Audio-gd NFB-28 Review (w/ Jot+Mimby comparison)

Discussion in 'Amplifiers and Combo (DAC/Amp) Units' started by k4rstar, Dec 18, 2016.

  1. k4rstar

    k4rstar Friend

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    I've had the NFB-28 in my possession for a little over 3 weeks now, and although I've been pretty satisfied with it I've neglected to write up any sort of formal impressions or review on the unit. Mostly because there was no relevant thread on it or for AGD gear in general, and to start one I figured I would supplement it with a proper review first.

    For those of you that don't know the NFB-28 is AudioGD's middle of the road combo unit and may be the greatest value in their line-up, but don't quote me on that as I haven't heard it all. It clocks in at $750 for the base model, you can upgrade the USB module (recommended if you plan on using straight USB to this thing) for an extra $45 and a fancy all-metal remote for $50.

    I'm going to be drawing comparisons to the Jotunheim and Modi Multibit throughout the review for several reasons: 1) They sit in similar positions in both companies line-ups 2) They're within ~$100 of each other 3) Both represent serious value options in the solid state desktop domain 4) Most people are already familiar with this setup and it'll serve as a good reference.

    You should take these comparisons with a grain (or shaker) of salt because the Jot/Mimby were already halfway out the door when the NFB arrived on my doorstep last month. As such, most comparisons will be from memory and I won't be digging too deep for a lack of A/B ability. I have borrowed some category headers from Marv's Schiit Amp Compendium and re-purposed them where necessary to make my thoughts easier to follow.

    For reference, I have tried both USB inputs and SPDIF/optical on both DACs. The Mimby definitely benefited more from moving off of USB than the NFB. I have not had any issues with USB drop-outs or drivers on either DAC, but my time with the NFB on USB was just for a short-lived test.

    [​IMG]

    The chain used to test both is as follows:

    RME 9632 > SPDIF COAX > NFB-28 / Jotunheim+Mimby > BAL OUT > HD650 (Stock)

    The NFB-28 has a much larger physical footprint than the Schiit setup, and I do miss having a tidy stack I could tuck under my monitor. It's still far from being absurd for a desktop solution such as it's big brother the NFB-27H which almost doubles it in width.

    The build is quite competent despite the stereotypes associated with a Chinese-made product, although it might be a little minimalist for some. Buttons feel sturdy, the HP outs have locking connectors and the volume knob is pleasant to operate. There is a blue LED display on the front which presents gain settings, input selection and volume. The choice of blue LEDs can be jarring, especially in the dark but an internal jumper allows you to have it dim after a few seconds of in-operation.

    Volume Control

    I think this deserves it's own section because the volume control implementation on the NFB-28 unit is a big feature, and I will be referencing back to issues relating to volume control (specifically with the Jotunheim) later. I won't embarrass myself trying to explain how the NFB-28 employs a digitally controlled relay-based volume control with 100 steps and makes use of I/V conversion to change volume levels. Basically, the goal is to have smooth volume control over a 90dB range with no loss in detail, dynamics or channel balance at lower volumes.

    I'd say this goal is pretty well met, I have found myself listening and enjoying music at lower volumes in comparison to the Jotunheim (for a multitude of reasons I'll touch on later) without an urge to turn it up. The digital display of volume is helpful for keeping volume levels normalized between recordings or even within an inconsistently loud recording.

    I've aired grievances over the pot on the Jotunheim before but it tends to retain heat from the unit, has a resistance to initial adjustments which makes fine tuning difficult and its indicator is difficult to spot or feel for. It is also not an amplifier which I enjoy listening at lower volumes with, but more on that later.

    Tonal Balance / Clarity / Background

    Audio-gd amplifiers seem to have a reputation for having a body and smoothness to them, and while this is by no means a thin SS sound it wasn't exactly as thick as I was expecting it to be either. Despite using the ESS9018 chip the treble presentation is smooth and non-offensive without being rolled to shit. I do not wince at guitar feedback or cymbal crashes like I experienced with the Jot, but I don't feel like there is a lack of sparkle or detail in the top end either.

    In fact my stock HD650s sort of just sound how I mentally expect them to, whereas with the Jotunheim they were a different beast, for better or worse. In direct comparison the Jot fed by the Mimby was a little thicker in the lower mids, a little leaner and more aggressive in the upper mids, and just a bit brighter and full of energy in the treble. On some recordings this can translate to more liveliness for the stock HD650s, but on others it's a no-go and the excess energy tires me out rather fast.

    In comparing the Jotunheim with the NFB-28 mentally and the Rupert Neve RNHP head-to-head I immediately wanted to give the Jotunheim the nod in clarity and background cleanliness both times. Over extended listening it became clear however that the Jot, like a few other Schiit amps I have heard, has a slightly thick and hazy characteristic that manifests itself mainly in the midrange. Listening at higher volumes alleviates this a bit, but it never really goes away. Clarity in the low frequencies and midrange goes to the NFB, the Jotunheim has crisper and perhaps more true to life treble timbre, but is also prone to a bit of steeliness as you go up in volume.

    Headstage / Image Focus

    Stage width left-to-right using balanced outputs on both units is virtually the same. The Jotunheim might have reached a tiny bit farther at extremes but its tough to say if I'm even remembering this correctly or if this presentation was more realistic.

    The biggest difference here is that an aggressive upper mid coloration on the Jotunheim combined with a seemingly paper-thin stage depth gives the Jot an up-front presentation, which can be another contributor to fatigue especially as you go up in volume. Some people don't seem to be fazed or bothered by the thin staging, but it was pretty much a deal breaker for me.

    The stage depth on the NFB-28 isn't anything extraordinary or special, but pretty much anything larger than the Jot is a win here. Another key difference is the Jotunheim has a tendency to "smear" or spread vocals out horizontally across its 2D stage and the listeners jaw, which can be extremely disconcerting. The NFB certainly doesn't exhibit this, and has a better center focus on the singer or vocalist, even if it is still a "detached head singing at you" type of thing. I wanted to initially say the Jotunheim had a slight edge in separation, but I believe that it's super sharp transients simply draw more attention to instruments spread across its plane to give that effect. I would rate separation horizontally a draw, with forward projection slightly in favour of the NFB.

    Macrodynamics / Slam / Lack of Compression

    There isn't much to say here other than at first coming from the Jot+Mimby the NFB-28 seemed bass-light until my ears had time to adjust. I want to say the Jotunheim has a greater degree of slam, but I feel like the Moffat Bass(tm) from the Mimbys closed form filter could be playing a big role there. The NFB-28 certainly isn't compressed in terms of macrodynamics, in fact I think it excels and gives a sense of ease to the presentation here. It's sort of the feeling you get when you just know you have tons of power on tap.

    The Jot is no slouch with lack of compression either, and actually takes a big victory over the NFB-28 with microdynamics. Gradations in volume are more distinguished with the Jotunheim and Mimby, and this is quite likely the biggest weakness of the AGD unit. This is why you may hear some people say AudioGD amplifiers come off as flat or boring sounding to them (you can argue this about the Jot on lower volumes too), but I don't think this weakness is easily identified in every recording.

    A really good example would be comparing the first two studio albums of The Cranberries (avg. DR of 13 and 11 respectively) to their third and fourth releases (avg. DR of 8 on both). On the NFB-28, the first two studio albums lack a degree of engagement or being able to dig into the music in a meaningful way that I've experienced from different setups in the past. The second two albums however sound great, and again referencing the excellent volume control I'm able to always find a comfortable volume despite how inconsistently mastered these two recordings are.

    Conversely, the Jotunheim sounded much better with the first two recordings of higher DR and was a hot, shouty mess with the latter two. Finding a good place to rest the volume knob was a constant struggle between tracks and at times I wished Dolores would just stop shouting at me. These are specific examples, and I don't want to give the false impression that louder recordings will always sound better on the NFB or vice versa, but hopefully they get my point across.

    Conclusion

    I think the Jotunheim is an amplifier that does a few things really well but also a few things quite poorly. Though I wouldn't recommend it with it's internal DAC, if you can spring for a Mimby and live with some of the shortcomings I described then it's not a bad buy. To me the NFB-28 represents a much less compromised sound and bests the Jotunheim in most arenas, including tonal compatibility with a wider variety of headphones for "only" $100 more. (good luck running HD800 on the Jot)
     
    Last edited: Dec 18, 2016

  2. gamerstudent

    gamerstudent Rando

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    I'd be very curious to know how the Modi Multibit pairs with the NFB-1AMP, and then having a straight comparison with the Jotunheim, while eliminating the DAC as a variable.
     
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  3. borrego

    borrego Incessant Audio-GD #1 Fan Boy

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    Do you have the TCXO upgraded on your NFB28? I had the very first version of the NFB1 9018 DAC from audio-gd, and did my owned TCXO upgrade when audio-gd first offered it (audio-gd sent me the TCXO, I de-soldered the old XO, and soldered the new TCXO). In my experience the TCXO improves microdynamics and coherency of the audio-gd 9018 DAC, making it almost a must have upgrade.
     
  4. es.fran

    es.fran Rando

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    I really miss a lot the audio-gd volume control. I find it really good for listening at low level, or with efficient headphones, and the display it's certainly a bonus that helps to locate an adequate position.
     
  5. k4rstar

    k4rstar Friend

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    I believe starting with the 2016 model these upgrades are no longer necessary or are included since it wasn't an option when I was purchasing.
     
  6. Psalmanazar

    Psalmanazar Friend

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    You're making the AGD sound like a dead-inside Chinese vampire (the hopping corpse) and the Jot like a pop-out book handing out paper cuts.
     
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  7. k4rstar

    k4rstar Friend

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    You should have just given me this analogy before I wrote this, would have saved me 1700 words.
     
  8. GoodEnoughGear

    GoodEnoughGear Friend

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    @Psalmanazar, do you write creatively? You're one fucking vivid dude, I can only imagine what would come out of a sustained effort.
     
  9. TheIceman93

    TheIceman93 Friend

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    Its all the Black Metal he tests his gear with.
     
  10. TheIceman93

    TheIceman93 Friend

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    How does the Audio GD compare to the Neve RNHP?
     
  11. k4rstar

    k4rstar Friend

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    I wrote some thoughts on the Neve amp using the Mimby to compare with the Jotunheim here.

    I don't have the Neve unit on hand anymore and struggle to make meaningful comparisons. Both the RNHP and AGD have inoffensive treble presentations and are slightly warm to me in the sense that they lack fatigue or harshness. I agree with Psalm when he says the RNHP unit can lack appropriate sustain, giving it a surgical cleanliness which in combination with some other quirks means it doesn't do any favours at all for some recordings. This weird interaction with some recordings was something I neglected to mention in my original comparison above since it only became readily apparent after I really had a chance to explore my library with it.

    I really don't think it represents a good value purchase at $499, it's clearly marketed towards the prosumer given Neve's choice of distribution channels and marketing. It doesn't really seem to have the output power and relies on a high degree of dampening to control the driver instead. The NFB-1AMP at $520 just seems like a way better buy to me.
     
  12. TheIceman93

    TheIceman93 Friend

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    Sweet thanks for the feedback. I couldn't find Psalm's review anywhere on this site.
     
  13. mrflibble

    mrflibble Almost "Made"

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    I will be ordering an NFB-1AMP soon. I presently have a Modi Multibit, Jotunheim, and Gungnir Multibit. Unfortunately, comparison with the Jotunheim will have to be from memory because I am selling both it and the Mimby to fund the purchase. Will let you know my impressions. I have been finding the Jotunheim too fatiguing even with HD650's.
     
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  14. k4rstar

    k4rstar Friend

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    Very nice, looking forward to your thoughts.

    He hasn't posted one, just notes we've exchanged.
     
  15. cskippy

    cskippy Friend

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    Great review. Although I'm curious why you didn't use the line in on the NFB 28 to compare amps, and vice versa use the NFB Dac and Jot to see how the DACs differed.
     
  16. k4rstar

    k4rstar Friend

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    I had already found a buyer for the Jotunheim and it was shipped out before the NFB-28 arrived. I did have a few days left with the Modi but a power surge made it go cold and I was too lazy to give it the 24 hours of warm-up it needs to properly compare. I regret it now, since it really would've helped concrete some of my impressions.
     
    Last edited: Dec 18, 2016
  17. Psalmanazar

    Psalmanazar Friend

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    Andrei from Discord took my thoughts on Chinese audio design philosophy and the anime soundtracks most Chi-fi is used for and compiled them into a meme:
    [​IMG]
     
  18. SSL

    SSL Friend

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    I love anime soundtracks.
     
  19. gamerstudent

    gamerstudent Rando

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    I find comparisons like this not so useful as you can't A & B it side by side. There is too much cognitive dissonance and placebo effect that can occur going off memory. Memory is a highly unreliable type of evidence for comparisons like this.
     
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  20. mrflibble

    mrflibble Almost "Made"

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    I've ordered the NFB-1AMP early using my magic credit card :) So, with a bit of luck it will arrive before I have to send the Mimby and Jotty off. If not, I am confident that I will be able to tell the difference between the NFB-1AMP and the Jotty even from memory. The forward nature of the Jotunheim is obvious - I will be disappointed if I cannot hear a difference!
     
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