Dr. Boogey... HELP!!

[thanal9999]

Hello...! I Just Built Dr. Boogey but I have a major problem. I adjusted the trimmers in order to get the best guitar sound possible with the help of a voltmeter and I finally managed to get a great guitar sound which was beyond my expectations. The problem is that I also get a very screechy sound that is driving me crazy...! It seems to disappear when I roll off the volume pot of the guitar.  (It is not the normal buzzing that many distortion effects have... it is a very, very annoying screech!!). I resoldered all the connections but the only thing that seems to help is the lowering of the first trimmer... The thing is that in the point that the screech stops the gain that the effect produces is very low. Do you have any idea what the problem is...?

[dschwartz]

shield cables, use lower gain fet (mpf102) for first stage, BOX IT on a metal enclosure, move away the gain pot from the input, use ONLY regulated power.

Do All of the above and the squeal (oscillation) will be gone.

[John Lyons]

Which layout did you use?

John

[thanal9999]

I am not sure about where I found it... I think it was at www.DIYguitarist.com...

[dschwartz]

Yup, that´s the squealing one...

[Bucksears]

That's my original one, which, I have to say, I've never really had a noise problem with. I DID have to drop Q1 and I think Q2 down to MPF102's, but that's about it. Mine has a rat's nest of wires, which are currently contributing to a little bit of noise finally, and I'm not surprised. Using all J201's (and the non-scaled-down tonestack) it has a ridiculous amount of gain that I couldn't control, but sounded fine later with lower-gain transistors thrown in.

There are plenty of people that built it using my layout and didn't have any issues (and I'm sure plenty that did) given proper wiring/grounding (myself included), but I wouldn't label it the 'squealing one'. 
However, I AM building one using Gaussmarkov's proven layout now that additional (technical) advances in improving the circuit have been made, whereas I was just trying to get things nicely laid out and not too close together.
I'll post a build report & pics of that one since it's a larger box-build and have extra footswitches installed.

This is such a killer circuit; I always laugh a little when I hear guys on TGP rave over FINALLY getting their hands on whatever little boutique 3-knob overdrive they've been waiting weeks/months for.
It doesn't get any more boutique than DIY.....

- Buck

[dschwartz]

Buck, sorry, i didn´t mean to imply that your layout was wrong..in fact i build 2 dr boogies with your layout and sounded GREAT!!!!!!
but after some tweaks and changing q1 to MPF.

whithout any mods, even with clean, shielded wiring, if you use all j201´s and place the pots too near ..it will squeal at max gain and high treble, no matter what else you do...

[Bucksears]

Buck, sorry, i didn´t mean to imply that your layout was wrong..in fact i build 2 dr boogies with your layout and sounded GREAT!!!!!!

No problem, and thanks!

whithout any mods, even with clean, shielded wiring, if you use all j201´s and place the pots too near ..it will squeal at max gain and high treble, no matter what else you do...

Absolutely. It's extremely sensitive. Once I dropped down to lower gain trannies in Q1 & 2, I still had a whopping amount of gain/bass but no serious noise issues.

[dschwartz]

yup..

and i totally agree that every other distortion box (except for a few) sound toyish compared to this beauty.

[thanal9999]

Thank you for your help. I 'll try your advices and see what happens...

[thanal9999]

Is there any substitution for the mpf 102...? It is a bit difficult to find it here. 

[the_random_hero]

Is there any substitution for the mpf 102...? It is a bit difficult to find it here. 

J201?