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2 Knob Bender

5/10/2000 9:29 AM
2 Knob Bender
Just on a whim I whipped up the 3 transistor bender soon to be published. I also added the Sweet Thing tone control on the end - FET and all.  
It sounds good/ok. It took a while to get a few transistors that sounded good.  
The hFE are 123, 73 and 103 right now. The hFE really matters. Although I put trimmers in there, it didn't really work too well. Only a small range of the trimmer works well.  
I will get the 2 knob specs out tomorrow. I forgot one of the schematics at work. Darn!  
I don't know about the germanium sound.... We will see....  
How many of you really like it for regular use?  
I think I have made about 10 pure Fuzz Face variations - they sound ok, just not something that I could use all the time. I've tried NTE, SBxxx, 2N388A, xstrs from the local store (yeah they still got germaniums) etc...  
I like the sound of germaniums going direct through a simulator - great angry sound!
5/10/2000 7:20 PM
Could only find one schematic of the Supa Fuzz online. A European site with a hand-drawn schematic of the Marshall version. Yugoslavian?  
So is this Supa Fuzz the same as the Sola Sound Pro Mk.II ToneBender or no? It's difficult to make out some of the component values.  
Here's the link:  
This guy has several schematix up. Don't know if they're lifted. Many of you guys probably already know of this site.  
The parent site:  
BTW, do HTML tags work at this forum?  
Guess I could try a bit and see.  
Sorry if this bombs.  
Hey it didn't - decent!  
5/10/2000 8:18 PM
"This guy has several schematix up. Don't know if they're lifted."
It's mostly the same old assortment of stuff lifted from the schematics archive, my site, Jack's site, and a couple of others. The supa-fuzz is different, haven't seen that one before, so maybe there's another place with some new ones.  
I guess you have to be careful what you download. I notice that the TS808/9/10 "wiring diagram" is actually the wiring diagram that went out with my now-obsolete and unavailable small-board screamer PCB. I guess somebody thought it was worthwhile to scan it and post it. Heh, heh, heh - can't wait to seen what happens when that wiring is used on a real tube screamer 8-)
5/10/2000 8:32 PM
Steve Daniels (Small Bear Electronics)

The first stage looks weird to me. He shows 10K base resistor to common and 10K collector resistor to V-. I might buy an emitter follower config for this stage, but that's not what he shows. Output is from collector. Comment, R. G. or others?
5/10/2000 9:00 PM
supa fuzz
thats the old leakage bias setup. It is a booster stage for even more gain into the FF stage. That M1 resistor is a 100k not 1meg thats an old style marking I believe. That 10k input z helps cut down the highs. This looks ok if I was to build it I would change the input transistor to Si and set up the boost section a little differently
5/11/2000 8:40 PM
Tobias Karlsson

"thats the old leakage bias setup. "
I HATE that setup, I remember when we at “Ampage” (RG, John G, etc) tried to figure out how the “Olson New Sound” was supposed to work and sound. I tweaked it in any kind of way that was suggested, never got it to sound like something someone actually would want to use.  
It also had that leakage bias setup.  
Crazy to construct effects that relies on some kind of “defect” in the components!!  
Best Regards  
Tobias Karlsson in Sweden
5/10/2000 9:05 PM
R.G. Re: 2 Knob Bender
Confusing, isn't it?  
What's really going on is that germanium is actually slightly forward biased with a resistor from base to emitter. You have to *reverse* bias the base-emitter by a fraction of a volt to really turn off the collector.  
Another name for this is "leakage bias" although that's not strictly accurate.  
...oops, I mean "GEO"...

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