I don't get it , why do all these dangerous lashups sound so good ? Had this one up for the last few weeks , started with choke loaded IRFP150 , found a bias sweetspot at 1.5A and went from there 
Could probably do with more current but I'd imagine the chokes are running on the ragged edge 
Original input valve was a 5687 , then changed to type 26 , now running 15E . Total lashup , using a voltage doubler to get 250V HT and running the 15E at 180V/2.5mA which is far too low , but it sounds good as it is The filaments of the input valves draw 20 watts each , the mosfets are running at 15 watts dissipation per device . Filament supply weighs 30kg . Not really chassis happy but never mind , I'm enjoying this thing as it is
316A
Could probably do with more current but I'd imagine the chokes are running on the ragged edge Original input valve was a 5687 , then changed to type 26 , now running 15E . Total lashup , using a voltage doubler to get 250V HT and running the 15E at 180V/2.5mA which is far too low , but it sounds good as it is The filaments of the input valves draw 20 watts each , the mosfets are running at 15 watts dissipation per device . Filament supply weighs 30kg . Not really chassis happy but never mind , I'm enjoying this thing as it is 316A
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My experiment with similar thingy, 5 years ago. 8AL9 tube and 2 x IRFP460
2 directly coupled stages, bipolar + / - 240V power for tube, CCS in anode (30 mA) of output stage of the tube driver.
Source follower loaded on a plain CCS. Choke filtered 40V.
Sounded like a charm, though dissipated 200w.
2 directly coupled stages, bipolar + / - 240V power for tube, CCS in anode (30 mA) of output stage of the tube driver.
Source follower loaded on a plain CCS. Choke filtered 40V.
Sounded like a charm, though dissipated 200w.
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