can I convert it to a guitar preamp by connecting r14 to ground not the feedback loop, removing c10 and c11, swapping 6n1n-EB tubes for a bit more output, changing R6 to a 47k pot with a 10k in series, swapping C3 for a 20uF and putting a 22k pot in series, swapping the coupling caps for something with less value and putting 1 or 2 gain stages in front of the amp?
the output transformer is drawn weird but I found a website that listed the turns of wire for the taps and it seems it's symmetrical between the 2 sides.
http://www.chipinfo.ru/literature/radio/197107/p31-34.htmlalso, I thought about connecting 5 (on the PSU) to the end of the bridge not after a dropping resistor. this would source about 340V (with load) + the 240 line voltage not 220. so basically it will source about 360v on the plates. but EL90's OR EL84's can only hold 250 volts. I don't think even new ones can hold about 110volts more.
so I'll probably not do that.
also, I think removing C6 would not hurt, it's basically useless AFAIK.
and disconnecting U3, U1, U2 boards. since I won't ever be using it originally again and it's too far destroyed to try to fix those boards.
pretty much I'm only after the output stage.
and I'll disconnect 1 of the heaters from the ground and put a 300 Ohm pot between the heater to ground.
maybe I'll even connect it to another heater lift divider but that, probably later.
also probably gonna remove everything for L1 tube also cause that's useless for me even if I use it as a volume indicator.
schematicRigonda102.pdf (262.74 kB - downloaded 375 times.)
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