Fuzzduster JFET Muff

[jubal81]

I liked my design from Chuck's contest so much I got a PPCB Muffin board and got it all boxed up.

The schematic is in the link, but the general idea is it's pretty much a Big Muff made over with all JFET transistors - including using them for the clipping diodes. The tone control is modified to a simple treble cut instead of the typical scooped Muff sound, so it really cuts through.

I also added a switch to take the source bypass cap on the first stage out of the circuit to make a 'high gain/low gain' toggle.

Ended up using BF862 JFETs since I have a pretty good stash. The minimum IDSS on these is 10mA, so I dropped to a 2.7K resistor on the drain since I've got a lot of resistor values in stock below 1K. The source resistors ended up between 330R and 470R and the drain voltages around 5.5V.

 

[Chuck D. Bones]

NIIIIIIIIIIIIICE!

Somebody has a JFET fetish.

 

[jubal81]

NIIIIIIIIIIIIICE!

Somebody has a JFET fetish.

 

[jeffwhitfield]

NIIIIIIIIIIIIICE!

Somebody has a JFET fetish.

A...JFETish?

 

[jubal81]

A...JFETish?

 

[fig]

Very cool, and complete (unlike some people's)!

Is that a relay in there or are you just happy to see me?

 

[Chuck D. Bones]

I just fired up my FuzzDuster breadboard and it rips! Lotta sustain, no noise. Thick sound, just like a Muff. I like your tone control.

The FETs I selected for Q1-Q3 ended up with 10K drain resistors and 330Ω source resistors. With source resistors that low, no bypass cap was req'd. Q4 has 10K on the drain and 2.2K on the source. Drain voltages are 5.1V, 5.5V, 5.5V, 5.0V, respectively. I used BA482s for the clipping diodes since they have the same V-I curve as some of my JFETs.

I'm going to try fiddling a couple of component values to see what happens...

 

[jubal81]

I just fired up my FuzzDuster breadboard and it rips! Lotta sustain, no noise. Thick sound, just like a Muff. I like your tone control.

The FETs I selected for Q1-Q3 ended up with 10K drain resistors and 330Ω source resistors. With source resistors that low, no bypass cap was req'd. Q4 has 10K on the drain and 2.2K on the source. Drain voltages are 5.1V, 5.5V, 5.5V, 5.0V, respectively. I used BA482s for the clipping diodes since they have the same V-I curve as some of my JFETs.

I'm going to try fiddling a couple of component values to see what happens...

Whew, those are some hot FETs!
I gotta get me some 482s. I really dig the raunchiness from those clippers.

 

[Chuck D. Bones]

Not that hot, Vp is around -0.8V and Idss is around 1.9mA.

I'm gonna try LEDs (4S&G).

 

[djmiyta]

U

Not that hot, Vp is around -0.8V and Idss is around 1.9mA.

I'm gonna try LEDs (4S&G).

LED’s seem to always win out for clipping for me more volume and smooth crunch on rare occasions an LED and schottky(?)sound amazing sockets are some of my best friends