Gibson GA5-T Skylark Tremolo Annoyance (6BM8 version)

[captntasty]

This a homebrew amp that started as a simple single tube (6BM8 triode/pentode) amp with as few components as possible and turned into a GA5T.

The problem I have is that when the trem is engaged the output becomes kind of distorted/fizzy - it's subtle but annoying. I have seen in reading up on this amp that the trem was not the greatest but after a bit of tweaking I find it to be fine - except for the extra distortion. Any ideas?

I found a redrawn schematic in another post on this site that replaces the .1uf cap connecting the trem to the output with a .047uf off to ground then a .84uf (?) where the .1uf would normally be. What would this accomplish?

Here's the schematic:
http://music-electronics-forum.com/a...-schematic.pdf

As always, thanks in advance...

[loudthud]

Many low cost tube tremolo circuits don't operate in the ideal fashon. This one has no Intensity control. Without getting too complicated and changing the way the tremolo works, I would simply add a resistor in series with the .1uF to try to reduce the intensity and limit the distortion. Experiment with something between 100K and 470K to see if that reduces the distortion to tolerable levels.

[captntasty]

Oops, I forgot to mention... I did slip a 250K pot in there to vary the intensity. Sort of in place of the bottom 220K resistor off to ground. In all points of the rotation there is that tiny bit of fizziness until the intensity is backed of completely. Is there a better way to set that up?

[loudthud]

I would try the cap mod. If that doesn't clean up the amp, you might want to try a different, larger output transformer.

[captntasty]

The extra cap off to ground did nothing. I'll keep experimenting..