Hofner Buzztone - no fuzz just clean boost

[Astroman]

I built Hofner Buzztone. The Problem is that I can not get fuzz sound it's like a clean boost. When I strum very hard I hear loud crack.

This is the project

http://http://tagboardeffects.blogspot.fi/2016/03/hofner-buzztone.html

Couple pics of my board and wiring

[Astroman]

Transistor voltages:

Q1 C 4,6v B 1,16v E 0,55v

Q2 C 0,85 B 0,64v E 0 v

Q3 C 2,5v B 0,45v E 0v

[PMowdes]

Check the orientation of your transistors.  

[Astroman]

Orientation should be correct. I have checked that and removed all transistors one by one. I also change tranies. It is not working.

[Travis]

There are cuts and potential bridges on the back side of your board that don't look good to me. I'd use
A DMM to check for continuity where it should and shouldn't be

[Astroman]

I drilled cuts and checked with DMM the board and could not found failure. With my telecaster sound is clean exept if I hit strings hard. I tested today pedal with humbuckers and made short sample with iPhone how it is acting.


Sample file

[Astroman]

I have built completely new board. The Board was not the issue. I changed transistors to pieces which has higher hfe. Now it's like a fuzz but crack sound is still there. Is the transistors bias causing annoying sound? Below is link to new sound sample.

https://drive.google.com/open?id=0B4u4sxZ14IFPU2RCMENrWlcxak0

[PMowdes]

Sounds a bit gated

Have a look here

 http://www.geofex.com/fxdebug/bias_prob.htm

It should explain what the problem is and how to fix it.

[Travis]

Ok with that in mind it kinda narrows down the potential problems. Transistor selection and biasing are jumping out of course, but unfortunately I have not built this pedal so I can't offer very concise advice

One thing that would help would be to use an audio probe to see which transistor(s) has the issue

If it's right at the start, removing the 22K input resistor may help. You could just move the input wire down to the other leg of the 22K resistor to bypass it.

Some things to maybe tweak.. again if it's Q1 that's gating, adjusting the value of the 1K resistor from emitter to ground may help. You could try adding a bypass cap (typically electro 4.7uf to 47uf) from Q1 emitter to ground, parallel with that 1K resistor.

Of course collector resistors can be tweaked to adjust bias

Could be a bad cap too. If you have a bad batch of caps it could happen on more than one board. This is less likely the issue, but an audio probe would be a sure way to find out

[Astroman]

I added 33uF bypass cap parallel with 1k resistor and changed the Q2 to germanium AC187.  Changing Q2 was the magic move. No gating any more and made the sound sweet.

Q2 transistor voltage with AC187

C - 0,314v B - 0,104v E - 0v

Maybe collector voltage was to low with BC108( 0,7 v). I will try just for interest if I got it working with BC108 by adjusting collector voltage.