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PostPosted: 12 Nov 2017, 06:26 
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Here is a headphone amp kit from Oatley. You can't actually order it now but you can soon. I have had this prototype for several months now but have finally mounted it. I have bread boarded it. There were a number of reasons that encasing this little gem may have been difficult. So a bread board (think the K12). It is on a Pete Evens chopping board. I'm know that will insure an organic sound.

All 6J6 NOS GEs, it doesn't get much better than that. I'm wrong it does get better, OPTs drive your phones. Think what you may pay for this if not an Oatley product.

Im not saying too much here a second prototype with changes will be out soon. More sonic comments then. For now, I'm enjoying it very much but there are some changes to be made which Oatley have agreed too.

Attachment:
Oatley HP 6J6 HP amp (432x800).jpg
Attachment:
Oatley HP 6J6 HP amp_2 (439x800).jpg


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Projects: "Lagoon" - tube preamp with cathode follower | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 12 Nov 2017, 07:25 
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Nice!

I like the sound of a 6J6 :D

IIRC when I did a loadline, it was something like 35K? :eek:

Keep us posted :up:

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PostPosted: 12 Nov 2017, 12:52 
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Geek wrote:
Nice!

I like the sound of a 6J6 :D

IIRC when I did a loadline, it was something like 35K? :eek:

Keep us posted :up:

What is your concern. I do t get it?

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Projects: "Lagoon" - tube preamp with cathode follower | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
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PostPosted: 12 Nov 2017, 16:50 
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No real concern, just transformer design above 12K gets more complicated.

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* Ratings are for transistors - tubes have guidelines*
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PostPosted: 15 Nov 2017, 07:02 
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Geek, the OPTs have 35K/8K marked on them.

I've spent some more time with this protype amp and have neatened it up a bit. Also found connecting mains earth to the tranni frames drops what little hum there is down even more.

The brd is dual layer and through a lot of the centre runs an earth plane. That now is also connected to mains earth. Tomorrow I'll have a listen once more. I'm finding I'm enjoying Sanctum so much I'm not trying this one.

The power tranni here is also in spec and also gets extremely hot. I should stop worrying about the Hammond on Sanctum and just see how it goes.

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Projects: "Lagoon" - tube preamp with cathode follower | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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PostPosted: 15 Nov 2017, 14:10 
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Where'd you get the OPT? I'd like to try a pair. I have buckets of tubes that look great at 35K on paper :)

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PostPosted: 15 Nov 2017, 17:12 
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You will have to talk to Oatley about that. I received the brd. fully assembled as a prototype to evaluate and comment. The OPTs and the power tranni may have been custom wound in China.

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Projects: "Lagoon" - tube preamp with cathode follower | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
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PostPosted: 15 Nov 2017, 17:13 
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mwhouston wrote:
Geek, the OPTs have 35K/8K marked on them.

I've spent some more time with this protype amp and have neatened it up a bit. Also found connecting mains earth to the tranni frames drops what little hum there is down even more.

The brd is dual layer and through a lot of the centre runs an earth plane. That now is also connected to mains earth. Tomorrow I'll have a listen once more. I'm finding I'm enjoying Sanctum so much I'm not trying this one.

The power tranni here is also in spec and also gets extremely hot. I should stop worrying about the Hammond on Sanctum and just see how it goes.


The figures I gave for the OPTs is wrong. It should be 35K/32ohm.

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Projects: "Lagoon" - tube preamp with cathode follower | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
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PostPosted: 16 Nov 2017, 00:37 
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Even better... I was thinking headphones ;)

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* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
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PostPosted: 19 Nov 2017, 16:53 
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The 6J6 is an interesting tube. One cathode shared by both internal triodes.

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Projects: "Lagoon" - tube preamp with cathode follower | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "retro-Hiraga" - Jean Hiraga Le Monster
Website: retro-thermionic


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