Low output from a tweed princeton 5f2-a

[u2bela]

I have an original tweed princeton that I am having a problem with. It powers up and sounds ok except for the fact that it is about half as loud as it should be. I have had a silverface champ and have a valve jr that are both in the same power range and this thing isn't getting anywhere close to as loud as it should be. Now to the list of things that I have tried so far with no luck. I started with known good tubes, I tried switching in a different OT, cleaned the sockets and pots and have now tried switching out all of the resistors and all of the capacitors except for the filter caps. None of the caps in the amp were original, they had been replaced with sprague atoms and orange drops. All of the voltages seem to be within tolerance but I will list them below. The only things left are the tube sockets, filter caps, pots and PT. Everything that I have switched out so far I have had lying around, but the other stuff I will have to order and isn't exactly free so I figured I would ask some people that have a lot more experience than I do before I swap anything else. Any advice or suggestions would be greatly appreciated.

Readings at tube sockets with 119VAC:
12AX7
1. 186
2. 0
3. 1.4
4&5 6.8VAC
6. 192
7. 0
8. 1.3

6V6
1&2 grounded
3. 354
4. 328
5. 0
6. 0
7. 6.8VAC
8. 21

5y3
2&8 368
4&6 309VAC

[MWJB]

You say it's "half as loud as it should be", do you really mean that it's half as loud as the SF Champ & the Vr? I'd expect it to be, both those amps run their power tube at the higher end of their voltage range. What happens when you fit a GZ34/5AR4 or a 5V4 to the 5F2?

[u2bela]

For another reference I played it on 12 next to a silvertone amp-in-case that can't be more than 1-2W and there was no difference in volume and the silvertone is running through a little 6" speaker. There is definitely something not right. I threw a 5U4 in there briefly just to see if it would make a difference but it didn't. I am really pulling my hair out on this one.

[MWJB]

Don't keep the 5U4 in there, it draws 3A, most Princeton/Champ style PTs only have a 2A rectifier winding.

Connect a true RMS AC voltmeter accross the 5F2A's speaker terminals & play...the reading will fly around some but try and determine an average. Square the average voltage, then divide by speaker impedance...what do you get?

Please post photos of the 5F2A dircuit, input jacks, tube socket wiring.

[u2bela]

Ok I took the measurements and got an average of about 1VAC across the speaker and it is a 4ohm speaker which would equal .25 VAC?

I just had the 5U4 in there for a second to rule out the rectifier tube.

Here are some photos. You will have to excuse the sloppy soldering on the resistors. I just wanted to swap them out real quick so that I could rule them out as the culprit and then I would put the original carbon comp ones back in.

[MWJB]

OK, you pretty well ruled out the rectifier already, with 309VAC from the PT and 368vdc at the first filter cap, that equates to a multiplier of x1.19...ball-park for a 5Y3GT in a SE amp.

Have you unlugged the speaker (amp off & unplugged from the wall) and measured the speaker's dc resistance at the RCA phono plug?

I notice in the earlier voltage readings you give a voltage for 6V6 pin 4, but not pin 6...odd because the screen wire runs straight to pin 6 then appears to have a jumper to pin 4?

Not related to your issue but you have no 22K NFB resistor connected to the speaker socket.

Check the ohms reading from the volume pot middle tab to ground as you turn the pot up & down.

[Bruce / Mission Amps]

Are you sure your speaker is OK?
If you have, as you stated, replaced all the tubes, caps, components, including the output transformer, then the only thing left to do now is to throw the amp away, it is not fixable... throw it out to me preferably.