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View Full Version : I need help with new 5f11 build--little volume


pjhalliday
02-14-2008, 03:12 PM
I have recently finished building a 5f11 copy, but am having some trouble getting it to work. I am getting very little sound out of the speaker and what does come out is very buzzy/distorted, decays quickly or cuts out, and is not very consistent. I have traced the circuit repeatedly--not that I couldn't have missed something--and have tried tubes from a working amp that I believe to be good. I am new to amp building and wuold appreciate any suggestions as to common errors/problems that could result in a problem like this. Thanks a lot.

Pete

MWJB
02-14-2008, 03:24 PM
What voltages do you get at the tubesockets?

Any pics of the circuit board?

pjhalliday
02-14-2008, 04:14 PM
The voltages are typically about 30% higher than called for in the schematic (b+ 420 rather than 340, etc.). I was attributing this to the combination of higher line voltage and a Sovtek 5Y3GT which I read does not provide the 50 V drop of a real 5Y3 tube. I'll need to get you a picture of the board.

pjhalliday
02-14-2008, 05:01 PM
Here is a picture of the board.

http://s269.photobucket.com/albums/jj53/pjhalliday/?action=view&current=IMG_6869_s.jpg

And the link...

http://s269.photobucket.com/albums/jj53/pjhalliday/?action=view&current=IMG_6869_s.jpg

MWJB
02-14-2008, 05:07 PM
Thanks PJ, but I was rather hoping for specifics, pin by pin.

What plate current do you have on the power tubes?

pjhalliday
02-14-2008, 05:33 PM
Thank you for insisting on the pin voltages! I missed a connection between pin 4 and the + side of the second filter cap. I'll get that on later today and get back with the results.

pjhalliday
02-15-2008, 01:42 AM
It turns out that after making that connection and swapping the output transformer leads to eliminate a squeal I have a fantastic sounding amp!