Warm And Bright

Ratings

Pros

• Bass quality.
• Balanced and very informative treble.
• Two tuning mouthpieces.
• Excellent level of construction and ergonomics, very compact size.
• Brilliant design.
• MS42 tips.
• Good passive isolation.

Cons

• Borderline sibilance and the first half of the midrange has less weight.
• Peak at 5kHz.
• The cable is the brand’s classic cable and there is no possibility of a balanced plug.
• It no longer comes with the branded zippered case.

Purchase Link

https://hifigo.com/products/nf-audio-ra15

Link to the Store

https://www.aliexpress.com/store/1103469624

Introduction

NF Audio is a headphone brand under Shenzhen Ningfan Acoustics Co., Ltd, which was established in 2014.
It has been almost three years since I reviewed an NF Audio model and now I have in my hands the latest IEM under this brand. This is the RA15, an all-metal dual-cavity dynamic transducer all-metal in-ear headphone. The MJC2L-10M driver uses a dual magnetic circuit capable of generating more than 1 Tesla. The mouthpieces are detachable, to achieve two types of tuning: warm (brass mouthpiece) and bright (stainless steel mouthpiece). The ergonomics have been improved with the new R-series and incorporate the high quality MS42 silicone tips. For the cable, transparent strands of oxygen-free silver-plated 5N copper conductor have been chosen. Thanks to the design of these IEMS the RA15s are able to offer a passive sound reduction of up to 25dB. Let’s take a look at what this latest model from the brand has to offer.

Specifications

• Driver Type: Dual-cavity dynamic driver with dual magnetic circuit.
• Frequency Response: 10Hz – 40kHz.
• Sensitivity: 108dB/mW.
• Maximum SPL: 125dB.
• Impedance: 32Ω.
• Distortion: <1%.
• Sound Isolation: 25dB.
• Jack Connector: 3.5mm SE gold-plated.
• Capsule Connection Type: 2Pin 0.78mm.
• Cable Type: 5N OFC.
• Dimensions: 150x132x50mm.
• Overall Weight: 160g.
• Starting Price: 89$.

Packaging

NF has not changed much in this respect and the RA15s come in a classic packaging with dimensions 150x130x50mm. The model name is vertically in white letters on the left side. In the centre you can see a real photo of the IEMS. At the bottom you can read that this model belongs to the Music series and the brand logo is on the right. At the top there is the classic flap for hanging. On the back you can see the capsules in detail in an enlarged photo of the two. Also the description of the model in several languages. The specifications are on the side of the box. After removing the outer cover you get to the classic black CD-type mould containing the capsules. Underneath is the carton that holds the MS42 silicone tips. The rest of the accessories are at the bottom of the mould. In summary, the complete contents are as follows:

• The two RA15 capsules.
• Four pairs of white silicone tips size XS*S*M*L, model MS42.
• One leatherette carrying pouch.
• 5N OFC cable.
• Instruction manual.
• Two pairs of tuning mouthpieces: warm (brass mouthpiece) and bright (stainless steel mouthpiece).

The brand’s classic, eye-catching packaging. In the past it came in a grey zipped case with the brand’s logo. Now just a leatherette pouch. Only one set of silicone tips, even though it is the MS42 model. There is no option to choose a balanced plug.

Construction and Design

The previous NF Audio models I have reviewed had a semi-custom shape, either in resin or metal. This time, the design is different, smaller and flatter and like the best ones, in metal. Without a doubt, it is a very careful and ergonomic design, with an external equilateral triangle shape with very rounded corners. The central part of the outer face is depressed, leaving a hollow where the brand’s logo is printed. The capsules are quite thin. At their edge, the connection interface projects outwards. The gold-plated 2Pin 0.78mm connection is inside an oval piece of rigid, translucent plastic. Close to this interface, but on the inner side, the letter indicating the channel is engraved. The model name and the Music series are printed on this first step of the inner side. There is also a hole. There is a second level which forms a semi-cylindrical step. The mouthpieces stand as a third level and there is another hole in their skirt. The capsules are all-metal, with a shiny rough finish. The mouthpieces are interchangeable and screw-on. The warm sounding ones are made of brass and the stainless steel ones offer a brighter sound. Both are protected by a perforated metal grille. The crown has a diameter of 5.8mm, while the middle part is 5mm, the length of the mouthpiece is 4.8mm.
The RA15 cable has a 5N conductor made of oxygen-free, silver-plated copper. It consists of 2 coiled strands, resulting in a soft, shiny, white cable. It is easy to handle and has a Velcro strap. The sleeve of the plug is unchanged from the other models, being cylindrical and grey, except for the flat part where the brand name is inscribed. The splitter piece is a triangular black plastic medal, with the logo on one of the sides. The pin is a metal ring-shaped pin that fits very snugly. The two-pin connector is covered by a transparent, rigid plastic sleeve. The sleeve is angled and has the classic vertical axis separation. The cables coming out of these connectors are protected by a semi-rigid and transparent sheath, which gives them an over-ear shape.
The cable is still the brand’s classic cable, but the capsule design has been improved to reduce the size of the capsule. The construction is very robust, the surface is very smooth and the capsules feel dense, yet pleasant and attractive.

Adjustment and Ergonomics

The capsules are really small and thin. The inner side, in three levels, fits very well to the inner morphology of my ears. The metallic surface, subtly roughened and very smooth, enhances the experience of contact with the capsule. The design is very suitable for the projection of the mouthpieces, despite its length and thickness, the insertion can be shallow to medium. The specification claims 25dB of passive isolation. I think the tips have a lot to say about this. But with my large tips filled with homemade foam, the isolation I get is quite high. The cable + capsule set is nice and the over-ear hooks don’t bother me.
NF Audio has really achieved a high integration of the new capsules inside the pinna. This allows for a very durable fit, very suitable for daily and outdoor use. Despite the density of the capsules, the weight is not very noticeable and does not cause any problems over the hours.

Sound

Profile

The NF Audio RA15s come with two tuning mouthpieces. The gold-plated brass mouthpiece produces a warmer sound and the stainless steel mouthpieces generate a brighter sound, subtly with less bass and more emphasis on upper midrange, even treble. The sound with brass mouthpieces is somewhat softer, while with stainless steel mouthpieces the sound becomes more vivid and splashy. One could summarise that the profile of both mouthpieces is a V-shaped upper mids oriented, with a bass slightly above neutral. There is a high point at around 5khz, which can be an annoying peak in a sensitive area of the human ear, as well as being conducive to sibilance and other undesirable artefacts. Clearly, excitation at this point can solve problems of clarity and transparency, but in a somewhat contrived way.
The following description has been made with the warmer brass filters. While the comparison will be made using the stainless steel filters.

Bass

All the previous NF Audio models I have reviewed have very good bass. The Plus (+) versions softened the low end too much, while the RA15’s fall off halfway in amount of energy. At all times, I liked the low-end behaviour of the NF Audio. The RA15s are no less and hit the low frequencies with firm, tight, concise and dense power. Such characteristics describe a dark, volumetric and deep bass, which becomes greedy and addictive. The bases are precise, with little aftertaste and an accelerated decay that means there is hardly any flavour. However, there is a certain rubberiness and elasticity, without ever sounding boomy. In the very low pure tone test, there is a subtle undulatory character at the low end, combined with a sensory and barely audible aspect. The sub-bass is not too noticeable in presence, but reveals that dark colour that the lower range of the RA15s possesses. As the hertz increase, the power increases, as well as a more natural colour and a purer, more canonical, colour-free behaviour. The overall result is a realistic, dark and deep behaviour, classic of a good dynamic driver, dense and with a good sensory component.
In music, bass is not predominant, but it picks up its prominence when it appears, especially in electronic music. It is clear that the upper treble and midrange are more present in the mix, but their colour, depth and presence proclaim the budding energy of an aspiring bass-lover.
In the heavy, complex bass test, with dirty, unfiltered bass lines, the RA15s handle themselves like a fish in water. They negotiate the difficulties with precision, daring to describe them with skill and in a full and rich manner. They never try to minimise or simplify the bass, but expose it in as much detail as possible, bringing out an ability to interpret the lower range in a reliable, fast, natural and realistic way. In this way, the lowest notes always have a beginning and an end, there is clear distance between different bass lines and the bass layers always feel well layered. Finally, the RA15s know how to distinguish bass from all other frequencies.

Mids

It is clear that, with the permission of the lower area, the V-profile of the RA15s leans towards a certain upper mid-centric tendency. This generates a certain hollowness in the first half of the midrange. There is a mixed feeling of warmth, of an incipient and present base in the lower male voices. But soon there is a kind of emptiness, an absence, and where the more corporeal part of the music should be born, there is a leap towards the high notes, the details and the harmonics. In this way, there is this perception of a sonic gap that can be more or less striking, depending on the songs or musical style played. For the most part, the warmth of the brass filter survives this sensation. Even the male voices can become very prominent and rich, but I never quite get a full, continuous and dense impression of them. The lower strings possess more forcefulness and physicality, while the rest of the higher instrumentation, before reaching the turning point, is discontinuous in its thickness. The positive result is that the brass filter achieves a neutrality in timbre, as well as a more realistic sonority, despite those peaks and flares present.
In contrast, the female voices possess all the splendour desired in the male voices. They are dense from beginning to end, one feels that blend of thickness and finesse that fills them with body, physicality, detail and nuance at both ends. The richness in them is very full. The same goes for the electric guitars, which are piercing, starring and vivid. Admittedly, even with the brass filter, the RA15s border dangerously on sibilance. But I must say that the detail is entrenched beyond a search for a forced protagonism and this confers a double ability: on the one hand, a more analytical sound within a slightly warm line; on the other hand, a shared presence between the fundamental notes and the nimble nuances, which helps to establish a musical balance on most occasions.

Treble

The treble of the RA15s has the classic V-tuning decreasing sparkle, the peak of which is between the end of the midrange and the beginning of the high notes. In the upper range, small peaks and valleys are combined as control zones, alternating sharp contrasts. They do not create an inconsistent zone, but it is not entirely homogeneous, although it will always be protected by the classicism of this frequency response.
Initially, the high notes are very well represented, with that initial crisp sparkle, on both sides of the sibilance boundary. The energy of the high notes is consistent and their persistence is also consistent, which enhances their realism and naturalness, without feeling forced. Stretching the response more horizontally would have been more detrimental and that’s why I don’t object to the current tuning in this area. The driver is precise enough to spread out details of much higher notes and marry them with that powerful initial energy. Moreover, it is capable of extending with presence into the upper treble, bordering the air zone.

Soundstage, Separation

Despite the brass filter, the stage is wide horizontally. It feels deep and with a good height that gives a certain zenithal aspect to the music, especially in the macro details, which seem to volatilise overhead, acquiring that characteristic gaseous aspect on these occasions. The sound is clean, separated, with a very good level of transparency. It feels uncongested and although the brass filter adds more warmth, it feels more on the side of musicality and a certain softness at the edges, rather than in the density of the mix. The music feels splashy, but the micro detail doesn’t quite come through. And it seems odd, in a driver that seems to have a very good level of exposure and informativeness. But, at such a small level, the RA15s are reluctant to appear in an obvious or exposed way.
On the other hand, the image is clear, well positioned, thanks to the distance of the elements from each other, both horizontally and in depth. In this way, the elements are isolated in an enveloping way. The sound does not become completely enveloping, but there is a noticeable lateral perception, even a deep and powerful lower base that emerges from below.

Comparisons

Rose QuietSea

For this comparison I used the Silver filter on the RA15s.
The Rose QuietSea is an IEMS whose initial price was under $100. But, now they are at $50, a bargain if one takes into account the quality of their accessories, possibly one of the best cables in the range, not to mention the zippered case. My least favourite thing about the Rose is the MMCX interface, which I am against because of its poor performance over time. Some of Rose’s own IEMS that I have reviewed have been among my favourites, but have fallen out of favour because of the continuous loss of connection due to the MMCX interface.
As I say, the Rose beats the RA15s in terms of accessories, much better cable, 4.4mm balanced plug and zipped case. In terms of design they are not the same, but they are similar in size. Both have a triangular shape, but the QuietSea are more regular, more isosceles-like. The Rose has metal parts along with resin parts, the RA15 is purely metal and heavier. The inner face is the most different, with that thinner edge of the NFs and that triple level. The Rose’s are smooth and steeply sloped towards the mouthpieces. The ergonomics are frankly good in both models. Perhaps the lighter weight of the Rose tips the balance in their favour. But the RA15s, being thinner, fit better in my ear, and the fit in relation to the tips used is better. The Rose’s oval mouthpiece is their main flaw, something that can ruin the fit. So, the RA15s, finally, are safer in this respect.
The Rose are easier to move and more sensitive.
One thing that can be observed in both frequency responses is that they are identical up to almost 1kHz. Then, the upper midrange and early treble are differentiated by the QuietSea’s double peaking in front of the RA15’s greater upward linearity. Then, the Rose’s seem a bit more excited in the second part of the treble.
Both are IEMS with 10mm dynamic drivers. The difference in frequency response in the bass is in the behaviour of the two sets. The behaviour in the very low frequency pure tones is highly similar, with a very similar character. The loudness is also similar. Perhaps the RA15s have a little more darkness, less colour and subtly more depth. I also think they have a bit more presence and punch in the mix. The sound and behaviour of the bass is very similar in both models, but the Rose’s sound more neutral overall, while the RA15’s area has more weight.
In the first half of the midrange the sonic equivalences continue. The neutrality of the Rose in the lower range seems to free up more of the central range. This gives the male voices a bit more prominence, although the timbre and behaviour is very similar. On this occasion, the greater weight leans towards the QuietSea, providing a little more richness in this first phase.
In the second midrange phase the female vocals of the QuietRose feel more transparent, leading, with more emphasis and energy. It seems that the 2khz peak can provide more emphasis on many occasions. But it can also be a double-edged sword in the realm of sibilance, which the valley between 3 and 4kHz is intended to compensate for. Although the RA15s also have excitation in this range, they seem a little more blended overall, keeping a little more balance with the other elements. In this way, the QuietSea’s feel a little more vivid, but also more punchy.
The QuietSea’s treble is not as quiet as the model name suggests. The high end is thin, slim, somewhat sharp, energetic and crisp. The RA15s’ treble is somewhat rounder and not as thin, subtly softer and more relaxed, without being muffled. Very good extension in the NF Audio.
The analytical and informative capabilities of the QuietSea are superior to the RA15s, the micro detail is also more visible. There is slightly more transparency and clarity in the QuietSea, while the RA15s’ soundstage seems wider and deeper, not as rounded as in the Rose. The RA15s seem more relaxed and musical, giving a sense of greater density and body, as opposed to the cooler precision of the Rose.

Conclusion

The barrier of neutrality can be difficult to find. There are several brands that I have been able to test that are on that complex path, with little margin for error, where any deviation from the ideal reference curve can be detrimental. I think NF Audio is on that path and demonstrates it with the RA15s. In addition, it adds a pair of tuning filters to offer two shortcuts to that reference point that has not yet been found in the range.
The NF Audio RA15s are perfectly constructed dynamic IEMS, very robust, ergonomic and very compact in size. The brand continues to offer its classic packaging and accessories, in a persistent exercise in change. With a splashy V-sound, excited towards clarity and liveliness, the RA15s enjoy a very well-grounded bass. The midranges are a bit of a struggle to find that desired neutrality between two waters, while the highs find a remarkable balance in the mix. With a more than good sense of stage and separation, the RA15s are IEMS that move away from the dark path that has been trodden so often of late.

Sources Used During the Analysis

• EPZ TP50.
• Tempotec V3.
• Burson Audio Playmate 2.
• Aune X8 XVIII Magic DAC + EarMen ST-Amp.
• Aune M1p.