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Single tube, Single ended, 20W, impossible?

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#22
I don't think EL156 with input step-up transformer will work well unless one has a beefy and mighty source. It's not a real solution, it's just shifting the problem from the driver to the source and usually it's just asking for more troubles......
It's that step-up the main problem.
45
 
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#25
Nearly 20 years ago John Atwater (of one-electron fame) had an SE shoot-out at his home in San Jose. The max power for most of the entries was on the order of 3W...But for the finale I set up my '13 Cubed' SE amplifier. 813's running into custom Doc Hoyer OPT's; 1300V on the plates and 2x SIXTY FIVE WATTS (130 watts total). Of course to spite the narrow minded group; the amplifier was all pentode; drive tubes were EF86's running 6AU5 cathode followers. The amps blew everything into the weeds with their premium OPT's and great circuit design. Later, Svetlana came out with the SV572 triodes. These beauties were good for well over 20 watts; the higher mu ones could easily do over 25 watts. Again, Doc Hoyer came up woth the output iron. I built several of these and sold them to fellow audiophiles.
 
#28
mik190 said:
Here is the single tube single stage 45W amplifier.

http://spbsound.narod.ru/SPbSound/schematic/schematic2.html

I read that some people build it in Russian forums.

Some people in Japane did similar as well as I heard.

I would like to repeat it at less powerfull tubes but did not find the scheme.
Click to expand...
WOW, this GM70 amp had a triple secondary output transformer!!... Very impresive, I wonder how it sound??

Any chance did you know the price of this GM70 Integrated?? ("МикроГМка")
http://spbsound.narod.ru/SPbSound/photo/photo7.html
Thanks
 
#31
My that's some coincidence. I just built a GM-70 amp. Insanely nice tube. And very cheap. That's a hammond 18v 5 amp trans for it's filament supply. Ya 60 watts for the filament. It's just like a light bulb. This is my first iteration. Just using a Hammond 300-0-300 transformer gives me 810v on the plate. The power supply is designed for max 1200v though. I will switch in a 400-0-400v Hammond after some more testing. Should get about 1050v on the plate. I'm stopping there.
 

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#32
MelB said:
My that's some coincidence. I just built a GM-70 amp. Insanely nice tube. And very cheap. That's a hammond 18v 5 amp trans for it's filament supply. Ya 60 watts for the filament. It's just like a light bulb. This is my first iteration. Just using a Hammond 300-0-300 transformer gives me 810v on the plate. The power supply is designed for max 1200v though. I will switch in a 400-0-400v Hammond after some more testing. Should get about 1050v on the plate. I'm stopping there.
Click to expand...

I would put a mirror between tube and transformer. Too hot and too close.
 
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