Dr Boogey squeal

[budjb]

Built a Dr Boogey per GM's schematic and layout, and the thing sounds great.  I've got a bit of a problem with squeal though 

I didn't use any shielded wire at all, and have some on order.  I've read that it's a good idea to use shielded wire on the connections from the tips of the input and output jack to the switch, but is there anywhere else I should use it?

I only get the squealing when the effect is engaged - when bypassed there isn't any problem.  If I keep the gain at around 9 or 10 oclock with volume levels acceptable it's fine, but anything around 12 or up is quite noisy.  Conversely, gain maxed out with low volume is fine as well.

When this thing is squealing though, this thing sings!

[John Lyons]

Keep your wires short and keep the in/out wires as far from each other as possible.
Use short wires everywhere and keep the wires to the tone controls direct as much
as possible. Sometimes the fets are a little too hot as well. Try an MPF102 in Q1.

John

[doitle]

The Dr. Boogey Squeal sounds like it could have been a dance from yesteryear.

[budjb]

Replaced wires from input to switch, switch to circuit input, circuit output to switch, switch to output, both wires to gain, and the wire to volume with shielded wire, and it did nothing to curb the noise

I'm going to attempt to shorten the rest of the wires to the other pots, and failing that trying the MPF102 in stage 1.  I hope one of these works, because when it's not whining it sounds freaking great.  I don't know what I'm going to do with it if these last options don't work out.

[Scruffie]

Well i'm suffering the same issue but on my ROG Thor build an 47pF cap from 9V to Ground halfed the noise at least so i'm gunna try that soon and you could also.

[doug0147]

I had the same problem at first. I made it from the same layout. Did you put it in a metal enclosure? I did 3 things and now the thing has no squeel at all. Even with max gain and volume.

1. replace trimpots with resistors
2. changed Q5 with a MPF102
3. put in a metal enclosure

After the first 2 I still had some noise, then I put it in it's box and the noise was gone. I wonder if I could of left the whole thing alone and just put it in a box the stop the noise. One thing I didn't do was use shielded wire. But it didn't seem to matter.

[budjb]

It is in a metal enclosure.  I'd rather leave the trimpots as they are, but using an MPF102 seems to be a popular option.

[ayayay!]

Replaced wires from input to switch, switch to circuit input, circuit output to switch, switch to output, both wires to gain, and the wire to volume with shielded wire, and it did nothing to curb the noise

And on each & every one of those, you wired the shield to ground on one end only right? 

If you did all that don't notice ANY difference, then I think you still have your trimpots set too high.  You need to crank your gain all the way on the gain knob, then dial down Q1 & Q2 to the lowest "max" gain you can live with and see if that still oscillates. 

Ignore voltages on those drains for now, just dial it taste.  One Dr. Boogey I did (exact same layout I've always used) had a voltage on the drain of Q1 at about 0.86 volts!  Sounded exactly like my other ones and there wasn't a lick of difference. 

And as always, take any of John Lyons advice above to heart.  He helped me with my first Dr. Boogey build and all was solved. 

[budjb]

I did only ground one end (pretty good info from a page on John Lyons' site).  I also set all my stages at 4.5V, and then 5.5V.  I played around with listening and dialing it that way, but not methodically.  I'll give your advice a shot.

One thing I have noticed is that with the gain past 12 oclock (with a 1M pot) the gain is just way too much anyway.  Muddy is a big understatement.  Maybe it'll give me a more usable range as well

[budjb]

I popped an MPF102 in Q1 and it didn't do much for the oscillation.  If I turn the voltage down too low to either Q1 or Q2, I really start to lose a lot of tone.  I haven't shortened the wires to the tone pots yet, and that's what I'll be doing tonight.

I'm losing hope with this thing

[frokost]

Squeal in the Boogey has been covered a number of times before. In some rare cases, putting a buffer in front fixes it. Does it squeal if you put a buffered pedal in front?

[budjb]

I'm not sure if my other pedals are buffered or not, they're all Boss.  I have plugged this into the end of the chain and it didn't help it.

[frokost]

All Boss pedals are buffered. It's not that then  .

With that layout, you should be able to get rid of the squeal, so don't give up yet  .

[budjb]

Shortened all the wiring that I can, no change in the squealing.  I've had to settle for using the MPF102 in Q1 with lower voltage than I'd like, as well as lowing the J201 in Q2 as well.  It sounds ok but it loses a lot of its sustain.  I'm wondering if using an additional MPF102 in Q2 may help?

[caspercody]

I first started making these projects with the Thor. I had squealing like you did. I re did the project using shielded cable to EVERY part that was connected to the pcb (all pots, switches, and jacks). Squeal gone. I use plastic boxes (can not afford a good metal one so I get the cheap Radio Shack ones). The trick, I think, is I solder the shield wire to the case of the pot, and any switches than to ground at the pcb. I have since made Dr Boogey, Sweet Thing, JCM800, BSIAB2, Plexizer, Diefet, Texas Brownie, and other non Jfet distortion boxes with no squealing. All in plastic boxes, and according to the schematic layout and voltage on drain settings.

Actually my Jfet builds are quieter than my IC based builds. Last night I experimented with using 18v on the Jfet pedals. It sounds thicker, and tighter in the sound.

Hope my little info helps. Try grounding the pots themselves.

[budjb]

Thanks for the advice.  This is in a metal box, however, so the pots should be grounded already.

[caspercody]

Is the box grounded? Is there any paint, or coating on the box or pots? I have to sand the pots with a file to be able to get solder to stick to them.

[John Lyons]

Bud
Can you post a pic of the guts?
Sometimes it's humbling I know....
We might get a better idea how to help if
we can see what you are working with.

john

[budjb]

Absolutely.  I'm not too particularly proud of it but it is my first build

I'll snap a shot when I'm home.

[dschwartz]

the dr boogie it´s also sensitive to the way you layout parts inside the box..
the rules i follow (well, they are pretty standard for high gain pedals anyway):
- NEVER put the input jack too close to the output section of the pedal (volume pot, last stages, too close to the PCB or over the PCB)
- NEVER put the output jack too close to the input section (input jack, first stages, gain pot)
- gain pot should be away from volume, treble and presence pots.
- input jack isolated from the box. Ground it from the input of the board.
- Use only (yes, only) regulated PS. (sometimes i include the regulator inside the box)
- Enlarge filter caps (i use 220uF)
- input-->switch-->board  wiring allways shielded and as short as possible
- Board-->gain pot wiring shielded if it crosses over the PCB

Good luck!!