Low level "buzz" in a digital unit????

[akozols]

Hi,

  It's not a question about a built unit, but I figure you will be familiar with the problem.  I have a Bozz ME-X, which is a multi-effect made about 15 years ago.  It doesn't have any distortion but has EQ, delay, chorus, flange, picth, and reverb.  

 When I play thru the unit, whether thru an amp or headphones, I hear a very low level "distorted version" of what I'm playing.  It's probably at 5% volume compared to the normal signal.  In fact, even if I have all the effects bypassed, I can still hear it.  

 You really can't notice it's there unless you intently listen for it.  Do you think it's caused by something, or is it just the nature of an older multi-effect unit?  I do have a schematic and could probalbly borrow a scope to try to see where it starts.



thanks,  al.

[Boofhead]

I'd start with the fact the bypassed signal has the distortion, this knocks out a *lot* of circuitry.   Undoubtably the unit uses JFET switching so follow that through, there might be something weird about it.  One possibility is a dodgy JFET.

Keep in mind though, one of the effect stages could still affect the signal - it depends exactly how the switching is done - I haven't seen a schematic for these so I can only speculate.

Unless there's something obvious from the schematic, the next best bet would be to start pulling out the switching JFETs in the effects path.  If you find a troublesome point then start looking closer at that part of the ckt - perhaps change the JFET.

[akozols]

Thanks,

  Right now I have the thing in pieces and have already eliminated alot of circuitry.  I'm stipping the guts to go from a 25" by 16" box to a small 10 by 10 box that can sit on top of the amp, just by removing uneeded stuff.  Perhaps I'll find something along the way.

thanks,  Al.