innerlight
Active member
PREAMBLE/RAMBLE:
Hello everyone!
Let me start by saying I HATE JFETs. If I build a pedal and it has a frustrating problem you can bet it has a JFET.
Rant over!!
That aside, I just built a Chop Shop after much recommendation from the forum. I've read all the tutorial posts from people talking through the calibration process.
The pedal is passing signal, and it seems like its all good to go except the calibration.
The JFETs are SMT bought from pedal PCB. I didnt know how to pre test their values so i chose two at random. I figured it has the trimmer pots so I can get them in the range right?
THE CONFUSING PROBLEM:
I calibrated Q1 and Q2 to within 6-6.6V as recommended, no problem there (photos included for each). With sag pot on minimum (full CCW), volume and gain maxed.
Pedal sounds fine (really good even) on that setting. HOWEVER as i increase the sag pot, wild squealing happens akin to a gated fuzz or feedback. I used a 2N222A transistor and it is inserted with the orientation matching the silk screen, is this correct? I tested all resistors before soldering so I know theyre ok.
Can someone please advise? I am officially lost. Seems like my build is fine and the problem lies in the JFETS. Should I de-solder those and try some other ones?
Any advice greatly appreciated
Hello everyone!
Let me start by saying I HATE JFETs. If I build a pedal and it has a frustrating problem you can bet it has a JFET.
Rant over!!
That aside, I just built a Chop Shop after much recommendation from the forum. I've read all the tutorial posts from people talking through the calibration process.
The pedal is passing signal, and it seems like its all good to go except the calibration.
The JFETs are SMT bought from pedal PCB. I didnt know how to pre test their values so i chose two at random. I figured it has the trimmer pots so I can get them in the range right?
THE CONFUSING PROBLEM:
I calibrated Q1 and Q2 to within 6-6.6V as recommended, no problem there (photos included for each). With sag pot on minimum (full CCW), volume and gain maxed.
Pedal sounds fine (really good even) on that setting. HOWEVER as i increase the sag pot, wild squealing happens akin to a gated fuzz or feedback. I used a 2N222A transistor and it is inserted with the orientation matching the silk screen, is this correct? I tested all resistors before soldering so I know theyre ok.
Can someone please advise? I am officially lost. Seems like my build is fine and the problem lies in the JFETS. Should I de-solder those and try some other ones?
Any advice greatly appreciated
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