Thank you 
.... here is a schematic, in the finish the power supply got a regulator for each channel for G2 voltage, instead of two 2x1k resistors in parallel... the Lundahls are configured for 4k5:8R... measured (with my pretty much limited knowledge and hardware, got cca 25Wpc before "visible" clipping on the 1kHz sine wave (1Vrms input)...
/edit - the schematics are completely done by member Davorin, I was just makeing it the way I saw it should look like... sounds pretty well, plenty of power, need to break in...
.... here is a schematic, in the finish the power supply got a regulator for each channel for G2 voltage, instead of two 2x1k resistors in parallel... the Lundahls are configured for 4k5:8R... measured (with my pretty much limited knowledge and hardware, got cca 25Wpc before "visible" clipping on the 1kHz sine wave (1Vrms input).../edit - the schematics are completely done by member Davorin, I was just makeing it the way I saw it should look like... sounds pretty well, plenty of power, need to break in...
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...new amp
Nice chassis idea!
...new amp
The alu chassis is that a 19 inch rack?
...yup, 3U chasis (cca 13cm height) and 28cm in depth... a bit small for what I crammed in it, sometimes it was like assembling a 4D puzzle 
I had to find place for 2 OPTs, one mains transformer (without a filament winding), pretty big choke and a toroidal transformer for filament... but in the end, its a healthy 19kg amp
I had to find place for 2 OPTs, one mains transformer (without a filament winding), pretty big choke and a toroidal transformer for filament... but in the end, its a healthy 19kg amp
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Brook12A clones. 2A3 in push-pull. Sounds great with Altecs. SUNil
Which Altecs do you use? I have a7's and I think 818 two 515's,
I built a 2a3 similar to the 12a, but mostly use a 811a amp with little feed back to get better bass the 515 is so over damped, In another JBL horn use a speaker with QTS .7 wonderful bass. needs to be packed with lotsoffluffy stuff. in another a7 use chinese speaker with the same data as the JBL e-145
Which Altecs do you use? I have a7's and I think 818 two 515's,
I built a 2a3 similar to the 12a, but mostly use a 811a amp with little feed back to get better bass the 515 is so over damped, In another JBL horn use a speaker with QTS .7 wonderful bass. needs to be packed with lotsoffluffy stuff. in another a7 use chinese speaker with the same data as the JBL e-145
811Amp
sunilI
I have built lots 811a amps using the design for record cutting amps using the same voltages as KT88/6550 you can use from 500 811 to 600 volts 811A has 40 watts class A, I have also built the same circuit 809 amps only about 400 volts.
The out put transformer is from 1.5k to 2K
sunilI
I have built lots 811a amps using the design for record cutting amps using the same voltages as KT88/6550 you can use from 500 811 to 600 volts 811A has 40 watts class A, I have also built the same circuit 809 amps only about 400 volts.
The out put transformer is from 1.5k to 2K
Attachments
Interesting I didn't know you could run the 811A in anything but class B. What voltage are you biasing the grid? I've used the 811A in A2 before.
I was looking at the 811 tube once but I just recall the various versions A, B, C, -10, -XXXX and not to mention the near-equivalents SV572.
What to use in a REASONABLE amp?
Sorry I sent the wrong circuit.
The Russia built the various version one is similar to the 845, they came out with a mu of 3-10-30 and the 572 180 similar to the 811a and American 572 -180, are very costly now as the Russians stopped production, the Chinese also have 811a and 572. The best tubes to use are Russian 811a’ and the USA 811a and 572. But they are becoming hard to get. One amp I built for friend the Russian 811a he used for 20 years, still measured Good, my friend decided he liked the sound of the Chinese 572, first lot lasted 18 month, but recent version have so far latest 4 years.
THe amp is biased about +18 volts depends on tubes
What to use in a REASONABLE amp?
Sorry I sent the wrong circuit.
The Russia built the various version one is similar to the 845, they came out with a mu of 3-10-30 and the 572 180 similar to the 811a and American 572 -180, are very costly now as the Russians stopped production, the Chinese also have 811a and 572. The best tubes to use are Russian 811a’ and the USA 811a and 572. But they are becoming hard to get. One amp I built for friend the Russian 811a he used for 20 years, still measured Good, my friend decided he liked the sound of the Chinese 572, first lot lasted 18 month, but recent version have so far latest 4 years.
THe amp is biased about +18 volts depends on tubes
