[simr]

I am the proud owner of the Citadel Amp This is just a customer impression.

Packaging was top class; Citadel is huge, heavy and impressive; I still building furniture around it

I feed this Amp with RME ADI 2 DAC and with Meze Empyrean planars. With Citadel I can really see now why Empy is a flagship headphone. Also the DAC was elevated quite impressive.

Compared with the good amp section of the RME everything is more in sound, soundstage is wider in all directions and more focused, instruments are well positioned in space and with more body and air. I can hear more details and textures; Dynamics and transients are just perfect for my ears. Bass is now deeper and hit harder, mids and highs are so sweet. Live recordings are teleporting me with the artists in the same place with them

I was worried about power but not after first minute of listening, still plenty of room without any distortions; I find Citadel fast, neutral, liquid and natural; this is what I was looking for. I like many genres of music, so depending on my mood I need my chain to serve me well in all cases and is doing very well.

After a huge leap of faith, I'm a very happy customer and recommend this Amp highly, also Thomas is very helpful and nice guy!

 

[UntilThen]

This is my first post on this thread but there are already 7 pages of posts. A lot of the posts are technical which is beyond my understanding. However after seeing a few pictures of the amps, I became pretty interested. I shouldn't be because I've been through quite a lot of ss and tube amps since I joined Head-Fi in 2015. A short journey but I've been through quite a lot of amps. Even right now I've 3 headphone tube amps and 3 solid state amps.

This is one photo from Sonic Trance that made me sit up. It uses c3g as driver tubes. Not many amps use c3g. My Glenn OTL amp does and that is one special very revealing tube.



So I started talking to Sonic who's ultra friendly. He doesn't strikes me as a trade member but more an audio enthusiast who just love talking amps and how that affects our enjoyment in listening to music through headphones or speakers.

Then Sonic showed me how he transformed the above amp into this balanced Mona Lisa. I couldn't believe what I see. It's beautiful !


Then he showed me another of his build that he use to drive his speakers. This has 2 chassis. One for the power supply and the other the tube amp. Beautiful !!! From someone who has a fulltime job and build his amps after work. The aesthetics are so good. That's good enough to grace my lounge room.


Then I learned that Sonic currently produce 2 amps for sale. The Citadel and Oblivion. He's going to produce an Oblivion with speakers output and an impedance switch ..... for me to review. No obligations to buy. I'm not a professional reviewer but why not.... It will be similar to my interest in any amp with tubes.

The Oblivion does look very striking. That's all I know about it at this point in time - just looks. I'll discover how it sound when it arrives in due time.

 

[UntilThen]

I prefer my amp to be transparent, fast and detailed while keeping the holographic soundstage. Not slow and goey "tube sound".

That's my preference too. It's the reason I prefer my Glenn Super 9 OTL amp using Sylvania 6sn7w metal base plus 6 x RCA / Sylvania 6BX7gt over the Woo Audio WA5LE using Brimar CV1988, EML 5U4G mesh plates rectifiers and Takatsuki 300b tubes. It was a 2 weeks period of comparison between these 2 amps. I wanted to prefer the WA5LE because it looks better but I can't deny that sound wise I prefer the Glenn OTL amp more. Yggdrasil and HD800 in attendance.

If Oblivion sound as you described then I want to hear it for myself.

 

[UntilThen]

Lastly I want to see how Oblivion drives my Axis LS88 4 ohms 300w max capable floor standers and it's little brother the Axis LS28 bookshelf 8 ohms speakers.



And because I love Axis speakers and I know the designer, John Reilly, I also have the Axis Voicebox S. https://6moons.com/audioreviews2/axis/1.html
Here I have the Sansui AU-717 driving it. I also have the Sansui au-Alpha 907MR and Redgum RGI120ENR black series integrated amps for comparisons. I don't expect Oblivion to drive my speakers like my powerful integrated amps but it would be interesting to hear what it does...

 

[SonicTrance]

Thanks for the kind words @UntilThen !

I've started to build some modules for the review amp now!

I suspect Oblivion will pair nicely with your floor standing 4 ohm speakers. That's where the amp has most power also.

Question: Does your speakers have a ground lug?

Some speakers do. I ask because Oblivions speaker outputs are balanced, so the black terminal is not ground but is carrying signal in antiphase to the red terminal. Then there's a centertap to ground.

If your speakers have a ground lug I can ad a ground connection at the back!

 

[UntilThen]

I don't think my Axis LS88 has a ground lug. This is a picture of the back showing the connections. I think it allows for bi-amping? However the bridge is there so I'm not bi-amping it.

 

[UntilThen]

I've started to build some modules for the review amp now!

No rush but I'm looking forward to it. I kept looking at the picture of the Oblivion on the 1st page of this thread. Somehow the tubes used makes the Oblivion look nicer than the Citadel. I also noticed that Maxx likes the HD800 with the Oblivion. That's good because my trusted HD800 is ready and waiting. I've kept it mint since I bought it new from Addicted To Audio in downtown Sydney. I'm more keen on hearing how Oblivion sound through my ZMF Verite Open LTD Pheasant Wood. This dynamic 300 ohms hp has a slightly warm sound but the clarity and details are very good due to the beryllium drivers used. I've always seek tubes that present a more neutral and brighter tone in my amp to pair with Verite. That and with Yggdrasil brighter and sparkly tone, I'm rather happy with this headphone that is very comfortable on the head and pleasing to the ears. There is no fatigue !!!

 

[UntilThen]

Oh Sonic, in case you didn't know, I'm in Sydney Australia, so it's 230v.

I don't normally see a fan being used in amps but it's used in your amps. Does the amps generate a lot of heat? I'm ok with the fan because you said it's quiet and can't be heard. A build in fan might be good because some Glenn OTL amp users use an external fan to cool it. Not that it's needed but they must be using quad 6080 which can get very hot.

 

[SonicTrance]

I don't think my Axis LS88 has a ground lug. This is a picture of the back showing the connections. I think it allows for bi-amping? However the bridge is there so I'm not bi-amping it.

Ok, so no ground connection is needed! All good.

I kept looking at the picture of the Oblivion on the 1st page of this thread. Somehow the tubes used makes the Oblivion look nicer than the Citadel.

I can build Citadel with EL81's as output as well. Just need to use either two 6AT6/6AV6 per side for the input stage, or replace them with a single 12AX7. The 6AV6's triodes are basically half of a 12AX7. The reason I used octal tubes in Citadel is mostly because of aesthetics. I thought it would look nicer "bigger chassis, bigger tubes" but I don't know, lol. The EL36's (6P31S) are pretty much the octal version of EL81!

Oh Sonic, in case you didn't know, I'm in Sydney Australia, so it's 230v.

I did know! And that's all good!

I don't normally see a fan being used in amps but it's used in your amps. Does the amps generate a lot of heat? I'm ok with the fan because you said it's quiet and can't be heard. A build in fan might be good because some Glenn OTL amp users use an external fan to cool it. Not that it's needed but they must be using quad 6080 which can get very hot.

It does generate some heat. It's not very efficient, lol. It runs in class A of course. The fan is a 200mm 700rpm fan, so very quiet. It's there to get the air moving inside the amp, that's it. The entire chassis acts like a big heatsink as well. It's totally fine though, just don't put it inside a cabinet or something. It needs to breathe!

 

[Maxx134]

The "Oblivion" amp remains my end game amp. Period.
That's it. I don't need anything else.
Game over.

I stopped after this.
No more amps with altered soundstages, or altered Tonality signatures, or added rich tube harmonics.

What I get is resolution, proper image placement, holography and transients galore.

Don't need brute power when I have enough without any audible distortion.

On the "Oblivion" version, I Dont loose totally the ability of driver tube rolling, if I wanted any change to the 0.005% signature change, that would only be percieved if I compared to another amp...

Comparing it even to the best solid state amp I tried, which, (by the way), was not the Benckmark HPA4, but instead, the PASS LABS INT-150 (speaker amp on the Susvara), and got literally the same exact signature minus a touch of bass oomph of the other amp (driving a Susvara!, which may have already been above neutral in bass),
which I touched up a notch in "roon" player, to achieve exact sig & performance level, at a much lower noise floor, which solidified my impression that I am in true end game territory.
So I am literally retired from the amp game as I have my reference amp.
Only for hobby fun, I play with others.

 

[Maxx134]

I didn't want to say this, as there is much musical gear out there and I still can enjoy them all, but...

The truth is that 99.999% of the other "tube" amps out there are just glorified old-school designs.

They put DC in their tube filament and think they are now modern.
Still old-school designs.

The put a CCS tail on a circuit and think they upgraded what is essentially the same old-school designs (of 50 years ago) ...

Or they put cool LEDs in the bias control circuit, just to look advanced. ..

Fake hybrids.
All are fake hybrids to me.

They put a tube (single ended even worse) in ancient old school topology, in their input stage, so it gives off its distortion, and then call it a hybrid...

So now, with ALL of them, you waste your time and money tube rolling... And rolling... And more tube rolling,
Which in reality is just like having different bias, linearity, and internal capacitance variations of different tubes...
All the while trying to find a sweet spot match between circuit bias setting, and tube, in a "designer chosen" circuit setting.

All distorted lenses into viewing the music.


***
In contrast, these amps take old circuit design and approach it totally differently.
A different topology approach with a different goal in mind.
A goal to remove all component "parasitics", the sonic influence of parts and circuit behaviors.

This is why this amp is not your usual tube, or hybrid amp.

This is also the only amp I know that uses components to their ideal performance advantage, which is tubes for voltage and solid state for current..
Then to remove parasitics, the coupling and of stages is of such high ratios, as to have no component influence. Then add to that ideal circuit parameters, and optimal usage of CCS and gyro to cause high transient response...

That's my take, on my own experience with amps.
You may be totally happy with your own gear.
The point is, in this hobby you do find musicality as you progress along the way, so enjoy it while you can, as that is fleeting until you arrive at a high level.

 

[Maxx134]

If anyone is curious to know the history of this topology, you can check out
the heated discussions in the MK6/8supermod threads when member MrCurwen entered and alot of discussion lead to sonictrance building off his designs in the "modern tube amp" thread, and now this thread.
I was a serious tube only convert until then, haha.

 

[UntilThen]

I can build Citadel with EL81's as output as well. Just need to use either two 6AT6/6AV6 per side for the input stage, or replace them with a single 12AX7. The 6AV6's triodes are basically half of a 12AX7. The reason I used octal tubes in Citadel is mostly because of aesthetics. I thought it would look nicer "bigger chassis, bigger tubes" but I don't know, lol. The EL36's (6P31S) are pretty much the octal version of EL81!

I'm not familiar with EL81 or the 6AT6/6AV6 used in Oblivion. So I dig around and found out the EL81 predates EL84. These 2 tubes are entirely different. EL81 was intended for early TV horizontal sweep application. Is there a reason for not choosing the more popular EL84? I don't know. Perhaps tubes don't make much difference in your amp design. Just a curiosity that's all. From this old write up. https://www.tiffe.de/roehren/VTV/VTV08.pdf

I was thinking that using Telefunken EL11 and EL12 spez might look good on the Oblivion but then again the small tubes you have there does look good in the overall scheme. Aesthetics are important and your amp has it but ultimately it would be how it sound.

 

[UntilThen]

On the "Oblivion" version, I Dont loose totally the ability of driver tube rolling, if I wanted any change to the 0.005% signature change, that would only be percieved if I compared to another amp...

So changing driver can alter the sound signature by 0.005%, which is as good as not changing. Just out of curiosity, how would you achieve that. Do you roll in a different brand EL81 or a different loctal similar tube to EL81?

 

[SonicTrance]

Perhaps tubes don't make much difference in your amp design. Just a curiosity that's all.

On the contrary, tubes make a big difference. The EL84 is not as linear as the EL81 and the EL84 has a little too high Ra for these amps. Also, there’s no reason to use the popular audiophile tubes. There’re so many super linear tubes out there for cheap that you can use!

Aesthetics are important and your amp has it but ultimately it would be how it sound.

Totally agree! SQ comes first, of course