Tube Amp Archive

:lol: 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...

I’ve swapped some values closer to old fender specs but brought the phase inverter back to stock schematic values

Here should be the original schematic

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/...

**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 thro...

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 a...

Finally got some time to sit down and work on the amp, as per tube depots recommendation, I replaced the filter caps( even though I knew they tested fine, which they did once tested after removal) Rechecked for any off value resistors or caps and re flowed most of the connections on the amp incase o...

checked the mix resistors on pin 2 of the second 12ax7 they are in spec, I added a 100pf cap across the NFB 27k resistor with no real notable change, then I switched it for a 66k resistor and it helped some but still has oscillation, I also re flowed a few joints that I thought might be suspect, its...

All the Voltages in post 1 look good. With all pots set to 5, touching a DVM probe (other probe grounded) to the Grids (pins 2 or 7) of the 12AX7s should produce a clicking or hum through the speaker. Touching 2 and 7 of the PI should produce loud clicks. I can't help but think you may have a short...

I may be wrong, but have you tried to reverse the OT primary plate leads. I don't know if you have NFB connected. If you do not have it connected then disregard. ah yes I forgot to mention I have tried that with no change, I got slightly better results now after swapping the mica cap that bridges t...

thanks for the suggestions so far, I checked the input jacks and speaker jacks , wired correctly and ohm out proper values aswell, decided to rebuild using only the tube depot jtm45 layout except I left out the NFB mods and the solid state rectifier, with the new layout the voltages are still within...

Im trying to finish up a jtm style build built off the tube depot and ceritone jtm45s, currently I get sound from the amp but super super low volume even when fully cranked on all knobs and fully cranked it is pretty distorted , the tone stack dosent do much but does alter the tone somewhat current ...