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Noble Audio 4S Custom Fit In-Ear Monitors

Noble Audio 4S Custom Fit In-Ear Monitors

When we were children I suspect many of us received, at one point or another, stern admonitions from our parents against putting foreign objects (pencils, bits of modelling clay, green beans, or the like) in our ears. But while those warnings were probably issued with our best interests in mind, the sad fact is that their effects seem to have lingered on in the minds of some full-grown audiophiles reluctant to try any sort of in-ear listening devices. As I see it, this is a terrible shame as one of the most potentially satisfying experiences available to today’s audio enthusiasts is to listen to music through a fine pair of custom-fit in-ear monitors (or CIEMs, for short). One such set of CIEMs would be the Noble Audio 4S’s (£630), the subjects of this review.

For those unfamiliar with CIEMs, let me mention that, unlike universal-fit earphones, CIEMs make no attempt to provide compact, ‘one-size-fits-all’ earpieces or small rubber ear tips of varying sizes. Instead, CIEMs provide earpieces custom-moulded to fit the exact contours of a particular listener’s outer ears (or pinnas) and ear canals. Indeed, there are few more personalised experiences possible in the world of high-end earphones than to own and enjoy a set of CIEMs crafted for you and you alone. The idea behind the make is that CIEMs’ custom-fitted earpieces offer exceptional noise isolation, while also providing earpiece enclosures of sufficient volume to house sophisticated, multi-driver arrays. Consequently, CIEMs not only give their owners fundamentally superior sound quality, but also provide quiet enough backgrounds so as to appreciate that sound quality in a fuller and deeper way than might otherwise be possible.

, Noble Audio 4S Custom Fit In-Ear Monitors

A few months back (in Hi-Fi+ issue 119) I reviewed Noble Audio’s flagship Kaiser 10 CIEMs and concluded that they offered a rich, sumptuous, and intensely immersive sound that, though perhaps not quite neutral enough to be suitable for monitoring applications, nevertheless invited listeners to become, “caught up in the complex, intoxicating beauty of music.” After that review was published, Noble Audio co-founder and co-owner Brannan Mason told me he hoped I might one day try a set of Noble 4-series CIEMs as he considered them to be the most accurately and neutrally-voiced of all his firm’s in-ear monitors. Mason’s comments sparked my interest, eventually leading to this review.

Early on, I discovered Noble actually builds three versions of its model 4: the standard Noble 4 (£300), which is a universal-fit earphone, the Noble 4C (£450), which is a CIEM supplied with acrylic earpieces, and the Noble 4S (£630), which is also a CIEM, but one supplied with earpieces made of flexible silicone material. In choosing the Noble 4S’s for this review I had two objectives in mind. First, I wanted to see how the 4S differed from Noble’s Kaiser 10 in terms of voicing and overall sonic characteristics. Second, I also hoped to learn how or if silicone earpieces differed in terms of fit, comfort, and sonic characteristics from the acrylic ones used in the vast majority of CIEMs now on the market.


The Noble 4S is a three-way, dual-bore, custom-fit in‑ear monitor that uses an array of four balanced armature drivers (two bass drivers, one midrange driver, and one high-frequency driver) per earpiece. The 4S’s ship with detachable, user-replaceable 1m signal cables equipped with industry-standard 2-pin earpiece connectors and a 3.5mm stereo mini-plug on the amplifier end of the cable. The monitors arrive in a sturdy, watertight, padded hard-shell carrying case that bears a Noble logo on the outside, with the owner’s name permanently etched into the top of the case. On the inside, the case includes the 4S packed within a velvet carry bag, a pair of Noble-branded rubber straps (used to attach portable audio devices or smartphones to a portable headphone amp or the like), a tool for cleaning the CIEM’s earpiece bores, and an owner’s identification card.

, Noble Audio 4S Custom Fit In-Ear Monitors

For my listening sessions, I fed the Noble 4S a mix of standard and high-res uncompressed PCM, DXD, and DSD-format digital audio files delivered either through an Astell&Kern AK380 high-res digital audio player (reviewed in Hi-Fi+ issue 126), or through my reference Lenovo-based music server running jRiver Media Center software. The 4S was driven by a variety of amp/DACs, including the Astell&Kern AK380, the Celsus Sound Companion One (reviewed in Hi-Fi+ issue 126), and the superb Chord Electronics Hugo (reviewed in Hi-Fi+ issue 111). For comparison purposes, I had on hand several top-tier CIEMs, including the Noble Audio Kaiser 10 and JH Audio Roxanne monitors.

As mentioned above, Noble Audio touts the 4S for its exemplary neutral voicing, so I was keen to learn precisely what Noble means by the term ‘neutrality’ in a practical sense. I raise this point because neutrality can sometimes have significantly different meanings for different companies (and listeners). For some, a neutral-sounding transducer would be one that potentially can serve as a fine analytical or diagnostic tool for assessing the quality of specific recordings. No doubt there is a place in the market for such CIEMs, but the trouble with listening to music through primarily analytical devices is that they too often sound like the sonic equivalent of cod liver oil: awful to experience, yet ostensibly good for you.

For others, however, a neutral-sounding CIEM would possess the uncanny quality of musical ‘naturalism’, where recordings are reproduced with almost complete freedom from obtrusive tonal imbalances, colorations, or other sonic aberrations, whether of an additive or subtractive nature. The emphasis, in this case, is on creating a transducer that has the rare and valuable ability to get out of the way and simply let the music speak for itself. I’m pleased to report that the Noble’s 4S is a prime example of a neutral CIEM in this latter sense of the term.

Right from the start, the 4S put me at my ease because it offered a compellingly natural, unforced, and unembellished delivery of the music in terms of tonal balance, detailing, and dynamics. With many transducers, one has the sense that the product is somehow imposing its own persona on the music—almost as if a literal filter or equaliser had been inserted into the signal path. With the 4S, however, no such unwelcome tone-shaping characteristics or ‘filters’ insert themselves as barriers between listeners and their music. On the contrary, the 4S is happy to serve as a fundamentally clearer, more unfettered, and more honest conduit for the music.


In terms of tonal balance, the 4S offers well-defined and yet unexaggerated bass; transparent and open-sounding mids; and pleasingly extended, tightly focused, yet also uncommonly smooth highs. The key point is that each of these frequency bands is well balanced and proportionate to the others. Indeed, I believe this is where the 4S’s quality of effortless naturalism originates. But another essential ingredient involves the fact that the 4S’s mids and highs are uncannily smooth, with no abrupt peaks, troughs, or rough edges in the Noble’s frequency response curve distracting or annoying listeners. Put these qualities together and you have the recipe for a CIEM that is at once highly accurate yet also engaging and easy to listen to for extended periods of time.

Far from sounding lean or astringent, the 4S has a certain robust and easygoing demeanour stemming from the fact that it consistently sounds unstrained and unforced no matter what types of music you play. If, for example, you put on an orchestral work with large brass fanfares and potent low-frequency percussion passages, such as Mark O’Connor’s ‘Fanfare for the Volunteer’ [Mercurio, London Symphony Orchestra, Sony], the 4S rises to the occasion with an admirable combination of grace, power, and finesse. The 4S presents the low percussion instruments with clearly defined pitches and textures, plenty of weight and depth, and tons of transient punch—all without exaggeration. Similarly, the 4S helps the LSO brass section sound appropriately burnished and blazingly brilliant as the music warrants; yet without a trace of blare, glare, or overemphasis. My point is that the 4S seems able to deliver precisely what the recordings at hand require—but without adding editorial embellishments of its own.

Similarly, the 4S is at ease with smaller scale pieces that place a premium on nuance and textural finesse. Listen, for example, to the brief but excellent 58-second-long track “Bell Painting” from Marilyn Mazur and Jan Garbarek’s Elixir [ECM], and note how delicately and deftly the 4S handles the high-pitched bells and chimes featured on that track, complete with their shimmering high-frequency harmonics and overtones. This track can prove difficult for some CIEMs to reproduce, but through the Nobles it sounds just right thanks to their inherent qualities of smoothness, detail, and balance. Similarly, try violinist Hillary Hahn’s performance of Vaughan Williams’ The Lark Ascending [Sir Colin Davis, London Symphony Orchestra, Deutsche Gramophon] and note carefully the 4S’s ability to capture Hahn’s impressive technique, which strikes a knife-edge balance between sweetness of tone and incisive articulacy. Once again, the 4S simply supplies just what the recording demands—nothing more and nothing less.

, Noble Audio 4S Custom Fit In-Ear Monitors

One final sonic characteristic of the 4S bears further mention: its wonderfully immersive quality of overarching coherence—a quality I also observed in Noble’s Kaiser 10 CIEM. Though difficult to put in words, this quality of coherence makes all the difference between hearing ‘a nice collection of high-quality drivers attempting to play music’ and something much better: a CIEM that transports you deep into the interiors of recordings, allowing each to define a listening environment all its own.

How did the Noble 4S fare in comparison to its more costly sibling, the Kaiser 10, or even to the more costly JH Audio Roxanne? Surprisingly, it held its own and then some. In fact, one could make a case that the 4S is more accurately balanced than either of the more costly units. In comparison to the 4S, the Kaiser 10 offers a noticeable touch of bass lift, subtly rolled-off highs, and perhaps a slightly higher degree of midrange articulation and definition. The JH Audio Roxanne, in turn, makes for a more difficult comparison because it offers user-adjustable bass output levels. With bass levels turned all the way up, the Roxanne delivers an overly prominent low-end response, but with bass levels turned down, the Roxanne still shows at least some degree of mid-bass emphasis relative to the 4S. Like Noble’s Kaiser 10, the Roxanne perhaps offers heightened levels of midrange articulation compared to the 4S, although the Roxanne’s extra articulation is undercut by a subtle ‘burr’ in its upper-midrange response. In the end, the 4S’s sheer neutrality and engaging smoothness enable it to stand tall in comparison to far more expensive CIEMs.


And what about the effects of the silicone earpieces? Simply stated, the 4S made me a believer in silicone earpieces. Because silicon earpieces can flex in much the same way as our ears do, I found them to offer a better and more comfortable fit, a more complete in-ear seal, and even higher levels of noise isolation than that offered by acrylic earpieces (up to 9dB more isolation, according to Noble Audio). The only downsides are that silicone earpieces do cost a bit more than acrylic ones, and take some getting used to until listeners master the appropriate techniques for inserting and removing the flexible earpieces. Noble has also figured out how to make silicone earpiece in different colours and with custom artwork appliqués — creative manufacturing know-how few other companies possess.

Noble Audio’s 4S CIEM it is at once accurate and transparent, yet engaging and easy to enjoy. Over time, the 4S has become the go-to reference I turn to when I want to know how a recording really sounds; but it is also the CIEM I look for when I want to immerse myself fully in my favourite music. What could be a stronger recommendation than that?

Technical Specifications

  • Type: Three-way, dual-bore, quad-driver custom-fit in‑ear monitors with flexible, silicone earpieces
  • Driver complement: An array of four balanced armature-type drivers per earpiece, comprising two bass drivers, one midrange driver, and one high-frequency driver
  • Frequency response: Not specified
  • Impedance: < 30 Ohms
  • Noise isolation: Up to 37 dB (or 9dB better than typical acrylic earpieces)
  • Distortion: Not specified
  • Sensitivity: Not specified
  • Accessories: Detachable ~1m signal cable with industry-standard 2-pin connector, cleaning tool, rubber straps, owners card, and rugged watertight hard‑shell carrying case
  • Weight: Not specified
  • Warranty: Two (2) years, parts and labour

Price: Noble Model 4 universal-fit version: £300, or $450
Noble Model 4C CIEM, acrylic earpiece version: £450, or $699
Noble Model 4S CIEM, silicone earpiece version: £630, or $999

Other: Noble offers a special Ownership Transfer Service where, for a $250 fee, it will re-manufacture earpieces for an existing set of Noble CIEMs to fit a third party owner who has purchased a set of Noble CIEMs second hand. To our knowledge, no other CIEM maker offers such a program.

Manufacturer information: Noble, 19 W. Carrilllo St., Santa Barbara, CA 93101

Tel: +1 (805) 886-5255

URL: www.nobleaudio.com

UK URL: www.nobleaudio.co.uk

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