System 100 patch sheet

System 100 patch sheet detail

So, er, to cut a not-particularly long story short, I bought a System 100 102 expander a while back. It came with a 104 sequencer for an only-slightly-outrageous price, so I decided to have it. After all that faffing with trying to clone one, as well.

I’ve had fun playing with it in the little time I’ve had, there’s been lots going on this year.

It seems like there aren’t any going spare on the internet so I’ve drawn up a patch sheet for the 101 and 102, here it is:


While we’re at it I’ve been peering at the “Being Boiled” patch sheets that Martyn Ware flashed up in various YouTube videos, here’s my attempt:

Being Boiled, ish

…and this is what it sounds like, with extra dicking around. Don’t get your hopes up.

…yeah, I know it doesn’t really sound much like the original record, but that’s what was written down, as far as I can tell.

I can’t think that over thirty years of aging components would have that much of a difference, so I suspect there was something else going on in the mix, maybe Ian Craig Marsh’s second 102 was involved.

Who cares anyway, it taught me that the CV timing input on the 104 sequencer is a fun thing to be used.

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DIY stripboard Roland System 100 ADSR envelope

System 100 ADSR front panel

The original envelope on the System-100 keyboard wasn’t really one of my favourite things about it. There’s precious little resolution on the decay slider for tuning in those tight bonky basslines, so I tend to end up moving the slider by infinitesimally smaller amounts to try and get the sound I want.

I should point out that it’s a different circuit to the possibly legendary System 100m ADSR envelope (“the snappiest adsr eg of the world…”). For once the hype is deserved, my stripboard 100m 140 clone felt super-snappy, with satisfying control ranges.

System 100 ADSR schematic

Let’s build the System-100 version anyway, maybe we can use different potentiometers or swap the timing capacitor size for something a bit smaller.

The rare-ish programmable unijunction transistor N13T1 was swapped for a 2N6027, although it has since been possible to get hold of the originals on eBay. The 700 LFO worked better with the N13T1, so that might be case here. I used 2SA733 and 2SC945 transistors as per the schematic, albeit the -GR variant rather than -Q, with 1N4148 diodes standing in for the 1S2473s that are splattered throughout.

System 100 ADSR stripboard

The original never quite fully opened the VCF so I’ve added a single opamp to optionally boost the level from 6v to 10v.

Here’s a video of the envelope in action – I left the text on there to keep the camera from trying to going apeshit trying to autofocus on the trace. Not being a storage oscilloscope makes it trickier to track slow moving signals but you get the idea.

In this test I’m using a 3.3uF tantalum for the timing capacitor as standard but smaller pots than the original: 500k for the attack, 100k for the decay (which is too small, really), and 500k for the release, all audio taper. At about 0:43 the sustain pot is turned to 100% which causes the voltage to ramp up slightly rather than staying level. I’ve not looked very hard into fixing this – I’ve just been turning it up to just below maximum.

Here’s the layout and the DIY LC file (without the 6v to 10v boost) should you feel in the mood to torture yourself with some stripboarding.

Roland System 100 ADSR envelope stripboard layout

Having been through all that, if you want tight and snappy then the 100m envelope is probably a better bet.

Due to other things (work, house move, more work…) the System 700 envelope PCBs I made have been left untouched in a box since March, I’m looking forward to getting those going and comparing them to the System 100 and 100m… eventually.

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DIY stripboard Roland System 100 VCA

System 100 VCA Panel

Continuing my suddenly obsessive System 100 stripboarding with a boring bit, the voltage controlled amplifier.

System 100 102 VCA schematic

I wasn’t expecting this to be amazing sounding, being not much more than a CA3080, but I thought it was worth a go as I’m trying to replicate the original as far as I can.

Here’s the original VCA, with the blue marking on the 3080 presumably to show that it has been selected for low CV feed-through. I’ve seen circuits for matching OTAs, but I’m not clear how best to select for low CV bleed. Maybe it’s just a case of trying a bunch of 3080s to see which is the least clicky.

System 100 VCA circuitboard

I wanted to keep the mix input from the 102, so I built the thing around Q337. Also not having a TA7136 SIP opamp to hand,  I just subbed in the usual (non-inverting) TL072-based CGS DC mixer on the end, which was a mistake.

As I understand it now, the System 100 VCF inverts the signal from the VCO, and the VCA inverts it again, so it’s all back the right way up. As it stands, my layout inverts it twice, so input to the VCF eventually ends up inverted.

Incidentally I can’t imagine the TA7136 will make much difference, but now I’ve just had some arrive in the post, I’ll build a version with it.

To give an idea of my general confusion, I spent an evening wondering why the output from the VCF was crazily offset by a number of volts, before realising that this would be sorted out by the capacitor C324, which is on the VCA board. Just because it seems all nice and modularised doesn’t mean that it is.

Here’s a demo with the envelope on the System 100 101 keyboard modulating the VCA cutoff.

It gets clicky like my SH-5 with the envelope on a short release and the filter cutoff low, it might be that I need to find a better 3080.

One mod that might be interesting is to boost the input to the VCA from the VCF to see how it overdrives. Maybe messing with R378 on the input to the CA3080 might do the trick.

Here’s a stripboard layout for the inverting version using a TL071, any corrections or improvements joyfully received in the comments below, taaaa.

Roland System 100 VCA stripboard layout

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