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

Listening to NFB-1AMP right now. Have been listening for only 20 mins after a 15 min warm up.

It's a big sucker, dwarfs the Jotunheim. You will need plenty of desk space. It came with a European power cable, which isn't much good in the UK - luckily I had a spare power cable.

Very early impressions in comparison to the Jotunheim: The most immediate apparent differences are the wider & deeper soundstage and improved instrument delineation. In the track Hey Mama (Nicki Minaj et al.) the bass presence is much more obvious and defined. Listening to some acoustic music right now and it is very musical. I feel that the NFB-1AMP is more engaging and fun to listen to than the Jotuheim. It feels like the Jotunheim was holding the Gungnir Multibit back.

I need to listen some more

 

audio-gd devices are quite sensitive to power cable... actually power cable grounding. You may want to use a use a travel adapter pairing with the 2 prong European power cable to see if you can get better dynamic. Many "ground" of the power lines aren't actually 0V.

I am in Hong Kong and also use UK13A plug. For all my audio gear I replace the power cords with either US or China spec 3 prong plugs to avoid the built-in 13A fuse required in the UK13A plugs.

 

Nicky Manaj used for gear evaluation. Yeah AGD is bassy as hell.

AGD made the typewriter drums in old death metal sound like Led Zeppelin and overwhelm the crappy Marshall Valvestate amps that they drums were mixed into typewritersi in order to not overwhelm. Guitar microdynamics were smoothed over as was the clipping and recording flaws in Led Zeppelin.

AGD turned The Stooges au naturel Fun House into the shotgun from Terminator 2. That sound effect was Napoleonic War cannons firing.

 

I just happened to use the Nicki Minaj track first. The impressions I posted above were my very first thoughts which therefore may not be definitive.

If I understand you correctly, you are saying that AGD exaggerates the bass? If you could give me specific examples of tracks that AGD affects in this way and the Led Zepplin tracks with the smoothed over microdynamics, then that would be very useful. I can then compare to Jotunheim. Thanks.

After further listening, I can confirm that the soundstage is wider and deeper in comparison to the Jotunheim. Certain instruments are easier to pick out with the NFB-1AMP, with the Jotunheim those instruments are relatively lost in the mix.

With regards to bass, I feel that the Jotunheim is tighter, but the NFB1-AMP has more presence.

The differences between the two amps is not subtle. I made some notes but they are not in front of me at the moment because I'm typing this on my phone in bed.

I will try and give more accurate impressions in the coming days. I do not find it easy to describe what I hear and I am still getting to grips with the associated terminology.

 

I think @Psalmanazar does not own any Chifi audio-gd amp and he only listened to it in meet/show environment.

Technicslly it is actually quite difficult (non linear gain? with built-in dynamic exciter VST plugin?) to have an amp which masks/smooths out microdynamics but exagerate the macrodynamics, and still gives more possitioning/imaging ques. To me positioning/imaging ques are part of the microdynamics.

An amp with poor S/N can mask microdynamics behind noise but I don't think the NFB1AMP is noisy?

The NFB1AMP has fixed gain of 16dB, which should be better at microdynamics than the 20-30 dB gain specially requested gain audio-gd amps @Psalmanazar had listened to?

 

@mrflibble, can you check if you can have single ended/RCA input to the NFB1AMP and still listen with balanced headphone output? I know higher audio-gd amp models can do single ended to balanced signal conversuon with their CASS circuits, not sure about the lower models.

 

Yes, I can confirm that balanced headphone out works when using single ended input from the DAC. It doesn't sound as good, however (maybe just lower volume?).

I do not notice any noise with the NFB-1AMP, nor with the Jotunheim. I will try and find some music with obvious microdynamics and compare the two amps. I am still training my ear, so it may take me awhile.

 

Eager to hear impressions but I would have been more surprised if there was no loss in quality by going to a SE DAC connection. Which DAC were you using with the amp for the balanced connection?

 

You'd better stay away from the Jotunheim, then; you may drop your monocle. The difference is so miniscule as to be not reliably ABXable, and you're reduced to pointing to tiny differences in measurements. Unless you're going for crazy long cable runs, it's no big deal, if the implementation is good.

Obviously, XLRs are less annoying than tight and scrapey/too loose RCAs, and they look big and important.. but I'd rather have a good SE multibit DAC than a balanced Chi-fi D/S one (for example) by far.

 

The chain I'm using for testing is:

Elfidelity AXF-8 --> Fisual Hollywood TOSLink --> Schiit Gungnir MB --> Schiit Jotunheim / Audio-gd NFB-1AMP --> Balanced Sennheiser HD650

I am therefore using Gungnir Multibit as my DAC for both connection types I only very briefly listened to SE, so my comment regarding the quality is of little meaning
I use Fisual Havana XLR for my balanced interconnects, and Techlink Wires XS RCA when testing SE.

I'm still listening to various music and debating whether to just write a few more comments or produce something a bit more formal. Unfortunately, I'm lacking in listening experience so am not sure if I can write something worthwhile that is truly indicative of the sound characteristics of the two amplifiers. But I could give it a stab providing people go gentle on me

Today, I have been feeling very tired. I will however, say that I broadly agree with @k4rstar and his write up concerning the NFB-28 - except that when keeping the DAC as a constant (as with the Gungnir Multibit + Jot or NFB-1AMP) I would say that the bass is more prominent with the NFB.

 

Gungnir Multibit won't be at it's best with SE out vs balanced, so that is also a factor.

 

Can you comment briefly on the sound of volume adjustments on the NFB-1? I remember reading something about an annoying clicking noise when adjusting volume while a track is playing.

 

The volume control uses relays so does indeed click when turned. The clicks are not audible over the headphones but emanate from the device itself - very much like how the Gungnir Multibit and Yggdrasil click when changing sample rate (these also use relays). When listening to the HD650's (an open back headphone) I can barely hear the click(s), only faintly in the background. I really like the volume control, it is very fine grained and a pleasure to use due its tactile nature and the reassuring feedback of the click when turned.

 

Here are some further impressions of the Audio-gd NFB1-AMP in comparison to the Schiit Jotunheim. It has not been easy for me to listen critically, especially for extended lengths of time. I'm not an experienced listener so am not always sure what to listen for. I have yet to gain the experience necessary to describe what I hear in terms of the correct technical vocabulary (although I know there are descriptions of the terminology elsewhere on the forums). I will try and describe the differences in sound as best I can, please bare with me.

The comparison was performed with the following chain:

Elfidlity AXF-8 → TOSLink → Schiit Gungnir Multibit → Balanced [HEADPHONE AMP] → Balanced HD650 (stock)

To begin, I would like to say that these two headphone amplifiers offer two very different presentations of music. The Jotunheim is about speed, attack, and tightness. The NFB1-AMP is more about soundstage, and musical involvement. They almost seem to be opposites (I've never heard a tube based amp, I imagine that these would be more opposite to the Jot than what the NFB is). But much is dependent on the genre of the music and on the quality /style of the mastering. In fact, the mastering and genre seem to influence how the characteristics of the amplifier are expressed.

The first track I will talk about is an orchestral piece, predominantly with violins and some brass instruments. It is “Jim Power in Mutant Planet” on the album “Symphonic Shades” by Chris Huelsbeck. This track begins with violins, builds with more violins and piano, and then adds the brass. With the Jot there is not much soundstage depth, nor does there seem to be much weight to the instruments. Everything is airy, light, and sprightly. Brass seems slightly strident and etched. There is an urgency and energy to the music with the Jot. Switching to the NFB is a big contrast. It is softer, perhaps less defined, more musical, less incisive, more relaxed, easier to listen to, flows better, and has greater soundstage depth. In comparison to the Jot, the NFB lacks urgency, and is thicker and slower – it kind of sounds a bit muffled and stuffy, like it has a cold. Perhaps, this is a characteristic of the HD650 that the NFB is unable to cut through?

Moving on to the “Turrican Soundtrack Anthology” also by Chris Huelsbeck and consisting of synthesized music. Listening to “Concerto For Lasers and Enemies”. The NFB sounds more organic, I feel like I'm more inside the music, whereas with the Jot I feel like I'm on the outside “looking” in. It is easier to pick out the instruments with the NFB, sounds are arranged better in space instead of being squashed into a smaller area. Sometimes with the Jot instruments can get lost in the mix because of the poor soundstage placement. With the NFB there is more bass presence, but the bass on the Jot is tighter and hits faster.

With some tracks the bass can sound a bit sloppy and loose on the NFB. Occasionally, I feel that maybe the soundstage depth or bass are being exaggerated with the NFB, it sounds like I am hearing reverb which is not present when listening with the Jot. I don't know whether this characteristic is due to the NFB or if it is due to the mastering or recording or if it is due to the HD650's. Ideally, I should have a third “reference quality” amplifier to compare with, then I would know which of the Jot or NFB is closer to the “truth” of a recording.

Next, on to some Zen inspired acoustic music. The title track from the “The Beautiful Suchness of Things” by Nick Molyneux, consisting of acoustic guitar and vocals. The guitar plucks seem to have more detail (or maybe just better transients) on the Jot, but the soundstage is flat. On the NFB the music has greater depth and is more involving.

I listened to more music, but on Spotify. Some Kylie Minogue, Rage Against the Machine, and Megadeth. I will try and summarize, but I am feeling rather tired. Kylie sounded lighter and more agile with the Jot compared to the NFB. With the heavy metal and rock, the instruments seem to sound better with the Jot, cymbals are clearer and guitars have more “twang”. This is probably due to clearer transients and decay. On the NFB I think they are still present, but less obvious. I would need to listen more to be certain. The Jot just seems more precise than the NFB. The NFB is better at placing the instruments in space, however. The treble on the Jot can be metallic and brittle. I cannot listen to the Jot for any extended time, without getting ear discomfort, a headache will follow if I persist in listening.

In my youth I listened to a lot of heavy metal (but I no longer own any – hence listening on Spotify). Listening to Youthanasia and Rust In Peace, the tracks do not sound how I remember them with the NFB but they do with the Jot. The NFB sounds off, I don't know why. I need to listen more.

A provisional conclusion: I do not like either headphone amplifier with the HD650's. The Jot is like a homicidal samurai whereas the NFB is akin to a slightly malnourished sumo wrestler. The NFB has no bite whereas the Jot is like a killer white shark in comparison. I can not listen to the Jot, so there is no point me keeping it, despite that it does some things amazingly well. The Jot is a flawed masterpiece. My ideal headphone amp would be like a Jot but with better soundstage, non-f*cked treble, and a volume control similar to the NFB. I plan to keep the NFB for some significant time, until I find something better.

Thanks for enduring my writing

 

Great review! Your description is true to the typical audio-gd headphone amps characteristic.

 

Gosh, that is good to know Thank you.

 

"厚實寬鬆", translated into "Thick, Firm, Wide, Loose" is audio-gd's sound signature across their products. This is the sound signature most of their Chinese customers and Kingwa himself prefer to. Transparency and Speed improves a bit if you use their ACSS/CASS connections. They never sound harsh for treble, neither providing a lot of slam for bass. So no fatigue for listening long hours, but also little excitement for short listening. Their "specially requested high gain" headphone amps are the worst sounding models. Nobody requests those in China.

Their amps sound like solid states version of ECBA. Isn't it a coincidence most ECBA customers are Chinese?

 

Darn, should have learnt Mandarin before ordering the amp

 

Perhaps you could consider placing a Freya (or Saga) in front of Jotunheim to "cure its ills" (and get bespoke volume control as a bonus):
http://www.superbestaudiofriends.or...reya-preamp-review-episodic.3725/#post-111869

 

@mrflibble sorry it wasn't your thing. I don't disagree with your review or comparison. I feel like the AGD amps rely on the AGD Sabre implementations to sound remotely good, and this isn't the first time I've heard of someone being disappointed pairing an AGD amp with a Schiit MB DAC. I hope you do find your ideal amp.