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Old 22nd January 2013, 04:26 PM   #1
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Default JLH Class A headphone amp from ETI not WW

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?


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Old 23rd January 2013, 09:31 AM   #2
RNMarsh is offline RNMarsh  United States
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It should work well for a small power amp... The electrolytics in the feedback are a neg. Thx -RNM
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Old 23rd January 2013, 09:49 AM   #3
AndrewT is offline AndrewT  Scotland
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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.
regards Andrew T.
Sent from my desktop computer using a keyboard
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Old 23rd January 2013, 03:56 PM   #4
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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.
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Old 23rd January 2013, 08:30 PM   #5
Telstar is offline Telstar  Italy
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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.
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
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Old 23rd January 2013, 10:44 PM   #6
forr is offline forr  France
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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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