Reply To: 6/12SN7 pre amp universal build

[marchunter]

Well well well, I have finished wiring my pre amp. The last thing I finished this morning was the heaters. Jim as usual was very generous with his answering my questions.
I wired it as to what I see depicted in the schematic. Jim tells me he would wire it a bit different and I can’t wait to see it. However he told me what I did will work fine. I’m trying to follow Jim’s design closely so that he and Charles can evaluate.
I then started to test the system and gave myself another problem right off the bat. I wasn’t getting the drop in voltage I was expecting. I only was getting .23 of a volt. This is where I figured out I’m not so smart. I was using the tubes Jim supplied with the kit. 12 volt tubes. Yes I know I’m stupid. I figured it out when I put a set of 6SN7s I have and got the perfect voltage drop then swapped the supplied to back in and again got a small drop. I then looked at them closely and saw, yes you are a moron, they are 12 volt. I write this down to keep others from doing the same thing.
Upshot is the heater circuit works perfectly.
I’m just waiting for a couple caps to install then I will be entirely done.
THANK YOU JIM.