I was just wondering about this particular socket…
sleeve and ring to GND, and Tip signal
EDIT : image deleted (bad version of the stripboard layout)
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Yes, your “synth in” and “mic in” labels on the stripboard layout here are reversed. They’re correct here.
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Now i’m lost
are you sure ? because on this input label “modular in” and after it’s the 1M to GND and 10uf cap
like here
no ?
“Mic/guitar in”
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i think i need glasses !!!
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Here is my version, with some changes.
One was to omit the instrument preamp. I have one already in my envelope follower module. For the transformers, Stone specified M 0222, which is not very widely obtainable. I used the Triad TY-141P.
As for the diodes, I went with 1N695 germaniums. I’m considering building a second RM at some point using Schottkys and seeing which I like better, or if I like both for different purposes. Beyond the transformers and diodes, I did make a couple of tweaks to Stone’s design, but nothing big.
Schematics, KiCad design files, Gerbers, and documentation in the GitHub repo: GitHub - holmesrichards/arrm: Active Real Ring Modulator synth module in Kosmo format.
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(I was a bit disgruntled with the carrier unbalance control, but then I found replacing the 330R input resistor I’d used with a 330k as Stone specified helped a lot. )
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Glad you got your gruntle back.
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The schematic’s link don’t work on your GitHub : “Error 404”
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@dud, Think that may have just been gremlins. The link just worked ok for me.
@analogoutput seeing ACME on your drawings makes my inner child want to go “beep beep”
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It has been modified, now it also works for me 
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So is the only change to your kiCad file that needs to be made is changing R4 to be 330k? I was just going to add the change and re-make the gerbers to send off. Just want to be sure no other changes need to be made first. Thanks, BTW, for doing the Ring Mod. I’ve been wanting one. 
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Oof, I changed R4 in the KiCad files but forgot to update the schematic PDF. Just did that, everything should be OK. Gerbers have the correct R4. No other changes (yet).
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Thank you! I have this odd row of space in my eurorack that is larger than 1U and smaller than 3U, but not quite large enough to be 2U. I decided to make it another row and just make custom sized modules for it instead of it being wasted space. I am using it as an FX and utility row. This is where I would like the ring mod to go. I’ll need to do some kicad layout adjustments in order to accommodate this odd sized row, but it’s worth it for a ring mod. Thanks for doing it! Now I just need a phaser and a good distortion and maybe a chorus if I can find a decent one.
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I’ve been trying to figure out why my RM is behaving differently than I’d expected, and maybe it’s because I was expecting wrong. As part of this I tried running an LTSpice simulation of a simple basic ring modulator, based on a file linked from here.
What I read in various places is that lower forward voltage for the diodes (e.g. germanium or Schottky versus silicon junction) is good because it distorts less. But what the simulation suggests is the opposite. Am I missing something or is this conventional wisdom wrong?
Here are outputs with a sine signal, square carrier. Sine amplitudes are ±0.5 V (blue) and ±1.5 V (red). Carrier amplitude is 5 V. Diodes are 1N914.
You can see the blue output is sine shaped, but with sign reversals, what I think of as close to ideal ring modulator behavior, but in the red output the sine shape is flattened at the top. If I then change the diodes to Schottkys (1N4817) I get these:
The blue output is noticeably distorted and the red is very flattened. Finally if I change the diodes to ideal ones with zero forward voltage (.model Didl D(Ron=0.0001 Roff=100G Vfwd=0)) I get:
The sine shape is almost completely gone and what you’re left with looks pretty much like a square wave though with some phase glitches.
But maybe you don’t care much about how much the sine shape is distorted. You probably do care about the output amplitude. The 1N614 output is close to ±0.5 V for the 0.5 V sine wave and around ±1.25 V for the 1.5 V sine wave. The 1N5817 is down to around ±0.4 and ±0.45 V. And the ideal diode gives you, wait a second, really? about ±0.6 and ±0.7 mV! Experimenting with the Didl model shows the forward voltage really is responsible for a lot of this behavior.
So at least in the simulation, it seems higher forward voltage diodes give less distortion and more amplitude. Is that true in real circuits? Why is the conventional wisdom that lower forward voltage is better in ring modulators?
(And yes, I know there are so called ring modulator circuits that don’t use weird diodes and transformers, and offer some performance advantages over the classic RM circuit, but that’s not what I’m trying to figure out right now.)
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On further investigation it looks like the big problem with the ideal diode model was its very low Ron. If I change that to Ron=1 I get reasonable amplitudes, and no significant Vfwd-correlated change in the output with input ±0.5 V (cyan line below). With ±1.5 V there is some effect of changing Vfwd (magenta through blue lines), with more flattening of the shape for smaller Vfwd. So it still looks like, as far as amplitude and distortion are concerned, lower Vfwd is worse rather than better. But obviously there are other differences between the 1N914 and 1N5817 models that affect the results.
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