[SOLVED!]Big Muff Face/Ram's head: only white noise when on

[Odiolitos]

Hi there!

I just built this Face/ Ram's Head version of the Big Muff, and it's actually doing nothing but noise when on (no guitar signal at all!) Here's some info:

1.Name of the project: Der Muff Ram's Head from Musikding.de.
2.Links to the source of the project web site with the schematic or project, layout and wiring diagram. Here's the schematic and the building instructions I followed.
3/4. I'd say I followed instructions to a T, but evidently, something went funny. I didn't change any components (although the parts list included a R24 which I couldn't find in the schematic or the board!
5. No conversion or change has been planned or (voluntarily) done.
6. When off, signal comes through perfectly. When on, though, I get nothing but white noise. Said noise, though, changes in tone and volume when turning the knobs, so I'd say they're doing something!

Here are the readings from the transistors. The power supply reads 10.10, for what that may be worth:

Q1
e 0,05
b 0,65
c 4,22

Q2

e 0,05
b 0,65
c 4,19

Q3

e 0,04
b 0,65
c 4,19

Q4

e 1,09
b 1,57
c 5,18

Thanks a ton!

[Kipper4]

Welcome.
You'll get more help and traffic in the building your own stompboxes section.
If I was you I'd report it to a moderator and ask them to move it.
Rich

[Odiolitos]

Thanks a lot for the pointer! Being new in the forum, I'm still to find my way around it...

Cheers!

[robthequiet]

When you say that the tone and volume of the noise change, does adjusting the sustain pot do anything?

In a case like this it's nice to use an audio probe to trace the signal and find the spot where it drops off.

[GibsonGM]

Hi, welcome!  Rob is right - make an audio probe and try to find where the signal stops.   Then tell us where and we can probably help you.
Do you know what the 'signal path' is for the circuit?

Instructions:

http://www.diystompboxes.com/pedals/debug.html

[Odiolitos]

Hi again!

Thanks for the quick response! Actually, all three knobs do their thing: volume decreases/ increases the noise volume, sustain makes it "hairier", and tone makes it more trebley... I accidentally built Sonic Youth's dream pedal!

I'll build the audio probe and test it tomorrow. Am I guessing right that I should go backwards in the signal path?

[Agung Kurniawan]

Hi guys, I have the same problem too. When I BB the Bug Muff Pi there is just annoying noise come out of it. The noise come from the 2nd clipping stage.

When I just using booster + 1 clipping stage + tone control + volume recovery. There is no noise at all.

I don't have any idea since the last time I BB my own ultra high gain BMP without any noise. I'm using BC549 for the transistor.

[R.G.]

1: is the wiring correct?
2: are the pinouts correct?
3: is the power supply properly bypassed?

It is very likely that the noise you hear is ultrasonic or RF oscillation so big that no audio can get through. Need a scope to see that though.

A 0.1uF ceramic from V+ t0 the bottom end of the emitter resistor on each stage may cure it. Maybe.

[antonis]

If the problem remains, after R.G.'s notes, check for proper mounting/value of C2 and/or C6 and/or C9..

[R.G.]

Good one, Antonis. That would do it too.

[duck_arse]

can we see photos of what you have built, please? that way, we can see if your input jack is correctly wired to your correctly wired bypass switch.

[my money is on input jack backwards wired.] also, welcome to the forum.

[Odiolitos]

GOT IT!!

Turns out the ground cable going to the underside of the main board frayed a bit, and because the connectors are so close together, it touched the in terminal. That's what you get with poor quality cable, I guess...

Anyway, thanks a ton, guys!!

[antonis]

[my money is on input jack backwards wired.]

your money is now out of your pocket.. 

[duck_arse]

perhaps, but all that cake we're eating somewhat alleviates the loss. good work on the bug eradication.