Need info on designing Mosfet audio amps

P

Paul Jones

Guest
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.
 
On Thu, 25 Nov 2004 20:53:15 +1100, Paul Jones <wiseguy@iinet.net.au>
wrote:

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.
Click to expand...

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

regards,
Johnny.
 
Try this link.....

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

Rich.

"Paul Jones" <wiseguy@iinet.net.au> wrote in message
news:41a58989$0$31706$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au...
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.
Click to expand...

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Johnny wrote:
On Thu, 25 Nov 2004 20:53:15 +1100, Paul Jones <wiseguy@iinet.net.au
wrote:


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?
Click to expand...
Yes, they are both there.
 
"Paul Jones" <wiseguy@iinet.net.au> wrote in message
news:41a58989$0$31706$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au
....
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!
Click to expand...
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%20sheets/apnotes.pdf

Hope this is of some help

Regards
Richard freeman
 
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