# class AB amplifier (30-50)W

Discussion in 'The Projects Forum' started by abdus, Jun 10, 2010.

1. ### abdus Thread Starter New Member

Mar 4, 2010
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i want to design a class AB amplifier ranges from (30-50)w.
can anyone plz send me schemetic?

Apr 2, 2009
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Mar 4, 2010
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4. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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sorry buddy, they are not complete schematics.
Just tutorials on output stages.

5. ### abdus Thread Starter New Member

Mar 4, 2010
22
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ohk..
but i want to built such an amp..

6. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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there is a 60W amp at tht site.
Did you not find it?

7. ### kubeek AAC Fanatic!

Sep 20, 2005
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Ok, 30-50W is a nice number, but...
50W per channel or total?
How many channels?
50W for what load impedance - 2, 4, 6, 8, 16 ohms?

Answer ALL those questions, then it is possible to talk about the actual design.

Apr 5, 2008
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9. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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10. ### abdus Thread Starter New Member

Mar 4, 2010
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50W total.but need to design a class AB amplifier
8 or 16 ohms load impedence

11. ### kubeek AAC Fanatic!

Sep 20, 2005
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25W into 8ohms -> peak voltage is sqrt(25*8*2)=20V
Depending on the output stage, the rails should be about 25-30V.
average current for one channel at full load is 14.1/8=1.8A, peak current 2.5A

The transformer for the power supply should be about 2x20V@2A, that is 80W to be on the safe side, could be a bit less powerful if you don't plan to use it at full power all the time.

The westhost amp looks nice, but be sure to use the circuit 1a, not the first one.
PSU smoothing caps nedd to be rated for 50V, at least 4700uF each, but more is better.

The 10ohm resistor and 100nF cap on the output should be rated for higher current, I would use at least 2W resistor and a quality film capacitor rated for 50 or 63V at least.