EQD Bellows/ Barrage Fuzz

[HamishR]

Here is Mr PCB's schematic:



Is this an example of a designer using a JFET backwards on purpose? Why would they do that? I know JFETS can be used like this but does it serve any function? What would happen if I was to turn it 180 degrees to put the drain where gate is and vice versa? Anything?

FWIW I built it exactly as per schematic and it sounds pretty good. I used a 2N5457 because I don't have any PF5102s and I have 1.17 VDC on the Drain and 1.6VDC on the Source. Sounds low to me (but what do I know??). Would it benefit from a higher Source voltage?

 

[giovanni]

I don’t think you can change the orientation. The JFET here seems to work as part of a feedback loop for Q2. I’m not familiar with this configuration, but since JFETs have very high input impedance, my guess is that it must have some advantages over a simple resistor.

 

[HamishR]

I think you're right. I tried a J113 in there and prefer the 2N5457. It sounds good with a P90 but not so good with a Strat. It's almost gatey with a Strat. Weird.

 

[geoffrey]

It is weird. I built the Moonn electronics version of this circuit and gatey is exactly how I'd describe how it sounded with my Strat. But that was with a 2N5457. I switched that out for a J201 and it sounds good

 

[HamishR]

Hmmm... Maybe I'll try a J201. I have plenty!

FWIW I did try reversing the 2N5457. No sound. You know, maybe you can't believe everything you read on the internet.

 

[Vilain]

I think you're right. I tried a J113 in there and prefer the 2N5457. It sounds good with a P90 but not so good with a Strat. It's almost gatey with a Strat. Weird.

I LOVE it with my SG special and home built Carmen Ghia. I can forget about time for hours playing with that simple set up.

 

[mdc]

It's a bazz fuss variant with the JFET acting as the diode.

 

[HamishR]

Oh, that makes some kinda sense! Thanks!