The Amp Garage

Either way would be fine. I don’t think the power stage voltage is all that critical, and you can adjust the first dropping resistor as needed. Maybe make the call based on source, cost, and shipping charges incurred?

Would i still be changing the 820R to a 1.2k or could I just change the 47R to a 33R? Either way will work for you since there is no presence control. If there were, changing the PI tail resistor would change the frequency response of the feedback, which would require a change to the presence cap v...

Yes, yours matches the hand-drawn schematic.

This comes up all the time. You can keep the same feedback resistor on the same tap, and put the speaker on whichever one it matches, or, move the feedback resistor to the tap the speaker is on, and adjust it's value by (New Spkr Tap/Old Spkr Tap)^0.5 Given the secondary hookup for the 1620, you wil...

No problem, and it basically reduces the output 1 dB if the feedback goes direct to the grid. Other than that, I don't know.

GAStan wrote: ↑Mon Apr 22, 2024 6:35 pmWould I have won? :wink:

You have a point there :^) To me, one component being in series with another means they have the same current.

GAStan wrote: ↑Mon Apr 22, 2024 5:59 pmDid I get it correct?

Would you have bet money that you did? ;^)

Hi Ryan, it's this. As drawn vs. the red. Your layout shows the red.

Raoul Duke wrote: ↑Mon Apr 22, 2024 12:32 pm I wonder how the layout’s dropping string values would interact with a Bassman spec PT? I realize the PI is different and that plays a part.

By the time you get to the preamp nodes it doesn't mater. If you keep the same dropping string, B+3 to 4, and B+4 to 5, the PI will fall into place.

The swap between the 10k & 2.2M was either a tip I received from someone (likely) or based on observation of other amps. The stability of the reverb was not great with 2m2 in series with the reverb send pot. I also realized that feedback made much more sense with 2m2 and the 10k in series with the ...

Re the voltages, most important is to get the V1 plates into line. As I said, I don't have any direct BM experience, and there aren't any voltages listed on the layout. The TF-130 PT was a Fender Twin replacement, so you should shoot for 440-450V B+1. I think I’m hung up on all the different color r...

Cheap, too!

sluckey wrote: ↑Thu Apr 18, 2024 4:43 pm I just installed a 100K master volume pot in my single channel DR. Lets you control how much signal is sent to the PI. Works fine for me. Take a look...
https://sluckeyamps.com/tdr/tdr.pdf

Gotta say, this is a really nice little amp! Love the look, too.

I have no idea why Fender wanted such high voltage on the reissue Bassman. The original 5F6-A voltage was shown at 450V. That OT look like the solution I think it is? Should be fine. I think you'd be good with the Black Bassman PT, or maybe Hammond 290DX. ...just trying to figure out the V1 resistor...

The Bassman RI would produce a pretty high B+1 voltage, 490V on the '59 Bassman reissue schematic. You could use it and drop the PI and preamp voltages down as you have done before.