Help with YuSynth Minimoog filter

I’ve asked about this on Muff’s but had no replies, figured I’d see if anyone here has any ideas. I’ve built a YuSynth Minimoog filter, should’ve been an easy build, but it’s picking up a radio station when using my bench power supply, or various things from other modules when hooked to my Eurorack cabinet. I have never had anything else do this and the cabinet has so far been quiet.

Here’s a link to a video

I figured it was some sort of ground loop or ground not connected but everything checks out fine, at least as far as continuity, shorts and power is concerned. Any ideas would be appreciated.

Thanks

Randy

That is a pretty extreme case of “ham radio” you have there. Long story short, you are acting as an inductor with your electromagnetic body field. The clear answer is that you need a homeopathic magnetic cleanse to clear out these bad consumerism vibes. :wink:

Did you accidentally use 1/8in stereo jacks instead of mono? That would just about do it.

Could be a ham radio problem, I did put on a bit of weight over the holidays. “Homeopathic magnetic cleanse.” Sounds painful, I’m in! I used mono switching jacks, same as I use on my other builds.

Well, then I’m just about all out of ideas. Looks like you will need to build your PCB a nice tinfoil grounding helmet just like the SP filter for Shruthi. :slight_smile:

Damn aliens and secret government agencies!

Hi piscione, I’ve built 2 of this filter in the last months so I could cross-check something. It looks linke you’re sitting next to a broadcast antenna… Although I never discovered radio signals I well noticed a high sensitivity of the filter circuitry to supply disturbances. I compared an old-style transformer supply (no noise occured) with a Meanwell switching-type which introduced high-frequency noise especially at high emphasis settings.

So I can partly confirm a certain stray pick-up sensitivity.

The supplies are Meanwell clones. The filter does work, sounds like it could be really nice, but the radio thing is a bit inconvenient. Do you have any hi-res photos of both sides of your PCB?

Unless you have shielding on your case or an RF shield over the circuit board then you can pick up radio.

Sometimes a PCB trace will be just the right length to pick up a radio signal.

Maybe adding some ferrites to cut off HF influences could do the trick. Most of my DIY modules have them in the audio paths…

I’m wondering why the ground tab of the Emphasis pot is supposed to be left disconnected. I ran .1uf caps from both power supply pins on the TL072 to ground, which helped a bit, and connected the disconnected Emphasis tab to ground. Now I only get radio if I actually touch the board somewhere. Had ferrites originally and replaced them with resistors. Could always have both I suppose.

Here some images, but these are self-made PCBs even though it’s the yusynth circuit. As you can see I use two LCL filter for the supply…

Wow, nice PCB! Do you have any of those to sell?

@Picard: I agree! You should sell kits.

Yeah, the PCB design took a while, and of course it has roundish traces for real analog feeling…

If you do a few more, count me in. For a real analog feeling, you should do wood PCBs.

Yeah, the rounded traces are fancy. If you do more, let me know the cost as well.

>wood PCBs.
The first breadboards were literal wooden breadboards. That is not out of the question.

Ok, I will ask the factory for wood. Oak or something…

You mean they weren’t made out of bread!?

>made out of bread!?

Of course they were! Bread was wood back in the good-old-days! It always came out of the oven much more warm and crunchy.

Breadboard?