From: hersberg@srv1.freenet.calgary.ab.ca (Russ Hersberger)
Newsgroups: sci.electronics.design
Subject: Re: Power Amp circuit bd layout?
Date: 19 Nov 1995 05:25:27 GMT
Organization: Calgary Free-Net
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#1. Keep supply lines from the power supply as short as possible. Take 
them directly to the outpu transistors. Do not allow any power supply 
current to run near the driver and input circuits. Distribute the power 
supply from the power transistors to the input circuits not vice versa.

#2. For 100 watts and a 4 ohm load, you need about 7.5 amps d-c. Use 16 
AWG wire from your filter caps.

#3. Ground planes are good. If you use them connect the power supply 
wire that is to be grounded to the ground plane near the power 
transistors. Connect the earth ground to the plane near to the input 
circuit . The grounded speaker wire should be connected to the plane near 
to the power supply ground.

Andy "LaLa" Chang (uachang@mcs.drexel.edu) wrote:
: Howdy,
:    I'm trying to design a new board for a 100W/Ch Mosfet audio power amp that
: I brought as a kit.  I'm wondering how important is it to have a good design
: for the layout of the components.  I read an article in an electronics
: magazine where the author talked about many different kinds of distortions
: associated with audio power amps.  Some of those distortions, according to
: the author, are results of bad circuit board layout.
:    Apprantly, even a bad ground layout can increase the amp's THD by 100 times
: at 20Hz @ 60W.  Is this true?  If so, can someone give me some pointers on
: how to design a good board?  Should I use big ground planes or small ones?
: Big or small power rails?  In case I didn't make myself clear, I'm talking
: about the size of the copper traces and the layout of them.

: --

: -----------------------------------------
: andy chang

:    uachang@mcs.drexel.edu
:    http://www.mcs.drexel.edu/~uachang



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Russ Hersberger 403 286 4096