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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?

Regards

Owen
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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.
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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.
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"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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