NF audio NE4

NF audio NE4 Evolution

One of the benefits of reviewing newer IEMs is that I get to progressively see advancements in our hobby. Much like anything tech related the earphone industry has seen a surge of newer innovative designs beyond using a mix of drivers which now sees quadbrid designs with 4 different types of drivers which back in the day no one in their wildest dreams would have been a reality but beyond that I am seeing more and more manufacturers include some way of changing up the stock sound of the given earphone. The easiest implementation is the two- three switch enhancement. First ever earphone I heard with tunable switches was at the Rocky Mountain Audio Festival in 2018. It was the InEar Prophile 8 earphones on display. I was impressed with a flick of a switch you got an immediate increase in bass and or treble or both.

That was when I realized this might be a thing for future earphones. Advance to today and we have numerous earphones that do the tuning switches. Another way of onboard tweaking would be the tried and true nozzle filters. Which works to change up how we perceive treble and works pretty well but overall these minor switches and nozzle filters have seen moderate at best in actually tuning the earphones base sound.

NF audio has taken this idea one step further in developing an actual way to not just do a minor tweak in sound here and there. They managed to figure out how to actually give you a completely different sound altogether using the outer plates on the NE4 shells. The plates are embedded with crossover circuitry using different parameters, frequency dividers that tax certain drivers on the host housing which changes the emphasis and the use of the programmed drivers it is using for a completely different sound profile. The idea of this is not exactly new as it was implemented to a much lesser degree on the A New X-One earphones with very mild changes to the sonics. NE4s use of this idea is not a minor tweak in each sound tuning. It is giving you an entirely different sound for each of the plates.

Before I continue with my report/ review I would like to thank Penon Audio and NF audio for the review sample. You can find out more and get yourself a pair here. The NE4 has been burned in for a weeks worth of time and sound evaluation was done using my sources; IBasso DX300Max, Fiio M15, Shanling M6pro, M5s,M3s,IBasso DX160,Sony ZX300, Pioneer XDP-30r, IBasso PB3 and IFI Black Label for amping.

NF audio has made some great sounding dynamic IEMS and this being my first go round of an all BA tuned IEM by the group, I was very surprised when the announcement I saw about the NE4 included a way of replacing the plates on the shells which somehow effectively changed the sound tuning to give you a different tuning with each plate. This idea on paper is great. I mean who doesn’t want to be able to change how your earphones sound depending on your mood on the fly. They include 3 different colored plates and each one represents a different tuning and use of the drivers.

The NE4 comes in a larger box as there are a lot of extras you get from your standard earphone package. The inner box contains their 3 CD display with the earphones themselves which had their black reference plate already installed and two extra plates. Red for pop and light blue for neutral transparent signature. It comes with a small allen wrench tool to install the plates with 4 extra screws just in case you lose one. The tool and screws are tiny, a bit like the screws you see on a pair of glasses. Very small so be warned. Comes with 2 sets of silicone tips labelled balanced and atmosphere. A stereo adapter and their proprietary 5N silver plated copper cables in litz format in single ended. Same cables they put in for their NM2+. Rounding out the accessories is their medium sized box using a magnetic lid to carry everything.

This accessories package is pretty much what you got with their dynamic earphones. Which was OK for them but for these? Not so much. There is nothing really to carry around the plates and the tiny tool and screws. A simple lined pouch would have been sufficient but the included box is not ideal to put your plates or the tiny screws and such. Only two types of tips? The earphones have three sounds but they only include two types. The cable is decent but I do notice the level of the sonics on the NE4 greatly benefits from nicer aftermarket cables. So the included stuff is just left overs from their previous earphones. Which is just OK however it seems NF audio has spent an enormous amount of research and development into the NE4 in creating something very groundbreaking, yet they include basic accessories that are more or less left overs from their previous earphones. I was expecting more to be honest. I can tell 99% of their effort was in the design of the sound of the NE4. Not so much what was included.


The use of 4 high precision Knowles BAs was the foundation for the base tunings using a new larger CNC machined aluminum alloy shell. The physical size of the shell is a bit bulky but the ergonomic design makes them very comfortable for my medium sized ears so no struggle with fit or use on them. These are a bit weighty at 360g but not so bad where they feel like heavy slugs in your ears. The plates themselves add some weight due to the circuitry inside them and the plates themselves are not a wafer thin material but you can clearly tell they have some electronics inside them. I would have liked to see this design just a bit more streamlined in design as it is clearly bulky and big. So small eared folks might have some struggles with how these fit.

With all the circuitry and metal the NE4 uses you would figure it has great passive isolation. It actually does not. Which was surprising. I find the isolation about average and I think it was more due to the venting that was required to get the sonics to be correct. So that was a bit surprising there. The trade off is some astounding stage presentation however.

As gimmicky as it may sound because to be honest I have yet to see your garden variety switches and or nozzle implementation drastically change the tuning, these are playing at a different level as far as optional sound from one earphone goes. The first plate you are greeted with is their black reference plate. These are easily my favorite tuning out of the NE4 and I have to give NF audio some credit. I was thinking no way is a 4BA IEM going to be worth the money they are asking for a set. Then I heard these with the black plate.

Reference plate.
SPECS:
Frequency Response: 18-22Khz
Sensitivity: 110/mw
Impedance: 10 ohm


This tuning uses all 4 BAs. 1BA for ultra low + 1BA for full range + 2BA for trebles. The sound balancing and tuning for this particular sound design I can argue is worth the cost alone. These are by far NF audios best sounding earphones easily beating their dynamic counterparts in sound quality. I suppose it will depend on how much of a premium you have about your earphone designs, dynamics vs BAs which can be debated on which one gives you the best sound. But here is the reason why.

For starters the sound presentation is fantastically wide. The NE4 reference tuning easily has the widest stage I have heard out of any of their earphones. The stage presentation is flagship level in presentation. Then there are the fine details of a well implemented BA design that clearly shows its strengths. They call this one reference for a reason. Having a mild 5dbs of bass boost with a reference level clarity and imaging across the sound. Its balancing is superb with the right amount of treble emphasis to cap it of. It is by far their best sound tuning out of the three plates that was included.

Its treble is nicely extended and is balanced well with a good presence for the region. Trebles are moderately imposed and not forced sounding which is a win in my book as it seems more and more manufacturers are all about imposing that treble in the tuning for the high fidelity tuning. Its BA based treble is well defined and has good agility and nicely textured. When called for, has good sparkle and shimmer but just ever so reserved for sparkles otherwise I have no issue with the treble end. The mids have a moderate 10dbs of upper mids presence which gives good clarity for the overall mids presentation.

The single BA used for the region seems to be a very high level Knowles BA as its sound presentation is really spot on with very good range and layering to the mids. It sounds like it is using more than just one BA for the region which is always a good sign. It has good body to the sounds, note weight is moderate and not thin sounding and has a nice seamless tonal balance between the trebles to the bass. The mids head a bit toward lush in tonal quality and sounds very natural with no strange BA timberal issues. Imaging is also a stand out of the NE4 reference tuning. There is really not much to complain about the mids of the NE4 reference as it shows a very high quality sound presentation for the overall tuning, then there is the Bass

Bass end of the NE4 is very surprising, showing similar impact and realistic characteristics that are closer in performance to their dynamic earphones. In fact I bet if you didn’t know NF audio was using a single BA for the bass on these it would have been difficult for you to tell they are using a BA. Its Bass timbre, tone and ability is accurate more than superficial sounding and due to the sheer speed of the BA design. Speedy metal becomes almost a religious experience.


Its sub bass is where you can tell they are using a BA but it is due mostly from not having a proper boost for the sub bass for their reference plate. The pop plate presents with much more authority in the region. As they are, its rumble is moderate in emphasis and decay is fairly quick. So here is where I wished NF audio implemented a very agile dynamic driver to handle the bass notes or if they could have tuned the sub bass with an uplift. I suppose I am spoiled by hybrids that do this aspect well. Otherwise for an all BA implementation NF audio was able to squeeze out every bit of the low end they could using the drivers they are using. I feel overall the bass end actually sounds very natural and its impact and tonality is spot on. It does surprisingly well for EDM and Jazz music even with the reference tuning due to that nice level of bass accuracy for a BA but for something that requires a bit more bass emphasis that is where the pop plate is all about.

Pop plate.
SPECS:
Frequency Response: 9-20Khz
Sensitivity: 104db/mw
Impedance: 6 ohm

The red plate is the most colored sound out of the three plates as it boosts the bass end 15dbs from flat transparent plates and about 10dbs from their reference plates. Pop plate utilizes a single BA handling the lows + a single BA for mids + 2 BAs for trebles. So how NF audio was able to boost the BAs for a massive 15dbs of emphasis from their transparent plate tuning is beyond me. The sound signature now becomes more of an L shaped tuning where bass is going to be a bit pronounced but what is surprising is just how controlled the sound is for being a bass infused tuning. The sound actually has more than a bit of control with some finesse thrown in and not much in the way of compromise to the mids and treble presence with that bigger bass end. By the sheer amount of boost we are talking about, bass is not as tight sounding vs their reference but you bet there is much more impact and sub bass is surprisingly good.

Mids presents with a bit more body and fullness to the sound due to an increase of the lower mids to bass vs the reference plate configuration and does a great job not to throw a big bass shadow for the tuning. The mids are able to maintain a good sense of clarity and show a similar well balanced presentation from the reference tuning. I do noice the mids side to side imaging is a bit more intimate for the pop plate and not as open sounding as the reference plate. This is probably due to that much greater bass emphasis. Mids presentation however is surprisingly clean and mids tonality shows a very slight hint of warmth over the reference plate. Again due to that bigger bass presentation. Bass infused music sounds tremendous with even greater impact which clearly stands out as a bass tuned earphone.

This sound tuning will appeal to fans of bass or when using the NE4 for outdoor use. Bass quantity is pushed to the limit here for what this single BA can do while retaining a good semblance of control and tightness. The issue here is with its very high 6 ohm sensitivity, the Pop tuning must be used on lower output impedance sources or you will not get the full bass effect from them. Somehow this is yet another aspect of the NE4 design that could have been a missed opportunity for NF audio. Don’t know how difficult it would have been to include a nice higher end dynamic inside this larger housing but I do wish they used a dynamic for this tuning vs using a BA.

To be fair, NF audio has a clear mastery of tuning the low end using this particular BA. The BA used for the bass seems again very much higher end as it is able to go from a fairly neutral emphasis to a full bored bass boost with absolute zero distortion and bass here sounds like a well implemented bass end even down to having some real sub bass texture. Pop here is every bit a quality presentation as their reference plate especially for folks that are into their bass. I can see many actually preferring this plate for music listening as this plate gives the best musical sound tuning for all the plates yet retains a high level of technicalities for the overall sound.

The treble aspects of all 3 plates have the most consistent aspect of their sound tunings. Treble is how I described on the reference plate for all three plates of course you will get a touch more treble perception depending on the varying bass infusion on the different plates but for the most part treble is fairly identical in form and function and presence as all 3 plates use two BAs for their treble presentations. .

Transparent plate.
SPECS:
Frequency Response: 20-30Khz
Sensitivity: 110db/mw
Impedance: 22 ohm

As drastic as the Pop plate is on one end, this one goes the complete opposite direction. Utilizing a single full range BA + two BAs for highs. I am sure you have heard neutral earphones before but I am willing to bet, you have never heard anything this ruler flat before. It is literally a straight line from 20hz sub bass all the way to the upper mids where it has the same 10dbs of pinna gain compensation and then its treble presence all the way to 20 khz. Some might actually refer to these as the actual reference sound. It is by far their most neutral tuning out of the three plates.

I can see a use case scenario for the blue transparent plates here for several occasions. First of all as a reviewer I have had neutral earphones in the past but not quite this ruler flat. These will make for perfect reference for just how colored your earphones are in comparison. Even stage monitors have some coloring to their tunings. Not these. For some reason the sound here is literally perfectly balanced from treble to bass but it also has the more intimate sound with an average stage vs the other two configurations. Could be due to utilizing a full range BA more closer toward the ear vs being a BA in the outer housing, also with a drastic impedance shift from 6 ohms in the pop plates to 22 ohm for the transparent plate. This plate tuning can be used with just about any source and even amplification with no problems.

The other scenario is for the sound engineer. I don’t know if there is an earphone out in all of earphone land that has the ruler flat response of these. You can literally tell just how much coloration your other earphones have in comparison. These are literally windows to your music, your hearing. These have the driest, cleanest tonality with the least amount of coloration and not just for the NE4 but any earphone. If you're a sound engineer and would like to get an actual reference tool for sound. These might be what you're looking for.

Needless to say I don’t know if I need to describe the sound on this plate as if you can imagine a straight line from 20hz all the way to 1khz and how that would sound. This is exactly what that is. It will reproduce any studio recording as what it is with zero boost in any part of the sound as it possibly can. So I can see how this plate can be used in such a way. It is surprising that NF audio included this particular tuning aspect as it would have been better to do an intermediate plate from reference to pop instead but since their background is music monitoring. This plate exists as a tool more so than listening to actual music using them. It is a bit too flat to really enjoy real music with, but if used as a monitoring tool, It could be an invaluable tool for the sound professional.

And you can certainly throw on the pop or reference plate for any real music listening.

And there you have it, three very distinctive tunings with three different plates. My time with the NE4 has been very eye opening as it has been interesting to see NF audios tuning prowess at full display here. Three very different sound signatures and with that let me address the hurtle for this actual ground breaking product.

As great as this product is. I will give NF audio every bit of credit on how they developed an actual way to give you three different earphone sounds using one earphone. The price of these are hard to swallow. Its sound is actually worth the price tag believe it or not. The reference plate sound is about on the level of Campfire Audios Andromedas and not only that but you get a bass version thrown in for good measure. However it is the idea of buying an all BA iem with 4 BAs that's the hurtle. These are in many ways groundbreaking, evolutionary, I can even say stupendous in what it does. But the cost to play on these are a bit steep for a relatively unknown product.

Competition ramps up so much in this price range right now, at the asking price these are facing tribrids and hybrids that are getting ever so close to summit fi level sound quality. 4 BA earphones don’t seem all that compelling no matter how well they are tuned at the price.This is a case where if you heard these you will hear the value in what NF audio has achieved.

I heard that NF audio plans to release more tuning plates which will effectively give you even more sound options. NF audio is onto something here and if you would like to take part in what they are doing with these. I can say without reservation the NE4 will be worth it but for the budget minded enthusiast. It will be difficult to see the value, groundbreaking or not. This review has ended up being a longer one as there was so much to cover about the NE4, I appreciate you sticking with me on this one and seeing it though. Whether these will be an option for the enthusiast or not, NF audio has done something very much new in the industry and I can only see this idea blossoming from here. As always thanks for taking the time to read and happy listening always.