Author Topic: question about making a big muff with an jfet based input and output stage  (Read 2768 times)

jubal81

There was a contest recently for alternatives to build on a muff PCB and I did JFETs all around. Came out great.
https://forum.pedalpcb.com/threads/what-another-contest.10105/page-9




snow123

Q1 (J201):
D: 2.75
S: 0.00
G: 0.47

Are you sure about Q1 as J201 n-channel JFET..??
yes? i'm using SMD j201s that i soldered onto a through hole adapter board

antonis

There was a contest recently for alternatives to build on a muff PCB and I did JFETs all around. Came out great.
https://forum.pedalpcb.com/threads/what-another-contest.10105/page-9


I'm not sure if snow123 would approve the above JFET "anorthodox" (according to his own standards) bias configurations.. :icon_wink:
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

snow123

There was a contest recently for alternatives to build on a muff PCB and I did JFETs all around. Came out great.
https://forum.pedalpcb.com/threads/what-another-contest.10105/page-9


I'm not sure if snow123 would approve the above JFET "anorthodox" (according to his own standards) bias configurations.. :icon_wink:
tbh i just dialed it in to where it sounded best, and didn't measure until afterwards.

PRR

There was a contest recently for alternatives to build on a muff PCB and I did JFETs all around.
https://i.postimg.cc/tsDrzvSQ/Fuzzduster-SCH.png

As I see that drawing: Q2 Gate has no DC path. If it works it depends on PCB leakage, which is unreliable.
« Last Edit: May 27, 2022, 05:41:38 PM by PRR »
  • SUPPORTER

antonis

As I see that drawing: Q2 Gate has no DC path.

At a first glance, I saw the same thing, Paul..

But it actually does have via R7, C4 short, Sustain wiper and R6..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

duck_arse

As I see that drawing: Q2 Gate has no DC path.

At a first glance, I saw the same thing, Paul..

But it actually does have via R7, C4 short, Sustain wiper and R6..

me counts three.
let's not mention the football

antonis

So, does that make us a crowd..??

P.S.
Finally, snow123 threads DO have "juice"..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

jubal81

There was a contest recently for alternatives to build on a muff PCB and I did JFETs all around. Came out great.
https://forum.pedalpcb.com/threads/what-another-contest.10105/page-9


I'm not sure if snow123 would approve the above JFET "anorthodox" (according to his own standards) bias configurations.. :icon_wink:

If it looks weird, it's drawn to be built on a PedalPCB Muff PCB. C4 is a jumper. The treble bypass on the gain control and Q1 bypass cap have to be added extra to the PCB, the orphaned resistors are left empty and the numbering matches the PCB exactly.
« Last Edit: May 28, 2022, 04:48:12 PM by jubal81 »

snow123

also, using J201s for Q2 and Q3 makes it clean up almost like a fuzz face.

To make the J201s work, I connected the sources of Q2 and Q3 to ground, used 5.1k for R10 and R16, and I lowered R7 and R12 to 2.2k to boost the gain a bit.

antonis

To make the J201s work, I connected the sources of Q2 and Q3 to ground, used 5.1k for R10 and R16, and I lowered R7 and R12 to 2.2k to boost the gain a bit.

May I notice that the above aren't in compliance with any schematic posted by you (till now, at least..)..??
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Phend

What will this new J Muff be called ?
  • SUPPORTER+
Fase or Phuzz that is the question.

snow123

What will this new J Muff be called ?
idk, JFET muff? im bad with naming things lol

snow123

To make the J201s work, I connected the sources of Q2 and Q3 to ground, used 5.1k for R10 and R16, and I lowered R7 and R12 to 2.2k to boost the gain a bit.

May I notice that the above aren't in compliance with any schematic posted by you (till now, at least..)..??
the names are in compliance with the last schem i posted (reply #55), but the values aren't.

duck_arse

I retract my previous comment, about "finished".
let's not mention the football

amptramp

What will this new J Muff be called ?
idk, JFET muff? im bad with naming things lol

Pinchoff Muff would keep everybody guessing.

anotherjim

Mufa Fett.
Croeso i Diystompboxes.

I have no April 1st project