Decade Fuzz = Hisss ?

Started by MartyMart, June 01, 2006, 04:22:19 AM

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MartyMart

http://www.diystompboxes.com/smfforum/index.php?topic=32415.0

Here's the original link to the schematic, sounding great but I have a very high hiss, which
the treble pot doesn't really remove ( ruins the sound ) and I can't see what's wrong  :icon_redface:
Any hints to removing this would be much appreciated as I LOVE the tone of this circuit.

Perhaps it's just a bit of a high-gainer problem, lower cleaner settings are fine.
Sounds to me like it's in the 8Khz and above area.

MM.
"Success is the ability to go from one failure to another with no loss of enthusiasm"
My Website www.martinlister.com

Eb7+9

#1
Marty,

I haven't tried this circuit but two things that come to mind are: (i) the Rangemaster stage is very much prone to hiss, and (ii) the amount of Emitter/Source bypass - it's in every stage (!) ... the second point means all your devices/stages need good noise specs ...

I would try making the bias variable in the RM stage - making both the emitter load variable and also the 68k resistor (replaced by 100k trimmer) ... once you've got the option of setting bias accurately in that stage try swapping in different devices ... Ge's are notorious for noise and the stock RM biasing needs tuning for optimum performance in this regard ...

MartyMart

Thanks, I hadn't thought of it like that  :icon_redface:
I'll use an extra trim pot and "fine tune" :D

MM.
"Success is the ability to go from one failure to another with no loss of enthusiasm"
My Website www.martinlister.com

Ry

It has everything to do with the GE you're using.  I have a handful of them, some are noisier in this circuit than others.  I'm planning on trying emitter load mod posted above.

Thanks for the tip.