Need info on designing Mosfet audio amps

[Paul Jones]

Hi everyone,

Could someone recommended a source of info on designing and modifying
class AB Mosfet audio amplifiers? I've got a few that I've half built
with some serious transistor substitutions but they obviously don't work
real well (drawing full current at no load...) and I don't know enough
about these types of amplifiers to fix them. The circuit I have is based
on the standard Hitachi design.

Books or websites or whatever!

Thanks,
Paul.

 

[Johnny]

Hi everyone,

Could someone recommended a source of info on designing and modifying
class AB Mosfet audio amplifiers? I've got a few that I've half built
with some serious transistor substitutions but they obviously don't work
real well (drawing full current at no load...) and I don't know enough
about these types of amplifiers to fix them. The circuit I have is based
on the standard Hitachi design.

Books or websites or whatever!

Thanks,
Paul.

It might just be oscillating. Have you fitted frequency compensation
capacitors and gate-damping resistors as shown in the application
note?

regards,
Johnny.

 

[Richard]

Try this link.....

http://sound.westhost.com/index2.html

Rich.

 

[Paul Jones]

It might just be oscillating. Have you fitted frequency compensation
capacitors and gate-damping resistors as shown in the application
note?

Yes, they are both there.

 

[Paul Jones]

Try this link.....

http://sound.westhost.com/index2.html

Thankyou!! Just what I was looking for.

 

[Richard Freeman]

....

Hi everyone,

Could someone recommended a source of info on designing and modifying
class AB Mosfet audio amplifiers? I've got a few that I've half built
with some serious transistor substitutions but they obviously don't work
real well (drawing full current at no load...) and I don't know enough
about these types of amplifiers to fix them. The circuit I have is based
on the standard Hitachi design.

Books or websites or whatever!

Try Profusion/Exicon :
http://www.profusionplc.com/exicon.htm

being the Manufacturers of Lateral mosfets they seem to know a thing or two
.....
although I often seem to have a bit of trouble down loading their
application notes :

http://www.profusionplc.com/static/images/data sheets/apnotes.pdf

Hope this is of some help

Regards
Richard freeman