ground point as you’d expect.
Anyway, it’s pretty obvious from looking at the schematic that the R31 (attached to the transistor output buffer, Q4) should be connected to -15V, and the track layout bears that out.
The ring mod is based on the LM1496 like the rest of the Rolands, and you’ve probably got three of those already, but anyway.
Here’s a tiny demo of clanking and white noise twiddling. The ring mod was in better calibration when I put it together, it’s bleeding a bit from one side at the moment.
There would be a demo of the sample and hold, but I’m presuming the lag pot has disconnected itself behind the panel, as it’s verrrrrrry smoooothed ouuut, barely even recognisable as a sample and hold right now.
Here’s the layout, and wonky BOM.
It includes the indicator for the clock out, which has separate ground and +V power supply connections, presumably in an attempt to keep the audio path clear of any clicks from switching the LEDs. On the original (and on mine) this is powered by 22V, but it should work off 15V.