The Trill Tremolo Thumping Problem, Help!

[Hallmar]

So my first pedal was a Tremolo that i designed a PCB after the schematic of the Trill Tremolo that modkitsdiy have
and when i turn one of the knobs or both of them to the top i get some huge thumping sound and it annoys the heck out of me

It's a very nice tremolo.

Does anyone have any idea what might cause this?
The capacitors maybe?
I've been bothering with this for months and found nothing.

I might also mention that i'm using 2n3904 transistors instead of the MPSA18, maybe that's the problem?

Thanks guys!

If i get it to work properly i'll improve the current PCB design and post it here for you!


Here's the PCB and the Schematic.






I also just finished a PCB of The Verb Deluxe by ModKits and when i've gotten the reverb module from Smallbear i'll test it, verify it and post it here!

[Jdansti]

I'm not familiar with this tremolo, but you might want to try a 100 μF or greater capacitor across the power and see if that helps. Alternately, try the same from the collector of Q3 to ground. Try to get the capacitor as close to the collector lead as possible.

[Hallmar]

I'm not familiar with this tremolo, but you might want to try a 100 μF or greater capacitor across the power and see if that helps. Alternately, try the same from the collector of Q3 to ground. Try to get the capacitor as close to the collector lead as possible.

Putting the 100uf between Q3's collector and ground just eliminates the Tremolo and just gives me a clean signal.

Putting it on the power changes nothing.

Damnit.

[Jdansti]

Well, it was worth a try. Sorry it didn't help.    Maybe someone else knows of a solution.

[Hallmar]

Well, it was worth a try. Sorry it didn't help.    Maybe someone else knows of a solution.

I'm thinking of throwing it away and just build the Pulsar Tremolo or something.

[Jerund]

I haven't looked up the spec sheets, but it seems like you may have already stated your problem... MPSA18's are pretty cheap at Mammoth, give them a try.  I just built one from the schematic and I have not problem like that at all.