How to set the Bias trimpot in a Gristleizer?

[gigimarga]

Hello all,

I've just finished a Gristleizer and I can't find any informations about how to set the BIAS trimpot. I used a 2N3819 as FET.
The LFO waveforms are OK all, but the effect it's too weak. When I modify the BIAS trimpot it becames harder, but distorted. Even I found a good setting for it, when I change the waveform or the mode (VCA/VCF) the setting don't sounds OK further.

Thank you all!

[Derringer]

when I built mine I left the bias control as a pot mounted on the enclosure
you have to tweak it to get the most out of each waveform setting

[gigimarga]

Thank you Derringer!

I want to avoid to mount the BIAS trimpot externally. Maybe another FET will be more stable?

[Derringer]

no problem
it's not the fet that's the problem
afaik, this is just the way the circuit is designed

and you doon't have to mount the "trimpot" externally
just run leads from the trimpot pads, lug/wiper/lug, to a 100KB pot (I think I recall this being a 100K pot) and have an extra knob on your box

[Derringer]

here's what mine looks like


the 4 knobs across the top are
Rate Depth Bias Volume

[gigimarga]

Thank you Derringer again!

Excuse my poor English...I wasn't able to say that I will not mount the trimpot externally...I will replace it with a pot...but it seems strange to me to do that because in the original article the author sais that is no need to mount it externally 

[Taylor]

I definitely think it needs to be external - I think just about everybody who's built it on my board has gone that way. You don't have to, but it's very limiting to not do so. Back when that article was written there weren't really many other circuits for this kind of thing, so there weren't many expectations as far as how an effect should sound. Just having something that sort of cut on and off was good enough for early industrial music AFAICT. 

[gigimarga]

Thank you Taylor...after some tests that I made today it seems to me that it's the only solution, too!