SE power amp as headphone amp?

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Hello,
While I'm quite happy with my "portable" player with 2 TPA6120 at the end, for best results at the main listening spot, I'm still searching for the best amp I can make. I was looking for a decent single ended class A design with transformer output, but yet could not find.

I had another project, started as low power guitar amp, but started on a hifi amp, again single ended class A with transformer output. During the project I realized it is a complete failure for guitar amp, so I built it as a hifi amp. It ended up very impressive. Not far away from my 2A3 PSE.
I also have an OTL headphone amp, with 6S19P at the end, I call it a monster and on cold evenings I was thinking to put it under my armchair, to have some additional heat :)
The 807 ended power amp makes less heat actually and it is very safe for the speaker (headphone).
Now, I was thinking, I put a 8 Ohm resistor load at the output and connect the headphone. It is heavier, but stable and less power hungry.
What do you think?
Do you guys have experience using tube power amp as headphone amp?
How would you make the load? I guess with several small resistor. For example 20 times 160 Ohm in parallel?
Thanks,
JG

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First you need a proper attenuation of input signal, I guess the gain of the amp is high? And yes, 8 or 16 load resistors for amp to work stable and then you could try various series resistor with headphones, the value should be as low as possible in theory, but some headphones sound better with some resistance, 2R2, 10R or even more. There was a standard 120R resistor in series long time ago, when headphone output was derived right from the power amp output... So you'll have to experiment a little, nothing complicated.
Btw, never experiment with the headphones on, until you are sure that everything is ok, you could hurt your ears...
 
Thank You.
I have stepped attenuator at the input of the power amp. Level should not be a problem. Also, I have mid impedance level headphones. 180 and 300 Ohm. The driving levels are not that far away.

What is the reason for the series resistor? Is that only further dropping level, or something else?

Thanks,
JG
 
Thank You.
I have stepped attenuator at the input of the power amp. Level should not be a problem. Also, I have mid impedance level headphones. 180 and 300 Ohm. The driving levels are not that far away.

What is the reason for the series resistor? Is that only further dropping level, or something else?

Thanks,
JG

Frequency response, dumping, the point of this is to experiment yourself...
 
I made one of these Rod Elliot 'Project 100' power amp to headphone adapters, in version 2 (2 Ohm version):

Project 100

Everyone with headphones and a power amp (with no DC on the output) should try one for themselves.


Thank you for shared "project 100" adapter circuit. interesting with it.
Can this adapter be implemented for a Single ended tube power with an output transformer with a choice of 16 ohm impedance or it should be with an output of 8 ohms?
how about using Line tube preamp with OTL for secondary coil 600 ohm.
thank you
 
Thing is, you need maybe a couple hundred milliwatts, if that much, for headphones, so using a power amp for them would be overkill. I'd want to go with a low noise low power amp, maybe 1/4 watt or so, made just for the purpose, and dispense with the large series resistor mentioned in the above posts.
 
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