For those who have built a Dr. Boogie...

[Surgeon]

How did you manage to get all j201s at around 4.5v? (if you did...).

All of them are biased correctly except for Q1 in my case. If I get it over 1.6v, the thing starts squealing really bad.

I switched Q1 by trying all of the 40ish j201s I have left but none of them offered anything better.
I was wondering if there was something I didn't try or do correctly.
My build is clean, I used shielded wire for the input, output and board's in and out. Wires as short as possible on the inside.

I do believe there's nothing physically wrong (or at least THAT wrong) with my build. Only thing I see that could be aproblem is the fact that I put both input and output jack sockets on the top of the box (as opposed to the sides) so they are a bit closer together than if they were on either side... still...

Everything's grounded properly too.

I haven't had a chance to play it extensively as I finished it late last night. It does sound good but I'm wondering if I'm not missing out on some more gain/tone from biasing Q1 to the expected voltage on the drain.

I used V2 by the way.

Any idea?

Gracias!

[Geiri]

It's not the same layout but I built the ROG Umble yesterday. It has 4 J201s that you need to bias. It could be the fact that the 100k trimmers have a huge range that it was quite difficult to bias them. First half or even further of the trimmer didn't change the voltage much but then by just barely touching it, the voltage jumps. In the end with a little patience, I got them all between 4.45 - 4.55v.

I'm thinking of building the Dr. Boogie soon so I'll report back when I have.

[Jon the Art Guy]

Do you have better suggestions for the trimmers? like if they were all on the high side, would it be easier to use a resistor in serial to the vr to get a wider sweep on the bias?

[Vince]

I've built two Boogies and yes they are a pain in the arse to get right. I ended up doing them by ear as one small tweak and it starts squealing. So I got them all as close as possible and then just tuned it by ear on max gain until the squeal had stopped.

[Vince]

I guess you've probably seen this?

https://www.youtube.com/watch?v=X4-UUDoSCPg

[Geiri]

Jon the Art Guy wrote

Do you have better suggestions for the trimmers? like if they were all on the high side, would it be easier to use a resistor in serial to the vr to get a wider sweep on the bias?

Not sure to be honest. It wasn't really hard but it took a little patience and accuracy to get it done. It only took me about 5 mins. I don't know if the Boogie is harder to bias.

[Madferret]

This might be a dumb question so sorry if I'm stating the obvious, but have you guys tried the 22 turn cermet style trimmers?  It definitely makes it easier to hit the sweet spot.

[Jon the Art Guy]

nope, but I will be when I do another buying run. Sounds pretty super-genius.

[Surgeon]

I'm not sure you guys get what I mean... maybe I didn't express it correctly.

I don't have a problem biasing them to 4.5v or whatever value I could think of. That's actually pretty darn easy (MMeter + probe + screwdriver, how easier could it get?).

My problem is that at 4.5v on Q1 I get an intense squealing, even with the volume of the guitar turned all the way down.

Obviously, when I turn it down by ear just below the squealing point, it doesn't squeal anymore and the pedal sounds quite good still.

I'm just wondering if there's any way to get rid of the squealing and get the bias at 4.5v on Q1 (I don't really know if it sounds better or worse at this voltage, I'm wondering...

I know some guys use MPF102s in Q1 and I've got some on order.
I read somewhere about replacing the 3.9k with a 39k and it tamed it, however it needed a bigger trim pot for that particular transistor due to this substitution.

As I stated, I think my build is pretty solid and well laid-out so I don't think it's just a matter of wiring position and whatnot (but I could still be wrong).

Anyways, that's what I meant.

[Vince]

I understood. I guess my point was that does it matter about being spot on if the pedal sounds good? I have no idea what mine were biased to by the time I'd finished. I just left it where it sounded good.