Threshold 400A Cascode

[Nelson Pass]

The 2n5876 and 2n5878 devices as well as the later MJ15's were not matched,
but were selected for adequately high current gain, as some of the parts came
up short.

 

[DrKarl]

just those with CLASSAsomething are looking as genuine (as from factory) outputs

resistor - it certainly looks poofed

Hi Zen mode,
do you know what are these CLASSsomething transistors? I am looking for one CLASSA8 7852 or equivalent one, any help is really appreciated.

Thanks and regards from Stuttgart,
Karl

 

[Zen Mod]

if Papa doesn't know, no one knows

I mean - he wrote several times about which transistors were used and which modern are appropriate, but I'm not remembering where .... those old ones from Pass aren't exactly my cup of tea, sorry

 

[Nelson Pass]

As I recall, the early parts were 2n5878 and 2N5876, but were marked for us as ClassA8 and ClassA6

I still have a box of them...

Also as I recall, later they were supplanted by MJ15031 and 32

 

[DrKarl]

Dear Mr Pass,

thanks for your reply. I am the owner of Threshold PCR1 preamplifier (such a fantastic device with dream musicality, thank you Papa for such a creation) with S1 power supply. As the S1 power supply blew its dc+ rail I suspect one of classa6 or classa8 could be the reason. I’ll receive the fuse replacement (250 mA fast blow) by today. Should I check the preamplifier with the new fuse first? Or what is your recommendation?

thanks from Germany Stuttgart,
Karl