[UntilThen]

Fascinating. I woke up this morning to see the HK54 tubes. Visually a very striking tube even just for display.

I had forgotten we talk about amps last year in the DV336se thread.
https://www.head-fi.org/threads/darkvoice-336i-336se-tuberolling-partii.348833/post-16059674

 

[triod750]

Tom Waits; Mule Variations; 'What is he building in there'?

 

[L0rdGwyn]

Fascinating. I woke up this morning to see the HK54 tubes. Visually a very striking tube even just for display.

I had forgotten we talk about amps last year in the DV336se thread.
https://www.head-fi.org/threads/darkvoice-336i-336se-tuberolling-partii.348833/post-16059674

Right now they are for display only! I have a few pairs, but would like to find some more. Discovered a guy on diyAudio is hoarding probably 75% of the world supply...

Unfortunately, my feelings about selling amplifiers changed pretty dramatically earlier this year. I am really sorry for it as I know there is interest and I hate to disappoint, but it just isn't something I am up for. Of course there are two excellent custom amp makers here on Head-Fi in @A2029 and @SonicTrance , and hopefully @2359glenn will make his way back here soon too. Maybe another designer will emerge, you never know!

 

[UntilThen]

Unfortunately, my feelings about selling amplifiers changed pretty dramatically earlier this year. I am really sorry for it as I know there is interest and I hate to disappoint, but it just isn't something I am up for. Of course there are two excellent custom amp makers here on Head-Fi in @A2029 and @SonicTrance , and hopefully @2359glenn will make his way back here soon too. Maybe another designer will emerge, you never know!

I've been fortunate enough to have Glenn and Tomas make me tube amps. Glenn made me the super OTL amp and drove me crazy with tube rolling. Tomas made me Oblivion and will be building Odyssey next month... which is a few days time.

Eric from the local scene made me the 300b amp just a month ago. In theory, I should retire from more tube amps but the irrational side of me say I have to sample what Mischa can do and I know he does wonderful stuff.

Then I will coax and persuade you to do the 75th tube amp for me.
http://vinylsavor.blogspot.com/2021/03/tube-of-month-75th.html

 

[L0rdGwyn]

Uh oh, maybe Thomas at Vinylsavor is taking plunge into the Eimac transmitter world! It's a very interesting class of tubes, HK54 falls in this category.

Just to expound on the amp selling thing a bit more, never say never of course, but I fear selling amplifiers will feel like a second job. I like to teach and I hope that this thread has inspired a few people to try their hand at DIY, I know of a few who have started their own projects, it really is very satisfying and I think many people could make a nice headphone amp. I always recommend to start with a Bottlehead kit to get the feet wet on the hands-on, point-to-point wiring aspect of building, then hit the books to learn design theory. Morgan Jones' Valve Amplifiers can be found in PDF format online, which is a great resource. I also like Merlin Blencowe's Designing High-Fidelity Valve Preamps, it is a little more readable than Valve Amplifiers, but print format only and doesn't get into power stages. Very good chapters on power supply design, tube constants, common cathode amplification stage, cathode followers, and much more.

 

[whirlwind]

I sleeved the 6F5 grid cap leads with paracord today, gives the amp a little pizzazz.



Here how it looks with some graphite plate RCA 801A.

Man, is it me or is that power tranny huge!

Those RCA 801 tubes are off the scale in pretty!

 

[L0rdGwyn]

Man, is it me or is that power tranny huge!

Those RCA 801 tubes are off the scale in pretty!

Thanks! It is pretty big lol. That transformer really makes the whole thing work. It has a 300V B+ winding, 100V B- winding, two 10V filament windings for the 801A, and a 6.3V winding for the 6BX7 and 6F5. Also has three internal electrostatic shields to prevent noise coupling between all of those windings.

 

[UntilThen]

Man, is it me or is that power tranny huge!

It's just you. Tomas had already ordered Sowter power and output transformers for my next amp. Then a month and a half later Sowter said they have stopped producing custom power transformers. @L0rdGwyn has the last of Sowter's custom power transformer. It's a beauty and that amp will be heavy.

 

[Galapac]

Thanks! It is pretty big lol. That transformer really makes the whole thing work. It has a 300V B+ winding, 100V B- winding, two 10V filament windings for the 801A, and a 6.3V winding for the 6BX7 and 6F5. Also has three internal electrostatic shields to prevent noise coupling between all of those windings.

Have you weighed the amp? Has it got a name yet @L0rdGwyn? You must name it and give it a custom nameplate.

 

[L0rdGwyn]

Have you weighed the amp? Has it got a name yet @L0rdGwyn? You must name it and give it a custom nameplate.

I haven't weighed it yet. It is heavy, but believe it or not, my 6A5G amplifier is heavier - the Lundahl transformers overall are larger and it has three chokes inside!

The amp is called Prometheus. My girlfriend code names all of my amplifiers, so it was her choice, after the Greek god who gave fire to humanity, so that is what it is called between us

 

[L0rdGwyn]

It's just you. Tomas had already ordered Sowter power and output transformers for my next amp. Then a month and a half later Sowter said they have stopped producing custom power transformers. @L0rdGwyn has the last of Sowter's custom power transformer. It's a beauty and that amp will be heavy.

I hope they will reconsider, I pled my case to Martin, I have been their #1 buyer for custom mains over the past year and a half lol he says they might bring them back in a more limited capacity at higher prices, but a large part of it is the fact that they have different technicians working on them since the Carnhill acquisition and the complexity is pushing the limits of their skill level. Also, Carnhill being a larger company, there is some fear of liability given the high voltage transformers some customers are ordering.

So if they come back, likely higher prices, less complexity, lower voltages.

 

[UntilThen]

No problem. Tomas have found a Hammond power transformer with the same specs as what he would have ordered from Sowter. With chrome silver side covers, they look the works and I can't wait to see and hear the amp. 11w in triode mode and a bit more in UL. I'm not power hungry but headroom and a quiet amp is always welcome.

It's the output transformers that matters to me for SQ and still waiting for Sowter to deliver that. Should be soon.

 

[Galapac]

I haven't weighed it yet. It is heavy, but believe it or not, my 6A5G amplifier is heavier - the Lundahl transformers overall are larger and it has three chokes inside!

The amp is called Prometheus. My girlfriend code names all of my amplifiers, so it was her choice, after the Greek god who gave fire to humanity, so that is what it is called between us

Is the chassis powdered coated steel?

 

[Zachik]

The amp is called Prometheus. My girlfriend code names all of my amplifiers, so it was her choice, after the Greek god who gave fire to humanity, so that is what it is called between us

Maybe I should contract her services to name my upcoming amp by @A2029
To be clear, I do have a working name, and couple others I am considering, but who knows - maybe she would have an even better name...

 

[L0rdGwyn]

Is the chassis powdered coated steel?

It is powder coated aluminum!