Anyone build a Maestro Ring Mod?

[vizcities]

I never find ring mods usable, but I came across a demo for one of these guys & was intrigued. Are there any stripboard layouts available? Fabbed PCBs? Did a search, but all I could find was GGG's etch template... not a dealbreaker by any means, but also not my first choice.

[Strategy]

The GGG one was one of my first builds (15-ish years ago) and it was very complicated, had help from an older friend with DIY knowledge, but it entailed assembling my own power supply on perf and lots of trouble shooting. At the time you could buy the PCB's from them I think. But, it has been really musically useful for me over many years. It sounds amazing, really very musical. It is the only version of the project that I'm aware of. I built it as kind of a desktop / keyboard-top module rather than as a switched pedal.
Strategy

[vizcities]

I had Haberdasher etch the GGG PCB a while ago & am finally embarking on this. Do you have a power supply layout and/or txer suggestion by any chance? The +/-15/+/-12 thing is a bit outside my usual building realm...

[jimilee]

Like this? Says unverified, so you'll be the first to verify it.

[matmosphere]

It's been on the bucket list for a long time, I've been hoping for somebody to design a good board for it. Ring mods are unwieldy at times, but they can also be amazing. I have a moogerfooger mf-102 and it's incredible as a ring mod, but jaw droopingly good as a tremolo. Best trem I've ever played by miles actually. I have often wondered if it and the Maestro share some DNA because the were both designed by Bob Moog.

[Strategy]

I'll see if I still have a schem for the power supply. If not, I'll post pics of my ring mod guts with values. My friend really thought it would be best with an internal transformer but mains power is dangerous stuff that I would not try myself and feel that an AC wall wart would have been fine going into this.
I'm trying to remember what stood out as pretty odd in this project (Toppopiccione, who had a cool DIY site that I think since went offline, was the originator of this GGG project IIRC.) It starts out as a regulated bipolar PSU like in synths, so it spits out a fairly conventional +/- 12V (IIRC) but then there are additional taps out for a less commonly seen psu voltage that goes elsewhere in the circuit maybe +/-10V? Sorry it has been so long since I worked on this I can barely remember and can't guarantee my accuracy here. Also can't guarantee I still have files! will dig up whatever I can, this is really a cool sounding machine that plumbs back to the origins and basic building blocks of synthesis and Tom Oberheim circuit designs. It's stayed obscure in DIY becuase of the learning curve but deserves more airtime IMO. 
Strategy

[Strategy]

PS @ matmosphere if I'm not mistaken, the Maestro Ring Mod and other circuits of that period are Tom Oberheim designs but the later wave of Maestro stuff ('silver wedge box with large control wheels' era) were Moog designs. -- could be wrong?
Strategy

[vizcities]

Hi Strategy - I'm building this in the next couple weeks. Any chance you could post the power supply? I was considering doing a modified MFOS wall wart supply, but I'd love something that's already been built/tested.

[ryland]

I also built the GGG one 20+ years ago.  There is a power supply schematic at GGG that I followed and have used for multiple bipolar supplies since.  It's rock solid.  The input is a 35VAC signal, which gets converted to the required +/- 12V DC.

http://www.generalguitargadgets.com/effects-projects/filters-other/maestro-ring-modulator/

[vizcities]

Hey ryland/Strategy: I figured out the PSU! However, the wiring for the board itself is confusing the heck out of me - I'm bad at reading schematics even in the best of times, and this one (particularly the mod section) is eating my brain. Any chance you could shed some light?

The schematic:

The PCB layout:

I think I have the input, voltage pads, and test points figured out, but the rest - output, jack pads for J2-4 (which the instructions recommend jumpering), switches, and pots - seems to be escaping me; I don't understand how the pitch, mod, and carrier jacks connect to the PCB, which in turn renders everything else incomprehensible. (The fact that my secondary reference, Dirtbox Layouts, includes a modulation switch not otherwise repped on the schematic doesn't help.) Any advice (or even just a few gut shots) would be beyond appreciated. My suspicion is that there was once a wiring diagram, but it disappeared when Topopiccione shut down his site...

[sammy-arfie]

Hey I'm building one of these right now, are you still having trouble figuring out the wiring scheme?

[Strategy]

It's been 15 years since I built this but I can open mine up and try and trace some of the spaghetti. I did all off-board wiring and had to have help from a more experienced friend at the time. There was no wiring diagram and some of the switching is counterintuitive. There's something slightly wrong with mine too- this was not a footswitch bypassed pedal IIRC, it's "always on" and it has an expression pedal input or something for activating the ring mod. On my build, sometimes on first power up I get no effect until I plug something into that jack. Still, even with a flawed distant memory and a slightly buggy build I might be able to trace connections
Strategy

[vizcities]

Hey I'm building one of these right now, are you still having trouble figuring out the wiring scheme?

Pardon the delayed response! I never really figured the wiring out and have moved to an apartment that is... imperfect for futzing with/figuring out electronics (i.e. I can use the kitchen table when my partner is out of town, but have no dedicated desk atm). That said, the wiring really is the only thing stopping me from finishing this as well. If Strategy posts some gut shots, I'll be as curious as you are.

Addendum: I did post an attempt at a wiring diagram at DIY Stompboxes, and it seems to have been approved by at least one member. The link: https://www.diystompboxes.com/smfforum/index.php?topic=128677.msg1240517#msg1240517

[sammy-arfie]

Nice, that looks great !

I'm actually learning Eagle right now, and I'm re-drawing the Maestro schematic into a single wide panel for my MU modular synth. Will post some updates as that moves along. I want to build a pedal version of it as well, possibly with an added LFO circuit, for a standalone unit.