5532 Output module is ready

KOSMO MODULES
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I designed an Output module for my Kosmo:

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in action

It’s inspired by Meebilt’s eurorack one, with several modifications and additions.

Main deltas are:

  • Very precise 10 LEDs output meter
  • “Quasi-floating” balanced line output driver, which also accepts unbalanced TS cables
  • Pre-amp to bring line level external instruments to Eurorack typical levels, with bi-color LED level indicators

While I’m aware many people wouldn’t dedicate rack space for an output module, I got interested in making one for several reasons:

  • I missed a nice master volume knob that could attenuate both L and R channels of my stereo VCA.
  • Modular synth levels are just too hot for most audio equipment, which are commonly designed around +4 dBu as a nominal level, and I want the final instrument to be robust and compatible with any venue equipment I might ever need to plug it to.
  • I fancy the effect of the LED bar meters.
  • It was a really nice challenge and opportunity to learn about audio circuitry design, with the help of Douglas Self book “Small Signal Audio Design”.

This is the first module that I have also fully documented in my GitHub, with assembly instructions and all. Maybe someone finds it useful.

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I will definitely find this useful! As always!

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I’ve got a few more modules waiting for assembly this weekend. I’ll PM you after I finish testing them all in case you want to receive some of the new arrivals. :slight_smile:

Regarding this one specifically, maybe you’ll prefer to order from JLC because I made a several improvements in the published Gerbers already. I could send you a set from the first run, but you’ll have to do some manual butchering on the PCBs yourself.

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I am thinking about ordering a set from JLC. I might have some spares… if you (the reader who is interested) are in (or close to) europe it could make sense to pass one on…
If there is enough interest i’ll order more than one batch an organize a manual non profit based distribution

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Awesome! I’ll keep an eye out.

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I placed my order at JLC. I ordered 10 instances. with taxes and delivery that makes 80€ total. i went for 10 because the scaling was much better. there will be spares :slight_smile:

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Mail Day Thread
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For attention when sourcing components: The only “kinda special” things here are the pan pot (dual gang with center detent), mode switch (DPDT “3 way”, so not a normal DPDT) and Nichikon non-polarized capacitors.

I’ll add links to the ones I used after work.

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Haha my previous comment is a mess… I had another of my recent modules in mind when writing it :zany_face: . There are no switches in the Output module and no pan pot with center detent.

Anyhow, links to the actual pot and Nichikon caps:

https://www.taydaelectronics.com/10k-ohm-linear-dual-taper-potentiometer-round-shaft-pcb-9mm.html

https://nl.mouser.com/en/ProductDetail/Nichicon/UEP1V470MPD?qs=Xdw6JNByzjx1i7mXAa41kg%3D%3D

https://nl.mouser.com/en/ProductDetail/647-UES1V220MPM