Those are interesting alternatives. I actually tried a hybrid of the two last week - speaker output across the inductor, but cap coupled at the bottom. Actually I tried the cap at the top AND the bottom legs. The advantage was that a MUCH lower voltage rating for the cap was required, and the total voltage was lower compared to the resistor load. I still needed a separate source resistor bypass cap since I didn't have the fixed bias voltage that these circuits do...
Marchand Electronics used another interesting connection on their EC616 and EC626 amps.
G
Ralph, are you looking for production quantity or fun quantity?
I might be able to help with the latter.
Caution here: some people are making fun buying the entire worldwide stock, so can be warned... (aka some acummulators people)
Fun aside, these SIT pieces are very rugged (***) and if seller matches at least the idss/mu group, buyer needs to acquire only the required pair, and pay some attention building these things
Personally I buyed only the required pair of them in my experiences.
*** CURIOSITY TIME: in fact, in my experience, only diodes and SCR are more rugged than SITs.
My own experience table with silicon semiconductors and ruggedness (not only for audio):
diode > SCR > SIT > LATMOS > V-MOSFET > TRIAC > bipolar
(aka some acummulators people)Fun aside, these SIT pieces are very rugged (***) and if seller matches at least the idss/mu group, buyer needs to acquire only the required pair, and pay some attention building these things
Personally I buyed only the required pair of them in my experiences.
*** CURIOSITY TIME: in fact, in my experience, only diodes and SCR are more rugged than SITs.
My own experience table with silicon semiconductors and ruggedness (not only for audio):
diode > SCR > SIT > LATMOS > V-MOSFET > TRIAC > bipolar
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Hoarders, loose your treasure, arr.
Pirate, here is mine and don't kill me ... they may not be as complementary as the 2SK82/SJ28 pair, but with a little source degeneration they're powerful pairs
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Ralph, are you looking for production quantity or fun quantity?
I might be able to help with the latter.
I'm looking for 4 good units, so I can build myself an fun little amplifier (its gonna be push-pull). It seems really unfortunate that these things aren't a little more common!
I'd love it if I could put positive voltages on them, like a vacuum tube. So far the only versions I have found are the Sony 2SJ which wants negative voltages. That ultimately likely will not make a lot of difference in my project since I plan a separate power transformer for the driver section anyway.
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For remaining 2SJ28's?
Nice!!
Yes nice and interesting topology we need ask the designer
V- Fetron 75 watts power version made with big hockey puck sit's not 2SJ28 ?
Wait for more informations from Mr. MR update
Best regards 
Yes nice and interesting topology we need ask the designer
V- Fetron 75 watts power version made with big hockey puck sit's not 2SJ28 ?
Wait for more informations from Mr. MR update
Maybe something like this...
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Hi all. Please caution with tokins. I have measure a lot of THFs and 2sk180, 182 and between them there are a lot of variability. I suppose that all what we can get from chinese sources are rejects from production. So may be necessary buy a lot, get curves and then select the better ones. I have mounted one lamp with two THF51 not very similars each other and really I can perceive what different are each other. Sorry