I think it's a bias control I'm after?

[Switch]

Ok, so what I'm after is this sound I encountered once after some quick and dirty soldering on my guitar. What it was, was kind of like a gate. Sound would only come thru if I hit the strings hard enough, and the sustain would kinda frizzle out to nothing.

I've heard similar descriptions of wrongly biased transistors, like you can only hear the loud parts of the signal (it sounds like a rough gate) or you can only hear the soft parts of the signal, like when you hit it too hard it chokes out.

I wanna build a pedal that can do this, preferably with a foot pedal to control the parameter in question.

Is this doable?

[petemoore]

Ok, so what I'm after is this sound I encountered once after some quick and dirty soldering on my guitar. What it was, was kind of like a gate. Sound would only come thru if I hit the strings hard enough, and the sustain would kinda frizzle out to nothing.
I've heard similar descriptions of wrongly biased transistors, like you can only hear the loud parts of the signal (it sounds like a rough gate) or you can only hear the soft parts of the signal, like when you hit it too hard it chokes out.

I wanna build a pedal that can do this, preferably with a foot pedal to control the parameter in question.
  The hard part of the treadle pedal is getting the treadle-pot drive system, check Search for 'DIY Wah Pedal'. Maybe a Wah pedal/pot?...ez way is tie a ziptie around the potshaft...
  Anyway, the FF makes a cool gating sound, use of a 20k will allow bias to be move I think past both sides of optimal bias, shutting the signal down totally...but can be made to only go from gating w/ low bias, proper bias and high bias by using...stop and tapering resistors, the actual low and high resistance value settings of the pot will depend on the resistors, perhaps something like a 10k pot with a 4k7 stop resistor.

Is this doable?

[Switch]

Cool cool, so it does certainly seem doable. 

Now, can this sort of effect be achieved without the fuzz/high gain like in a Fuzz Face? If possible, it'd be handy to be able to do it without fuzz/overdrive.

Also, I'm really quite n00btacular with circuit building, but this seems to me just like a true bypass circuit, with this little fancy bias sorta thing thrown in the signal path. Am I right in thinking that?

[Somicide]

true bypass only refers to the switching method used.  http://www.generalguitargadgets.com/index.php?option=content&task=view&id=172&Itemid=200 this shows the switching options here, not sure if it explains it so I'll do my best.  True bypass has your signal either going straight through to your amp, or through the circuit.  The bypass is like the freeway, and when the switch is pressed it's the detour through the circuit.  The other method using a simpler switch has the output jack connecting to both the circuit output and bypass output.  The switch here works more like track switches for trains. 

[Switch]

Yah yah, thanks Somicide, I know about the wonders of true bypass, I've built a true bypass box myself actually to get around my boss gt-3.

What I mean is like, this new box, it would be a true bypass circuit, while it's on the signal would be going thru this 'bias control/choker thing' circuit, and while it's off the signal just goes thru to the amp. I think i'm right in thinking that?

Anyhoo, so does anyone know what'd be involved in building this circuit? It seems like a bias control kinda thing, so I'd just need a clean-ish sounding transistor and I'd have a variable resistor (pot) going into the base emiter? 

[Switch]

Anyhoo, so does anyone know what'd be involved in building this circuit? It seems like a bias control kinda thing, so I'd just need a clean-ish sounding transistor and I'd have a variable resistor (pot) going into the base emiter? 

[aron]

I think you could it with any single transistor circuit - like a FET preamp circuit or something like the LPB-1. Then you need to use a pot value that's smaller than the bias range you are looking at. Then I would use a wah pedal or expression pedal (like the Bespeco) to patch into the box or build it right into the expression pedal.

Seems like you would have the collector then a trim pot, then the expression pedal pot, then another trim pot. Both trims control the boundaries of the pedal sweep. All of this is in series. Collector (or Drain)->trim->expression pedal pot-> trim->V+.

You should be able to go from gated to clean. It can also be done with the emitter resistor, but there's less travel resistance there (you need a much smaller value pot).

[Switch]

Ahh dude! You're quite fantastic! 

So this setup you're suggesting, it'd go from gated to clean, could it also go to, err, 'reverse gating'? As in, cutting off the peaks of the signal?