Minnow / Maestro FSH-1 LFO Ticking Noise

[markuus]

Hi all,

I just built a Minnow (Maestro FSH-1) and am getting really pronounced ticking from the LFO in Sample/Hold mode whether bypassed or not.

I've read around about how other people have addressed the issue in this pedal and others with LFOs, so I have routed the output wire that would otherwise pass directly under IC2 (which I think is the source of the noise as I understand) under the board on the oppose side of the enclosure. I have tried a few different variations on the wire routing, but there didn't seem to be any change.

I could only source a B2M pot with solder lugs, so I had to connect the resonance pot with some short wires from the lugs to the board. I originally had those coming around to the top side of the board, and I tried shortening them and keeping them on the bottom side of the board. No impact there- same noise either way.


Here is the noise:

Any suggestions? Should I tried shielded wire between the 3PDT board and the jacks? I've read other people say that wire routing should address this problem, but I can't seem to get rid of it that way.

For people who use shielded wire- what kind do you use? Where do you get it?

 

[markuus]

Also I have spent time experimenting with the trim pots. Adjusting those has a huge impact on the sound of the pedal of course, but the ticking doesn't change at all regardless of how those are set.

 

[Bret608]

I had a similar problem on a FSH I built a while back (Madbean Sharkfin PCB), but for me, the LFO ticking only came through in bypass. Like yours though, it was only on the sample/hold side. I always suspected that it actually had to do with the rate LED. You could try disconnecting that and seeing if it helps. I had intended to try this on mine but I ended up selling it.

 

[fig]

RG174 is popular for shielded. Google for best price & shipping. I don't think it will eliminate your ticking, but if you use it on the input side and only ground one end, it may reduce the effect. Have you tried another 1044?

 

[markuus]

@Bret608 It's definitely worse in bypass. The ticking seems to go through the filter when effect is on, so adjusting the settings/trim pots can cut it down quite a bit. I had thought about the LED- I have it connected with some wire so I could place the LED lower down on the enclosure, and I'd tried moving it around and that didn't seem to impact the noise at all. Maybe I'll try removing it and see! Thanks for the suggestion!

@fig thank you! I was really having a hell of time finding the right kind of wire. I tried swapping around a few of the other ICs, but not the 1044. I'll give it a go!

Thanks! Got a couple additional things to try....

 

[fig]

The charge pump can interact with noisy PSUs as well so make sure you run clean juice.[credit to @Chuck D. Bones esq.]

Maybe also try a buffer before the pedal?

 

[Diynot]

This was my last resort fix:
Shielded coax on input/output as well as foil tape covered shield boxes connected to ground over the ICs (I used the little plastic tubes that they ship ICs in).

 

[markuus]

@Diynot That makes me feel better at least! Seems like it's a recurring issue with this one.

I saw someone else did something similar, and I was looking at doing that too. Did you totally surround those ICs, or is it sort just surrounded on three sides? Also are you grounding those little shield boxes to the ring of one of the jacks or some other way?

Thanks!

 

[markuus]

Also @Diynot great idea on using the little plastic tubes. I was struggling to get some cardboard measured out, but was making a mess of it. This is so much neater and fits perfectly.

 

[fig]

This was my last resort fix:

Did it resolve the issue or reduce it to an acceptable level?

 

[Diynot]

Yeah, I got the basic idea from another post on the forum too. They are only covered on 2 sides and top. I cut the very middle of the tube out so I had a little “clip” to hook under the sockets. I did connect both boxes together with wire and then to the ground lug. It has removed the tick almost completely.