Valve Headphone Schematic wanted

[Val33]

Hi All

Can anyone point me in the direction of a schematic for a nice valve headphone amp?

I've looked for ages but can't find anything with any pegigree.

Thanks

Val

[alfie2902]

What about Nick's OTL headphone amp http://www.hificollective.co.uk/pdf/otl_head.pdf

[Val33]

Thanks for the link Alfie, I'd not seen that one.

Val

[Puffin]

I made this one. Not bad.

http://www.elektor.com/magazines/2009/july-047-august/improved-hybrid-headphone-amplifier.985428.lynkx?tab=2

[jostber]

You have some interesting schematics on page 1-3 in these search results from circuitdiagram.net:

http://circuitdiagram.net/search?cx=partner-pub-7733378411944456%3A2066739178&cof=FORID%3A10&ie=ISO-8859-1&q=headphone&sa=Search

[alfie2902]

Thanks for the link Alfie, I'd not seen that one.

Val

IIRC there's a thread about this headphone amp on the forum & Marco used or still uses one of these I believe.

As Nick the designer posts here any help you need would be close at hand to!

[Val33]

I followed up on Alfies suggestion and have now built Nick Goreham's OTL Headphone amp and very nice it is too :)

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020295/P1020295.jpg

I've built it exactly as designed and used all parts as suggested by Nick. The only difference is that I integrated a Caiman DAC in the case. The caiman was stripped of all bits that would not be used (switches etc), fitted with Elna caps and Murata regs and is run in passive mode with Arcotronics caps. The case came from China via ebay. The tubes are Russian 6AS7G and NOS Mullard ECC83. The dac can be powered up independently of the amp so that it can feed directly to my desk speaker system when required.

This was my first non kit build. I started with a dummy layout on cardboard using some gash resistors to help me work out what would work.

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020269/P1020269.jpg

And now the real thing:

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020275/P1020275.jpg

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020280/P1020280.jpg

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020285/P1020285.jpg

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020287/P1020287.jpg

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020289/P1020289.jpg

The power supply section

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020291/P1020291.jpg

Finished

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020304/P1020304.jpg

Looking a little crowded!

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020306/P1020306.jpg

The Caiman squeezed in down the side.

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020307/P1020307.jpg

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020308/P1020308.jpg

The aftermath of debris on my desk!

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020293/P1020293.jpg

That nice glow of tubes :)

http://www.valwalker.co.uk/Val_Walker/My_Albums/Pages/OTL_Headphone_Amp_files/Media/P1020298/P1020298.jpg

A very big THANKS to Nick for making the design available and being available to offer help and advice when I got stuck.

Val

[Ali Tait]

Nice job Val. It is indeed a bit crowded!

[realysm42]

How does it sound? Great looking job!

[Val33]

Thanks.

I'm not very good with describing how things sound, but I know what I like and I like this!

The noise floor is fantastic, bass is the best that I have ever heard through headphones. the mids and highs are equally good, but it is the bass that I have really noticed. I'm hearing frequencies that I don't believe I've ever heard before!

It wasn't the cheapest amp to build, mainly the cost of the transformer and chokes pushing it up, but I'm very glad that I stuck with the recommended parts as they work so well.

It still needs to run in properly and I've got some other output valves to try, but to be honest, I don't think I'll be looking for a new phones amp for many years :)


Val

[Ali Tait]

Aye, Nick comes up with some very good designs.

[Val33]

Just dusted off this amp after it sitting idle for a few months and plugged in my new AKG K551's. (on offer at Amazon for just £99)

WOW :)

Been sitting here enthralled for the last three hours!

My previous Headphones, Grado SR80i, sounded good, but these are just superb. They still need some running in, got about 12 hours on them so far, but they already sound incredibly open with great range. I can't find anything to not like about them.

Val

[The Barbarian]

Strange how people need to listern through all that circuitry when i use listern through just a Resistor!

[6L6]

Doubtful... A resistor alone isn't going to have any music in it.