Single ended headphone amplifier

[audiodesign]

In these years there was many interest about my SESS Tube Headphone Amplifier published on Headwize (http://www.headwize.com/projects/sho...ciuff4_prj.htm) because it is simple and it give a very good sound.

Now I have decided to start a new project using all my new experiences and the best components on the market like the new amorphous C-core by Lundahl.

This continue on:
http://www.audiodesignguide.com/NewH...Amp/index.html

[azazello]

Very nice Hi-End project !!!
Good luck!
/I have similar with 6J52P-6Ж52П- Russia for Sen. 580D/.

[Stixx]

Might well be one of my future projects
(and headphone amplifier No. 6 then... )

Nice documentation!!

[athos56]

So would it be possible to put a resistor between the secondary of the opt so that 32ohm headphones could be used? Or maybe a different transformer?? I'm never sure which lundahl tranformer I would need or which winding arrangement to use...

[audiodesign]

This ampl. can be used only with headphones with impedance more than 150 ohm

[dsavitsk]

Originally posted by athos56
So would it be possible to put a resistor between the secondary of the opt so that 32ohm headphones could be used? Or maybe a different transformer??

The Sowter 8988 and 9351 are both designed just for this. In the US, Electra-Print will make you a custom 5 or 10K:32 OPT for not too much.

As for the original design, I think 9mA/180V is a little low for the D3a. rp is closer to 4K than the 2K it is capable of and it does not look like a super linear spot. Maybe OK for high Z phones, but run it with more current at a lower voltage (~20mA/150V) for low Z.

You can spend all day searching for just the right cathode bypass cap and never find it. It, and the final PS cap, are both right in the signal path and represent the real limiting factor here. For the cathode bypass, I think you are better off with some sort of fixed bias -- LED, battery, etc. It is a huge improvement over a resistor and a cap.

For the PS cap, there are a number of solutions -- I found a gas tube shunt regulator worked well. But, you may never get rid of all the caps, so the existing regulator should be fine, too.

I don't mean to sound too critical -- overall it is a good way to run headphones.

[athos56]

Originally posted by dsavitsk


The Sowter 8988 and 9351 are both designed just for this. In the US, Electra-Print will make you a custom 5 or 10K:32 OPT for not too much.

As for the original design, I think 9mA/180V is a little low for the D3a. rp is closer to 4K than the 2K it is capable of and it does not look like a super linear spot. Maybe OK for high Z phones, but run it with more current at a lower voltage (~20mA/150V) for low Z.

You can spend all day searching for just the right cathode bypass cap and never find it. It, and the final PS cap, are both right in the signal path and represent the real limiting factor here. For the cathode bypass, I think you are better off with some sort of fixed bias -- LED, battery, etc. It is a huge improvement over a resistor and a cap.

For the PS cap, there are a number of solutions -- I found a gas tube shunt regulator worked well. But, you may never get rid of all the caps, so the existing regulator should be fine, too.

I don't mean to sound too critical -- overall it is a good way to run headphones.

Thanks for the info, I asked because this SE design looked simpler than the transformerless Aikidio design I was looking at.

[audiodesign]

The D3A in my schematic is configurated with a bias of 18mA

The Primaries of the transf. are in parallel to have a gap for 18mA

[audiodesign]

Also the LL1689/9mA can be used to drive 32 ohm headphone if used with primaries in series but it is necessary know the voltage necessay on output.

Give me the specification of your headphone and I will try to design it.

[athos56]

thats a great offer, if you design it I will build it! My headphones are 32ohm, Grado SR-225's. I'm trying to find the other necessary info now...