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Elekit TU-HP01 Hybrid Portable Headphone Amplifier - Review

Posted by vkung on June 5, 2014 at 18:51:24:
http://digitalaudiodirections.blogspot.ca/2014/06/elekit-tu-hp01-hybrid-portable.html
Elekit TU-HP01 with Sony MDR-7502 - click to enlarge

Elekit is a Japanese company founded in 1973 who offers a variety of kits in many categories. They have built a solid reputation by offering high value kits in the audio space to audio geeks in Japan. Now Victor Kung brings a number of Elekit models to the North American market through his VKmusic site. I met Victor at RMAF in 2013 and was intrigued by the design and value pricing on the products he brought to the show. A number of products stood out during the many short listening sessions at his booth including the TU-8200 integrated / headphone amp and the TU-HP01 portable headphone amp. Since I have no kit building expertise whatsoever, I decided I would like to review the TU-HP01. Unlike many of the Elekit audio offerings this one comes completely assembled! A huge thank you to Victor for the extended loan of the Elekit TU-HP01.

The TU-HP01 is a hybrid design using small low power Raytheon 6418 tubes on the input and a very good opamp for the output. Actually buyers can choose between getting the amp with two popular opamps or an opamp rollers cache of 7 opamps. Trust me for the marginal difference in price, get the 7 opamp package. The amp is designed to power headphones with impedance between 16 and 32 ohms and runs off of 4 “AAA” batteries. The amp features 3.5 inch mini stereo jacks for input and output, an on/ off volume control, high/low gain switch and power and low power indicator led. There is an additional front panel that has the writing upside down if you are using in a place where the original panel writing would be upside down. I did not really see a need for it. Also included is a Allen wrench to open the front panel to swap opamps. Additional specs can be found on the VKMusic website.

Let's talk a moment about the amp and its possible uses. The small size and light weight of the amp make it possible to take the amp with you when traveling or when you want high quality tunes both in the office and home for example. The use of batteries allows for clean power and lets you use it on a train or plane. Battery power gives you about 10 hours of listening with most headphones so you will want to have a few sets of rechargeable AAA batteries to keep the running costs lowest over time. Not a big deal these days since most folks have moved to rechargeable for X-box controllers, remotes, mice and the like and have at least one muti-battery type charger in their house. Make sure you get the low discharge long shelf life rechargeable batteries like the Sanyo Eneloop so you always have nearly a full charge even when sitting in a drawer.

Since the TU-HP01 uses small tubes, you do have to pay attention to microphonics or the tubes ability to translate vibration into an audible noise that the circuit can amplify. Elekit has done a few things to mitigate this yet you will still get a slight low level high pitched ping when you first turn on the amp as the tubes warm up. You can also get these slight pings if the amp is moving around like it did in my pocket while on a few walks. Even though the pings were very low in level it is best not to take this amp with you while running or walking and have it rhythmically banging around in your pants pocket. Placing it in a jacket breast pocket for the commute or a backpack for a trip across campus and you are fine, you just don't want it moving a lot. I have used the amp at my desk, on my nightstand, on the tray of a plane, in my hotel and at the coffee shop. These tubes are long life and will probably not even have to be replaced, just treat the amp well and enjoy.

Top of amp - click to enlarge

Well what is so great about his hybrid amp? I do not know why tubes make some devices sound so good but for some reason when well executed and in a well designed circuit they just do. The Elekit amp exhibits the same smooth but clean effortless presentation of the music. Compared to many chip and solid state portable headphone amps this one lets you hear layers effortlessly and with more three dimensionality in the midrange. Vocals and instruments are less in a two dimensional space and more discernible as individual with more body. Clarity is superb even with this more rounded and fleshed out presentation. Focus holds true as well as space between instruments, while some amps just seem to present a flatter less defined picture of a wall of sound. There are some great portable amps out there and the TU-HP01 can hang with many of them, even those priced much higher. The strength of the hybrid from Elekit is its ability to bring you convincingly real tonality, with realistic space and an ease to the presentation that just does not fatigue. It does not do it by faking the low end with a bass boost or artificially sharpening the highs to fool you into thinking it is more detailed. It is a pretty honest little amp that maintains these traits even though the sound can be quite different depending on which opamp you are using. I will try to detail out what I heard while rolling all 7 of the opamps in the deluxe kit in the section below.

Nearly all of my critical listening was done on several very good closed headphones including the Sony MDR-7520, Focal Spirit Professional, and NAD Viso HP-50. I also used my Vsonic VSD1S iems to check for any undue hiss with a sensitive iem and it passed with flying colors. There is some very low level noise that can be heard without a signal and the volume pretty high but you would be blasting your music at that poinit and never be able to hear the slight noise floor. You will notice that all the cans I used are under 50 ohms and they are relatively sensitive. They all sounded great and will go louder than I would prefer with the TU-HP01. All of my listening was with the gain set to low and I did not need to set the volume more than about 1 o'clock for loud listening with all the cans. I did pair it with a Sennheiser 650 for a quick listen but it would not be something I would recommend. And all the headphones sounded much better on an absolute scale to me than with just the headphone out of the 5th gen Apple Ipod Touch. For most of the listening I used the Touch with the DAC of the HRT Microstreamer. And yes as good as the Microstreamer is as an amp, the Elekit amp sounded even better. I can think of several dedicated desktop amps in the $300-$500 range that would be overshadowed by the sound quality of the Elekit. I can also think of at least one $500 and under desktop dac/amp combo whose headphone amp I would not prefer over the Elekit. And of course you will get even better sound with an even higher quality dac, like the Matrix X-Sabre DAC in my main system.

On an absolute scale there are a few things that one gains if you go upscale with some headphone amplifiers. The Elekit hybrid soundstage is relatively compact and is not helped by the fact that I used closed cans in my listening. You can get a more spacious soundstage width with a much bigger investment in an amp. The other area you can improve is soundstage depth and ambient cues. I think this has to do with power supply and even though we are using batteries, you can get a quieter and blacker background by spending more. This blacker background can help with even more focus and depth as well as let little cues become more apparent. And one last area that you could improve upon is dynamics. Surprisingly several opamps exhibit startlingly good dynamics, yet an amp like the Violectric 100 I reviewed will really startle you.

Rear of Elekit amp - Click to enlarge

Now that we have a good overview of the sound of the hybrid Elekit, lets have some fun. And boy, I did just that for many hours comparing all the opamps that come with the Sound Comparison Pack version that sells for a mere $250 for the amp and all seven opamps. I listened to all the opamps with the Ipod Touch as a source, running through the HRT Microstreamer DAC and fixed out to the input of the Elekit. The Apple player was used on the Touch and four of my favorite songs were used to directly compare the opamps. All comparative notes were based on listening through the Sony MDR-7520 headphones.

The test tracks are not any weird audiophile stuff but rather decently recorded pieces that I like. All were full resolution 16/44 AIFF files aside from the Peter Gabriel which was 24/48

Artist Album Track
Johnny Adams One Foot in the Blues Ill Wind

Edgar Meyer & Bela Fleck Music for Two Woolly Mammoth

Peter Gabriel Half Blood San Jacinto

Alison Krauss Live Ghost in This house

Now before you start reading let me remind you of how we audio geeks get down in the weeds sometimes. The nits and opinions in the notes below are just that, nits and opinions of what I hear when comparing to an ideal playback of the track. So remember I am trying to point out some differences and using an absolute scale most of the time to do so.
Muses 8820 – One of the two standard chips in the 2 opamp package

Johnny Adams- Organ could be a bit deeper but voice very good, average soundstage, background could be blacker.

Edgar Meyer – Bass good overall but could be a bit more gutsy on bowing, banjo good with plucks a bit soft and mellow overall. Crowd noise and soundstage just okay. Handled complex interplay well.

Peter Gabriel – Peters voice can be quite sibilant yet this chip kept it in check. Piano and depth good, highs and percussion a bit distant and soft. Loud passages a bit glaring

Alison Krauss -Voice close miked and breathy as it should be. Guitars warm and detailed. Hi-hat work could be a bit more defined.

Overall more open and clear with better decay as compared with straight out of HRT HP out.

JRC-4580D

Johnny Adams- Clean cymbals, wider soundstage, leaner organ mid-bass, leaner in bass, but voice clean and clear

Edgar Meyer – Banjo open, more mid centric less big overall. Seems to make bass smaller in size with smoother bowing sounds. Seems a bit rolled at extremities.

Peter Gabriel – Clean piano, volume need to go up a bit, Bells don't ring long enough, Less sibilance on vocals, mids, mids, mids. Depth could be better.

Alison Krauss- Clean smooth mids

Muses 8920

Johnny Adams – Organ is nicely open and deep, very good voice, beautiful texture and tone.

Edgar Meyer – Nice balance, mid centric with very good detail and bass. Best yet for digging out detail.

Peter Gabriel – Nice piano attack, less sibilant, bell attack a bit more distant, good depth, better instrument attack, nice mids and smooth details yet a bit glaring on loud parts. Blacker background

Alison Krauss- Slight emphasis on upper mids. Nice balance overall. Could be a bit aggressive with some cans, but I liked the chip.

JRC 3414AD

Johnny Adams – Midrange is good, mellow on the attack, extreme highs seem a bit rolled, low bass rolled a bit.

Edgar Meyer – Smooth banjo less open, mid centric lacks attack and detail. Quite rounded overall. Seems less impressive than previous JRC.

Peter Gabriel – Virtually no sibilance on voice, soft highs, needs to be turned up.

Alison Krauss – smooth mids, can crank up the volume without compressing.

JRC 4560

Johnny Adams- Lower mids more prominent, upper high end a bit polite

Edgar Meyer – Overtones on banjo and bass smooth and rounded, good bass overall, basshead like!

Peter Gabriel – Piano is warm, some vocal sibilance, attack and bell decay are pretty good. A bit too forward on vocals, reaching to turn down. Better than prior JRC.

Alison Krauss- Pleasant overall with less breathy vocals and more mellow guitars.
OPA 2134

Johnny Adams – A bit on the dark side but very nice overall, maybe nice match for brighter cans, Reminds me of a good tube amp.

Edgar Meyer – Delicate banjo, quiet and easy to hear into the mix. Mids a bit laid back, very good space between instruments, Upper harmonics seem rolled but great fundamental tone. May be slight upper bass emphasis.

Peter Gabriel – Low sibilance on voice. Good decay and depth – Good instrument space.

Alison Krauss- Good mids, nice dynamics.

Muses 02 – yes, Victor surprised me with a super premium opamp that is not part of the kits but can be had – It is the most expensive of the bunch.

Johnny Adams- Nice close presentation of the organ, warm, vocals a bit rich and slightly less depth. Most tube like of all.

Edgar Meyer – Banjo open and smooth best yet, nice deep bass, great depth and decay, effortless presentation, slightly warm and all the great tube tone.

Peter Gabriel- Turn it up, lots of space, piano is excellent, bells delicate, low vocal sibilants, relaxed.

Alison Krauss- Slightly warm yet still breathy and pure tone on voice, more 3d character to instruments, good micro-dynamics.

OPA 2604 – The second standard opamp in the two opamp version

Johnny Adams- Beautiful mids on voice, phat bass yet clean, not as open way up top.

Edgar Meyer – Rounded a bit on bass bowing and lack of decay

Peter Gabriel – Piano and Bells set back a bit. More laid back sounding overall. Metallic sheen on top of voice, highs muted and a bit slow sounding.

Alison Krauss – Warmish vocals, thicker guitars, vocals set back with slight sibilance.

Yes, I removed the screws on the front panel to make changing opamps a bit easier - nice glow though

Okay – That was fun! As you can see there are lots of small differences to be heard with the various opamps. And they all might act to support the ultimate sound you get with your headphones. A lot of what I heard was due to the Sony being the constant and your results may not match what I heard. To recap, I like the Muses 8920, Muses 02, OPA 2134 and JRC 4560 as my faves.

Overall, I think it is best to opt for the 7 opamp package at $250 vs the $225 amp and 2 opamps. Sound quality and value is very good with this amp. I cannot think of a portable amp package that offers this much sound flexibility and matching to your low impedance headphones. If you have a desire to get great moveable sound on a $300 or less budget and don't mind rechargeable batteries, this is an easy purchase.