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owenhamburg 22nd January 2013 05:26 PM

JLH Class A headphone amp from ETI not WW
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Dear all,

Being a ETI (Electronics Today International) reader years ago as a teenager I had a recolection of a Class A headphone amplifier by JLH that I had not seen the circuit for in a long time.

Then I saw this link Headphone Class A Amplifier.

The ciruit looks simple, and I should like to build a good headphone amplifier for minimal cost and have an irational desire to have a class A deisgn. This will probably not happen in a short time scale but I would be interested to hear your opinion on this circuit.

My questions:

Do you think its a good design? If not why not?

Do you think I can scale it up to larger powers (Say 20 W) if I like it?



RNMarsh 23rd January 2013 10:31 AM

It should work well for a small power amp... The electrolytics in the feedback are a neg. Thx -RNM

AndrewT 23rd January 2013 10:49 AM

A BJT version of the F5 !

Even the protection is similar. BUT importantly it has an RC to allow transients peaks to pass !!!!!!

JLH is no fool.

owenhamburg 23rd January 2013 04:56 PM

Thanks for the feedback, I may look into building it sooner but some other things are more pressing in my DIY like finishing off the subwoofers and some software I want to write/finish.

Telstar 23rd January 2013 09:30 PM

JLH was a great designer, no doubt. But the circuit is not original in the way his class A amp was, I would go for that one with lower power devices and lower rails.

forr 23rd January 2013 11:44 PM

I remember this circuit. I have always a bit worried by the direct connection of R2 et R3 to the power supply rails.

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