I tried germanium diodes on my Bum fuzz. and, noticed they reduces the volume dramatically. the maximum volume of the pedal was almost identical to guitar’s output volume. the pedal worked great with almost zero noise.
I came back to the silicon diodes. and, found out the reason why germanium diode clipper’s output level was that low.
The voltage drop of Germanium diodes is 0.35V while silicon’s is over 0.5V. the answer was simple and helpful.
they are the Germanium diodes I tried. bigger than the stock silicon diodes. the picture of stock silicon diodes is following it