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September 2015
Enjoy the Music.com Review Magazine
Estron Linum Balanced Two-Pin 2.5mm TRRS Custom IEM Cable
Thin is in!
Review By Steven R. Rochlin


Estron Linum Balanced  Two-Pin 2.5mm TRRS Custom IEM Cable

  As a member of the Head-Fi discussion board community since January 2003, it has been wonderful to be part of the flourishing personal audio community. Cables like the Estron Linum Balanced two-pin 2.5mm TRRS (€145, or around $160) as reviewed here are what's fresh and new, yet is something more of an evolution in my eyes. My love of personal audio dates back decades before that as my first experience with headphones was before first grade school. The closed back headphones were by Koss, 'natch, and was a revelation. I've been hooked ever since! During my teens to early 20s sold electronics and became manager in short time of a big box store. After that gig did a stint with a high-end personal audio specialty store. It wasn't called 'high-end' back then, yet the top gear was an Aiwa stereo cassette player that also recorded (in stereo!) and the Sony D-10 (or was it the D25?) at that time. Hey, it was the 1980's in Miami and was a musician so some of my memories at that time might be a bit, ummm, shall we say 'hazy'.

So as the years passed have watched the whole personal audio ebb and flow. If someone would have told me decades ago it would be where we are today I would not have been surprised. There is something incredibly special about being able to tune out the outside noise and turn up the music. With our lives becoming ever-more chaotic in so many ways, plus the unwanted noise during constant airplane travel many of us deal with, our ears are bombarded by external sounds (noise) all the time. Good thing we now have custom in-ear monitors, as they highly reduce those harmful and unwanted external noises while also ensuring a nearly silent sanctuary for our ears to be basked within the glory of our tunes.

Estron Linum Balanced  Two-Pin 2.5mm TRRS Custom IEM Cable

So what comes next after custom in-ears within the now properly-titled high-end personal audio? Cables! Just as the high fidelity home audio market discovered that cables make a difference, the personal audio guys are now playing catch up. My previous world premiere review of the Double Helix Cables' Symbiote Fusion 4 and Symbiote SP 8 CIEM cables with 3D printed rose gold highlights brought my beloved Noble Kaiser 10 to new heights in their ability to provide hour after hour of musical bliss. Ok, let's admit it right here and now that the Double Helix cables are not what you'd call small and discrete in appearance. Due to their size, they can be a bit challenging, especially if you're trying to be a bit discrete. Then again the Double Helix cables boldly show the world you deeply care about getting the very best, or at a minimum add to your cool vibe of diggin' tunes. But what if, just if, you want to be a bit more laid back cadge (short for casual, 'natch). Maybe you want your CIEMs to hide in the 'shadows' or, dare we say, desire a cable that sounds different? Perhaps you're a stage musician and thus want to have your precious hearing-saving CIEMs hide in the shadows on camera.


You Can Never Be Too Thin Or Too Tall
Now before you haters go on hating, my mom said the above title. Thin and tall, yeah, that's my mom talkin'. Thin is also the first thing I thought of when seeing the Estron Linum two-pin balanced 2.5 TRRS CIEM cable. So who is Estron you ask. They are a specialist in development and manufacturing of miniature wire solutions with very fine cables and connector systems. For years Estron's products have been used inside hearing aids, as big thick cables have no place for such small health devices. Unlike us music lovers with big bold headphone and massive brick-thick portable audio devices, people who need hearing aids for health reasons generally desire to keep them more visually discrete. Fortunately for us, Estron also produces cables for in-ear monitors, headphones and loudspeakers.

Their cable designs are done in Denmark, with production and office facilities in Denmark, China and Vietnam. They work hand-in-hand with their customers to produce products as requested. The more requests, the higher the probability they'll design and sell a new offering to the masses versus one-off designs. While the Linum two-pin balanced cable only comes with the very small 2.5mm male TRRS connector, if there's enough demand they might offer a larger 3.5mm size male connector. Advantages of this are easier to source TRRS to TRS adapters and of course it is more common to go from a larger to smaller size than a small connector to a larger one. Also, a 3.5mm would be sturdier to then go to 2.5 than going from 2.5 to 3.5mm. The 2.5mm version perfectly fits Astell&Kern's PMP balanced output and so this review was done with the outstanding Astell&Kern AK240.

Estron Linum Balanced  Two-Pin 2.5mm TRRS Custom IEM Cable

Estron, by the way, are certified ISO 9001 and are REACH and RoHS compliant. So basically they adhere to top professional standards. The Linum cables are extremely thin and flexible. When I say thin, we're talkin' a mere 0.9 mm! Yup, less than a single mm and so are virtually invisible to the eye of others when you're wearing them. The cable design “is typically Danish which is famous for combining simplicity and functionalism” says Estron. As for weight, the entire assembly including connectors is 2.7 grams (~0.095 ounces) and the Music product is their lightest model. Estron's wire for the Linum two-pin balanced 2.5mm TRRS as reviewed here uses six Litz conductors made up of seven individual strands. Each strand is silver plated copper, whilst an enamel coating keeps each wire from direct electrical contact with the other until it reaches the end connectors.

Ok, so now you might be thinking with a cable so very thin, it must be easy to break. Ah, you'd be wrong! With a pull strength 60N (13 lbs.), the wire itself combined with aramid fibers during assembly ensures they are very durable. The Linum outer jacket is made from TPA, which is skin-friendly and UV stabilized; and thus it will not turn yellow if exposed to sunlight. Another factor you might be thinking is that with a cable so thin, well, they might easily get tangled. Special memory wire does not tangle easily and so far they are about 85% right. Let's face it, all cables of length will tangle to some extent, yet it is in how easy it is to untangle them that makes a big difference. During my review this cable tangled only a very few times, yet were easy enough to undo the mess I made… and I can easily make a mess of headphones cables!


The Sound Of Small
As for sound, I did try the Estron Linum Balanced  two-pin 2.5mm TRRS custom IEM cable on the Noble Kaiser 10, JH Audio 13, and Ultimate Ears UE18 Pro. With the Noble they didn't quite sound right to my ears, yet with the JH Audio 13 and UE18Pro it was most impressive. In fact the UE 18 Pros have never sounded better in many ways, and so I'll focus my review with those CIEMs. Went back and forth with the stock Ultimate Ears UE18 pro cable and the Linum and there is no way I'm going back to the stock cable. The bass was at least a half octave deeper, tighter, and more defined with the Linum, while the uppermost frequencies have a newfound extension and smoothness. The midrange filled in nicely and overall there was more resolution, a wider soundscape over the stock unbalanced cable and a touch more dynamic finesse. As much as I have loved the UE 18 Pro for their accuracy and honest sound, with the Linum Two-Pin Balanced CIEM cable they were still honest and accurate yet took on more frequency extension in both directions while delivering a broader, deeper soundscape.

Estron Linum Balanced  Two-Pin 2.5mm TRRS Custom IEM Cable

With the JH Audio 13 the results were the same and they brought their performance up a notch. Everything sounded a bit more natural, yet still quite accurate. Bass, like with the Ultimate Ears UE18 pro, was extended a bit further yet retained accuracy without ever getting bloated. The highs were also a touch smoother a slightly more extended. So basically the results were the same with the JH Audio 13 as they were with the UE 18 Pro. If you're still using a stock cable on either of these CEIMs, you really should try the Estron Linum Balanced  two-pin 2.5mm TRRS custom cable.

Overall, there were big dynamics revealed as there were added microdynamic shading, yet there is one kinda strange thing going on. The initial attach and brief sustain for the first fractions of a second were great, then there was a faster drop-off and then leveling off until notes disappeared. It is as if something very briefly 'in the middle' of the dynamic structure dropped off a bit faster than usual. Thus smooth decays into a black background were more like initial reduction in volume level, then brief and fast drop-off followed by smooth final disappearance. Had hoped one of my 2.5mm to 3.5mm adapters I got in Singapore would have worked so I could test the cable with other digital audio players, yet something was not quite right and thus it did not work correctly. So am a bit perplexed where to go from here, as I can only use this cable with the AK240 (and original AK120 as reviewed here) at this time.


So where does that leave us? Cables can indeed be dependent on the devices you use with them. No cable is perfect, or best, in all situations. Love the reasonably-priced €145 Estron Linum Balanced  two-pin 2.5mm TRRS IEM cable with the Ultimate Ears UE18 Pro and JH Audio 13 as they have breathed new life and use into these accurate sounding CIEMs. There is no way I'd go back to the stock cables due to the many improvements I hear with the Linum. Still, let us hope they make a normal 3.5mm version as then I would not need an adapter for a majority of digital audio players, including the new Astell&Kern AK380 with 3.5mm balanced, Sony NW-ZX2 pseudo-balanced, Questyle QP1R and every other PMP that uses a 3.5mm headphone jack. The ball is in your court Estron. Please count me as someone who'd love to have a balanced two-pin 3.5mm TRRS offering, which is easy to then use a 3.5 TRS unbalanced or 3.5mm to 2.5mm TRRS adapter. Oh, and please also allow me to follow-up this review when you do make the 3.5 TRRS version as would really enjoy giving them a listen. The Estron Linum Balanced  two-pin 2.5mm TRRS custom IEM wire is a winner for those who desire a thin, lightweight cable.



Sub-bass (10Hz - 60Hz)

Mid-bass (80Hz - 200Hz)

Midrange (200Hz - 3,000Hz)

High Frequencies (3,000Hz On Up)



Inner Resolution


Fit And Finish

Value For The Money


Type: TRRS balanced two-pin cable for in-ear monitors
Wire Configuration: Silver plated copper Litz wires
Impedance: 1.5 Ohms
Crosstalk: Virtually zero
Cable Length: 50"
Connector: 2.5mm TRRS
Tensile Strength: More than 60N
Weight: 3.4 grams
Cable Diameter: 0.9 mm
Available with 2-Pin, MMCX and T2 Connector
Options: Custom cable length and / or incorporate an earhook shape.
Price: €145 (approximately $160)


Company Information
Estron A/S
Industrivej 5, Knudlund
DK-8653 Them, Denmark

Voice: +45 86 84 88 77
Fax: +45 86 84 90 95
E-mail: info@estron.dk 
Website: www.Linum.dk/linum-balanced/


United State Distributor:
Warner Tech-care Products, Inc.
1655 Terrace Dr. Roseville
St. Paul, MN 55113

Voice: (800) 328-4757 ext. 101
Fax: (800) 328-4756
E-mail: leeh@warnertechcare.com 
Website: www.WarnerTechCare.com














































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