Well, 2 years ago when I started to search for period correct parts , #40 was one of the more visually documented of the type. However, outside of the preamp board, i'm using some values in other places that are actual values taken from an amp in the same range of S/N's.
Structo wrote:Looking good TM.
Are you going to use a film cap for the presence?
I finally installed my FET board yesterday!
Thanks Tom,
Yeah I debated whether to install a tant or not, but in the spirit of the build I went ahead and installed a fim cap. It worked out because I just happened to have some large values orange film cap.
How do you like the FET? Did you use the stock cap values?
TM
I had a bunch of notes I collected about the FET and I used Jason's FET board.
I did change C3 to 22uF and the input ceramic to 470pf.
Hopefully the 22uF won't be too large but I wanted it to bypass full range.
The 470pf is supposed to flatten the high end a bit.
I wired in a pot for R3 and R5 to dial in the bias voltage and supply voltage.
I ended up with a 1.5K for R3 and a 20K for R5.
Weird but that is where I got the 20v and 10v.
But my dropping string is also different from the Dumbles.
Everybody's amps are probably different as far as the FET bias goes.
David Root wrote:Tom, Mike, I use NTE 452 in my FETs and I find 22K and 2K5 works pretty close.
David, I have a 2N4416A on this board with 2.2k and 22k resistors. I'm hoping this will get me close. The only other real changes are a 120pf cap and 10uF source cap.
