[OctavianH]

@Isaacc7
I usually don't post pics mid build but thought I'd make an exception here. Mainly to show Isaac of course.

Thank you for doing this, helps a lot in our planning of future amps.

The four output sockets are in the back row and driver tubes at the front. Below each output tube socket you have a trimmer to adjust the negative grid voltage.

This is exactly what I want on manual bias. To be able to adjust the grid bias / tube. I will include this on my future Citadel build scheduled for 2025.

 

[UntilThen]

A very impressive amp. Can’t wait to see the final result.

 

[OctavianH]

@Isaacc7 is a very experienced customer and he knows exactly what he wants. This is my most expected build because I am fully convinced that he will use it finding a lot of new tube combos. Since all UltraSonic amps have the same pedigree I wait for his amp like "air". I know that this will help me level a lot.

Good luck @Isaacc7 , looks stunning.

 

[SonicTrance]

@Isaacc7 is a very experienced customer and he knows exactly what he wants. This is my most expected build because I am fully convinced that he will use it finding a lot of new tube combos. Since all UltraSonic amps have the same pedigree I wait for his amp like "air". I know that this will help me level a lot.

Good luck @Isaacc7 , looks stunning.

Bear in mind this is mainly a speaker amp with a headphone output. There really is no need for all this power for headphones. Isaac listens mostly through speakers so this makes sense. But yeah, it's a very versatile amp indeed!

 

[OctavianH]

Bear in mind this is mainly a speaker amp with a headphone output. There really is no need for all this power for headphones. Isaac listens mostly through speakers so this makes sense. But yeah, it's a very versatile amp indeed!

What I want is to be able to use electrically unmatched combos on output and have the same precision as in the manual grid bias. I need fast and precise amps because of my musical preferences, and you are able to do them. I would like to have a Citadel, fully balanced, with manual adjustable output grid bias so I can use a quad of GEC E3375 or GEC ATS25. I have a big collection of outputs but not all of them are electrically matched. I want to use in this Citaldel EL34, ATS25 or E3375 quads.

 

[baronbeehive]

I just learn that there is a store there that carries the Oblivion amp and ZMF headphones, etc. https://www.beyondthemusicid.com/

So joining this cult, am I free to leave when I want to? Or is it a case of ''You can check in anytime but you can never leave".

Yes... beware... that's dangerous talk .

 

[OctavianH]

Yes... beware... that's dangerous talk .

Remember that you are @UntilThen and not TheEnd.

 

[baronbeehive]

Yeah convenience is big factor, especially if you live in an apartment. I usually stream using Qobuz - it has actual high-res files and its music suggestion algorithm has really come a long way since last year. It actually suggests songs that are not just of the same genre, but have the same vibe and rhythm when you finish an album.

For the albums I REALLY like I would download them in DSD on HDTracks. I realise this is a huge burden in terms of memory storage and sometimes the DAC can be a bit flaky when playing these large files. The improvements from 192 kHz file is really marginal but I don't mind going the extra mile for more 'special' recordings.

Yeah, they have a much greater selection on HDTracks nowadays than when I first went there. I still find some high res disappointing though, probably from copying from a poor master.

That algorithm sounds more sensible, the predictive feature is a bugbear of mine, usually nothing like that track you are comparing.

 

[UntilThen]

Yes... beware... that's dangerous talk .

I quote it wrongly. From Hotel California.

You can check out any time you like
But you can never leave

 

[UntilThen]

Bear in mind this is mainly a speaker amp with a headphone output. There really is no need for all this power for headphones. Isaac listens mostly through speakers so this makes sense. But yeah, it's a very versatile amp indeed!

What is the rated power for this amp?

 

[baronbeehive]

@Isaacc7
I usually don't post pics mid build but thought I'd make an exception here. Mainly to show Isaac of course.

This is the push pull version of Odyssey with manual grid bias. The four output sockets are in the back row and driver tubes at the front. Below each output tube socket you have a trimmer to adjust the negative grid voltage. The red measuring terminals is for external voltmeter to read that voltage. There's only one black terminal as it's just ground anyway.
In between each pair of output tubes there's a little toggle switch. Toggle to the left to measure the anode current of the left tube on the mA meter and toggle to the right to see the anode current of the right tube on the meter.
In the middle there's a panel voltmeter and below it is a trimmer. Here you adjust the B+ (also anode voltage). The range will be around 240V-400V.
The two large toggle switches are for the heaters. Up is 6.3V and down is 12.6V. One switch for driver tube sockets and one for output tube sockets.

Isaac, do you need me to label everything or can I leave it as is? I think the "clean" look would get destroyed as there would be lots of labels lol

Btw, this is the heaviest amp I've built to date! That Monolith PT is a beast! The amp weighs 26.5kg as it is now even without bottom cover and lots of components missing!

Fascinating, lots of switches to play with!!

Adjusting the B+ would act also as a tone control as that would change the tube operating points?

 

[OctavianH]

Tomas, if this is not confidential, I would like you to tell me who is the next Eternity owner.

 

[baronbeehive]

I quote it wrongly. From Hotel California.

You can check out any time you like
But you can never leave

Wonderful track and guitar from Joe Walsh. Interesting that the chords in the backing arrangement are identical to Jethro Tull "We Used To Know". I often wondered if they did that deliberately.

 

[SonicTrance]

What I want is to be able to use electrically unmatched combos on output and have the same precision as in the manual grid bias. I need fast and precise amps because of my musical preferences, and you are able to do them. I would like to have a Citadel, fully balanced, with manual adjustable output grid bias so I can use a quad of GEC E3375 or GEC ATS25. I have a big collection of outputs but not all of them are electrically matched. I want to use in this Citaldel EL34, ATS25 or E3375 quads.

If we use grid bias it's no longer a Citadel. The output stage in Citadel is a LTP stage with gyrator plate loads and a CCS tail. The tail has a constant current across it at all times (hence constant current source) and is what finds the proper operating point for the tube.
I guess we can build some sort of hybrid. Should work.

What is the rated power for this amp?

I won't know for sure until testing and it varies heavily with tubes and different operating points of course. But easily 20W+.

Adjusting the B+ would act also as a tone control as that would change the tube operating points?

Don't about tone control but yes. It's mainly there so he can use tubes that otherwise would burst into flames at 400V on the anode.

Tomas, if this is not confidential, I would like you to tell me who is the next Eternity owner.

He can speak out if he wants to. I actually don't know his nick on the forums.

 

[OctavianH]

If we use grid bias it's no longer a Citadel. The output stage in Citadel is a LTP stage with gyrator plate loads and a CCS tail. The tail has a constant current across it at all times (hence constant current source) and is what finds the proper operating point for the tube.
I guess we can build some sort of hybrid. Should work.

I will think about this, I like to have control and set up everything. I have OCD and this helps me organize my things. It helps in my work but also makes me think I over control everything. Yeap guys we are all crazy. LOL