Help with ROG Multiface

[boedonaldson]

Howdy, i just built the multiface off ROG and i am having a problem. I have 2 2n5088 (BC 549) trannies in the sockets and a 0.12uf caps in teh input and output sockets. The problem is that when i turn up the volume knob i get the fuzz but also an extremely high pitched squeal. Any suggestions or help is greatly appreciated.

[burnt fingers]

Ahhhh the squeal of a fuzz.  My Fuzz Face did the same thing.  First, try to shorten the input and output wires to eliminate any noise ( if you can shorten them).

  That's the only thing that did any good on mine but it still squeals if I use 5088 or 5089's in bothe sockets.  You can try to use a lower gain tranny. 

The plus side, of my build anyway, was that i was testing late at night and was turning the volume on the fuzz way up to hear it.  When I tried the next day, at normal volumes, I realized that I didn't need half the volume on the fuzz, so at about 11 oclock on the dial, it's sufficiantly loud.  I still replaced q2 with an mps2369.  It sounds real good and no squeal unless both knobs are dimed.


Found my old thread
http://www.diystompboxes.com/smfforum/index.php?topic=42227.msg305706#msg305706


Scott

[boedonaldson]

I notice that when i turn the 10k trimpot the frequency of the squeal goes from lower to higher. My god this squeal nearly killed my hearing. How should i wire the volume pot? I may have it wired wrong!

[petemoore]

  I made the mistake of looking at a FF with the output cap coming right off the collector, I like it less loud the way it sounds coming from between Q2CR and the ~1k.
  If the FF is squealing, altering the bias also alters gain, the pitch and amplitude of the squeal will change.
 
 

[boedonaldson]

By the way this is the multiface, not the fuzzface. Just a couple more things i noticed: It is not the volume control as i went straight from teh output cap to teh output socket and it done the same thing. When i removed the outut cap there was no squeal, but no fuzz either. I have the grounds on the input/output sockets grounded to each other but not teh circuit, should i ground this? What are some lower gain trannies to try (mine on teh front say things like BC547,549 etc, what are these subititutions of?) Help would be appreciated,cheers.

[zjokka]

You're definitely grounding to much, look at the lower line in the layout that's marked GND ( http://www.runoffgroove.com/multiface.html ).
Input cap isn't grounded directly. I would start off with equal input and output caps, but that wouldn't hurt the setup.

As far as compatible transistors are concerned, just TRY anything you have (as long as it is NPN). That's the whole point of the Multiface.

Also don't forget to read the SILI FACE page, there's some info on how to fight off the noise, and in fact, the MULTIFACE is a SILICON FUZZ FACE is a FUZZ FACE.

good luck still!
ZJ