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DIY Stompboxes => Building your own stompbox => Topic started by: HitTive on August 28, 2012, 02:21:45 PM

Title: Big muff pi - problem
Post by: HitTive on August 28, 2012, 02:21:45 PM
I made Big muff from http://www.generalguitargadgets.com/projects/17-distortion/108-big-muff-pi . I hear only hiss.
Voltage:
Q1,Q2,Q3:
C:4,78
B:0,75
E:0,15

Q4:
C:4,5
B:1,5
E:0,98

Can anyone help me?
Title: Re: Big muff pi - problem
Post by: Bill Mountain on August 28, 2012, 04:27:19 PM
Quote from: HitTive on August 28, 2012, 02:21:45 PM
I made Big muff from http://www.generalguitargadgets.com/projects/17-distortion/108-big-muff-pi . I hear only hiss.
Voltage:
Q1,Q2,Q3:
C:4,78
B:0,75
E:0,15

Q4:
C:4,5
B:1,5
E:0,98

Can anyone help me?

Those voltages look fine to me.  I'm terrible at debugging advice.  Have you checked for solder bridges?  Does the bypass work?
Title: Re: Big muff pi - problem
Post by: runmikeyrun on August 28, 2012, 11:06:10 PM
"what to do when it doesn't work" stickied at the top of this forum.  Also, an audio probe would be an invaluable tool to use.
Title: Re: Big muff pi - problem
Post by: aron on August 28, 2012, 11:10:35 PM
>I hear only hiss.

That implies to me that you have working transistor stages and somewhere you have a break in the signal chain. Turn down the sustain knob- does the hiss diminish? If so, your signal is probably OK after the sustain knob, but no good before. Suspect the jack wiring and anything before Q1's base.
Title: Re: Big muff pi - problem
Post by: HitTive on August 29, 2012, 03:26:39 AM
Now, effect work (all potentiometer work) but I still hear loud hiss.
Title: Re: Big muff pi - problem
Post by: HitTive on August 29, 2012, 04:12:09 AM
and i have no voltage on sustain potentiometer.
Title: Re: Big muff pi - problem
Post by: aron on August 30, 2012, 07:19:53 PM
Wait.... does it work now? You hear the guitar signal? What changed?
Title: Re: Big muff pi - problem
Post by: Mufftastic on September 04, 2012, 12:06:35 AM
Work backwards.  I am guessing the hiss changes with the volume.  Does the bass/treble content of the hiss change with the tone?

I just finished a pedal with the GGG board and mine is as quiet as can be (noise wise). 

+1 on if the hiss changes with the sustain setting.  Is the noise only when moving the pots?