I'm having some problems with self oscillating/squeal in the boost mode.
This happens when volume and gain is at about 12 o'clock and more (only in Boost Mode)
I have matched the transistors and I use 33K for the bias resistors to get about 4.4 Volt at all testpoints.
Have anyone else experienced this?
I tested it outside the box and thought it had to do with all the long wires on the test rig.
I boxed it up and got the same result.
I tested all resistors and caps before I soldered them in. Normal mode works like it should.
EDIT:
I have now desoldered the transistors and bias resistors and soldered in sockets.
I got the j201's from Tayda.
EDIT2:
I got my TweedyBird up and running with J201's from the same Tayda batch and it's working fine.
Can someone with a black '65 clone crank the volme and gain pot in Boost mode and report back ?
I use a Jazzmaster with 1MEG pots btw.
EDIT3: Installed shielded cable from input jack to 3pdt switch and from 3pdt switch to input at board.
Did not help much.
If I add a buffer in front the problem is solved.
If I only tested that before butchering the board and installed sockets and destroyed a good transistor :D
Does not anyone else experience this?
If I dont plug anything in the input jack and turn up gain and volume in boost mode, it self oscillate like CRAZY.
btw. It sounds freaking AMAZING!
I got a production unit so I could compare mine with the real deal.
There are no 10pF's in the production unit, there are 3 100pF caps. (WIMA 100/100) I soldered one out to measure it, and it is 100pF.
When I swapped the three 10pF in my build with 100pF there are no more squeal.
Here is a photo of the production unit:
(http://home.online.no/~tv79/gitarnorge/galleri/Wampler%20black%2065.jpg)