Payback looper - Tone control

[Jaicen_solo]

I've built my payback V1, which works perfectly, with the exception of the tone control.
For some reason, the tone control acts like a sort of volume cut, and sometimes makes the ISD lock up. I can't figure it out, and i've tried it with a couple of different pots with the same result.
It's quite irritating, because it works just fine in every other aspect. I'm thinking it has something to do with the output section of the ISD chip, because there's just a 1uF ceramic cap between the chip and the tone control.
Anybody have any ideas what's going on?

[The Tone God]

It is a extreme pass filter. You can always lower the cap value if its too much cut. As for the ISD failing I can't explain that unless it is some how loading down the speaker output. Its the first time I have heard of this. Try a different cap value to see how it behaves.

Andrew

[Jaicen_solo]

I don't know what was going on with it, I suspect there was some sort of loading occuring.
I used a non-polar ceramic 1uf cap to couple the speaker. When I replaced the 1uf cap to the op-amp with a 10uF polar electro it started working just fine, so perhaps the speaker coupling cap needs to be polar?
Either way, I swapped the tone control to the wiper of the playback pot and used a 0.1uF film cap which works just fine and seemed to give a better range across the pots rotation.

Just for information, my payback needed a whole load of filtering on the digital supply of the ISD to get the noise down to acceptable levels. I had to put a 470uF cap directly across the power pin of the ISD. With that in place, the noise floor is acceptable when recording and in playback. Before, it was much too noisy whilst recording.