Headphone Buffer Amplifier

Low-impedance (under 50 ohm) headphones will play well at home with your receiver and on-the-go with your smart phone, and that's why the vast majority of in-, on-, and over-the-ear headphones are low-impedance designs. High-impedance models are much better suited to home than on-the-go use. Sennheiser and Beyerdynamic are two companies that offer high-impedance consumer headphones with up to 600 ohm-rated designs.
Audioreputation.com
 

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In practice if you want to have perfect thermal tracking (no DC drift), it is better to make top and bottom identical.
https://www.diyaudio.com/community/threads/mosfet-follower-headphone-amplifier.95841/post-1130743

My own experience is that CFP measures well, but sound a bit too bright.
I only use them for portables with very low bias.


Cheers
Patrick
Thanks for your comment. I visited your link. To use LU1014 is an elegant solution. To use MOSFETs for cascode also benefit.

I have not built my circuit, so I can not tell about sound.
I take your word for that upper and lower should be the same.

Anyway I will post an upgrade with J113 transistors. With lower THD as well.
 
Headphone Buffer Amplifier upgrade Revision 2.
With J113 FETs.

Devices
3 x J113 FET
1 x BD139
1 x BD140

Power Supply
2x12VAC Transformer
Regulators LM7812/LM7912 or LM317T/LM337T

Adjustments
Adjust potentiometer for zero offset on the output.
Replace R6 if necessary for ~100mA in output stage.

As can be seen the THD is lower than my first version.
Like THD 0.045 is acceptable for a circuit without global feedback. Ask Nelson Pass!
 

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