new to solid stage, help please

[lt cdr data]

ok getting interested in SS amp design.

Few questions if I may,

What are typical mosfets makes used? just the hitachi 1058?

what are the requirements in terms of current, volts and power (also hi freq?) i.e. ratings.

What's a typical bias current for a class AB amp.

What are the things to bear in mind for the VAS stage driving them, apart from input capacitance?

thanks in advance

 

[lt cdr data]

ok I have managed to find the answer to the first point,

I'll elaborate on that, should you always use output devices that are audio ones, or can you get away with other power transistors, and what makes them audio ones specifically?

with the 2nd point, ratings, its advised to use around 25%? so if your ouput device is 100 watts, you need 4 output devices for a 100 watt amp?

thanks again just trying to get my head around the starting points.

 

[AndrewT]

Hi,
range of classAB bias 10mA to 300mA.
Mosfets used 2SK1056, 1057, 1058, 133, 134, 135, 225, 226, 227, 1529, 1530, these are just some of the Lateral (enhancement mode). I believe some of the Exicon and Buz are also lateral.
there are hundreds of Vfets Hex etc that are used in audio.
For BJT info & good theoretical background go find Leach (power amp only) & ESP sites (design info on whole range of audio projects) & Doug Self ( amps preamps discrete opamps grounding balanced topologies etc.) For FETs go to Nelson Pass.