6GM8/ECC86 Tube Headphone Amp Hybrid

[lineup]

This is a way to use low voltage tube to drive headphones.
Uses 4 transistors for the output.
Is adjusted to give some THD with 2nd harmonic.

 

[ElArte]

Looking good. Did you try to build it? It does look like starvation voltage on that plate. I wonder how it performs across the frequency range.

 

[lineup]

No, I will not build it.
The output level is +10dB on 32 Ohm.
I might test and run at 10kHz.

 

[jean-paul]

What is it with publishing untested imaginary/simulated stuff? Either design/simulate, build and test and then publish for others to enjoy and learn or just don't. Sorry.

Or should others build it and report back that the design is a success or a failure? Clean hands approach 🙂

 

[lineup]

I have changed circuit in first post.
Power supply 48 Volt.
The triode is no more starved.
The Fourier shows 2nd harmonic is 56dB above 3rd.

 

[lineup]

My testing is at +10 dB and 1 kHz into 32 Ohm.

You are welcome to comment or question.

 

[lineup]

The Frequency Range is 2.5 Hz to 3.5 MHz.

 

[lineup]

Nelson Pass frequently looks for 2nd harmonics in his amplifiers.
He does this because he thinks this give good sound.
This amplifier of mine gives a lot of H2.
It should sound well.

Here is the harmonics spectrum:

 

[lineup]

I added one divider at the input to reduce gain.
The overall gain is now x3.07.

 

[lineup]

If needed I can do a version for 300 Ohm.

 

[Charm]

Please do it at 300 Ohm. Is there a replacement for KSC1845? Thank you.

 

[Merlinb]

Or should others build it and report back that the design is a success or a failure? Clean hands approach 🙂

+1. He wants someone else to do the hard work for him.