Change the 2nd filter resistor from 22K to 10K tonight. I raised the 3 stage voltage from 92vdc to 138vdc. Figured it wouldn't be a bad thing to give the 12ax7s more voltage.
The amp really sounds alive now! definitely a good change.
Next up, making a parallel input with the extra tube, and removing the normal channel and using the bright channel instead. Which the bright cap on a switch.
You can probably reduce that dropping resistor further. I'd probably try a 1K 1W. The draw across that resistor is less than 0.4W, but I'd go up a notch to be conservative.
I might also be tempted to reduce the 5K dropping resistor to around 2.7K 5W. This will boost your screen voltage closer to plate voltage. I don't think that's a big consideration at the operating points you have. What it will do is pass more voltage downstream for the preamp section.
The 1st preamp tube in a 5E3 usually operates at around 200V on the plates. I suspect you are losing some of the "feel" of the design with lower plate voltage on the preamp tubes. I'd shoot to get V1 closer to 200V. You should get more clean headroom (not that you have a lot with a 5E3) as you raise preamp plate voltage.
You won't experience "not so loud" until you have a 1W amp. What you built (without doing any math) is probably still in the 15W range.
I'm partial to Sylvania's. That's because I managed to find some that are clearly NOS (without boxes) and they are very robust. I've got a pair running in my variant of a TW Express with Va around 335. I figure, heck, who cares if the tubes blow up -- they were cheap and I've got quite a pile of them.
Otherwise, RCA's are nice, too. I don't think you can go wrong.
1 channel into parallel triode->vol->phase inverter. Apparently during the process I removed the caps for the tone.
My plan is to wire up the tone control, and then may be us the extra 1M pot for a master volume. The 6aq5s didn't really drop the output so it'l a bit loud for what I need.
Not sure what i'll do with the extra socket, I had wired an extra gain stage at one point, but couldn't tame it. maybe I'll try again.
Still a fun amp
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