Ok, I've sourced 2 x 2N404 Ge trannies with hfe of Q1=72 and Q2=130, and leakages are Q1= 15uA and Q2=65uA, it sounds killer until about 3 o'clock where some fizz creeps in with each note picked and the sustain dies like you can hear the transistors shutting off. I've tested the trannies myself (the correct way and not just with the DMM function) and matches with what I was given. This is a sunface clone http://tagboardeffects.blogspot.com.au/ ... kt275.html, it appears to be biased ok as I'm measuring 4.5v on the Q2 collector with the bias knob at around 2 o'clock. Is this normal?
I even breadboarded the thing again with another batch of components but same trannies and it still does the exact same thing.
Any ideas greatly appreciated, thanks.
BYOC Ge Fuzz face fizzy and no sustain at high gain
-
poiureza
- Breadboard Brother
It looks like the bias gets off with full gain.
Can you measure the Voltages at Q1 and Q2 at 7'oclock and 3'oclock gain settings ?
What is your sun dial setting ? 2'oclock gives you 4.5V @Q2c with max or min gain setting ?
You could always swap the 33k resistor for say 47k or 20k and see how it goes ... sometimes it works
Sooooooooo much depends on the particular hfe values and leakages in this circuit ...
Can you measure the Voltages at Q1 and Q2 at 7'oclock and 3'oclock gain settings ?
What is your sun dial setting ? 2'oclock gives you 4.5V @Q2c with max or min gain setting ?
You could always swap the 33k resistor for say 47k or 20k and see how it goes ... sometimes it works
Sooooooooo much depends on the particular hfe values and leakages in this circuit ...