Headphone Amplifier TU-05b In response to requests from owners of the TU-03s series is unique...

Analog Squared Paper TU-05b

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  • Headphone Amplifier TU-05b

    In response to requests from owners of the TU-03s series is unique design TU-05, from the housing that was more compact and lighter, has achieved high portability and modular frame structure. Without muddy buck-boost switching power supply with improved efficiency, the use of lithium-ion battery, the purity of the TU series, it is a full tube headphone amplifier ultimate newly reconstructed. You can vacuum tube can be replaced easily like a lens of a SLR camera, and you can feel the difference in sound, Nde enjoy the tube than ever.
    Symmetric design circle white illumination tradition, with no plug-in starter switch, were examined in black anodized, to ensure a high robustness.

    Specifications Output 30mW +30 mW
    Compatible headphones 8Ω ~ 200Ω
    F 30 ~ 30,000 [Hz]
    W 130 H44 D180 [mm]
    Charger power only

Recent User Reviews

  1. KrissBill
    "A small Single Ended Triode amplifier with natural sound"
    Pros - For music lovers more than for sound lovers. Built to last forever and survive technological changes.
    Cons - Don't know what to say
    I listen to classical music, jazz, pop, old jazz bands, great historical recordings from labels DECCA, CHANDOS, TELARC, NAXOS, PHILIPS, CHESKY. I regularely go to concert (classical). My "ideal" system would be portable and reproduce the sensations I have in a concert room.

    I will first describe my own system and the "why" of each element.

    First a MacBook Pro with more than 1.5TB of high definition music (24bits, mostly with 96KHz but also 44, 48 88, 192..). The music comes from Qobuz, a french company with a wondeful service. With a $200 annual subscription, you get access to a huge catalog of discounted high-res music, with regular promo that add even more discounts. You also get high-res streaming, and iPad/iPhone apps. (yes, I want to help them because they provide treasures at a low price and they are desperately in need for new customers to survive). I feel it is like buying master paintings for an incredibliy low price instead of having reproductions...

    After testing several bit perfect applications for the Mac, I chose PureMusic, the more "analogical" in my opinion.

    Then a "totaldac d1" USB cable, considered as a top contender, designed by a guy who works with his ears and designs some of the best DAC available, unfortunately these one are out of reach for me.

    Then the DAC: I chose the Resonessence HERUS plus. Few words about this one, chosen after testing few other DACs: it is unbelievely powerful for what is basically a dongle: music flows with weight, details, and a very good imaging. It is very close to a CHORD Hugo, the CHORD bringing even more details at the cost of substance: i find the Herus with more body and impact than the CHORD and since it is much cheaper, I chose the HERUS. The same remarks apply to the CHORD MOJO. Then my beloved EarSonics Velvet IEM: this one has everything, I will qualify it as the "grand" sound IEM (40 ohms).

    Let's speak a bit about the HERUS. I ordered my HERUS at the same time I ordered the TU-05, except that I got my HERUS three months before my TU-05. Three months during which I tried to figure out why I had ordered an additional amplifier less powerful than the HERUS itself, since the HERUS was delivering almost everything that I was expecting. So basically, what could add the TU-05 except distorsion since the source was already extremely satisfying to my ear ?

    Then I received my TU-05, number #63... I will not describe the beauty of this little thing, some already did it much better than I could, and the pictures  from Shikada san on facebook already give a very good idea.

    I bought a short audioquest "big sur" cable to connect it to the HERUS.

    With hundred of hours of HERUS music in my ears, I pluged-in the new TU-05.

    So, is there microphonics from original tubes? mmmmh, maybe a very very small effect if you ping the amplifier with your nail, but you have to listen hard. The amplifier is silent: no noise. The original tubes are 1U4 Raytheon from the US Army and 3S4 from General Electrics. The amplifier comes with a small 100-240V charger, 9V 1.3A. Charging takes about 8 hours.

    The sound was very different from the HERUS alone, with a sense of immediacy, a little less details, or better say, better integrated details: you do not "hear" the details, they are just there, flowing with the music. With the HERUS alone, I use to think "this is great, I can hear a strong echo, the room must be large and reverberant", with the TU-05, you just FEEL in a big room, the echo is integrated with the musical message. It is also more natural, more "analogic"... no, in fact, it is "fully" analogic: there is not one ounce of digital or electronic in this sound. The sound is less analytical than with HERUS alone, and it has a lot of flesh. The space is not wider, it is just more believable. The sound is not more transparent, but it is definitely much closer to what I can hear in a concert room. It is also very refined, particularely with human voices and violins/cello: we get one or two levels up from an "excellent reproduction" to a "natural reproduction", where words have less meaning than physical sensations and feelings. It is strange to try to analyze what you hear with this amplifier, because the words usually used to describe an amplifier lose their meaning: sibilance, distorsion, timbres, dynamic, decay... with a source as perfectly recorded as possible, a good DAC with details, and a TU-05, I believe the result can be very very close to the original experience.

    So yes, the TU-05 adds pure beauty to music, urging the need to spend even more time listening to music. Old recordings, those recorded with vacuum tubes equipment, get a new life.

    I use rating stars in iTunes because, with 2000+ albums, some kind of classification is needed. With the TU-05, I am adding one star to every single album, because even "so-so records" are much much more interesting through the TU-05!

    Bass: using "Pure Music" on a mac, it gets access to built-in plugins, one of them being a very precise equalizer. I know, it is not very "audiophilic", but by adding few dB at 20Hz, 25Hz, 31.5Hz and 40Hz I think I get 30Hz flat. The TU-05 will not go much lower, while the HERUS would. Anyway, at no time did I feel I was in need for more bass, there is already plentyful. Maybe I will switch tubes later for experiment.

    Just close your eyes and listen: this TU-05 is damn good at making you feel you are listening to the real thing! a fantastic experience of music immersion.


  2. AnakChan
    "A funky transportable tube amp that rivals desktop amps"
    Pros - Packs a great sound in a small transportable package.
    Cons - A tad on the heavy side for daily on-the-move use, better plug protection for clumsy ppl like me


    Analog Squared Paper is small business run by Kageyuki Shikada. He makes each one of these amps by hand and they're effectively made to order. I won't belabour the specs and details of this amp as ianmedium has done a wonderful job at covering all of that in the Analog Squared Paper thread and in his review of this product. But I'll get into what this amp has done for me.
    Shikada-san was extremely generous to loan me the TU-05b and TUR-06 for reviewing and I'm very thankful to him for such an opportunity.

    Getting Straight Into The Sound

    I'll admit from the start that I'm a noob when it comes to tube amps at the time of writing this review. I've only purchase my first headphone tube amp (Zana Deux) beginning of May 2013, and I've borrowed my friend's Shindo Labs Corton Charlemagne for my home speakers during the same duration. Prior to that, I've dabbled a little with the Woo Audio WA7 and an occasional demo of the portable ALO Audio Continental series, as well as Fostex HP-V1.
    Although those portable tube amps were nice, the TU-05b really is in a league of its own and borders on being a desktop tube amp instead. It delivers a full sound that gives a large sense of space in terms of soundstage and imaging. The amp was pre-tuned to low/mid gain and I didn't need to turn up the volume to get that fullness and richness of the sound. Another immediately notable quality is the smoothness in rendering that's typical of a high end quality tube amp that's often read about. This tube amp reinforced what I've always read about the infamous "tube signature".
    In terms of its frequency response, my particular TU-05b capped at around 30Hz however the maker assures me that with some modification the sub bass can extend lower. However, even for what it can deliver at 30Hz is extremely pleasing with the fullness and richness of it's bass presentation. There's this purr to the bass which almost gives it a life of its own. The quality continues to extend to the midrange and vocals especially are, again, rendered smoothly with an analogue-like texture. I've read a lot about how some amps can sound "digital", by listening to the TU-05b, I can understand the contrast much better. The treble continues with it's smoothness and airy highs without any sibilance. It's probably one of the clearest trebles I've heard in a portable/transportable (irrespective of OpAmp or tubes).

    Practicality and Use

    This amp though is by no means a practical amp. It's about 1kg, and at least for me, probably not so easy to walk around with. However if I'm going specifically to sit down at a coffee shop for an hour or two, that could be a case scenario of practical use. In Tokyo where "anything goes" no one would probably care if one had something like this on the table but in other countries, it may catch a stare or two. It's definitely quite a funky looking amp which probably screams out a certain level of geekiness but also style (to my mind anyway :wink:).
    I did have a problem with the TU-05b and I need to deeply apologise Shikada-san for my clumsiness. In taking pictures, I removed the PostIt labels from the ports. I accidentally attempted to plug the headphone cable into the charging socket as I wasn't paying attention and inadvertently short circuited the TU-05b. Of course I'd offer to pay for the damage I've done to it but it also got me thinking of how the charging port could be improved to prevent idiots like me doing such a thing again. I must say that I've never done such a thing before to other devices (well most other devices are USB charging) but looking at something like the CLAS -dB, Rx Mk3, or DX100's round charging socket, it's not so easy to short circuit the batteries for those as at least one of the two connection points are more recessed. I think this is one area that could be room for improvement. Again, most people probably aren't as clumsy as me but further prevention couldn't hurt.


    To my mind and my ears, this amp will not fail to impress and for the kind of sound it's able to deliver, and will continue to satisfy for a long time. As such, I personally see this amp to be a worthy investment. In addition, if one wants to play with the sound for a little variety, this amp is very open to tube rolling. ianmedium has done quite a lot that which he's shared in the thread. This amp will not bore.
    TUR-06b on the left (to be reviewed later), TU-05b on the right
  3. ianmedium
    "The worlds smallest SET amp, also I believe the only battery powered SET amp commercially available."
    Pros - Clarity, speed, detail retrieval, musicality
    Cons - Not an amp for Bass heads!
    Review of the Analog Squared Paper TU-05 transportable Tube amp..

    I thought is was time to do a more comprehensive review of this amp as I have now 7 weeks and around 250 hours use of the amp under my belt.

    This review will be based upon using non standard tubes. There is nothing wrong with the sound of the stock tubes it comes with. If I had not heard another tube I would have been happy with the sound of the Tung Sol/ Sylvania combination that Shikata San provides with the amp. However they are I have found somewhat microphonic and even with many hours use that never really subsided.

    One of the many great things about this amp is the tubes it uses! They were designed for old radio sets both domestic and military and so were made in very large numbers and thus are relatively cheap to buy so you can afford to tube roll to your hearts content (I know I did!) To give you an idea and set of four Mullards tested NOS came to less than $40 including shipping.

    More on tube rolling in a little while but first initial impressions of the amp.

    Shikata San builds these one at a time and to your individual requirements if necessary but to call this amp a product of a DIY builder earning a few bucks on the side would do a great injustice to both Shikata San and his amps.

    I prefer to think of the maker and company as a bespoke audio company crafting beautifully made amps for people who's main motivation is to extract the most from a musical performance.

    This is definitely a niche product and will not appeal to many. It is not a bass lovers amp. If you like thumping bass look elsewhere. It is most certainly hand made and all that comes with a hand made product so if your looking for paper thin joints in the case work look elsewhere. Having said that the case is beautifully hand crafted, solid and looks wonderful to my eyes. One thing more about the case. It is something that requires some sort of stabilization so as to prevent it toppling over. I cobbled together with wood a frame to hold it in and to isolate it. (Isolation has become less important with different tubes but if you use the stock ones you will need something like cork or sorbothane under the amp to help with microphonics).

    Inside though is where it is at! Everything is beautifully laid out and hard wired. Top quality components are used with note especially to the stepped attenuator which is the best volume pot I have used. Even with sensitive IEM's there is no channel imbalance at low volumes.

    Oh yes, this amp does something that I have not seen in any other class A all tube amp and that is drive low impedance headphones, right down to 8 Ohms!

    You have to treat this amp somewhat like you would a low powered SET amp in that the headphones you use need to be carefully matched to the amp. This is not a huge issue unless your headphones are rated over 200 Ohms as this amp does not drive headphones with greater than that.

    I really encourage you when ordering to tell Shikata San what headphones you use. I did and he ended up giving me an amp with two gain settings, Low (8~32 Ohm) and mid (16~120 Ohm) You can also have the option to replace one of those settings with a High setting (64~200 Ohm).

    One of the great reviewers here on Headfi, AnakChan tried a demo amp recently at a HiFi show in Japan but experienced a mis-match with headphones and amp that produced distorted bass. I am looking forward to hearing his thoughts on the amp when he gets a proper review sample and is matched with appropriate headphones

    I promise that I will come to what this amp sounds like soon but first I want to talk tubes!

    I truly feel that to do this amp full justice one needs to hunt out some higher quality NOS vintage tubes. Over the past few weeks I have gone on a binge of tube buying so as to not only get the desired sound for me but also hopefully to help anyone else lucky enough to purchase this amp get the very best out of it.

    Now, if the stock tubes were not microphonic I would find them very enjoyable (BTW it has not only been my amp that had microphonic tubes, another member here experienced the same with his) however there are gains to be had in experimenting.

    I dont want to say one tube is better than the other but rather say that differing brands bring slight sonic differences to the table. Want a warmer signature? Then go for Mullards, Want more air and treble? Go for German tubes such as Telefunken or the ultra rare Lorenz Stuttgart made tubes ( I managed to score two of these rare beauties for the Voltage gain/ 1U4 stage and am really glad I did!)

    Want something a little sweeter combining the best of those two brands then La Radiotechnique from France might be the answer.

    Good all-round worka-day tubes that sound great can be found in RCA's or GE's from the US.

    I have found two combinations for me that rise above the rest. An all Mullard set up or, my favourite after much switching, Mullards in the power section (3S4) and the Lorenz's in the voltage gain section (1U4).

    The Mullards underpin the music with a firm foundation and a deeper tighter bass while the Lorenz's bring speed, detail and air to the mids and treble. This combination is very far removed from what one thinks of traditional tube euphonic sound which brings me to what it sounds like!

    Well, in a word, nothing!
    I feel this amp is almost transparent, sure it brings traits to music but none that are not already on the recording in the first place. I feel it conveys music authentically. A guitar sounds like a guitar, a piano sounds like a piano, drums.. Well, you get what I mean! Even electronics such as in Kraftwerk's music sounds like electronics.

    I find this amp to retrieve details that are deep within the sonic like no other amp I have heard this side of home amps such as Nagra or Naim to name two I have fairly good experience with. But all that detail retrieval is not at the expense of musicality, this is after all, a tube amp!

    The ability of this amp to convey the acoustic a recording is made in, the texture of instruments or vocals is very compelling and draws one into the performance so that track after track, album after album are enjoyed until one reaches the point where the battery runs out (around 7 hours)

    All of this is accompanied by an inky black, deep background. With headphones in and no music playing it feels like the world has disappeared so deep and black the sonic background is.

    Treble is free from any grain, one can listen to a high note increase and never does it break down (unless you push the volume to far!) mids, well, its a tube amp, 'nuff said!

    Bass, ah, bass! Now, if your into car door rattling bass then walk away right now, if your into deep deep bottomless bass then sir/madam, here is the door. However, if you like tight, defined, textured bass, bass that has you moving and grooving then this amp will provide you with limitless amounts of the stuff. Bob Marley and the Wailers sounds wonderful with this amp You can hear the distorted bass lines driving the music along and the fun is in hearing so clearly the distortion of the bass not just some wooly blob thumping away!

    Acoustic bass has so much texture, notes rise and decay naturally, one can hear the bass's body move as it is played.

    Strings are another strong area with this amp. One can tell gut from artificial so easily. The resonances in the body of a violin are conveyed so clearly one can hear them decay within the instrument and the waxy feeling of bow hair against string is tangible.

    When it comes to percussion, the sound of a drum stick on cymbal's sounds like wood hitting metal, one can feel the texture of both. Likewise brush work on the natural skin of a drum feels grainy as it brushes against the grain of the skin.

    I leave though the best for last and that is vocals.

    I love early music the sound of voices in a small church or room unaccompanied are something I have experienced in real life many times and this amp conveys that perfectly I feel. Texture, and I make no apologies for multiple uses of that word in this review, is the thing with a voice.

    For the emotion to be conveyed authentically so that one can fully engage with the artist one needs to feel the texture of the vocal, how the voice comes out through the mouth, how the air moving then hits the listeners ears and so engages and emotional response is vital to realistic vocal reproduction I feel.

    So often now software is used in mixing to take that texture out and thus we end up with X factor vocals. Thankfully early music is immune to that I have found so that one can feel the resonance of the vocal as it hits the air and your ears hear it, this amp conveys that so well!

    I want to talk a little about volume. I have noticed that there are sweet spots for each album with this amp. Take the volume too far and the sonic picture starts to fall apart, take it even further and the sound becomes harsh and glassy. Find the right volume level for each album though and it is magic! Thankfully the optional (read, you have to have this one upgrade if no other!) stepped attenuator is so accurate and does what any good volume pot should do, get out of the way of the signal that achieving the right level is effortless

    And so I come to the end of this review. I do want to say again, this amp is not for everyone, in spite of my glowing review there will be many who will not like this amp as it is a gentle amp, not in your face, not a piece of HiFi, it simply gets out of the way so that the music and emotion can flow. It will not command or power, it will not take a vice like grip of music, if that is how you like music conveyed ( and note, I am not saying right or wrong, we all find our musical nirvana in different ways after all) then this amp is not for you.If you like to use a wide range of different impedance headphones or ones that are power hungry this amp is not for you.

    However, if you like music conveyed in a natural way, not emphasized but rather the performance allowed to build and be created before your very ears and you are prepared to go to a little effort in matching headphones and making sure your source and music is of the highest quality (think high bit rate if your using downloaded or ripped from CD music) then this amp may be for you.

    If your prepared to think of this amp as transportable rather than portable and battery life and size and weight are not issues then this amp I feel might be right up your street!

    Combine that with the utterly delightful experience in dealing with the affable Shikata San and the thought that your amp is designed for your needs and the sheer quality of build and sound and I feel this amp at just over $1000 is somewhat of a bargain!

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