[joseph69]

Here, here, here & here are some posts from the 'Focal Utopia Thread' regarding amplification.

 

[UntilThen]

At 2 am on the 28th of Dec 2019, I got up and listen to Endless River by Pink Floyd and Fear in A Handful of Dust by Amon Tobin. Some songs I repeat through each of the 3 amps. Eventually after an hour I settle down to enjoy the music on Oblivion. Tomorrow morning I leave with my wife for a beach house up the coast for the weekend with some friends. I'll return on Sunday night and spend another 2 days listening before writing my impressions on New Year's Eve. It's the start of the new decade. A momentous point in time.

When I wrote this almost a year ago, I have the faintest idea what 2020 will bring. That very moment in time - at 2am on the 28th Dec 2019, I must be the happiest person on earth, listening to music on 3 gorgeous amps. Alas, 2020 brought along calamity after calamity. Bush fires, Covid-19, working from home and the US Election. Sigh

I have not use Oblivion for more than 2 months but that's about to change as I journey back to Canberra this Sunday. All this while in Sydney, I have been using Burson Conductor V2+ and La Figaro 339. I have even left Verite and HD800 in Canberra. I have LCD-3f, Beyer T1.2 and HD650 in Sydney. Yeah I'm looking forward to listening to the combo of Yggdrasil and Oblivion again with the various headphones.

Now to reflect on my audio journey as we race towards the end of 2020. Pretty soon it will be Christmas.

I hope you folks are doing well !

 

[baronbeehive]

When I wrote this almost a year ago, I have the faintest idea what 2020 will bring. That very moment in time - at 2am on the 28th Dec 2019, I must be the happiest person on earth, listening to music on 3 gorgeous amps. Alas, 2020 brought along calamity after calamity. Bush fires, Covid-19, working from home and the US Election. Sigh

...

I hope you folks are doing well !

Don't know which is worse of the 3 things you mention. Thanks for the good wishes, I hope so too, lets all hope for some relief from this weird alternate universe we are living in atm .

 

[SonicTrance]

Here's another Citadel complete! This one has a true power input add-on that does not only bypass the volume pot but the entire input stage. The signal is injected straight into the grid drivers that drives the 6P31S grid's. First amp that has this feature and it worked out great!

 

[Bonddam]

Does any of the amps ever need to be biased?

 

[SonicTrance]

Does any of the amps ever need to be biased?

Short answer is no!
All stages, except for the input stage in Oblivion which uses fixed grid bias, is biased through a CCS tail. No adjustments are ever needed.

 

[Bonddam]

Short answer is no!
All stages, except for the input stage in Oblivion which uses fixed grid bias, is biased through a CCS tail. No adjustments are ever needed.

Good hate extra work!

 

[SonicTrance]

Good hate extra work!

The first review amp I built (@Maxx134 Oblivion) has a trimmer on each side to set the current to the output tubes. That's the only one I built with that feature as it's unnecessary and could potentially damage the amp if your not careful, so I decided to use fixed resistors instead.

 

[Maxx134]

The first review amp I built (@Maxx134 Oblivion) has a trimmer on each side to set the current to the output tubes. That's the only one I built with that feature as it's unnecessary and could potentially damage the amp if your not careful, so I decided to use fixed resistors instead.

The Oblivion remains my number one reference amp.
It is the most accurate amp in every aspect I have heard so far.

 

[BzzzzzT]

Here's another Citadel complete! This one has a true power input add-on that does not only bypass the volume pot but the entire input stage. The signal is injected straight into the grid drivers that drives the 6P31S grid's. First amp that has this feature and it worked out great!

Tomas, thank you for all your hard work in building this amp and working with me to get everything put together! The power input is a first, as far as I can tell. I have never seen it done before in any tube amp before, let alone a headphone amp. These 6P31S are brilliant tubes and a wonderful choice! I can't wait to hear this amp! I know it will sound much better than the amps I have built in the past! I was listening to a solid state amp and really missing tubes. I found myself running the signal through my tube compressor and tube preamps on my recording setup to get some more harmonics. It will be really nice to have a full fledged tube amp again.

 

[SonicTrance]

Tomas, thank you for all your hard work in building this amp and working with me to get everything put together! The power input is a first, as far as I can tell. I have never seen it done before in any tube amp before, let alone a headphone amp. These 6P31S are brilliant tubes and a wonderful choice! I can't wait to hear this amp! I know it will sound much better than the amps I have built in the past! I was listening to a solid state amp and really missing tubes. I found myself running the signal through my tube compressor and tube preamps on my recording setup to get some more harmonics. It will be really nice to have a full fledged tube amp again.

It's been my pleasure! I hope you'll enjoy it for many years to come!

 

[baronbeehive]

Here's another Citadel complete! This one has a true power input add-on that does not only bypass the volume pot but the entire input stage. The signal is injected straight into the grid drivers that drives the 6P31S grid's. First amp that has this feature and it worked out great!

Hey Sonic, you aren't standing still LOL!

That add-on should have yet more sonic benefits.

 

[Maxx134]

first review amp I built (@Maxx134 Oblivion)

Hmm I think I may have the oldest Oblivion amp, lol.
Although changing the tubes in this amp realistically don't matter, as they retain the same overall level of quality, realism & refinement, I did swap out my stock tubes.
I ended up with some rare Mazda and mullards, more so to complete my visual tastes.


Also, thanks to the single ended driver stage, I did manage to tube swap some tiny tube changes, in the realm of sonics of probably 2-3% ( in wire territory differences).

The output stage tubes gave no sonic flavor, but the Tesla tubes seemed to give me a slight more dynamics, compared to my Mazda. Still, I kept the Mazda in for the beauty of the bottle.


I posted a link a few pages back in thread for anyone looking for those.
They are shorter and less bright tho..
The stock tubes are my backup tubes when I run out, but I think these tubes being run optimally should last very long, correct? so three pairs should last lifetime???


The driver section tubes were the only place I could try to add anything to the sound, and did so with mullards, which are known for having most tube sound. So although the signature was still neutral, I did feel a tiny hint of tube flavor injected in (maybe 2%) which was what I wanted to do. Just a hint of tube..

I have heard more amps since, but not want to part with my Oblivion, as once you reach summit-fi, the only difference is choice, and I prefer the more accurate soundstage over flavor or image difference.

I don't think the Citadel would not allow any variance, as it is front end is more refined and balanced.
Still, It's great to have a designer who is open to choices as I have seen the Citadel with different configurations.

 

[SonicTrance]

Hmm I think I may have the oldest Oblivion amp, lol.

Yes! You have the first one! The first one I called Oblivion anyway

Also, thanks to the single ended driver stage, I did manage to tube swap some tiny tube changes, in the realm of sonics of probably 2-3% ( in wire territory differences).

The output stage tubes gave no sonic flavor, but the Tesla tubes seemed to give me a slight more dynamics, compared to my Mazda. Still, I kept the Mazda in for the beauty of the bottle.

The input stage in Oblivion is, like you say, where you can expect to hear most difference from tube rolling. That tube also have a flat load line, like the balanced output stage, but is grid biased and doesn't draw constant current.
The tubes in the output stage in Oblivion, and both input and output stage in Citadel, have flat load lines and draw constant current. The tubes are operating in their linear region at all times. That makes it hard to tell tubes apart if both are NOS and have similar grid curves. It's all about the curves! =)

The stock tubes are my backup tubes when I run out, but I think these tubes being run optimally should last very long, correct? so three pairs should last lifetime???

Yes, they should last a very long time. The EL81's are run at 3,5 W and are speced for 10 W!

Still, It's great to have a designer who is open to choices as I have seen the Citadel with different configurations.

The silver version of Citadel uses 6P7S output tubes instead of the 6P31S. That's mainly for aesthetics though =)

I'm designing a new amp in the coming months. It's going to be a SET amp with much more power than Oblivion and Citadel. Going to be great for speakers but also headphones of course! It's going to be called Infinity. I'll post here with updates on that!

 

[Maxx134]

Yes! You have the first one! The first one I called Oblivion anyway

You should start numbering them.

I'm designing a new amp in the coming months. It's going to be a SET amp with much more power than Oblivion and Citadel. Going to be great for speakers but also headphones of course! It's going to be called Infinity. I'll post here with updates on that!

Fantastic!