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Angstrom Audio Stella Headphone Amplifier

Rating:
5/5,
  • HEADPHONE AMP

    Built entirely by hand

    Circuit Topology: Single ended with proprietary
    Circlotron output stage configuration.
    Power Output: 10.5 Watts per channel
    Total Harmonic Distorsion: 0.3% @1 W. - 1% at max. power
    Output: In Current
    Total Bandwidth: 12 Hz to 85 Khz
    Input Inpedance: 100K Ohm
    Zero Feedback
    Slew Rate: 20 Volt / microseconds
    Rise Time: 2.3 microseconds
    Hum & Noise: Less than 2.0 mV RMS - 90 db (20 Khz unweighted)
    Residual noise: 43 microVolt
    PSU Energy Storage: Approximately 150 JOULES
    Dimensions: 48 cm W x 16 cm H x 43 cm D.
    Net Weight: 30 Kg.

Recent Reviews

  1. Dillan
    Holy grail acquired: Angstrom Stella
    Written by Dillan
    Published Nov 19, 2017
    5.0/5,
    Pros - Aesthetics, background silence, midrange beauty, versatile
    Cons - Heavy (70 lbs)
    Introduction

    By: Dillan

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    Starting my headphone journey was a path I never knew would lead me to the destination I currently find myself. A distinct passion for music and a deep appreciation for high-end products was a recipe for my becoming an audiophile. It makes perfect sense looking back and I wouldn’t trade any of my experience for the world. Without the long list of products I have had the pleasure of using... I wouldn’t have the appreciation for such holy grails when I happen to stumble upon them. Today I sit on my bed, LCD-4 as my weapon of choice, plugged straight into my new Angstrom Audio Stella headphone amplifier.

    Angstrom was a company I had started paying attention to recently. In fact, a lot of Italian products have surprised me lately in respect to all of my quirky hobbies. Call it luck, but my last four or five purchases from Italian makers have all but left me mouth open and exuding praise. I don’t know if these guys have Da Vinci blood running through their veins or what, but I have been thoroughly impressed with the design and engineering of Italian product makers as of late. Angstrom Audio (www.AngstromAudio.com) has really been a pioneer in high-end tube based amplifiers over the last two years. Their popularity is finally starting to rise and with good reason. Let me first say that without even taking their products themselves into consideration, their communication is utterly magnificent. I actually felt as if I were treated as a friend instead of a customer. That, with me, goes quite a long way as their products do tend to be a little pricey, so I definitely have high regard for customer service that makes me feel like an appreciated individual instead of “just another customer”.
    Before I give away all of my verdicts, I will dive into the more technical and tangible aspects of my headphone amp. I will say however that if you are interested in anything from Angstrom, but perhaps you want it slightly different than the default… They will certainly provide quite an amazing custom experience for you. These products are hand built and not mass produced using a template of uncontrollability. This provides you with the capability of changing things up to fit your specific needs and wants. In my situation, I wanted to have a set of XLR inputs on the back to satisfy my custom cabling. It doesn’t operate in balanced mode, but it does allow me to use a setup that I had already here waiting, regardless of it transitioning back to single ended after the plug. In general, without even dissecting the product itself, the road to receiving my Stella product was very much enjoyable and even now after having received it, I still haven’t been forgotten about. I usually tend to support companies from my home country of America, but Angstrom is definitely an exception as I feel they really define the word excellence from top to bottom. Definitely a huge shout out to Matt and the rest of the wonderful team for all that they do. Before we dive in, let’s check out the specifications.

    Technical Specs

    Built entirely by hand.

    Circuit Topology: Single ended with proprietary
    Circlotron output stage configuration.
    Power Output: 10.5 Watts per channel
    Total Harmonic Distorsion: 0.3% @1 W. - 1% at max. power
    Output: In Current
    Total Bandwidth: 12 Hz to 85 Khz
    Input Inpedance: 100K Ohm
    Zero Feedback
    Slew Rate: 20 Volt / microseconds
    Rise Time: 2.3 microseconds
    Hum & Noise: Less than 2.0 mV RMS - 90 db (20 Khz unweighted)
    Residual noise: 43 microVolt
    PSU Energy Storage: Approximately 150 JOULES
    Dimensions: 48 cm W x 16 cm H x 43 cm D.
    Net Weight: 30 Kg. (67 lbs)

    Packaging


    So as a writer and reviewer, I find myself in a first-time situation where I can’t actually put into words just what my experience here was. I have never seen nor heard about a product so immaculately packaged. I hope from the pictures that at least some justice is served, because I actually felt like royalty receiving something… well… royal.

    [​IMG]
    [​IMG]

    The wooden box delivered to my house was quite heavy and industrial looking. It displays the words “Angstrom Audio Lab” etched into the center, while “Made in Italy” rests underneath. To caution the deliverers, they also took the time to etch markings on the sides to instruct the orientation of which to keep the box. After opening the box I was met with a perfectly assembled collection of tubes, a booklet and some extra tools and parts all in cutout foam padding. This was put together almost like a well-executed puzzle piece and once this was removed, an even prettier arrangement were waiting.

    [​IMG]

    A beautiful velvet cover in red wraps around the amplifier at the bottom of the box. This was one of the few times as an adult I felt that same excitement I had as a child on Christmas day. “Angstrom Audio Lab”, again, is written on the top with “Made in Italy” underneath, but this time in gold. The guys at Angstrom sure do have world class presentation skill, that’s a fact. I took the velvet covering off of the (heavy) amplifier and couldn’t wait to get it fully assembled. Just a warning to some of you, this is a 70lbs amplifier. I actually had to upgrade my rack for fear that the shelves couldn’t contain this beast.


    Assembly

    The assembly did take some time, but not because it was complicated, it was just a lot of tubes that needed to be carefully and accurately plugged in… twenty to be exact.

    [​IMG]
    While assembling the tubes in their respecting locations, I couldn’t help but notice the internals of this well-made machine. You can very much see the depth in which they went to make sure you were getting the best of the best. Hand assembled point to point contacts with silver wiring. Everything very neatly organized and purpose driven. I have to say it was very impressive viewing the inside of this. Not to knock on anyone specifically, but I have had amplifiers which sounded pretty good, but under the hood looked like a nightmare. Handmade does not have to mean messy or unorganized and Angstrom is most definitely proof of this. At this point in the process I was smiling ear to ear at just how well this was packaged and displayed. The tubes were each labeled with a hand written note that easily and precisely instructed me where to place each one. I personally have such a wide range of headphones ranging from very efficient to power hungry monsters, so Angstrom sent me three sets of drivers ranging from low power to medium power to high power. Once all tubes were plugged in securely, I put the metal top back on and screwed them in tightly. Now it was ready to jam.

    Sound

    Obviously you can make a product appear to be amazing, but what does it really matter if it does not sound as good as it looks. I think most audiophiles, including me, much prefer an amazing sound to something that just looks amazing. What happens when you have something that does both? Well, you have a unicorn that you should really hang on to.

    I mostly used my LCD-4 for this review as it has long been my favorite headphone and I feel it can transparently allow me to inspect the sound of whatever I plug it in to. I am one of the few self-proclaimed “audiophiles” who actually keeps his ideals down on this planet. I don’t believe aftermarket cabling changes the sound immensely nor do I even think an amplifier itself can do such a thing. I do believe a tube amplifier will have the most prominent influence on sound in comparison to a solid state amp however. My two biggest fears before receiving the Stella were #1 with so many tubes, the background would not exactly be silent and #2 the partnering with my LCD-4 would just be too warm and veiled. To spoil the surprise, I was met with a completely black background and a very crisp and clean signature which matched very well with my headphone from Audeze.

    [​IMG]
    My setup here consists of a PSAudio Directstream DAC and I swap between my computer and the Sony WM1Z for the source. Obviously I am using my LCD-4 as my reference headphone, but I did switch it up with the HD800S from Sennheiser, as well as a few high-end Grado offerings.

    Low frequency- The low frequency with the Stella was probably the least impressive, but not to say it was bad. I do not consider myself to be a basshead per se, but I do enjoy a good rumble when the music calls for it. (Hence my love affair with Audeze’s house sound) The low end sort of hints at the overall signature as a whole in the fact that it produces very clear and distinct music accurately and effortlessly. The detail in the bottom end truly is astonishing; however I do interpret a perceived minute audible roll-off whether tangible through charts or not. While the focus is not in this frequency specifically, it does get the job done. I would use the words “clarity” “detailed” “quick” and “thin” for the low end frequencies. I wouldn’t particularly take points off, I just think this particular area of sound may introduce favor or non-favor to listeners who concentrate on bass above all else. I do respect quality over quantity so in that regard, it is a clear winner.

    Mid frequency- This, in my opinion, is where the Stella absolutely shines. Voices and instruments which are associated with the middle frequencies are absolutely stunning to my ears. Stevie Wonder sounded incredible, as did Janis Joplin and Chet Bakers trumpet. I actually found myself closing my eyes on many occasions as I slipped into a euphoric state while listening to some of my favorite albums. I would also describe the mids as quick and detailed, but with a little more forward presentation than the low end. I have used many amps with my LCD-4 and using the Stella almost sounded like a veil was lifted. A veil hiding the smaller details and clarity that one may never knew existed. Transitioning from the low end into the mids was sublime. It felt as if a train were going on the rails and never hinted at derailing as it rode neatly on the well assembled track. This transition did introduce slight warmth which is a little hard to explain. Neither the low end nor the mid frequencies would be described as warm, however the transition itself could be described in this way. Overall I do feel instruments in this area were best, but vocals definitely were a very close second. I think female vocals especially were enjoyable and I cannot say enough just how clear and detailed this amp was, especially in the mids.

    Top end- The treble was a little sharp, but not sibilant. Above and Beyond acoustic album had a few parts which I would describe as sharp due to the prominent high end of the Stella. I would not say the Stella puts a resounding significance in this area, but the unveiled nature definitely does not hide anything here. The transition from the middle frequency is again very enjoyable. This time I did hear a slight upward swoop, but this was not unpleasant in any way shape or fashion. High hats were delivered with a snap and other instruments like the flute were very crisp and clean. Females going into the higher spectrum were also very good, even when riding the line between the swoop I described. The LCD-4 could play a major role here too as it has a slight bump in the treble as well. So I believe this signature exacerbated this aspect a bit. I think most everyone would rave about the high end of the Stella. It delivers an almost perfect representation of the music with such a euphonic cleanliness that doesn’t even hint at sibilance. At the very most you could say it is slightly bright. I really enjoyed the higher end frequencies; it does a very fine job.

    Conclusion

    To conclude this review I would have to wrap up by saying this is one of the best, if not the best piece of audio equipment I have ever had the pleasure of enjoying. Although the Stella headphone amp sits around $14,000 depending on customization, I feel that it is actually worth the asking price. My only complaint in the process of obtaining this amplifier was the fact that they did not accept a better method of payment. PayPal or anything of the sort was definitely out of the realm of possibility and I was forced to use my bank to transfer the funds which had to be done in person and wasn’t exactly easy or instant. As for the amp itself, I feel the packaging was really the most impressive. Not that the sound was unenjoyable, but the presentation was such a work of art that it absolutely blew away any competition it could ever face. The sound signature may not fit everyone, but it certainly is something I have been enjoying almost on a daily basis. I have been searching for almost a decade now for the ultimate amplifier to complete my setup and it is such a relief to have this in my procession as I truly believe it checks every box needed to be called my personal grail. For the first time in forever, I absolutely do not have any desire to “upgrade” the amplifier at all. In fact, all of my setup seems to be my permanent listening stack. The amplifier really was the missing piece of the puzzle and with such clarity and depth of every detailed note, I am satisfied beyond belief. How they were able to create a completely silent background with so many tubes is beyond me. If you were to close your eyes and just listen, you could definitely mistake this piece of equipment for solid state. I brought Stella to a few audio shows since receiving it and the response was overwhelmingly positive. The only negative comments I received were about the weight and size. Overall, as I stated, I believe this to be my personal holy grail when it comes to headphone amplifiers. The three sets of tubes will perfectly power any headphone in my inventory and the sound signature is not boring or overly exciting. I want to thank Angstrom for being so helpful and creating such a wonderful product. You guys truly take no shortcuts and create some of the best looking and sounding items on the market.
    1. View previous replies...
    2. pedalhead
      I've been looking after one of these amps for a friend for the past 11 months (I have really cool friends!), and agree that it is quite superb. Honestly, I tend to suspect that a lot of high end (ie high price) amps are "chassis engineered", and so approached the Stella with quite some skepticism. However, I have to admit that this is the most enjoyable headphone amplifier I have ever heard.
      pedalhead, Oct 24, 2018
      Dillan likes this.
    3. pedalhead
      Slightly contrary to Dillan, I find the bass performance to be one of its strongest areas. Whereas tube amps can often have loose or rolled off bass, the Stella's to my ears is tight and punchy, and slightly elevated (which I like). Most of my listening is with HEK v2 headphones, and other amps I own or have recently owned include a First Watt F7, Wells Audio Enigma, Cary Xciter, Schiit Ragnarok.
      pedalhead, Oct 24, 2018
      Dillan likes this.
    4. pedalhead
      The only downside I'd say is that I'm terrified of troubleshooting when one of those twenty tubes starts getting noisy!! And it needs speaker taps. Sorry for the multi-posts, there's a limit on characters for replying to these reviews.
      pedalhead, Oct 24, 2018
      Dillan likes this.

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