Barnshart
Member
Just got finished building 2 Chop Shops. The first one I made appears to works just fine, however the second one has far more gain and starts to squeal and oscillate if the gain or sag knobs go to high.
These are my first jfet builds, but I'm almost certain I understand the biasing. I am using the SMD J201's that Robert solderd on for me.
I am setting my DMM to read DC current on a setting that simply reads as "20" which I assume means 20v.
I take the red probe of the DMM and place it on the biasing pad on the PCB, and my black probe I'm putting onto the middle leg of where the throughhole equivalent of the SMD transistor would go. Ive dialed in both sets of transistors in my pedals to 6.66 with ease. I'm certain each pair of transistors in both pedals are biased identically....
So what gives? Any idea why one might be a super gainy squaling monster?
These are my first jfet builds, but I'm almost certain I understand the biasing. I am using the SMD J201's that Robert solderd on for me.
I am setting my DMM to read DC current on a setting that simply reads as "20" which I assume means 20v.
I take the red probe of the DMM and place it on the biasing pad on the PCB, and my black probe I'm putting onto the middle leg of where the throughhole equivalent of the SMD transistor would go. Ive dialed in both sets of transistors in my pedals to 6.66 with ease. I'm certain each pair of transistors in both pedals are biased identically....
So what gives? Any idea why one might be a super gainy squaling monster?
