Apex HiFi Sangaku Hybrid Amp

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Huxleigh, Aug 19, 2016.

  1. jexby

    jexby Posole Prince

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    any progress on this amp making SBAF loaner tour like it did on HF?

    would love to hear it paired with Yggdrasil, HE1K and possibly Utopia.
     
  2. purr1n

    purr1n Desire for betterer is endless.

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    If there is enough interest, we can buy it. As far as contacting TTVJ to get a loaner, Nick is out of commission for the time being, and I'm too busy with other stuff.
     
  3. MisterRogers

    MisterRogers Ethernet Nervosa

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    I'd be very interested in having a turn at a loaner of this amp.
     
  4. MrButchi

    MrButchi Gear Master Europe

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    Hi to all. I'm going to try to organize this loaner. In order to set it up, all interested members please shoot me a PM.

    As the Sangaku comes in either 110 or 230V, if we have Americans AND Euros, we'll need to make a choice and see what is possible (or not). So please do also specify if you're a 110 or a 230 person.

    If/when we have enough interest and I achieve a favorable contact with TTJV, I'll set up a separate thread.

    Cheers.
     
  5. JWahl

    JWahl Acquaintance

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    Repost of my review from the TTVJ loaner program, if anyone is interested.


    Introduction:


    The Sangaku is the first Apex Hifi product I have had the opportunity to audition. It is one of, if not the first headphone amps to utilize the new Korg Nutube, which is a miniaturized vacuum tube based on previous Vacuum Fluorescent Display. It uses much less power and generates less heat than traditional tubes. But what is especially unique about the Nutube is that it is technically a directly heated triode. So, the Sangaku is unique in that it is a DHT hybrid headphone amp. Yet it retains the smaller footprint of traditional solid state headphone amps.


    For comparison, I have owned a few comparable amps in price and performance over the past few years. Namely the DIY Torpedo III amp, the Trafomatic Head 2, and the Eddie Current Super 7.


    Setup:


    Chord Mojo as DAC using a generic 3.5mm to RCA cable from Amazon. Focal Elear and modded Sennheiser HD-650 as headphones. Mostly used the Elear though. Macbook Pro using Vox player and PC using JRiver MC 22.


    Build:


    Build quality seems pretty standard all black Apex style. Nothing fancy. The relay switched inputs and gain with LEDs are a nice touch. Unfortunately, the Nutube is inherently microphonic by nature of being a DHT which never really gets “hot”. Switching inputs or plugging in a headphone results in an audible “Ping!”


    Sound:


    The sound of the amp is difficult to describe without sounding paradoxical. The midrange is clean and clear, yet has a sweet slight warmth. Treble is extended and more present than a lot of amps, and in combination with the midrange creates a certain lucidity to the imaging that is slightly reminiscent of (though not the same as) top SET DHT amps. The greatest strength though IMO, is it has an excellent sense of rhythmic drive. This is most apparent with small ensemble Jazz with a lot of rhythmic stuff going on.


    One thing that must be taken into account when reading this review, is that I find this amp to be very transparent to source. So much so, that I almost was going to give it a lukewarm review, but discovered my nitpicks were with my source. I recently applied a tweak to my Mojo of adding a large RFI ferrite suppression choke to my USB which made a noticeable improvement to the DAC, and the improvement was readily audible through the Sangaku. The clear and open midrange and treble does not do any favors to digital hash present in the source. Having previously owned the Schiit Yggdrasil and Gungnir Multibit, I can imagine they would pair well with the Sangaku. The amp seems thoroughly resolving enough to take advantage of what the Yggdrasil has to offer.


    Therefore, I’m hesitant to try to nail down the sound description in too much detail. Simply because it lets the source shine through. However, it’s not a “wire with gain” so to speak. It does apply it’s own tube harmonics in a tasteful way. And maybe not the tightest bass I’ve ever heard. I deliberately haven’t commented on the bass, because I think it’s just carrying over some of the Mojo, but maybe a touch looser. Again, I think the Gungnir Multibit might be a better match. I thought the Torpedo III had better bass, but I had the Gungnir when I had the Torpedo III.


    My only regret with this review, is that I don’t currently have more equipment to try with it. I would love to try the HD800 with it, having owned it twice. I also have no balanced headphone cables at the moment to try with it. I don’t think the amp is fully balanced, but it may have a differential output. I’m not sure though, I’d have to ask the designer.


    I do think this amp can really keep up with some of the best out there, but source matters. It brings it’s own unique and addicting flavor to the mix, without spoiling the original sound. If I had to sum it up I’d say airy yet rhythmic. Not the absolute tightest across the frequency spectrum, but still clean and clear. Looseness probably isn’t the best descriptor, but rather it’s the harmonic decay that gives it some nuance and detail to trailing edges of music. This also helps to convey rhythmic information.


    Value:


    This is a tough one for me, and an area I am personally really nitpicky. On sound alone, it competes well against similarly priced amps, despite stiff competition. But when you compare it to the previous Peak/Volcano combo at the same price, it’s clear this amp is more cost effective to manufacture. The copious use of op amps and simple case work, psychologically make it harder to swallow at the price point. I’m guessing that they really just don’t want to have to build a ton of them to keep up with the demand of a lower price, so they are intentionally lower volume, perhaps. It probably has to have a certain margin for it to even be worth Pete Millett taking his time to design. That kind of stuff is time consuming, especially when it’s not your day job.


    This doesn’t mean it’s a poor value by any means, it just means there is probably a healthy margin. But probably less so than a lot of big name manufacturers. If anything, this is a testament to Pete Millett’s design chops, that he can take generally pedestrian parts, and make a stellar sounding amp out of it. I really don’t have any problems with the choice of power op amps in the output stage. There is nothing inherently wrong with them, just less flexibility in integrating into a design. But they are implemented well in the Sangaku.
     
  6. jexby

    jexby Posole Prince

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    you have owned a few comparable amps like T3 and EC Black Widow, yet you can't describe Sangaku in relative terms?
    taken into account, this amp is transparent to source. (so it sounds like nothing?)

    RFI choke suppression for Mojo is relevant how? your DAC made the amp sound better?
    can't nail down the description because the source shines through.

    Value:
    a complete wish wash of nitpick with stiff competition yet Sangaku is more cost effective to manufacture.
    what?
    a healthy margin. great. = medium mark up compared to sonic bliss?
    nothing inherently wrong = no problem with op amps in output stage = nothing wrong = less flexibility = implemented well.

    Jeebezus man.
    go out of your way to cut n paste a wishy washy review from HF that when "read between the lines" is tripping over itself to say nothing BAD, about the Sangaku amp. yet in turn says nothing at all about Sangaku in summary.

    CurrawongminidongfromPacificRim would call this a great review.
    Here on SBAF it = -1.
     
  7. JWahl

    JWahl Acquaintance

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    Noted. I was hesitant to repost it here because I realize it's not the best review. I just know there isn't much in the way of impressions out there yet. It's more wishy washy because I had trouble isolating whether my nitpicks were due to using the Mojo as the source, rather than the amp.

    I still like the Torpedo III better overall, but that was also with the Gungnir Multibit and not the Mojo.

    The RFI suppression was relevant due to the degree of improvement on the Mojo, and the fact that it was easily noticeable through the Sangaku.

    In comparison, the Torpedo imposes enough of it's own signature on the sound, that moving it from the Gungnir Multibit to the crappy onboard pc line out, was a less dramatic change than I expected. This is what I mean by transparency to source.

    I'll just go back to lurking for now, though.

    There's others who can articulate this kind of stuff better than I can.
     
    Last edited: Dec 11, 2016
  8. JWahl

    JWahl Acquaintance

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    I'll go ahead and add a few criticisms for clarification. My review was admittedly rushed due to being "obligated" to do a review. I apologize for that, and I've been around this community (since CS) long enough to know better.

    First, I found the treble to be fatiguing long term. I think the harmonics of the amp may exaggerate the "digititus" of the Mojo, hence why I said I thought the Gungnir Multibit would pair better. I also found the bass to be looser than the T3 with less slam overall. With the HD-650 this comes off as a little bloated especially. Like another reviewer, I didn't really like the HD-650 with it much, the combo lacked engagement. Especially relative to the T3 which I liked with the HD-650. Unfortunately, I didn't have the Elear when I had the T3, so I'm not sure how it pairs. It could very well have too much slam and impact.

    The "harmonics" I speak of seem to add a trailing edge decay to the original signal, most notably in the bass and treble. This produces some of the issues I mentioned. It's less objectionable in the midrange, where it adds more natural decay that may lost in the original recording and ADC process. Though for some who prefer a pure matter of fact presentation, this could be a problem.

    Overall, I did really like this amp and feel it is comparable overall to similarly priced amps I've owned. I think it would be worth getting in the hands of others here who have broader equipment experience and better written articulation.

    Hopefully this is more helpful than my previous post.
     
  9. jexby

    jexby Posole Prince

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    @JWahl thanks for the additional impressions which are very helpful actually now.
    indeed we all realize DACs behind the amp will have some effect, am sure someone down the road will hook up Sangaku to a Gungnir Multibit one day.

    I realized you were around long ago and knew HF censorship doesn't exist here.
    so fear not, tell it like it is - rather than try to sugar coat or minimize product characteristics.
    :D
     
  10. JWahl

    JWahl Acquaintance

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    Thankfully, @JoshMorr did provide his impressions using the Gungnir Multibit with Mutec 1.2 converter on the first page. We both also seemed to share the impression that we didn't like it with the HD-650 despite difference in sources. I usually have no problem criticizing something I don't like. If anything, I tend to downplay enthusiasm of things that I do like, so it don't come off as new toy syndrome. I'm not particularly a fan of the "Everything Is Awesome!" types of reviews.

    I also exchanged some PM's with @jelt2359 who mentioned he recently took delivery of an EC Studio and was comparing the two, so maybe he can chime in some more too. He saw my review and mentioned he doesn't find issue with the bass out of his sources (Hegel HD30 and Chord Dave) but said he thought the Mojo lacked bass definition.

    And also, for the fellow DIYers and parts nerds, I was able to snap some pics of the internals. I checked with Pete first out of personal respect, and he said he doesn't mind. He said he's "Proud of the guts". Unfortunately, I can't seem to figure out how to upload them, or I'm guessing it's disabled for newer/less active users. I only see the option to externally link photos.

    Pete also answered a few questions I had that were unclear to me from previous info. That the output stage is DC coupled to the headphones, but the Nutube is AC coupled to the output stage via capactors is one. The output stage uses 4 x OPA551 power Op Amps. Interestingly, these are the same ones used the Project Ember and Project Polaris amps. Which makes me very curious about those amps as a "budget" alternative.

    Otherwise, I pretty much concur with JoshMorr and Jelt's impressions, with the caveat that fans of darker sounding amps, or those looking for the last word in authority and slam, need not apply.
     
  11. gbeast

    gbeast Mighty Moral Power Ranger

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    go to imgur and upload the photo there(you need an account. It is free), Then use the direct link to copy and paste in the image url here.
     
  12. jelt2359

    jelt2359 Friend

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    Written in a PM to JWahl, long before he received the loaner. He asked for a comparison with the ECP L-2 :

    Between the two, L-2 and Sangaku, the Sangaku has a smaller soundstage. The L-2 sounds bigger, more expansive. At the same time, while the Sangaku attack is quick enough; the L-2 is actually a bit tighter in its attack. The L-2 is just a bit leaner overall. The Sangaku does however have richer, lusher mids. These mids are wonderfully self-contained, as in they're not syrupy or mushy, but clearly separated note by note, yet the notes all come with an internal pink blush, the tube 'glow', so to speak. Very nicely done. Pete calls the Nutube a mini 300b and this kinda sounds like what you're getting here. The L-2's mids are also more laid-back and relaxed and have a longer, more natural decay, although interestingly because of this longer decay, the separation here is not as clean and clear-cut from note to note, as the Sangaku. I would guess that's the tube (L-2) vs solid state (Sangaku) output stage I'm hearing.

    One word about the soundstage, I don't think the Sangaku is poor at this at all. However with the L-2 you notice it instantly as a standout trait.

    All impressions were with LFF Code-X (a planar), and Chord DAVE.
     
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    Last edited: Jan 31, 2017
  13. JWahl

    JWahl Acquaintance

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    Thanks for the tip, gbeast.

    Here are the internal shots, as promised.

    [​IMG]
    [​IMG]
    [​IMG]
     
  14. Comzee

    Comzee Facebook Friend

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    I've been looking at this amp for a few weeks now. I have a T3 (I bought from JWahl) and it's just a dime.
    I'm on the loaner for Sangaku, but at the time I would get it the $200 promo would be over. I'm really having a hard time deciding... hmm hmm hmm
     
  15. MrButchi

    MrButchi Gear Master Europe

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    I'm on the loaner. Gonna contact TTJV soon.
     
  16. JWahl

    JWahl Acquaintance

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    If you're on the loaner anyways, I'd wait and compare the two directly. The Sangaku is nice in it's own way, but more of a sidegrade IMO and it would come down to personal preference. Plus if you like the Sangaku more, I could always buy back the T3 from you come tax refund season ;)
     
    Last edited: Dec 14, 2016
  17. cooperpwc

    cooperpwc Friend

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    This is the part of the review that interested me. :)

    I am not suggesting that opamps cannot be used in an excellent design but I do have generalized pervasive gnawing feeling somewhere deep inside that this is not an ideal implementation of the Korg Nutube.

    Perhaps Peter Millett was making a statement that there are limits to what can be achieved with the Nutube 6P1? It is after all intended as a guitar tube.

    I would love to hear the Sangaku but I am not sure how likely that is over here. Absent that, my instincts say wait for another Nutube amp - and perhaps a nextgen Nutube. It looks like Korg could be onto something. I wonder if they might pursue the audio market directly?
     
  18. JoshMorr

    JoshMorr Friend

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    With my brief experience with the amp it far surpassed my expectations, as I was also curious how this would work. I am less worried about the original design intent of the tube and more about the sound, as many of the nos tubes used weren't originally manufactured with headphone amplifiers in mind. Not trying to champion the Nutube or Sangaku as the greatest amp or tube out there, but the NuTube did "fix" some of the problems that non tube amp guys have (doesnt get super hot, doesnt burn out, doesnt sound warm and gooey).

    I have been half curious about the limitations of the tube as well, and @Jh4db536 pointed out an experiment for someone with DIY skills would be this simple head amp using the korb nutube.
    https://www.tindie.com/products/microwavemont/nutube-amp-kit-a-vacuum-tube-in-new-century/
    While I don't expect it to sound like the Sangaku, it might give you a taste of the tubes inherent qualities.
     
  19. MrButchi

    MrButchi Gear Master Europe

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    Ok so awesome news: I'm just off the phone with Todd from TTVJAudio.com.
    Not only is he cool with the loaner (starting in a month or so), but he's also gonna join us on SBAF, which I think is really pretty cool.

    Welcome in advance Todd!
     
    Last edited: Dec 15, 2016
  20. cooperpwc

    cooperpwc Friend

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    This is absolutely right. Some of the greatest tubes historically were crafted for military use where clarity was the highest priority.

    It is amazing that the DIY amp is recommended to be run off a 9-volt battery. A low power tube indeed.
     

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