Search:

Easy as that, eh? Hats off to you, sir. :)

I’ll go with a decent 9V PSU for now and iron out the finer audio details then see how much more energy I have for power supply design.

Thanks...

Swapping the power supply for a better one (a Korg 9V PSU instead of a random cheapo) eliminates almost all of the noise. Gah.

If I wanted to make the circuit more resilient to cheapo power...

@fdaniels good question! I had tried that a while back, but not recently. Running the circuit from a 9V does indeed eliminate the noise.

So... I need to filter the power supply?

I came across this post that sounds like a very similar problem to mine, and it made me wonder whether my skimpy breadboard cables were not giving me a clear enough ground connection. I swapped all...

The JFET buffer is quite common in guitar pedals (this sort of thing), but a TL07x buffer makes sense too (and should be better quality). I’ve swapped the buffers out for TL071s – they work fine but...

@fdaniels thanks for the pointer on the inductor position – I think I misunderstood your earlier recommendation. This makes much more sense.

Here’s the full circuit that I’m tinkering with. One of...

Quick experiment – I don’t think this is the correct approach, but it does eliminate the noise and maybe that would be helpful in diagnosing the problem.

I grounded the mixer to the Teensy audio...

I’ve made some progress! A few steps forward, a few steps back.

I bought some 33uH inductors and added them to the circuit as @fdaniels suggested. They reduced the power supply whine a little....

@jonr @fdaniels @MarkT @Blackaddr thanks for the tips! That all makes a lot of sense. I’ll make some tweaks to the circuit and see how I get on.

I’ve been working on a Teensy 4.0-based music machine for a while, and I’m getting down to the last niggly noise issues. I’m hoping this is something people have solved before, but I haven’t managed...