Which transistor for my amp?

[OliverD]

I'm looking for a readily available, "modern" transistor for new my amplifier's gain stages. The problem is that I'll have about +/- 85 V rails, so the transistor should have a Vce rating of about 180..200V. I need both NPN and PNP.

Other requirements:

-> Ic(max) ~ 100mA
-> Ptot ~ 1W
-> fT ~ 200 MHz
-> hfe(typ) ~ 200...400
-> low noise, good linearity, low Cob

Do you have any suggestions?

For driver and output stages, I already setteled for 2SA1930/2SC5171 and 2SA1987/2SC5359.

 

[sam9]

check out sound.au.com. Somewhere in the downloads is a compilation of transistor data. About 1400 items.

 

[OliverD]

Thanks for the link! It's a big collection of mostly 2N... types...

Unfortunately, there was no transistor that meets my requirements... Maybe I need to redesign my input stage to run from a different (lower) supply voltage...

Any more suggestions?

 

[till]

i would use parametric search at onsemi or fairchildsemi. com. But with that high voltage i can´t find that high hfe

 

[Christer]

Not quite what you want, but 2N6517/6520 from ON will at
least handle the voltage and Pd required. I think it is very
difficult, if at all possible, to make high-hfe devices for very
high voltages.

 

[davesaudio]

make your own darlington pair to get the gain?
(yes has some drawbacks- I know, just tossing ideas)

 

[OliverD]

Thanks for your suggestions...

2SA1376 + compl. is the only device that would fit perfectly from the specs, but I doubt whether it is suitable for audio... And it seems to be obsolete...

Seems I have to redesign my input stage

 

[Christer]

Not that I know what design you had in mind, but a common
way to deal with the problem that may perhaps be a feasible
redesign in your case is to use lower-voltage transistors
with high hfe and then cascode these with high-voltage
transistors.

 

[OliverD]

Yup, I'll cascode the VAS and driver stages, but I don't want to cascode the input stage in this particular design. Maybe I'll just provide an additional (lower voltage) power supply, I don't know yet.

Anyway, to revive this thread, does anybody know a modern replacement for 2SA1376/2SC3478? Datasheet is here: http://www.necel.com/discrete/images/pdf_e/TC-3529.pdf

Also, I want to replace the famous Toshiba 2SA1145/2SC2705 as used by LCAudio. Datasheet available here: http://www.lcaudio.dk/2SA1145.pdf

Can anyone help?