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Oblivion | UltraSonic Studios

Discussion in 'Headphone Amps (full-size)' started by Maxx134, Mar 22, 2019.
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  1. Benny-x
    I see. I looked up the specs for meters, but I either couldn't translate whatever terminology was being used or the value you mean isn't stated in any reasonably listed way. I think it's the later, as I've really been grinding it out on Google to find that kind of input sensitivity number.

    Anyway, thanks for the help with that. I'll use the trim pots like you said and try to get it all sorted. I'm pumped.

    Back on topic, what's the status of the balanced version of this amp? Will you have an upcoming thread about that or any pics?

    I am going to stretch a guess about the builds, but maybe they're done to order? If so, are there any options about the paint colour(s)?

    The black is straight forward, but a touch of blue or red for the chassis and black for the transformer cover(s) and knobs would serve up some eye candy~
  2. SonicTrance
    I understand you mean Citadel when you say the balanced version. Just to be clear though. Oblivion is also balanced output. It's only the input stage that's SE. If someone buys the Citadel I hope they write some impressions here or in a new thread. I'm not allowed to start any such threads. I have a website in the makings though.

    Yes, I build to order. We could always discuss different chassis. Nothing is set in stone. As for me painting though, that's too much work, lol.
    Last edited: May 1, 2019
    joseph69 likes this.
  3. Benny-x
    Yes, I was meaning the Citadel when I mentioned "the balanced version". And yeah, my focus is just one that input stage as all my gear runs balanced and if you didn't have a balanced input stage then I'd need to gear up my own conversion stage from BAL->SE. Not hard, I suppose, and especially so if you take the easy route of just grabbing the hot side of the BAL signal and then terminating to RCA. Anyway, things I'm not interested in focusing on for now as I wanted to ask more about the Citadel.

    I thought the Oblivion chassis looked fine design wise, I just wasn't a total fan of the all black train engine approach.

    In the updated build pictures by Max, there's a knob missing from the front panel. Was this an output select knob? And if it's missing, but the internal parts are the same, then what happened to the speaker taps?
  4. SonicTrance
    Yes, that second knob on the front is for a selector switch. The speaker outputs are optional. The customer didn’t want them. All other internal parts are the same, yes.
    Maxx134 likes this.
  5. Thenewguy007
    Could there be any tweaks or upgrades in a a build?
    Like say getting a more boutique transformer, like Lundahl, or possibly setting the amp to accept different tubes, something that might give out more watts for the more hunger planar headphones?
  6. SonicTrance
    If you mean a Lundahl power transformer it's a waste of money TBH. At least in these amps. You won't notice any difference in background noise as it's already quiet with the transformer I use. If you mean output transformers then I'm not sure. Maybe some possible sonic improvement but price would go way up of course.

    The whole idea with this circuit is to use parts to what they do best in each position. By doing so eliminate the need for "audiophile" parts. So, tube rolling and different coupling caps and so on will not have the affect it has on a traditional circuit. I can build an amp made for tube rolling but it will not sound as good.
    I understand that people wanna tube roll. It's fun! I was the same way before MrCurwen introduced me and mentored me with this design. There's no going back now!

    These amps can power planar headphones no problem. Maxx used Abyss which is very hard to drive. I could, theoretically, build an amp with more power but the heatsinks required would be massive and I would also need to use a louder fan. I use a 200mm 700rpm fan now that's barely noticeable, just to get the air moving inside the chassis. There's no need for massive wattage headroom in this circuit. I drive my 89db 6 ohm floor standing speakers no problem.

    The only option I'm offering ATM is speaker outputs, but I'm open for discussion.
  7. MrCurwen
    As SonicTrance mentioned above, I'll restate as the designer, this circuit was specifically designed to provide high end performance with low end parts. It will not benefit to any significant amount by parts shopping. If you want to shop parts, go another route.

    There are some possible improvements, but they are very small. To 99.9% of people they are not worth the money spent in them. If you don't trust my or Sonic's assesment of this, you should listen to the stock version of these amps first, and then think about it again.

    I made this design originally just to avoid getting anything but cheap parts. It's the gimmick of this design, the point of it. To see how far you can go with "normal" parts. Turns out you can go beyond "pretty" parts. So why even bother with the pretty parts. Leave them behind.

    World will run out of old production 2A3's way sooner than it ever will run out of well made rugged old production EL81's or EL36's or other TV sweep tubes. You'll be well set with those tubes.
    PaganDL, hikaru12, cskippy and 2 others like this.
  8. Maxx134
    Most stock headphones tube amps are full of compromise and we are expected to deal with it by tube rolling and parts upgrading.
    Then we are forced to accept this as norm, while dishing out THOUSANDS for those units...
    You become numb of this problem and think it is the norm.

    This is unacceptable. We should not have to be expected to have to resort to upgrade parts and "holy grail" tubes to reach end-game sound.

    I can be a fanatic when it comes to upgrades, just look at my LDMK8(!)
    Thi is the first tube amp I can say NEEDS NOTHING..
    Which is actually a double edged sword for me, because I had planned to make a big monster tube amp (and you know how overboard I can get with the visuals, lol) but now that plan is put on the shelf because this amp is that good. It is so dam good I feel no need to upgrade. It's sonics are reference quality.

    In truth, I expected crickets here for responses, because it is too dam good for it's own existence, and I feel it would slaughter anything under $3k
    I would be quietly selling my gear to get this unit.
    To me, it is that good.

    The only amp I would consider replacing my Oblivion amp is to try the Citadell, or swtich to something I feel is as good which is nothing except an EC Studio, or the specific Pass speaker amp I mentioned, but they both have the drawbacks of price.

    There are also complications.
    The speaker amp will have hum on most headphones and would need a speaker box.

    The tube amp would be VERY dependant of tube selection and tube age, as it is still an oldschool design.

    I avoid ALL those issues with these amps. The performance is rediculous and needs to be heard.
    I would have liked to do a comparison of this amp with a famous hybrid design like the now out of business cavalli amps.
    I am pretty sure thier implementation is not like this one either.

    It was dead, dead quiet even with sensitive headphones...

    I attribute the amps superiority of transient delivery, in making the AbyssPhi sound noticably better than in the other amps tested.
    I do not believe differences would have been so noticable on easier to drive headphones, which reach their limits too early and stay in mid-grade level.
    That's why we tested with end-game headphones.

    Tube rolling has the problems of not only affecting tonality, but also dynamics and soundstage.
    It truly is better to not have to be burdened with this, while having all the best attributes of tubes.
    If I had to pick, I would probably pick the Citadel if I had balanced. It would also eliminate even the slightest chance of driver stage to affect sound. Although the circuit is optimal and transparent on the Oblivion, there was a ever so tiny difference in driver tube swap. Both tubes I tried were amazing but the stock driver tubes chosen sounded a tiny bit more open.
    My guess is that the tubes I swapped were brand new and so would sound different first used, while the stock tubes were also new but "broken in"

    It is set to run so gently that it is never noticable.

    It must not be underestimated how important this is to elevate the real world performance of the amp, wich in my testing proved to rival any headphone amp.

    This is an enigma. Most designers see a circuit in a program like "splice" and think it will behave as intended in real life.
    In reality they do not.
    Your design approach instead differs from traditional approaches by paying attention to different circuit behavior that I haven't seen.
    What you explain as parasitics and transients and the way the tubes are implemented are unique as no other tube amp I seen.
    You are being humble to say the word "gimmick" , and a more accurate description would be "innovative approach".

    I agree, and believe this is because the market has been fooled into thinking that they need to rely on a certain tube for best sound.
    The best tube sound is actually is no tube sound at all.
    Just their benefits of dimensionality and soundstage preservation, which is what we have here with these amps.
    Last edited: May 5, 2019
    FlySweep likes this.
  9. Maxx134
    Most consumers will not know what a CCS or a gyrator is and how it was implemented in this design.
    Also I have seen some companies make a big deal out of usage like one nicknaming such an added circuit as a "speedball" option.
    I think a link to the other DIY thread of SonicTrance would help those understand this topology:
  10. baronbeehive

    I agree with Maxx here.

    You are falling into the same trap that we all used to fall into, namely that power is overridingly important. Actually there are different approaches to the problem of power delivery, for example, more than enough power, balanced power, regulated power, decoupling for power reservoirs etc etc. What is important depending on the design is to have power of around 1 watt and then to address the problem of fluctuating power from transient depletion and parasitics. I think most designs approach this from the other way round. If this can be achieved as efficiently as possible that is the problem addressed.

    From my understanding and from Maxx's review this amp will drive anything without so much as batting an eyelid, he will correct me if I'm wrong. What has bee achieved here is a real understanding of the intricacies of the circuit and the functioning of the components within that circuit so that they all function together optimally. If any of the parameters were to be changed then the same components would probably not work so effectively, for example I seriously doubt that this design would work with much higher power because that goes against the design goals of just enough good clean power, efficient recovery, low parasitics and open loops. If more power was used that would introduce a whole set of new problems to deal with, and which would necessitate a different design. This is the real achievement in this particular design as I understand it. Since this has been achieved on stock parts there is no need to upgrade whatsoever, indeed that may not be a good idea because the circuit has been designed with the components in mind.

    My friend has a tube amp with only a few watts to drive floorstanders, and the power beyond about a quarter to is totally deafening, massive overkill.

    So at a stroke no more worries about tube rolling etc. that's very welcome indeed as far as I'm concerned!
    Last edited: May 6, 2019
    Maxx134 likes this.
  11. SonicTrance
    I'd like to point out though that I'm not using the cheapest parts available. I use NOS Russian film caps, Nichicon 125C electrolytics and ohmite power resistors. Still not boutique parts of course but optimal for its job and high quality. That's what's important.
    PaganDL likes this.
  12. Maxx134
    Also of note, is that speaker amps that push out many watts only give up to 1-3watts in class A, before the less desirable class A/B kicks in.
    The initial class A section is the most desirable and effective area of use, so it is the actual spec to look for, when looking into amps, especially speaker amps.
    Last edited: May 6, 2019
  13. Maxx134
    Before you came with this design, this idea of parts quality "NOT" affecting the circuit was pretty alien to me, and probably most people.
    Traditional tube designs are all still very dependant upon parts quality, or parts adding sound, or as you call it, "parasitics".

    From my own research, I can name the brands of caps that are responsible for the "house sound" of a few top amps not even mentioned here, which would be an embarrassment to them.

    The "parts quality" sound is the result of the "parasitics" term MrCurwen used.
    There is no avoiding this on traditional designs, and, as far as I can see, most designs in general seem to compound this already sad issue, by making even more compromise by cost cutting (due to competition).

    So none I seen, take on this approach of these new amps here, to adress "parasitics".
    Normal designs, and the software used to make them simply are not addressing this issue.

    This is why we hear of effects like "mosfet mist" or thermal noise, or oscillations or various types of sound from different film caps, or other types of parts quality sound when replacing them.

    Designers that follow these circuit designs do not take into account these effect results.
    None are designing for the avoidance of these "parasitics" to affect the circuit.
    Designers seem to have accepted as the norm, that we must accept the inherent flaws which happen in real world usage, and so rely on parts quality.

    This is one BIG reason which sets this amplifier apart from the rest.
    But there are two more issues that effectively push this amp into the performance level it is at.
    Power delivery, and transients.

    The issue of power, which is usually not efficiently implemented, and consensus of how many watts stated in "spec sheets" doesn't really alude to the actual performance, which is not only about how many "clean" class A watts, but how much the PSU hampers delivery and responds to demand to feed the circuits.

    In contrast, the focus of this design offsets the need for huge expensive power supplies (which can still be "slow")...
    Remember, the largest cost of amplifiers is usually because of the traditional PSU section.
    So the modernization of this area is a HUGE plus.
    Both the effectiveness and the delivery of power is benifited.

    Also, the placement and implementation of CCS & gyrators in the circuit, enabling the focus on "transients" delivery, was not only an effective solution for power demands, but had a real world effect on performance.

    It gave the amp a type of dynamic delivery that I was reminded of when I listened to a Viva amp.
    It was this main trait, IMO, that proved to be the critical reason why the demanding Abyss Phi behaved the most lively on this amp, and was also able to "wake up" the Susvara enough to perform similarly to using a speaker amp.

    Speaker amps makes the Susvera climb higher to become more responsive, but not all sound clear.
    You need a real TOTL speaker amp to have clarity as well as power.

    Currently, my Oblivion model is my reference amp to compare to others, kind of like my yggy used to be my reference point to compare to other Dacs, but I since moved on from original yggy(A board), to a very slight more immersive/lively performance in same realism level, with the Holo Spring Dac.

    Both the Holo & the Dave share a similar aspect of slight liveliness/immersion over yggy(A), but not better in realism as they are all at similar level.
    I have not compared latest yggy(B) to the Holo, only to yggy(A) even though I have access to do so and should.
    I still like the yggy just as much though, and expect comparisons to yggy(B) to be more accurate overall, but at this high a level, I would consider all four just a preference choice because the realism is still there.
    Sorry for tangent on Dacs.
    Last edited: May 7, 2019
    nick n likes this.
  14. SonicTrance
    Here're some initial impressions of Oblivion from a customer using LCD-4 and HD800. He'll probably add something later as well.

    Thenewguy007 likes this.
  15. Gethyn
    Well that would me me! I recently bought an Oblivion amplifier from SonicTrance and have had time to listen to a variety of music using my Audeze LCD4 and Sennheiser HD800 headphones. I am somewhat in awe of the members here with technical knowledge and an understanding of circuitry, sound, electronics, etc. My feedback (I would never dare to call it a review!) will be as someone who loves music and simply knows what they like without being able to necessarily explain why.

    I'll start with a potted history as this may help members understand where I'm coming from, and perhaps what appeals to me, sonically.

    I have enjoyed listening to music through headphones since I was a teenager and I remember my first pair - Sennheiser HD414 - giving me so much pleasure. I subsequently bought a pair of Sennheiser HD580s which I kept for almost 20 years. A few years ago I decided to upgrade the HD580s and in a matter of a couple of years went through a number of headphones.


    Beyerdynamic T90. Initially loved them, perhaps because they were very different from the HD580s, but soon their bright and sibilant character became too much for me. (I had previously tried Grados and also found them to be overly harsh/bright sounding).

    AKG Q701. Very enjoyable, comfortable, but I knew I wanted something 'better'.

    Philips X2. Fun, lively, good soundstage, but still not end game.

    Audeze LCD 2.2 (pre fazor). I'll never forget the moment I first heard these and I knew this was the sound I was after! Full, rich bass, wonderful mids, enough detail and clarity, but with none of the sibilance of the Grado/Beyerdynamics. They also allowed me to kick back and just enjoy the music without having to analyse it or concentrate too much.

    Sennheiser HD800. As much as I loved the LCD2s for rock, soul, vocals, etc. they lacked the clarity, soundstage and sparkle that I wanted for classical, jazz and some acoustic music (my musical taste is eclectic). The HD800s filled this gap perfectly and, with the right amplifier - I'm getting to that! - gave the detail and soundstage that I felt the Audezes lacked, but without the treble spike that others had criticised them for.

    Audeze LCD3. A smoother and more refined sound than the LCD2s and for a while I kept both pairs, not knowing which to sell. An advert in the local classifieds made the decision for me . . .

    Audeze LCD4. I couldn't resist a virtually brand new pair for half price! They are more refined than the LCD2s with a smoother bass, richer mids and added detail. The LCD2s are more fun, but for serious listening the LCD4s are everything I want for rock, soul, vocals, etc.

    I now have two pairs of stunning headphones which complement each other perfectly - LCD4 and HD800 - and I cannot believe that I will ever change them.

    For years I had driven my headphones from the headphone output of my amps (Audiolab 8000Q, Peachtree Nova, Naim DAC-V1), but when I bought my first Audeze headphones I started to look for a dedicated headphone amplifier. I also tried running a balanced set-up for the first time.


    Trafomatic Audio Experience Head One. I loved this amplifier with the HD800s and regret selling it. It was compact, beautifully made, lovely to look at and the sound was full and rich, adding some welcome warmth to the Sennheisers. It was perhaps a bit too warm for the Audezes though so not ideal for my needs.

    Woo Audio WA3. I'm not sure if there was something wrong with mine, but it just never sounded very good and I sold it very quickly. Not much more I can say about it.

    Bryston BHA-1. My first balanced set-up. This worked very well with both headphones and the balanced set-up gave a wider and fuller soundstage and a feeling of space to the music. It was dynamic and had plenty of power to drive the LCD4s (no mean feat). However, I was not convinced that the Bryston sounded any better than my portable equipment . . .

    I have a PW AK120 (similar to the RWAK120) with balanced output to an RSA SR71b amplifier. I bought balanced cables for the HD800 and LCD4 headphones and this small set-up drove both headphones perfectly and in back-to-back listening tests I really couldn't hear any difference between this and running them from the Bryston and my main system. I eventually sold the Bryston and just used my portable gear when listening through headphones. It did seem ridiculous to own two reference level headphones and run them from a portable set-up so I decided to once again explore a dedicated headphone amplifier. Phew!

    The Oblivion:

    I play music from files on a hard drive as well as hi res audio from Tidal, running through Audirvana on a dedicated Mac Mini. I have a Teddy Pardo audio system so use a Teddy USB cable to the Teddy DAC then to the PR1 pre-amp and then to the Oblivion amplifier using RCA cables. I have inexpensive custom made balanced XLR cables for both pairs of headphones.

    HD800. I have the volume at 12 o'clock most of the time. To some extent the Oblivion brings the sound of the HD800s closer to that of the LCD4s and I mean this in a good way. They retain the clarity, detail and soundstage that I want for the kind of music I use them for, but the Oblivion adds some warmth, taming the occasionally bright treble in a similar way that I experienced with the Trafomatic. I can perhaps best sum it up by saying that the sound is no longer clinical, but more natural whilst not losing any of the detail. There is more heft or body to the music and it definitely sounds richer. With the Oblivion I could easily imagine having the HD800s as my only headphone or perhaps adding a cheaper planar headphone for kicking back and enjoying rock, pop, etc. I still prefer using the HD800s for classical, acoustic and jazz music, but I can also happily use them for other genres too.

    LCD4. I have the volume between 1 and 2 o'clock for most listening. The Oblivion seems to enhance all of the best qualities of the LCD4s whilst drawing out some that were perhaps a little hidden previously. The bass is tight, full and natural with no unnecessary or added punch beyond what is already in the music. I love mids in music, especially vocals and The Oblivion/LCD4 combo delivers this in spades. It is hard to describe this without resorting to cliche, but the mids are natural, warm and rich and the sound envelops you as you listen. What the Oblivion adds is an increased soundstage and level of detail that I haven't previously heard. There is space between and around the instruments. I find myself literally moving my head from side to side to 'see' where the instrument is and where the sound is coming from! I feel totally immersed in the music and I cannot believe that sound could get any better, at least not for my taste and the way that I like to listen.

    I am very fortunate to be able to indulge myself in this hobby and since buying the headphones and now the amplifier, I have started to listen to music as frequently as I used to years ago. I hope my thoughts might be of use to some of you. I have benefited from reading the posts of other members over the years and I have been meaning to write something to give a little back. Purchasing the Oblivion and - I hope - completing my system has given me the motivation to set down some of my thoughts.

    Finally I would like to thank SonicTrance and Maxx134 who have been very helpful, answering my questions and giving open and honest views about the Oblivion amplifier and comparisons with similar products from other manufacturers.
    Last edited: May 13, 2019
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