This and That:
Nice protective carrying/storage case with soft green rubber inside.
The in-ear's shells are quite huge and bulky. Definitely not for small ears.
Nice design (metallic paint with soft transition from blue to black). Okay build quality (sturdy though).
4-pin (2x 2-pin) connectors on the shells.
Actual acoustic crossfeed implementation (called NatroSound by LEAR) by using two dynamic drivers per shell, the 2nd one with delay.
The optional NSC-03 cable features adjustable bass and crossfeed while the bundled NSC-01 has only got one switch to activate or bypass the crossfeed drivers.
The NSC-01 doesn't have a chin-slider but a single mic/remote unit, whereas the NSC-03 lacks the mic/remote but has an integrated chin-slider.
Somewhat microphonic cables (NSC-03 somewhat less). Ear guides could be easier to mould.
Sound:
Low impedance sources, largest included single-flange silicone tips.
Tonality:
NSC-01 Cable:
NatroSound disabled:
Tonally, NS-U1’s midrange and treble are pretty balanced sounding, with some extra boost in the midbass and especially sub-bass.
The integration of the sub-bass emphasis is nicely done and really mainly concentrates on the lowest frequencies.
At around 500 Hz, the LEAR’s bass starts to evenly rise in a straight line and reaches its climax around 70 Hz with about +10 dB compared to a strictly flat in-ear like my Etymotic ER-4S. It can keep this level down to 20 Hz without any roll-off (it even gains 2 dB towards 20 Hz).
There is no real fundamental range bloom, wherefore neither unnecessary warmth nor thickness in the root is present. So the lows are punchy but there's no bleed.
From 1 to 4 kHz, I hear an moderate, gradual lift wherefore voices are ultimately slightly on the brighter and thinner side, though still tonally pretty natural sounding. Right afterwards, the level goes back to a normal level again, slightly sinks below zero and comes back to roll off rather quickly above 10 kHz.
Overall, the tuning is executed pretty well and sounds natural, with only slight metallicness due to the 4 kHz lift.
NatroSound enabled:
Midrange and treble levels are only slightly altered (slightly less upper midrange elevation, however slightly stronger 4 kHz lift), however there is some change in the bass and fundamental range: although the climax is still reached below 100 Hz, the emphasis is about 5 dB stronger and the root clearly gains warmth and body because the elevation starts to climb around 800 instead of 500 Hz as before. As a result, the mids are on the warmer, fuller side with enabled NatroSound, however also with some muffled tendencies.
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NSC-03 Cable:
NatroSound disabled:
The main advantage over the regular cable is the ability to adjust the bass quantity.
Doing this, the sound can reach from “bass-shy and mid-centric”, “quite neutral” and “balanced midrange and treble with sub-bass emphasis à la NSC-01 but with a bit more fundamental warmth”.
If one chooses a milder, more natural or neutral bass range, there is one flaw though: the lower midrange and fundamental range are recessed while the mid- and sub-bass are neutral, which leads to some imbalance.
NatroSound enabled:
The root and lower mids also gain more warmth, but this can be regulated really well to tonally correct mids as long as the bass adjustment is not at the max position and the NS adjustment isn't einther.
The main advantage of the NSC-03 is that, once NatroSound is enabled, one can adjust the bass and NS intensity to create a neutral or natural, just slightly elevated bass, as the activated NS control adds the lower midrange and fundamental range energy that is otherwise lacking with disabled NS. Therefore, the only way to get a fairly neutral bass and good tonal balance and accuracy is to adjust the bass and NatroSound potentiometer
Resolution:
NSC-01 Cable:
NatroSound disabled:
The NS-U1 does a good job for an in-ear with dynamic drivers and somewhat surpasses some other dynamic driver in-ears in the same price range in terms of realism and control, despite not quite reaching the LEAR LHF-AE1d’s strengths in some areas.
The bass is rather quick, tight and controlled for a dynamic driver, with firm and quick upper bass as well as well controlled sub-bass that is however slightly softer than the upper bass but no less controlled.
Midrange and treble sound realistic, with a good and overall natural presentation of the upper frequencies, though I wouldn’t mind just a little more midrange details.
NatroSound enabled:
The bass appears softer, the mids sound somewhat coated, the treble veiled, and the more present bass body doesn't appear natural.
Compared to disabled NS, the NS-U1’s sound appears coarse and not as refined or precise anymore, which is also because of the different spatial presentation.
For the pure resolution, I surely wouldn’t use the NSC-01’s NatroSound feature, as it unfortunately degrades the sound quality.
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NSC-03 Cable:
NatroSound disabled:
The resolution remains identical to that of the NSC-01 cable, however a slightly tighter bass can be achieved by reducing its quantity with the potentiometer.
NatroSound enabled:
When the bass and NatroSound potentiometers are just sparsely used to create near-neutral bass quantity, the dynamic 6 mm drivers are less strained which is also audible – the resolution is almost identical to that of the NSC-03 cable with deactivated NatroSound and only slightly muddier.
So yeah, NSC-03 with reduced, neutral-ish bass quantity and mild NS is definitely the way to go.
Soundstage:
NSC-01 Cable:
NatroSound disabled:
Even with disabled NatroSound switch, the in-ear’s soundstage is better than average in terms of expansion to the sides and depth, with a realistically appearing imaginary field of sound.
The positioning of instruments in this imaginary room seems authentic as well, with good separation for an in-ear with dynamic drivers for that price, although some better BA-based multi-driver in-ears around $200 have sharper instrument separation.
Even though there is slightly less depth than width, instrument layering is precise and audible.
NatroSound enabled:
With enabled NS, the soundstage gains more intimacy as well as more spatial depth at the same time, with somewhat less perceived width due to the gain of depth. In most cases, the front projection really leaves my head, but at the cost of instrument placement and separation precision that seem somewhat foggier, less precise.
A few comments regarding the NS-effect’s naturalness: with many recordings (especially old and many modern ones that were mainly created the with the computer), the soundstage seems somewhat more authentic (many ping-pong stereophony effect tracks finally become listenable with activated NatroSound), with some others the authenticity remains identical compared to disabled NS (but with a different presentation), and with few recordings, the NatroSound effect sounds slightly less authentic.
Most of the time, the spatial presentation with enabled NatroSound appears more plausible, especially when directly compared to when NS is disabled and one suddenly gets the feeling that the imaginary room is flatter, with something somehow missing compared to enabled NS.
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NSC-03 Cable:
NatroSound disabled:
Taming the bass a little and bringing it closer to a neutral levels, the instrument separation as well as placement gain precision and tonal elements are more precisely positioned in the imaginary room compared to the NSC-01 cable with disabled NatroSound.
NatroSound enabled:
With also reduced bass quantity, the soundstage appears both deeper as well as clearly more precisely layered than with enabled NS on the NSC-01 cable.
To my surprise, the soundstage width with the NSC-03 cable and engaged NatroSound isn’t really narrower compared to the same cable with disabled NS, as long as the NS potentiometer isn’t turned up to the max.
Although the instrument separation sharpness is slightly less clean compared to disabled NSC-03 NatroSound, this difference is much smaller than compared to the NSC-01.
And because of all of that, the spatial presentation is very enjoyable, has got better forward-projected and is more precise.
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Additional Notes:
What I have generally noticed is that with NatroSound turned on, I experience much less fatigue after long listening sessions.
Especially with the NSC-03 cable that lets me achieve a neutral bass with enabled NatroSound, the spatial impression appears somewhat more natural.
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In Comparison with other Dynamic Driver In-Ears (NSC-03 Cable):
Sennheiser IE 80:
With fast music, the NS-U1 manages to keep the better control and sounds audibly less muddy, as its bass is quicker plus better controlled, even when NatroSound is engaged by ~ 80% and even when it is set to 100%.
The LEAR sounds quicker, cleaner and more detailed, with the better reproduction of singers’ variations and minute treble details.
In terms of soundstage, both in-ears are surprisingly close.
With deactivated NatroSound, the Sennheiser’s soundstage appears more spacious, more distant and deeper. With engaged NS, the NS-U1 is better at conveying a realistic impression of intimacy and depth, and the soundstage also appears more coherent. In addition, the LEAR has got the more precise instrument separation as well as placement.
RHA T20:
The LEAR has got the somewhat faster, but especially better controlled bass.
Also when it comes to general resolution, the NS-U1 is the somewhat ahead, putting out somewhat more details in the midrange and treble.
Without NatroSound, the soundstage size of both in-ears is about identical and the spatial precision is comparable as well (as long as no tracks with fast bass strokes are played, as then the LEAR is the winner). Enabling NatroSound, the NS-U1’s projection of closeness is better and it generates the deeper stage with more precise layering.
Echobox Audio Finder X1:
The victory in the category of bass speed (NSC-03 with maximum bass, no NatroSound) is the Finder’s. In terms of bass control however, both in-ears are about on the same level and the LEAR shows the identical amount of details in the bass.
When it comes to general resolution, the NS-U1 is very slightly ahead in the mids and treble.
What the LEAR does better by a certain degree are things like naturalness of its sound presentation (I don’t blame the Finder for it as it is clearly designed as a consumer-tuned fun IEM and I really like it for that purpose).
Spatial closeness and naturalness are a bit better conveyed by the NS-U1 with disabled as well as enabled NatroSound, with the overall somewhat larger soundstage as well. It’s basically more or less a tie, with one aiming for more fun and the other for more naturalness and balance.
LEAR LHF-AE1d:
The NS-U1’s bass is tighter, faster and has got superior control, but the AE1d features the higher resolution in the midrange and treble. Additionally, it also sounds even more natural and realistic.
With disabled NatroSound, both in-ears’ soundstages are about equally good. With activated NS however, the NS-U1 features the better impression of proximity, but also slightly loses some of its spatial precision.
Conclusion:
Best to be used with the NSC-03 cable and activated NatroSound, as that's the only way to achieve a quite neutral bass response.
I'm not a fan of the stock sound signature with the NSC-01 cable that only enables and disables the acoustic crossfeed, while I like the sound signature with the NSC-03 cable that has got bass and crossfeed controls wherefore I can achieve a neutral-ish bass response by setting the bass and NatroSound potentiometer accordingly and eliminate the negative effects on precision that come with a 100% crossfeed setting by only adding a mild dose of NatroSound crossfeed.
It's not a must-have in-ear but definitely a really interesting one that performs well on the technical side and it leads to much less fatigue after long listening sessions with enabled NatroSound.
However, its shells are so big and bulky that they will only fit few people with big conchas, and unfortunately the sound signature changes with enabled/disabled NatroSound crossfeed, which (the latter) is a disadvantage compared to a good electric/digital crossfeed solution.