dr. boogey....

rtill · October 22, 2006, 11:34:31 PM

woo hoo! built the Dr. Boogey and it sounds GREAT!!!! just has a high pitch squeal and clips when I play like it's being pushed too hard even at low volumes....is this because I need to adjust the trimpots or because (what I've read....) the first stage transistor needs to possibly be changed to a mpf102? I'm sooo excited yippeeeee! The tone is AWESOME!

mojotron · October 23, 2006, 12:47:41 AM

Well I think some of use have the same issue, and agree that it sounds awesome - even though there is squealing. The latest train of thought on the squealing is that the wires in the tone stack will cause oscillation in the circuit if too close to other wires. Also, power supply filtering is pretty important. If you read the posts on the Dr B you'll see that some have (RDV) have overcome the sqealing by very carefully making your wires very short, and keeping them away from some wires.

I think we are close to figuring this out in the gerneral case.

rtill · October 23, 2006, 01:46:00 AM

I think I have it down to the first stage.....when I adjust the trimpot ....one direction, the squealing gets worse, but the sustain is longer, and in the other direction the squeal goes away, but the sustain cuts out like it's too much for the tranisitor and there's no in between ....does this make sense?

any ideas?

Xavier · October 23, 2006, 03:54:19 AM

I highly suggest you that you use the small layout for the power supply regulator I used (some posts below). Saved me some problems.

Also, check if you have the squealing WITH the guitar connected.

And, as Mojo says, neat wiring is key to this project.

MetalUpYerEye · October 23, 2006, 07:27:16 AM

I am required to inform you that my Dr. Boogey wiring looks like a bowl of spaghetti and in my best english...

'Dat sum' bitch don't make no mo' noise than its sposta!

No but really, mines a mess and its one of my quieter pedals.

rtill · October 23, 2006, 10:28:08 AM

Quote from: Xavier on October 23, 2006, 03:54:19 AM
I highly suggest you that you use the small layout for the power supply regulator I used (some posts below). Saved me some problems.

Also, check if you have the squealing WITH the guitar connected.

And, as Mojo says, neat wiring is key to this project.

where can I find "the small layout" you're talking about?

Xavier · October 23, 2006, 11:05:40 AM

Quote from: rtill on October 23, 2006, 10:28:08 AM
Quote from: Xavier on October 23, 2006, 03:54:19 AM
I highly suggest you that you use the small layout for the power supply regulator I used (some posts below). Saved me some problems.

Also, check if you have the squealing WITH the guitar connected.

And, as Mojo says, neat wiring is key to this project.

where can I find "the small layout" you're talking about?

In my gallery you'll find it (page 9)

mojotron · October 23, 2006, 11:30:48 AM

Quote from: MetalUpYerEye on October 23, 2006, 07:27:16 AM
...
No but really, mines a mess and its one of my quieter pedals.

I have a couple of questions for you.

1) Are you using all J201 FETs?
2) Are you using a battery?
3) Are you getting an 'unreal' amount of gain out of it?

Thanks...

$uperpuma · October 23, 2006, 11:41:01 AM

I hear using shielded wire, grounded on one end from the input to the switch and the stwitch to the board input will help reduce noise...

Bucksears · October 23, 2006, 12:05:23 PM

I haven't messed with shielded wire (yet), but I did wire mine up very carefully so that everything is pretty much to exact lengths without the 'bowl of spaghetti' that MetalUpYerEye refers to (LOL).
Mine is noisy due to the high gain, but it's not squealing. With an MPF102 in Q1, the range of gain is great
I revamped my Dr. Boogey PCB (finished it last night), allowing for more space between most parts/tracings and (socketed) 'Miller caps' on all five transistors. I hope this does the trick. The new board is about the size of the old one and I will post the Parts Layout and PCB after I've had a chance to look it over one last time for mistakes.

It does sound awesome and it's my favorite 'metal' pedal.
- Buck

rtill · October 23, 2006, 12:08:23 PM

Quote from: mojotron on October 23, 2006, 11:30:48 AM
Quote from: MetalUpYerEye on October 23, 2006, 07:27:16 AM
...
No but really, mines a mess and its one of my quieter pedals.
I have a couple of questions for you.

1) Are you using all J201 FETs?
2) Are you using a battery?
3) Are you getting an 'unreal' amount of gain out of it?

Thanks...

1- yes, all j201's,
2- yes battery
3- I wouldn't call it "unreal" amount of gain....pretty much what I'd expected....sounds great aside from the squeal and cutting out.

rtill · October 23, 2006, 04:03:03 PM

....what if I use larger cap values on the tone stack and presence? do you think that may quiet the squealing?

MetalGuy · October 23, 2006, 04:23:17 PM

My observations concerning the squealing are:
1/ When in the enclosure make sure you connect all pot caps to ground.
2/ Keep the input as far away from the output as possible.
3/ At high volume the doctor was still oscillating. The output level was close to 1V so I added a resistor before the volume pot thus decreasing the max output level to ~250mV and now it's OK.

MetalUpYerEye · October 24, 2006, 11:09:40 AM

Sorry for the late reply...
I used an MPF102 in the 1st position as I had read that people were having a tough time with all J201's I figured it simpler to just use an MPF102 and be done with it. I am using a battery. Unfortunately i've never had the pleasure of owning a power supply for my stompboxes. Luckily I dont gig and am usually very meticulous in unplugging my gear when i'm finished or taking a break. Never having the need for an AC adapter plug, I never installed one on this pedal (or any other for that matter) And yes, I get what I might describe as a rediculous amount of gain from my Dr. Boogey.

In case you're wondering... My other gear consists of a Gibson Les Paul Studio, 100 watt Carvin combo, a few assorted stompboxes and normal guitar cables no longer than 10' each. The Les Paul is almost dead quiet through Dr. Boogey. I've also used my Strat through Dr. Boogey and it gives a bit of noise, even with a humbucker in the bridge position. I think the guitars wiring, pickups, etc. have a major impact on the noise/squeal level and might be a good thing to look into when trying to tame your Dr. Boogey.

mydementia · October 24, 2006, 10:38:09 PM

Xavier - what kind of Zener is that? I threw one of those power supply regulators together with a 9.1V Zener I had and now I only get 3.5V from a 9.1V supply - doh!! I'm not sure what a ZL9M3 is...

Thanks in advance.
Mike

Xavier · October 25, 2006, 03:39:51 AM

Quote from: mydementia on October 24, 2006, 10:38:09 PM
Xavier - what kind of Zener is that? I threw one of those power supply regulators together with a 9.1V Zener I had and now I only get 3.5V from a 9.1V supply - doh!! I'm not sure what a ZL9M3 is...

Thanks in advance.
Mike

It's just a 9,1V Zener, the one I used in particular has that silly name (ZL9M3

). I can't say what happens to your circuit, but must be easy to figure out. Only 1 resistor, 2 caps and the Zener. Are you using the correct Zener?

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