FET drivers for BJT outputs?

[east electronics]

you may take a look in a few Luxman schematics they had some approach like that one will be the LV102 and also there has been a model from Zeck Pro amps that work like that all of them available schematics on the internet

 

[Walkalone]

Driving by FET, this advantage get higher Z of OPS, light load for Vas, Vas not overload when Z load lower and high speed.
But, problem is: not have truly complementary pairs and Ciss too high. If you want resistant to the influence, you must run Vas at higher quiescent current.

Why do you not try T-triple EF3? I'm think, in current,this is best way.

 

[Dave Zan]

Driving by FET, this advantage get higher Z of OPS, light load for Vas, Vas not overload when Z load lower and high speed.
But, problem is: not have truly complementary pairs and Ciss too high. If you want resistant to the influence, you must run Vas at higher quiescent current.

Why do you not try T-triple EF3? I'm think, in current,this is best way.

Driver FET is not driven by VAS, but by BJT pre-driver.
FET is not used to make an easy load for VAS and Ciss is not so much problem.
I already use a triple, but not EF3, instead CFP Pre-driver+Driver then EF output.
FET is to provide more speed than BJT so there is more freedom to stabilize the CFP internal loop. Also free of second break-down so possible to increase the bias and improve turn-off of the outputs.
Make sense?

Best wishes
David

 

[Samuel Jayaraj]

The K2013/J313 pair is no longer in production and available. So suggestions should exclude this otherwise very good pair.