Stromberg Carlson PA conversion output volume issue

[Oregonblues]

**edit- turns out it was my output transformer, started to notice it was now a bit distorted on any volume so I clipped in a similar spec and it solved the issues**

Hey everyone, I’m in the midst of trying to convert a old stromberg Carlson no.19 model PA to guitar/bass,

I’m passing signal fine through the amp but to me it seems the output volume is severely lacking, it’s just not loud at all and you can fairly easily talk over the amp when at max volume, I’m assuming there is just something I’m not quite seeing to get it to open it up a bit more, I can provide the original schematic but I’ve changed some values to more what you’d see in fenders

Currently here is the Pinout voltages with no signal, any ideas would be greatly appreciated, I’ve swapped the tubes with no improvement

1st tube - 6sj7
1: ground
2: 4.7 vdc heater
3: .746 vdc grid 3
4: -.3mv dc grid 1
5: 0.0 cathode
6: 23.62vdc grid 2
7: 4.8vdc heater
8: 145.7vdc plate

2nd tube 6sf5
1: ground
2: 1.06vdc
3: -3.5mv dc
4: empty
5: 113vdc plate
6: empty
7: 4.8vdc heater
8: 4.8vdc heater

3rd tube/phase inverter 6n7
1: ground
2: 4.5vdc heater
3: 115.2 vac plate
4: 0
5: bouncing from -1.5 to 5mvdc
6:128.5 vdc
7: 4.5vdc heater
8: 3.16vdc cathode

6l6gc tubes at 42ma on bias probe meter

4th tube 6l6gc
1: ground
2: 4.5vdc heater
3: 402vdc
4: 311.5vdc
5:30ish mv dc
6:none
7: 4.5vdc heater
8: 23.9vdc

5th tube 6l6gc
1: ground
2: 4.45vdc heater
3: 402vdc
4: 311.5vdc
5: 31ishmv dc
6: none
7: 4.5vdc heater
8: 23.9v

6th tube rectifier gz34
2: 408v

[maxkracht]

I rebuilt a number 20 last year, i'm guessing the 19 is pretty similar. The OT had a bunch of taps for stuff that isn't much use to us, like 500 ohms, perhaps you just had one of those connected by mistake.

[Stevem]

Why are you reading DC for the heaters?

[Oregonblues]

Not sure on the dc for the heaters, reading in AC gives the same, may just be the multi meter I have being weird.

As far as the output taps I have the original schematic from the bottom plate and traced it to the 4 and 8 ohm taps and came off of those, I’m still getting a bit of low end oscillation/double notes and trying to sus it out

IMG_6750.jpeg

[Stevem]

Your posted schematic clearly shows 6.3 VAC, is that what you find on the socket for the pilot lamp?

It’s going to be hard to troubleshoot an amp with a meter that may not be reading right!

I would also cut short and heat shrink off all the other non needed wires on the secondary side of the OT .
You only need the black , silver / slate and white wires .

[Oregonblues]

Ya know sometimes the problem is just staring right at ya. Verified the meter is reading correctly, getting about 5.6vac at startup on the heaters and it slowly drops voltage, when I stopped observing it was down to 5.12vac,

Edited: I clipped in a heater transformer, reading correctly 3vac but it’s interesting how high the original heater voltage is