Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dogburn on January 18, 2026, 10:33:29 am
-
Quick question: I'm starting to build an AA1164 Princeton Reverb, and I've got a 330-0-330 V PT that came along with the cabinet I bought (basically this was someone's abandoned project). Since I'm not sure if the PT 5V tap has the current to handle the usual 5U4 rectifier, I'm planning to use a 5V4. The question then is what should the value be for the first filter cap? I've got a 40-20-20-20 cap can and was planning to use the 40uF for the first cap, but I've read recently that the 5V4 should have a lower value for that cap.
So my current plan is to skip the 40 and use the three 20uF caps in the can plus add a 20uF cap on the board (for the preamp tubes, grounded on the preamp ground buss). Is that a reasonable way to go? Don't really have space for a board for four separate caps
Here's the standard schematic just in case:
https://el34world.com/charts/Schematics/files/Fender/Fender_princeton_reverb_aa1164_schematic.pdf
-
I would use the 40 for the first filter cap. But it you are really concerned, use one of the 20s for the first filter cap and use the 40 for node D. I don't see the need to use an additional 20 on the board.
-
Thanks!
-
I like to use the Allen Amps system. A separate 22U cap mounted on a terminal strip for the first (reservoir) capacitor. The power transformer center tap is connected directly to the reservoir cap ground. A jumper connects them to the cap can ground. That helped with the reverb hum I was having in my Princeton Reverb builds.
Also helpful was using a 220u cathode bypass cap on the reverb recovery triode. I suggest buying one with your next parts order just in case.