Single End Class A, No Global Feedback with J113 and IRFP240. 4 Watt.

  • Single End
  • Class A
  • No global Feedback
  • 2 Stages with J113 and IRFP240
  • Max 4-5 Watt

Here is the simplified idea.

And the actually fully working circuit.
It can deliver more than 5 Watt into 8 Ohm.


  • J113 IRFP240 Single End_Simplified.jpg
    J113 IRFP240 Single End_Simplified.jpg
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  • J113 IRFP240 Single End 067.jpg
    J113 IRFP240 Single End 067.jpg
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Joined 2003
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As you might have understood - I'm on the hunt for some proper driving of my 16 ohm 18sound compression drivers :) so I'm listening!

I also have a flat with electrical element heating so a bit a class A will not hurt ;)

Would this be suitable - anything better? Suggestion?

Here is Some figures of THD.

Watt THD
1W 0.067%
2W 0.100%
3W 0.130%
4W 0.166%
5W 0.216%
Max 5.7W at THD 1%

Also attached is the harmonics with the Fourier Analysis.


  • Fourier Analysis.jpg
    Fourier Analysis.jpg
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  • J113 IRFP240 Single End 067.jpg
    J113 IRFP240 Single End 067.jpg
    44.4 KB · Views: 137
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Reactions: 1 user
How would I add an Aleph current source? To my circuit.
Look here , it is a version of the Zen amplifier by Nelson pass. The Aleph I would describe as a controlled current source.
For a mu amp example, this is something I cooked up some time ago:

The bottom mosfet gets the output signal of the top mosfet into its gate through C5. So now the bottom mosfet becomes kind of a controlled current sink.
They used to call this a totempole arrangement I think, nowadays mu amp is more hip.
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Nice! I'll have to get those circuits onto a simulator for a closer look. I'm basically looking at varying the output impedance vs frequency, e.g. by having a controlled current at high frequency, pulling against a muted voltage source. Whereas at low frequencies, the voltage source gets a stronger input signal and the CCS side has reduced impedance so it also runs as a voltage source.

I can do it with 'servo' style feedback, but I want to be able to use different filters that aren't constrained to a low phase shift for negative feedback.