DIY Fuzz Face Problem

[Vlad7329]

Hi everyone. My first project. It is fuzz face on germanium transistors on a breadboard. Transistors are Soviet mp41a and mp42b, I measured their hfe and it's fine. Both pots are linear.
The problem is the following: when I plug in guitar to my sound interface through my fuzz face, it works without battery. The sound is old school low gain fuzz , actually tone without battery is very cool. But as soon as I connect battery to the circuit there is no sound at all.
What can possibly be the problem? Why does it work withou battery? I am a newbie in electronics and I am confused.
I attach some pictures, schematic and sound samples (without battery:))

https://soundcloud.app.goo.gl/SRWVxV1PWwvqPAis6

[Bunkey]

Hi,

I can't see everything in the pics but it looks ok..
You haven't got the transistor pinout backwards, do you? (or the battery)

...But as soon as I connect battery to the circuit there is no sound at all.
What can possibly be the problem? Why does it work withou battery? I am a newbie in electronics and I am confused.

When there's no power you'll still let half the sound wave through the C-B transistor junction as it's just acting as a diode with a forward voltage (or threshold) of ~0.2v; this will give you asymmetrical half-wave clipping; then if you're connecting power the wrong way for the transistor and it's reverse biasing that transistor junction, the sound won't pass any more because the diode is switched off at a potential of 9v when the wave peak is only 1v at best and no longer passes the threshold (which is now 0.2v + 9v).

Check your battery polarity is right first, then check transistor pinouts and try swapping C & E around.

Good luck

[Vlad7329]

I tried swapping e and c, but I've got the same result: the pedal produces some fuzz, but the gain is low, also when I connect the battery it's the same story as before - the sounds stops altogether.

[Big Monk]

Voltage! We must have Voltage!

Post the schematic you used and measured voltages (plus source voltage).