AAW Black Amp impressions thread

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Erroneous, Feb 2, 2021.

  1. BarryT

    BarryT MOT: Austin Audio Works

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    Had trouble with video editor so here is the skinny but in text.

    To start with the output impedance for each independent line (L+. L-. R+, and R-) is 20 ohms, so for SE it is 20 ohms and for balanced it is 40 ohms.

    What is the significance of that? None that I can tell other than I made a choice when I designed based on 60 years of making such choices, and the fact that there are 20 output transistors per amplifier, being complimentary systemic in design, that is 10 for each polarity, each has a 200 ohm resistor in its emitter lead it so it is 20 ohms to the load. Obviously there is more to it than that but at this point we drop off into some pretty eclectic reasoning that is in effect a part of my secret sauce to make the whole greater than the sum of it's parts.

    The arguments for a non-zero output Z are focused on the no feedback issue, the elimination of active damping and output sensitivity to load variations and back EMF, a whole other story. Nice thing is that running any amplifier of this design, even my 100 watt version, is virtually immune to output loading, even shorts.

    I hope this clears some air, these are areas I am a bit passionate about having a lifetime of designing and building really big amplifiers for R&R concert use.

    Thank you, Barry
     
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    Last edited: Feb 22, 2021
  2. crenca

    crenca Friend

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    We post impressions in this thread I think....if not let me know.

    Received it yesterday and been listening to this amp for about an hour this morning, comparing it to DNA Starlett and Asgard 3. I have been using my 300 ohm Drop HD6XX's because I have sold my ZMF's, my various Focals are too warm with this 20/40 ohm OI (SE vs 4 pin bal) and I don't want to use EQ to evaluate. This is a good amp, much closer to Starlett (if not equal in many areas) technically than the Asgard 3. I am enjoying the detail in the mids, and the clear upper mids/treble that is without any hardness and glare that I can tell. Slams hard, with nice textured and detailed bass.

    I have some questions in to Barry and will post a full review in next few days.
     
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    Last edited: Mar 6, 2021
  3. bilboda

    bilboda Florida boomer

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    I would try the Focals without equalization and see for yourself if the OI is a factor with this amp. By all accounts it should not be a factor, a belief espoused by Barry and the Bakoon amp designer. Don't rule them out without trying them. My Verum's were wonderful and at the top of their game, granted, planar's.
     
  4. k4rstar

    k4rstar Britney fan club president

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    please post impressions/discussion of the Austin Audio Works Black Amp here

    loaner thread: https://www.superbestaudiofriends.org/index.php?threads/loaner-ic-austinaudioworks-black-amp.10426/

    AAW website: https://austinaudioworks.com/amp-description/

    [​IMG]
    [​IMG]
     
  5. crenca

    crenca Friend

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    Well I could be convinced. Just spent some time going back and forth between Asgard 3 (<1 ohm OI), DNA Starlett (setup for 9 ohm OI), and Black Amp SE output (20 ohm OI) using Focal Clear which is nominally 55 ohm HP with rise in bass at 50hz to > 300 ohm:

    https://www.superbestaudiofriends.o...ments-and-impressions.5568/page-2#post-182491

    I think I can readily hear a bit of expected bass bump as I move up in OI, but its tough because A/B/C'ing like this sucks. Is it just natural differences between the amps? I am not confident at this point. Maybe an one of our resident EE's can comment on the idea that a "current mode" topology makes OI irrelevant to dynamics with impedance curves like the Focal Clear.

    I have to say that really enjoying the Black Amp with many tracks. As I write this I have switched to the Utopia and I am trying to discern the differences with voices between it and the Starlett. The Black Amp's speed, separation, and stage makes it a little easier to pick detail out compared to the Starlett, but the inner note nuance might just go to the Starlett by a hair... In any case its a nice problem to have ;)
     
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  6. bilboda

    bilboda Florida boomer

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    Nice update. I think you should go full on balanced with the Focals. In for a penny in for a pound. Your ears will tell you what's up. Adjust the gain on the back. There is a rough guide on the label.
     
  7. crenca

    crenca Friend

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    Final impressions before I send it off to the next person on the tour

    On the black Amps output impedance (20 ohm SE, 40 ohm bal):

    I think it matters at least some. I had a conversation with Barry yesterday and I asked him to explain his perspective on this. His answer was beyond my experience and understanding but I don't think he said anything to the effect that a it does not matter because this is a "current mode" topology. Looking at Barry's own measurements of output VRMS vs HP load in ohms (https://austinaudioworks.com/amp-specifications/), we see the amps output increases as HP resistance goes up. The Focal Clear/Utopia's have a typical dynamic driver rise in the bass of resistance, I believe the Black Amp is giving more output and thus boosting the bass a bit.

    By the way if you get the chance have a chat with Barry as he is a great conversationalist. He is more than willing to explain his design philosophy/goals in a helpful and non-confrontational manner, doing his best to explicate in a way you understand given you background and technical knowledge. His experience and perspective on the hobby, the industry, and life in general is refreshingly relevant and honest as well.

    The sound:

    No doubt to @ChaChaRealSmooth chagrin, I am going to use the word "clarity". This amp brings a clarity to the table that is missing from my other amps. It is SS obviously, so it has a speed and transient attack that is fast but not not overly square or grainy. This is true from bottom to the top of the frequency response, with upper mids and lower treble being fast and clear without any steeliness and glare. The FR is balanced and nothing jumps out at me as out of place. The bass is textured and detailed. The voices and mid centric instruments are neither forward nor recessed - everything is in place. Overall I think the amp is a click to the right of neutral, and this probably enhances its sense of clarity.

    The stage has width and depth, wider than my DNA Starlett I would say. The resolution, balance, stage, and the fast-but-smooth uppder mids/treble leads to excellent instrument separation and placement. At the same time voices and instruments have that inner note weight and texture that I am used to hearing out of the Starlett, though the Starlett just edges the Black Amp out here.

    This amp really wakes up my unmodded Drop HD6XX, and if it was my primary HP I would sell my Starlett and use the Black Amp. I suspect it would also have been my preference with ZMF's if I still had them. My Utopia benefits more from the Starlett's strengths, but even here I am really having a tough time declaring a winner so I won't.

    I did not focus too much on this, but I did not detect any significant difference in quality between SE and balanced inputs.

    Downsides:

    On top of the OI issue, the noise floor is not the lowest I have heard. IEM's are a no go, and the Focals picked it up though it was very slight and a non-issue with music to my ears. A central design goal of this amp was to feed the current Audeze's wanted. Barry is a one man shop so the amp does have a bit of that DIY feel - a little play in the input selector for example. The pot is too unbalanced to be useful until 9 o'clock, though by reducing the input sensitivity with the gain dial on the back this was a non issue for me. I asked Barry if the pot was upgradable but he thought the extra cost would not be worth it.

    TL;DR:

    About the best SS headphone amp I have heard - has many of the EC BW2's strengths without as many sins of commission. Not for IEM's and possibly high sensitivity/low impedance dynamics unless you willing to adjust.
     
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    Last edited: Mar 9, 2021
  8. zonto

    zonto Friend

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    BLACK AMP LOANER IMPRESSIONS

    @crenca's post inspired me to finally write up my loaner impressions as well.

    Chain: Yggdrasil Analog 2 --> RCA outputs --> Mogami 2497 interconnects --> Black Amp RCA inputs. More info in my profile.
    Headphones: Focal Utopia and Sennheiser HD600, both with XLR cables (though I did try Utopia single-ended as well).
    Other amps compared to: Schiit Asgard 2 and Schiit Ragnarok 1.5

    NON-AUDIO IMPRESSIONS
    • The loaner unit was not the greatest build quality, but I assume production models are better.
    • The gain was hard for me to match. The volume pot was very sensitive, and even when turning the gain knob on the back all the way down, I was still only able to get to around 9-9:30 on the pot with the Utopia and around 10-11 o'clock on the pot with HD600. When matching the gain knob's impedances written on the tape by the knob to my headphone impedances, I could barely get to 9 o'clock on the volume pot.
    • The amp had an audible noise floor on both headphones when not playing music. Ragnarok was dead silent when I compared.
    • The power cable has a proprietary connector on one end and a wallwart on the other end. I forgot to write down details of the wallwart.

    AUDIO IMPRESSIONS

    General Impressions:

    • The Black Amp had great resolve and was less edgy than the Asgard 2 (even after the Asgard 2 had been left on for a couple weeks). Awesome cymbal detail and realism, could hear stick placement on intricate cymbal work and cymbals sounded less hazy than they did on the Asgard 2.
    • Lack of bass and midbass impact with Utopia when compared to both the Asgard 2 and Ragnarok. I'm bolding this because my disappointment in the bass department is my biggest complaint. I don't understand why this is the case because of the interaction that should be happening with the Utopia's impedance curve and the Black Amp's output impedance. When I used the ECP Torpedo 3 years ago for instance, I couldn't stand the Utopia on the Hi Z output because the sound got too boomy in the bass; always had to switch to Lo Z. That didn't happen on the Black Amp, so something else must be happening that an engineer would have to explain. Maybe something to do with the current vs. voltage drive or something else with the amp's topology.
    • Smooth midrange that wasn't pushed forward. I don't think this is a "midcentric" amplifier though, as the treble is not rolled off. (Treble rolloff is one thing I really didn't like about the Jotunheim 2 loaner I recently had in.) More aptly described as a "mid-and-treble-centric" amplifier" perhaps.
    • The Black Amp had a more complex and interesting presentation than either Schiit amp. It felt like more of a window into the music. Very clear sounding. Harmonics and instrument interplay was better presented on the Black Amp than either Schiit amp. It reminded me a little of my time with the Valhalla 2 years ago and what I've read elsewhere on SBAF about good tube amps.
    • Great sense of depth.
    • Wanted to keep listening, which is a good sign.

    Black Amp vs. Ragnarok (level matched):
    • The Ragnarok clearly has more bass impact. Bass lines on rock were disappointing on the Black Amp / Utopia, and often lost in the mix a bit. Sounded a bit muddy and hit like a wet noodle. Ragnarok is low output impedance, but has much more kick on Utopia.
    • I heard new things on songs on the Black Amp, even after having just listened to the same song on the Ragnarok. Black Amp was more resolving. Could hear little gradations in vocals much easier on the Black Amp.
    • Switching back to the Ragnarok after listening to a song on the Black Amp often sounded weird/wrong in most respects. Not sure what to make of that (as I view the Ragnarok as a neutral amplifier, so is the Black Amp the outlier / more colored somehow?). On certain rock albums though, switching back to Ragnarok felt more like going "home" because of the bass presentation, despite not having the same addicting qualities in the midrange and treble.
    • I also noticed that snare drums did not have the same crack on the Ragnarok that they did on the Black Amp, and cymbals didn't sound as natural.
    • The Ragnarok has noticeably less layering and microdynamics, smaller image size (could just be putting the listener further from the stage, which I like), and some comparative edge in the midrange.
    • The Black Amp had better stage height and vertical imaging than the Ragnarok.
    • The Black Amp places the listener closer to the stage than the Ragnarok. I don't love this generally. As an aside, I hated how the Jotunheim 2 did this, as with the Jotunheim 2 I felt I kept wanting to push the performers/music back away from me. Didn't hate this on the Black Amp, but preferred the distance from stage on the Ragnarok.

    Black Amp + HD600:
    • I thought this was going to be a good match given my experience with the Utopia noted above, especially the Black Amp's midrange performance. I was wrong. I didn't think the HD600 sound great with the Black Amp or the Ragnarok. Think this headphone really needs a tube amp (liked it on Valhalla 2 and ECP Torpedo 3). The Black Amp would probably be a better amp for the HD650 given its midbass bump and more rolled treble. HD600 needs more bass impact than the Black Amp provides.
    • My other takeaway after using the HD600 for an hour or two was that it made me realize just how smooth the Utopia sounds in comparison. Yet another reason the HD600 stays in the box most of the time.

    My Wife's Impressions:
    • My wife is not an audiophile. She thinks most of the hobby is ridiculous and only tolerates the living room speaker system. She'd prefer we didn't have a TV at all. However, she loves the Utopia headphones.
    • She listened for 20 minutes or so on a variety of her own music and said she noticed lots of little details she hadn't before (resolution).
    • She also said she was disappointed in the bass (Michael Jackson songs), but that the Black Amp sounded awesome on acoustic music (Taylor Swift's new song with Bon Iver). Whenever something lacks bass, she calls it "tinny". She said the Black Amp sounds tinny. She also says the Ragnarok sounds tinny with the Magnepan speakers in the living room, whereas the Coda amplifier does not sound tinny with the Maggies. :)
    XLR vs. SE output:

    As the Black Amp is a balanced amplifier, I compared the SE output and XLR output with Utopia the first night. In my notes I wrote that the XLR output had more air, space and nuance, and more bass kick. I did not compare the two outputs again on Utopia or at all with HD600, so take with a grain of salt.

    TL;DR

    • I liked this amp, and think it's the best overall amp I've heard the Focal Utopia on. However, what I dislike about the amp is enough to make me not want to buy one.
    • In the end, this amp was just disappointing for me on rock, pop, and hip hop due to the lack of bass impact and bass muddiness / bass getting lost in the mix. For folk, acoustic, and classical the amp sounds amazing. The Ragnarok is a better all-rounder and can power speakers too so it better suits my needs for now, especially since I mostly listen to rock on headphones.
    • I think the Black Amp is best suited for headphones that need a lot of current, are not high sensitivity (noise floor), and have a frequency response that's more bass-heavy than neutral and/or treble-heavy.
     
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    Last edited: Mar 10, 2021
  9. dematted

    dematted Almost "Made"

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    For what it's worth, I heard the amp for a short period myself (though I felt like I shouldn't post impressions as I had a migraine at the time), and my preliminary impressions most closely line up with @zonto's. Compared to the ZMF Pendant, I was pretty shocked by how light on its feet it sounded in the bass, and there was a general lack of bass heft, weight, and slam throughout both the sub and midbass. The mids also sounded just a tad lean. However, the resolution was excellent, and the layering, separation, and sense of stage were all markedly superior to the Pendant. Mid-range and treble timbre were also pretty excellent. But the general lack of tactility and slam in the bass makes me place this amp into more of a "specialist" than "general-use" category, at least for my personal auditory tastes. Perhaps excellent for bass-heavy headphones that bring a lot of slam to the table (like the ESX900, for example) that can make up for that short-coming, but not an amp that I think would work particularly well with many of the headphones that SBAF enjoys.
     
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    Last edited: Mar 9, 2021
  10. crenca

    crenca Friend

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    Barry explained to me the wall wart is an aluminum box stuffed with resistors (thus the weight) that delivers 16 volts of AC to the Black Amp.
     
  11. BarryT

    BarryT MOT: Austin Audio Works

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    Barry Thornton here, designer of the Black Amp.

    One of the reasons for the SBAF tour for the Black AMP is that your input it the best critiquing I can possibly get for the sonics of the unit. As I have mentioned before, the shortcoming of my listening is my personal bias and the limited number of headphones I have.

    Your collective remarks have been most illuminating and educational.

    Something I have conjectured about in designing and building the AMP is the output impedance and its effects on the headphones. Reading your remarks has made it clear to me that I made the output impedance TOO HIGH at 20 ohms and that I am in effect starving the bass to many types of headphone.

    Thinking it over I realize that this is an issue such that I would ask this.

    I would like to pull the AMP back and lower the output impedance into the area of 5 to 7 ohms. It is my belief that this will significantly improve the bottom end in most phones without effecting the mid or high end qualities. This will not take long as it is a change in about 20 resistors. It is important that I do this particular amplifier as this assures that only on variable is changed at a time so that we all can understand the resulting effects.

    I would therefore ask whoever has the amp to send it to me as soon as practical, will modify and return it immediately while sonic memories are fresh.

    Please let me know of your decision to do so and send it to

    Barry Thornton
    Austin Audioworks
    350-256 12400 Highway 71 W, Austin, TX 78738 and I will get it back to you in a few days.

    My phone is 512-912-6820, give me a call. Thanks, Barry
     
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  12. k4rstar

    k4rstar Britney fan club president

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    I just spoke to Barry, going to re-route the amp to him after @Phantaminum has had his chance to try it out, he will make his desired adjustments, and if @Phantaminum is open to it he can receive the same unit back to be able to do a comparison!

    Also looking into potentially get a second unit as production allows to create a second loaner list and get more ears on this amp sooner.
     
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  13. bilboda

    bilboda Florida boomer

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    Everybody's ears and expectations are different. It can be hard to say if an amplifier is putting out correct bass volume except by our experience based on what we are used to. I heard clear correct well timbered and defined bass and was happy with it. I only used high Z headphones and planars though. No dynamics with low z. Should have tried my portapros, elegia and jvc iem's but I only used the headphones that I actually use. If there is enough time, I would like to hear the new version as well. I now have an LSA HP2 and this amp would seem to share the hp's strength. New detail in strings mids and lots of plankton. I am fairly all in on this amp already and it would be great if the change does not affect any other aspect of it's performance.
     
  14. BarryT

    BarryT MOT: Austin Audio Works

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    Sina asked for some eye-candy so her are some photos of the Black AMP's guts.
     
  15. Armaegis

    Armaegis Friend

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    I think you messed up the image posting? I don't see anything there...
     
  16. BarryT

    BarryT MOT: Austin Audio Works

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    I have tried several times with Sina's help but the forum system will not let me post images, seems I need an approval that I can not get. I apologize for the failure, I wish I could show you things. I will paste a note on the DAC page for that too must come to an end without images so you can see what I refer to.
     
  17. Armaegis

    Armaegis Friend

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    @BarryT
    Perhaps email the pictures to Sina and he can post them for you?
     
  18. tommytakis

    tommytakis MOT: E.T.A Headphones

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    Hi @BarryT I made a step-by-step guide for you with pictures. Please let me know if you need further clarification on any part

    1. figure out where you stored the images. For teaching purposes, I've downloaded the front and back pictures of your amp in my desktop.
    [​IMG]
    2. Now on SBAF, right below the text box, you should see 3 click-able options "Post Reply" "Upload a File" "More Options..." Click on "Upload a File"
    [​IMG]
    3. Then a small window will pop up for you to choose the images you wish to share. Click "Choose File"
    [​IMG]
    4. Find the files and double click on the image files you wish to share. In step 1, we figured out where the images are stored so this should be piece of cake.
    [​IMG]
    5. If done successfully, you will see the file you selected at the bottom of the text box on SBAF forum
    [​IMG]
    6. If you have more than one image to upload, repeat steps 2-4. If successful, you will now have another file preview showing below the text box
    [​IMG]
    7. After you finish writing your post, Choose whether to show your images as a "Thumbnail" or "Full Image"
    upload_2021-3-21_10-9-52.png

    8. You did it! Congrats :)
    AMP-front.jpg AMP-rear.jpg
     
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  19. rlow

    rlow A happy woofer

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    @tommytakis in the past, you couldn’t upload a file unless you were a Friend status (I assume that’s still the case). I asked in the DAC thread whether @BarryT could perhaps be updated to a MoT status to give him file upload privileges (not sure if thats the case when you become MoT). Perhaps @purr1n or @zerodeefex could take a look at it.
     
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  20. BarryT

    BarryT MOT: Austin Audio Works

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    The problem is that I don't get the same screens as you because of my status. With Sina's help I have tried all that you show to no avail, thank you for your time an effort but this is beyond our level. Bilboa will be publishing The Black AMP images.
     
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