Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: blown240 on November 01, 2011, 01:58:48 pm
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This is the first layout I have ever setup myself. Please let me know if there are any glaring errors.
Thanks!!
Red = Capacitors
Blue = Resistors
(http://i268.photobucket.com/albums/jj26/thebattens/Upright%20Preamp/B15nchannelboardcopy.jpg)
Its based on this section of schematic:
(http://i268.photobucket.com/albums/jj26/thebattens/Upright%20Preamp/preampboardschematic.jpg)
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Screen or grid?
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I would think that you'd want a Log pot for VR1.
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Since I've been following the other threads, and I know what you are doing with this,, I'd suggest putting all the plate R's, coupling caps, and cathode R's (so thats R8,R7,C3,R16,R15,C10) on a separate board with the CF circuit, and put all the tone stack stuff on its own board. I think you'll be fiddling with the tone stack components a lot more than the basic gain stage and CF components...
I'd move R2 and R5 off the board and as close to the tube pin as possible. maybe a short tag strip next to the tube socket and let the grid stopper (R2) be soldered directly to the grid pin with the body of the resistor as close to the tube socket's "pin tag" as possible. you could even put R5 on the other side of R2, back at the switched input jack if you want (like a blackface fender). run shielded wire between R2 and the input jack with the shield chassis grounded at one end or the other.. Ampegs ran shielded wire from socket to eyelet board wherever instrument signal was carried (findsome gut shots of some bluechecks online).
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Thanks for the replies.
Not a bad idea putting the tone stack on its own board. Maybe I should do 1 board with the tone stacks for both channels on it. Then 1 board for plate R's, coupling caps, and cathode R's. And maybe a 3rd for the CF.
I will probably also have a small board for the rectifier.
I plan on making my own chassis for this project, so space wont really be an issue, although I don't want it to be HUGE.
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The size of the layout/schem pics are too big to keep going back and forth and comparing. You also are missing the sockets and some other things to the layout. We can't see what you're planning for the grounding scheme, the smoothing caps, etc. You don't need a bunch of boards if you do this correctly. But as said earlier, grid resistors directly to pin sockets is best. It appears your ground could be on the "controls" side and some of the parts marked canthode & anoded should be directed on the socket's side since that where they're heading (if & when possible). Keep your grid wires short and away from higher signal and/or current sources or shield as needed and these cannot be avoided. There's much more but hard to say what is what the way things are presently and w/ the various missing info.