Germanium Diode Filters? (was: EMS Schematics)

[Don Tillman]

   From: Christopher_List at Sonymusic.Com
   Date: Mon, 4 Nov 1996 11:37:05 -0400

   People use germanium diodes in fuzz-boxes to get more tube-like
   distortion - yes?  My understanding is that this is because they don't
   have as sharp of a cutoff between on and off as silicon diodes. 

No, people do not use germanium diodes in fuzz boxes to get more
tube-like sounds.  The Fuzz Face is the famous fuzz box that used
germaniums (initially) and it sounds nothing remotely like a tube amp.
That was the point, actually.  I mean, distorto tube amps were readily
available, tuned buzz-saws were not.  It's still used today because it
sounds pretty cool, but nothing like a tube amp.

   What would be the eefect of making a diode filter with germanium
   diodes? 

Well try it, and report back what you find!

I've run a guitar signal into a pair of back-to-back germaniums under
various conditions and I was completely surprised at how awful it
sounded.  Really.  Sort of sitar-like, a buzzy sproing.  Silicon
diodes and LEDs sounded much more like a tube amp.

FETs in the proper circuit can sound an awful lot like a classic tube
amp though.  I think I once proposed building an FET ladder filter
here, but you'd need to either ignore exponential tracking or build a
corrective CV circuit.

  -- Don