[leftside]

No cliche or obsessions for me. This is not my watering hole. I didn't find Oblivion but it found me. It's the reason I'm here.

Like Indiana Jones who is the raider of the Lost Ark, I was on a mission with 2 other tube amps in sight. I name them Berlin and Sydney. Berlin is going to use Telefunken EL11 as drivers and Telefunken EL12 spez as power tubes. Sydney is going to use 12AU7 as drivers and KT66, KT77, 6L6, 6V6, KT88, etc as power tubes. Sydney would probably have cost me US$2000 in tubes alone. Both would be set amps using Lundahl transformers and Jupiter caps, special chassis, Yamamoto's sockets and all the boutique parts.

Then I met Oblivion and after 2 weeks with it and my other amps, in the period between Christmas and the week after New Year, I was stopped dead in my tracks looking for the Lost Ark because it is right here with me.

Right here with the big picture so no one can miss it. https://www.head-fi.org/threads/oblivion-ultrasonic-studios.902926/page-24#post-15411044

GOTL and Studio Six will be sold soon. If you're after a GOTL watch out for my 'for sale' listing in Head-Fi.

I stop fantasising about Berlin and Sydney. I don't even care about tube rolling anymore. I am just exploring music these days ...... and wondering how different the 'balance' Citadel would be from Oblivion.

Notice not once in my review did I mention about price disparity between the amps. I don't really care. What matters to me is which one sound more appealing to my ears.

As for selling the EL tubes, I'm not in a hurry. I would rather be selling all the EL tubes together for someone who might want to progress with Berlin. If not I'll just hoard it for 10 years then pass it on to my son with the instruction that it's not to be sold until 2050. By which time they would be the only NOS EL11 and EL12 spez tubes left on planet earth.

Can't argue with any of that. If I didn't already have the KT66, etc tubes I'd probably also be ordering a Citadel or Oblivion. My new years resolution was to not buy any more tubes this year (I have 900 and my music room is full). So far, so good...

I too will be leaving a bunch of tubes sitting on the shelves. My 1101 amp also uses CCS, and a design that doesn't involve tube rectification. The bass is so powerful, that sometimes I find myself looking for tubes that turn down the bass a little, or I switch out the LCD-4 and plug-in the Stellia. No more tube rectification for me.

Quite the journey we've been on I'm settled on 2 amps (1101 V6 aka "Thunder" and Glenn 300B), but a third will be purchased in the latter half of the year - most likely "Lightning". If shipping wasn't so expensive, it would have been fun to do an amp swap at some point.

 

[MrCurwen]

Sonic of course already replied, but I'll put my thoughts out also. I am the designer who put together the topologies these amps utilize.

- What is the concept behind the design of a small looking round transformer housed in a hefty sized amp? (apologies for a dumb question)

Like already said, it's just the power transformer. Whether or not the visual of the cover looks nice is subjective. I think it looks very nice, it has good synergy with the black hats the output tubes have.

The PT is not small, it's overkill. Same for the OTs.

- Is this an OTL or a SET (transformer coupled) amp, and is there any advantage of this over a SET amp?

If SET stands for single ended transformer coupled, then no, the amp is not SET since it has a fully balanced output stage.

As said, it is a parafeed design. Utilizing parafeed and sufficiently low output impedance driving the OT primary, the OT becomes 'transparent'. In technical terms it just means that all the nasty parasitics and reactances the OT primary coil has, are oversaturated with current, and thus satisfied.

The advantage of this approach is that you can use a 'cheap' OT with "bad bandwidth specs", and get a flat and full bandwidth response out of it, with sharp transients (transients are difficult for reactive coils) and full transparency. All this without using any big name iron. The OT is simply "played out of the equation".

And yes, I came up with this approach by not affording good iron. I made good iron obsolete. Cheapness is the mother of invention or cleverness.

- Would this be advisable to pair well with the HEDDphone One? It's a new variant of AMT transducer that is said to have similar amping requirements as a hard to drive low-z planar, with the following specs: 87 dB SPL for 1 mW, 42 ohms.

Yes, the amp can drive almost anything. Real output impedance is very low, so it can handle whatever you may throw at it, including, as mentioned, speakers (within reasonable volumes).

- Moreover which headphone impedance specs is this said to pair well with?

All.

Let's take an optics analogy. The OT acts as a lens. Impedances on the primary side are 'high' and on the secondary side 'low'. Now if you have a 'low' impedance on the primary side, the secondary side focuses this like a lens, to make it even lower. So plenty of overkill drive available for all loads.

 

[DecentLevi]

Hey guys thanks so much for your replies. This amp certainly does seem intriguing and unique. I'm a little slow to reply because of my work schedule and just barely started to skim through this thread. I didn't see any price on the previous page, only talk about $7 tubes, can someone post a link to that price difference? I will respond later when I have time, and oh about my first response I was a little light-headed at the moment so my words could have been a little 'off'.

 

[SonicTrance]

Hey guys thanks so much for your replies. This amp certainly does seem intriguing and unique. I'm a little slow to reply because of my work schedule and just barely started to skim through this thread. I didn't see any price on the previous page, only talk about $7 tubes, can someone post a link to that price difference? I will respond later when I have time, and oh about my first response I was a little light-headed at the moment so my words could have been a little 'off'.

I just finished a Citadel with impedance switch, speaker outputs and RCA inputs. This is the first Citadel with the new layout. I'm very happy with how it turned out.



I also have an announcement to make.
I'll have to start a business soon as orders are coming in. This will, unfortunately, mean price increases. This is not something I want to do, but I have to if I want to keep on selling these amps. This will still be my hobby and not my full time job.

I'll give people a chance to order with current prices until February 1st, then I'll do the price increases.
I'll also change from USD to EUR. This is because it's easier for me to shop for parts with EUR (it's still not Swedish currency). I've already made the change to EUR on the website without any price increase.

New prices as of February 1st will be:
Oblivion: 1750 EUR
Citadel: 2150 EUR

With this increase my overall profits will still much LOWER than it is now.

 

[UntilThen]

Quite the journey we've been on I'm settled on 2 amps (1101 V6 aka "Thunder" and Glenn 300B), but a third will be purchased in the latter half of the year - most likely "Lightning". If shipping wasn't so expensive, it would have been fun to do an amp swap at some point.

Thunder and Lightning, that's AC/DC song Thunderstruck !

Last year I was pretty much 'ampstruck'. This year and going forward I'll keep it simple and easy on the wallet. I am very happy with Yggdrasil > Oblivion > Verite / HD800. Furthermore the amp drives my Axis Voicebox S at a level I'm comfortable with at near field listening. The amp is quiet. No hiss or hum. Just quiet. Each time I power it up, it goes through the routine. The meter needle shoots up to 30 and I know I'm ready to start listening. For once I didn't scout ebay daily for tubes to buy. I've been weened of expensive tubes dependency. These RCA 6AV6 and Siemens EL81 that Sonic send is perfect.

Each time I go back to Studio Six or GOTL, I miss the amazing clarity and details plus the expansive soundstage and precise imaging of Oblivion. The 3D effect is real. The amp reveals how a headphone should sound. There's no glare or harshness. This last point is very important with HD800. I could listen to music with HD800 and Oblivion and never felt the need to mod the headphone. There's no glare or sharp peaks. Simply not there. The fast transient speed and agility of Oblivion is my favourite.

After about 5 intense years with Head-Fi, I'm ready to walk off into the sunset with this combination... and enjoy travels and holidays with my wife.

Yup the expensive shipping for us to swap our amps to try, will sink Dow Jones.

Enjoy your amps Leftside !

 

[DecentLevi]

No cliche or obsessions for me. This is not my watering hole. I didn't find Oblivion but it found me. It's the reason I'm here.

Like Indiana Jones who is the raider of the Lost Ark, I was on a mission with 2 other tube amps in sight. I name them Berlin and Sydney. Berlin is going to use Telefunken EL11 as drivers and Telefunken EL12 spez as power tubes. Sydney is going to use 12AU7 as drivers and KT66, KT77, 6L6, 6V6, KT88, etc as power tubes. Sydney would probably have cost me US$2000 in tubes alone. Both would be set amps using Lundahl transformers and Jupiter caps, special chassis, Yamamoto's sockets and all the boutique parts.

Then I met Oblivion and after 2 weeks with it and my other amps, in the period between Christmas and the week after New Year, I was stopped dead in my tracks looking for the Lost Ark because it is right here with me.

Right here with the big picture so no one can miss it. https://www.head-fi.org/threads/oblivion-ultrasonic-studios.902926/page-24#post-15411044

GOTL and Studio Six will be sold soon. If you're after a GOTL watch out for my 'for sale' listing in Head-Fi.

I stop fantasising about Berlin and Sydney. I don't even care about tube rolling anymore. I am just exploring music these days ...... and wondering how different the 'balance' Citadel would be from Oblivion.

Notice not once in my review did I mention about price disparity between the amps. I don't really care. What matters to me is which one sound more appealing to my ears.

As for selling the EL tubes, I'm not in a hurry. I would rather be selling all the EL tubes together for someone who might want to progress with Berlin. If not I'll just hoard it for 10 years then pass it on to my son with the instruction that it's not to be sold until 2050. By which time they would be the only NOS EL11 and EL12 spez tubes left on planet earth.

UT I congratulate you on such a fantastic discovery. Both of us have been on a similar audio journey for the last 5 years with many twists, turns and discoveries / innovations. Absolutely, no judgement whatsoever based on things like manufacture names or cost. Personally I don't care about brands such as clothes or electronics, as long as the specs or fit is good. But for the Ultrasonic Studios brand, it does seem like a maverick of an little known company in its' own class. I also put little wight on price in this hobby, because all too often people dismiss a piece of gear just because it doesn't 'cost enough', so then the more for the lucky ones to look past it like a cheap headphone. By no means does this amp look cheap, and I am just starting to understand it and the design, certainly looks like something to behold.

For my current amp journey, I do say I'm in too deep with another project. I'm toward the end of a multi-month wait list for a SET amp from Glenn Studios that I custom ordered with options such as single or two stage function, driving speakers, rectifier socket that can also be interchanged with a Hexfred diode with and a few internal upgrades. Especially I'm interested in trying the sound of many 6L6 series and EL12 power tubes, along with dozens of driver types (including multiple purchases I've got in anticipation). The dear adapter craftsman Deyan has already finished custom making over a dozen adapters for the amp which cost me also. In the end this path will cost more and by no means would I say it will sound better without first comparing both, but I would hate to turn this all down after all this momentum. At least I can experience all the flavors of my Glenn SET amp, and look towards Ultrasonic Studios as a possible option.

 

[DecentLevi]

No, the amps I build are not made for tube rolling. I have selected tubes that are very linear, still cheap and are quiet. Those are the three most important things when selecting tubes. There're also some other things like internal resistance in the output tubes can't be too high.


Not sure I understand your reasoning here? Would you have preferred a bigger PT? It's an 250VA audio grade toroidal transformer under there and they make excellent PT's for audio use. It's highly overkill for these amps. There's no power supply noise at all. If there's some tiny background noise it's coming from the tubes. The large chassis is needed to fit everything on the inside.


None of the above.
Oblivion has SE input stage and balanced LTP output stage. Citadel has LTP input- and output stage. The output is parafeed transformer output.
There're many advantages as I see it. Some advantages my amps has over a traditional SET amp is the overkill transient control, no need for boutique parts for high fidelity sound. You can read all about this topology on my website, link is in first post of this thread. I'm not allowed to post the link.
Also like to point out that there's nothing wrong with traditional designs either! Downside is you need to spend $$$ for great sound.


I'm building a Citadel next month for a guy with those cans on pre-order. So, I guess we'll hear some impressions later! But it shouldn't be a problem at all. Especially if you get the hi/low impedance switch option.


Basically all impedance's work. There're great impressions with low Z planars as well as high Z dynamics. It also drives speakers.


I can build with SE output but I'd recommend getting balanced cables for your cans instead.


Price increases a bit soon as you can read on previous page.

Understood about tube rolling. So your amp would seem to be basically built for the best possible operation points around certain tubes. I would see myself also possibly still being interested to roll 1-2 other variants of the same tube type, if applicable and only if ensuring they are 100% within tolerance level.

Apologies for my wording of that question about the design, I knew my words weren't coming out right there. I was comparing your amps' appearance to that of a Glenn Sutdios EL3N SET amp with the 3 fairly bulky transformers in the back, and on some of the photos your Oblivion amp actually looks small (yup, eyes playing tricks on me LOL), and there I saw your amp with what appears to be a circular transformer in the center that looks somewhat small relative to the chassis. But now I know this is not the same amp topology as the former OTL / SET amps I was familiar with, hence the different design. And I'm curious is the transformer smaller than the Lundahl used on Glenn's amps? (I'm sure size shouldn't matter, just curious only).

In terms of TLP or parafeed, and the difference between the Oblivion vs. Citadel, these are things I will learn as time goes by. I've barely had the time to start reading this thread with my schedule.

You were saying basically all impedance's are driven well. That's interesting. Is it something akin to 'current mode' amplification, in that the amp automatically adjusts bias depending on the resistance it detects from the headphone?

If I were to eventually get one of your amps I would prefer it to have RCA input and both balanced and SE outputs so I can also use it with a few of my headphones that are not user friendly for cable swapping.

 

[MrCurwen]

You were saying basically all impedance's are driven well. That's interesting. Is it something akin to 'current mode' amplification, in that the amp automatically adjusts bias depending on the resistance it detects from the headphone?

In the end it all comes down to having current delivery capability. Bias is fixed to a present current amount by a powerful CCS.

Low output impedance driving a downstep OT will result in radically low output impedance on the secondary side. What output impedance in this context means is simply ability to deliver almost any amount of current the load would ask. Ultimate limiting factor here is the preset bias set in the output LTP. If that current runs out, the amp hard clips. This is not easy to accomplish.

 

[baronbeehive]

I also put little wight on price in this hobby, because all too often people dismiss a piece of gear just because it doesn't 'cost enough'

Indeed, I have come across this attitude with my APPJ amp, a $180 amp which holds its own with the big boys. Since owning and upgrading this little amp over the last 10 years or so I have never looked back!

 

[SonicTrance]

You were saying basically all impedance's are driven well. That's interesting. Is it something akin to 'current mode' amplification, in that the amp automatically adjusts bias depending on the resistance it detects from the headphone?

In the end it all comes down to having current delivery capability. Bias is fixed to a present current amount by a powerful CCS.

Low output impedance driving a downstep OT will result in radically low output impedance on the secondary side. What output impedance in this context means is simply ability to deliver almost any amount of current the load would ask. Ultimate limiting factor here is the preset bias set in the output LTP. If that current runs out, the amp hard clips. This is not easy to accomplish.

MrC answered nicely. The power output measurements I've posted on my website is right before hard clipping, and that's at ear bleeding levels for headphones.

If I were to eventually get one of your amps I would prefer it to have RCA input and both balanced and SE outputs so I can also use it with a few of my headphones that are not user friendly for cable swapping.

It would complicate things somewhat but it's doable.You wouldn't be able to use the SE output and balanced at the same time though. There would have to be a switch to toggle the SE output.

 

[mordy]

Indeed, I have come across this attitude with my APPJ amp, a $180 amp which holds its own with the big boys. Since owning and upgrading this little amp over the last 10 years or so I have never looked back!

Out of curiosity - which model APPJ amp are you referring to?

 

[baronbeehive]

Out of curiosity - which model APPJ amp are you referring to?

The Miniwatt N3, now called the APPJ PA0901A speaker amp, reviewed by 6moons. The amp model has been revised recently but is still available in its original form.

 

[UntilThen]

UT I congratulate you on such a fantastic discovery.

I don't get fazed easily now by gear, so 'congratulate' doesn't seem quite appropriate. Nevertheless I thank you for your good intentions. You probably have not read through the thread because if you had, you would have known that Oblivion was send to me for review. Sonic was going to pay for shipping both ways. On my part, all I had to do was do an appraisal, in comparison with my other amps - tell it like it is - then send it back to him.

However I like what I hear in Oblivion - a lot - so I told Sonic that I'm buying it instead of sending it back.

And that's how I had that chance encounter with Oblivion. I have never make much mention of the fact that Oblivion is an incredible value for money because all the boxes that the amp tick for me has been more important. Primarily sound and quietness. Nothing else matters.

 

[DecentLevi]

Sonic of course already replied, but I'll put my thoughts out also. I am the designer who put together the topologies these amps utilize.

Like already said, it's just the power transformer. Whether or not the visual of the cover looks nice is subjective. I think it looks very nice, it has good synergy with the black hats the output tubes have.

The PT is not small, it's overkill. Same for the OTs.

If SET stands for single ended transformer coupled, then no, the amp is not SET since it has a fully balanced output stage.

As said, it is a parafeed design. Utilizing parafeed and sufficiently low output impedance driving the OT primary, the OT becomes 'transparent'. In technical terms it just means that all the nasty parasitics and reactances the OT primary coil has, are oversaturated with current, and thus satisfied.

The advantage of this approach is that you can use a 'cheap' OT with "bad bandwidth specs", and get a flat and full bandwidth response out of it, with sharp transients (transients are difficult for reactive coils) and full transparency. All this without using any big name iron. The OT is simply "played out of the equation".

And yes, I came up with this approach by not affording good iron. I made good iron obsolete. Cheapness is the mother of invention or cleverness.

Yes, the amp can drive almost anything. Real output impedance is very low, so it can handle whatever you may throw at it, including, as mentioned, speakers (within reasonable volumes).

All.

Let's take an optics analogy. The OT acts as a lens. Impedances on the primary side are 'high' and on the secondary side 'low'. Now if you have a 'low' impedance on the primary side, the secondary side focuses this like a lens, to make it even lower. So plenty of overkill drive available for all loads.

Oh yes I think it looks quite great too. I just didn't understand what I was looking at and poorly worded my question. It seems to not need transformers quite as large as the 3x for a Glenn SET amp, or they're hidden under the hood. It has a futuristic and symmetrical look.

Yup by SET I meant single ended triode transformer coupled amp. I think OT is output transformer, but could you fill me on on what LTP and CCS stand for?

In the end it all comes down to having current delivery capability. Bias is fixed to a present current amount by a powerful CCS.

Low output impedance driving a downstep OT will result in radically low output impedance on the secondary side. What output impedance in this context means is simply ability to deliver almost any amount of current the load would ask. Ultimate limiting factor here is the preset bias set in the output LTP. If that current runs out, the amp hard clips. This is not easy to accomplish.

From what I can understand it seems you have made a major breakthrough in design that allows the amp to have lower distortion and better dynamics than traditional ones and is adaptable to any headphone impedance. One couldn't really ask for a better amp concept than that, seems a huge accomplishment.

 

[DecentLevi]

MrC answered nicely. The power output measurements I've posted on my website is right before hard clipping, and that's at ear bleeding levels for headphones.

It would complicate things somewhat but it's doable.You wouldn't be able to use the SE output and balanced at the same time though. There would have to be a switch to toggle the SE output.

I think I would only want a toggle switch if somehow it can be in place without adding to the signal path, or somehow with such fine quality conductors that it won't degrade the ultimate purity of the signal to the headphone. (comments on that?) Otherwise I'd probably just go for a good (external) balanced XLR to 6.5mm adapter for the occasional headphones that need it. (if such adapter wouldn't short circuit anything).

Speaking of switches, I read the Citadel has an impedance switch. Would you say this improves the compatibility with headphones even more than the Oblivion amp? Because to my understanding, the Oblivion has a way of adapting to almost any headphone impedance automatically. Also does the Citadel have this same sort of topology stated by Mr.Curren as "current delivery capability. Bias is fixed to a present current amount by a powerful CCS."? thanks