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JUST AUDIO - uHA-120 headphone amp

Discussion in 'Portable Headphone Amps' started by robinhifi, Nov 16, 2010.
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  1. RobinHiFi
    Don’t know if this has appeared already?
    I took part in some of the testing for the uHA-120, there were 3 different units with differences in the components in that test so I cannot give a full description of the sound of the final design. I have a good idea which unit most closely represented the final design as I got to speak with Justin who is the designer and gives the first part of his name to the brand.
    Justin clearly knows his stuff and has big plans involving DACs and balanced designs, his enthusiasm for getting the very best out of these units is infectious – I have an iBasso D10 which I love but I have to say that the amp stage in theuHA-120 blew it away. The sound in general was powerful with a true feeling of accuracy, very detailed without oppressive at the top and deep smooth bass. I used Grado SR325is, Shure SRH840 and Ultrasone HFi780 worked well for all three.
    The uHA-120 had a compelling sound but was also beautifully built feeling really solid with a reassuring weight which felt just right for the size, the casing and its printing has been really nicely finished.
    Just Audios other amp is the AHA-120, a pure class A variant of the uHA-120 and they will also be offering some studio quality custom interconnects.
    Website is http://www.justaudio.co.uk
  2. RobinHiFi
    The uHA-120 offers possibly the best  solution to exceptionally high quality headphone amplification, which will also fit in your pocket. Ideal for the discerning audio enthusiast or professional, requiring bigger box performance in a smaller more convenient high quality product.​

    Unlike many similar products in the marketplace, we decided to use a discrete output stage, enabling us to fine tune the circuitry to provide the best possible performance from the design choices made. To confirm the best sounding configuration, we involved an independent  panel of enthusiasts - with combined exposure to most of the products sold in the UK market - to blind test several pre-production units (each of course with a slightly different configuration).

    The amplifier includes the option to upgrade the standard high quality stereo potentiometer (used to adjust the volume) and rotary power switch, to a custom made Vishay P11, which we fit as standard to our class A variant (the AHA-120).



    Maximum Continuous Power output:

    60 mWrms/channel into 32 ohm @ nominal (3.6V) battery voltage;
    10 mWrms/channel into 300 ohm load @ nominal battery voltage;
    16 mWrms/channel into 300 ohm load @ fully charged (4.2V) battery voltage;
    28 mWrms/channel into 300 ohm load with 5.2V USB power supply;

    Distortion (THD): <0.005% @ 1KHz (-20dBu to 5dBu output level)*;

    Dynamic range (dBA): >100dB

    Bandwidth (-1dB): 10Hz-40kHz

    Output impedance: < 7 ohm

    Output current limit: +/-80mA per channel

    Maximum Gain: 12dB;

    Battery recharge time (max): 2.5 hour fast charge; 6 hour normal charge;

    Dimensions (approx): height=23mm; width=52mm; length=85mm

    Weight = 125g +/-1g

    Both channels driven with 32 ohm headphones connected.

  3. b0wl1ng
    I am very pleased with my recently purchased amp, a very well manufactured and robust pocket sized portable amp, (exact size and depth of a packet of 20 cigarettes), I have been interested in an audiophile quality small portable amp for quite a while.
    As soon as I switched it on and the low warm thump of the vishay volume pot kicked in I was keen to play some music with it, my source and my primary use is a 4th generation 80gb iPod classic LOD line out and Apple lossless format.
    I was most keen to be able to use a portable amp that would be able to drive my low impedence Denon AH-D5000 cans that I adore, I did speak to Justin the designer and owner at Just Audio, he was extremely helpful and most informatve and extremely enthusiastic , as it should be with a newly developed product.
    I was very impressed with this amp, the sound quality matched with the Denons was warm and luxurious, superb detail and every nuance there to hear, the highs were crystal clear, the mids warm and liquid and the bass most excellent.
    I have also listened with my Grado 325i cans and the sound quality is also exceptional, I would consider myself an audiophile from way back to the 70s and more high end gear has come and gone over the years than you could shake a stick at.
    This gorgeous little amp ticks all the boxes for me, a true pocket sized audiophile quality amp, just perfect whilst cooking and on the move, a very, very, impressive product and a snip at the cost.
  4. cn11
    I was approached by Justin at the UK meet Saturday to give some of the IEMs a run through his new amp. He sort of walked over a bit sheepishly, bespectacled, and asked if I'd be willing to try out a new amp with some of the IEMs at the table, and then slinked away (I suppose he knew how good his amp is, and didn't have to wait around to see my reaction). Well I was in the middle of chatting with a couple of the other HF'ers who until Saturday were only screen names to me. And at the same time I was finishing up listening to a pair of RE272s straight out of my Sony X, while unknowingly having this gem of an amp just sitting in front of me waiting to be listened to. I started off with the RE272s, and thought, hmmmm.... this is rather bright. I then decided to try it with my Sony EX1000s so I was using a familiar phone, and when I pressed play I was amazed at the scale of sound I heard. The notable things right away were the bass, soundstage/air/headroom, and tactile treble quality. Very nice stuff. I decided to plug in my Arrow 3G for comparison, and immediately it sounded like the stage size had collapsed. And I noticed the bass sounding thin (no bass boost activated), with not as much treble extension either. I finished up that song with the Arrow, and went on part way into the next and then paused to quickly swap back to the uHA-120. And yes, there it was again, that huge scale. It's a ballsy amp for sure. I had never heard that level of bass, flat, on any portable amp. This includes the RSA Mustang and Shadow, ALO Rx, and the mentioned Arrow. The bass is even more deep and extended than my Lisa III w/power module (bass knob flat). 
    Once back in the States at work, I've been listening while cranking away on projects, paired with my Pro 900s. Talk about a huge, detailed sound, with stunning bass. Wow. Now this is system synergy. Really, really large sound, with the most crystalline treble, and wonderfully expansive mids. The only way it's lacking in comparison to the Lisa III rig is in soundstage size, and perhaps a little air. The bass is superior, and I think possibly even that crystal-like treble quality. I'm hard pressed to choose between the two for sound quality.
    Kudos to Justin for designing such a superb sounding portable amp. It's a long-term keeper no question.
  5. Kunlun
    So, about $322.
    It's comparible in price to the arrow and ttvj slim, larger in height but it seems much better sound than the arrow.
  6. cn11
    Yes, a bit chunkier, but pretty similar to the size of the RSA Mustang from my recollection. It's only 1" thick at the black bands, and about 7/8" at the case.
    The sound is definitely a noticeable jump over the Arrow. It's at the same level as the much bigger Lisa III rig. I really wasn't expecting such a nice sound from the amp when Justin handed it to me. Had to have it.
  7. b0wl1ng
    It is a very good amp, I have one of the first ones produced, number 004 , where this amp really scores is in its detail, very precise and accurate,plus the built in Lithium battery is a real plus factor.  
  8. Somnambulist
    It was fun seeing your reaction. It certainly did sound great with my stuff too and while I was dead-set on wanting an Arrow after hearing it slightly earlier in the meet, it's given me food for thought! It did sound larger, livelier, and as you've said elsewhere, the bass response felt like the Arrow 3G with the bass boost on +1. The only thing going against it for me would be the form-factor, as I think things like the TTVJ Slim and Arrow match the dimensions of most modern players better and make for an easier to pocket experience. That said, it's still not that big.
    Btw if anyone is on Facebook, they have a page. Get them more 'likes'!:
  9. cn11
    Hah, yeah, it was some reaction I'm sure. It was also funny to have soozieq ask me 'well, what's it like?', and to have to say 'ummm.....it is markedly better than the Arrow'. Then to see her reaction to that because she had the Arrow right there and was in the middle of being amazed by it. All she could say was 'nooooo, dammit!'. That was really the most fun part of the meet for me- that sort of shock of an unexpected discovery.
    The Arrow is of course still an amazing and special little amp. And I think with its feature set currently there's no competition in the portable market at all. Especially if you want something with which you can add a touch of bass slam to more analytical sounding IEMs. I don't foresee selling either amp for a long time. 

    That's awesome you have one of the first produced. I guess his amps have been relatively unknown around HF for almost a year or so. I hope that starts to change. It really is highly detailed, and the treble is just beautiful. Knowing how nice this one sounds, it makes me curious about how the bigger, class A 'AHA-120' sounds...... 
    My amp serial number is 18.
  10. Kunlun


    Could you compare the sound of this to the ttvj slim?
  11. b0wl1ng
    My thoughts exactly, if the uHA-120 is this good the class A , AHA-120 will probably be up alongside the best three, the Lisa, the Stepdance and the SR 71B.    
  12. Nuwidol
    I listened to the AHA-120 (2 of them running parallel in balanced actually) driving the HE-6. I'm not joking here. One amp per channel can give the HE-6 a decent sounding presentation. I'd been listening to the HE-6 through the Lyr when Justin approached me & asked if I'd like to try his portable amps running them. I was a bit skeptical at first but after he'd set everything up & handed them back to me I sat there in disbelief. I actually preferred the HE-6 out of the 2 portables. They toned down that hard aggressive sound of the HE-6 & turned them into something a lot more forgiving.

    Well done to Justin for coming up with 2 great products. He's actually in the process of designing an amp for IEMs too (The UHA was made with full size cans in mind).
  13. b0wl1ng
    That is amazing, thought only a generator could power the HE-6s to full glory. 
  14. Somnambulist


    Haven't heard the TTVJ, sorry!
  15. Jazzyfi
    Great news! I'll wait for the IEM version of uHA-120. Hopefully something in that can compete with pico slim in terms of thinness.

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