M800 Overdrive - Trimmer Pots

[dankmetalsounds]

Hey all,

I'm new to building pedals. I've ordered parts to build the M800 Overdrive but unsure how the trimmer pots should be used. Is there a target voltage that they should be set to, similar to biasing tubes? Or is there a range and you adjust to taste? I haven't been able to find this information on the forum.

I'm using J201s from Stewmac, which should be decent quality, consider they are almost $6 a pop

Thanks!

 

[temol]

You can start with 1/2 of the supply voltage on the drains of the transistors. Then experiment. Next time buy mmbfj201 (smd version) and adapter boards. You could have full set for the price of two from Stewmac.

 

[dankmetalsounds]

Thanks, Temol! I'll do just that. Do you have any recommendations on what position the pots should be at? Or should I sweep through the range on those after each adjustment on the trimmers?

Interesting bit on the mmbfj201 - do they yeild the same tone as the full sized version?

Thanks again, sorry for the noob questions

 

[temol]

No recommendations. Just connect the circuit to 9V supply and measure voltage between GND and drain of each transistor. Adjust the trimmer to get 4.5V.
J201 = MMBFJ201, just different package.

 

[Chuck D. Bones]

Hey all,

I'm using J201s from Stewmac, which should be decent quality, consider they are almost $6 a pop

Thanks!

What makes you think there is a correlation between price & quality?