Rooth Professional Audio’s Custom In-Ear Monitors

A while ago, I managed to listen to demos of the entire product lineup from Rooth Professional Audio. For those of you unfamiliar with the brand, it’s a sister brand to Unique Melody — its custom in-ear monitors are developed and built in the same laboratory as UM’s, but is staffed differently and its marketing is handled by different people. Whereas Unique Melody is headed by UM Australia/Global and by Stephen Guo in North America, global development for Rooth is entirely in the hands of HFI International, headed by Tomo Okabe.

Rooth LS8+ (LEFT) and LS-X5 (RIGHT)

While Rooth has not been the biggest name amongst in-ear enthusiasts in the US or Europe, it has sold very well in Asian countries such as Japan and Korea, sold in popular stores such as e-earphone and Earphone Shop; HFI itself is based in Japan, but plans on expanding Rooth’s order base and the brand currently undergoing an overhaul of their marketing materials, website, and packaging.

The overall Rooth sound is tilted toward the brighter side of things, but has a smoothness that suits my listening tastes well. It seems to have brought out a product lineup that has more of a Japanese-style sound signature, and I can see why the brand is so popular in Japan. In addition, the “house sound” is also consistent across its products from the entry level LS2 to the flagship LS8+ — anyone would be able to tell that they’re of the same family.

Unfortunately, I didn’t get long listens to every single product, but I managed to write notes on each of the models:

LS2:
The baby Rooth only has two drivers — not very impressive in today’s world of eight, ten-driver CIEMs, but don’t be fooled — it is quite neutral and a competent monitor. I quite like the sound; it has a very slight, but enjoyable bass boost that never gets in the way of the very neutral sounding midrange and treble. It utilizes an ED-29689 for the mids and highs, and a CI-22955 for the lows, two very commonly used Knowles balanced armature drivers, especially in a dual driver, two-way configuration, and I’d say that it works pretty well.

Update: I also had the chance to take a gander at one of the QC frequency response printouts included with every single Rooth product, and the LS2’s bass shelf is ruler flat; save for a bit of an upper mid/lower treble boost, the LS2 is very neutral-looking in response.

LS3:
In the short time that I listened to it, I wasn’t a fan. I took it out after a few minutes. I should’ve given it more of a chance, but to me, the LS3 had quite a bit of shakiness in the upper midrange and lower treble, characteristic of the typical peaks and valleys nature of TWFK mid/high system. I used to quite like that sound, as it delivered fairly sparkly highs with intimate mids, but I’ve gone away from that type of sound lately.

Update: If you’re curious how the LS3 sounds, GoldenEars has done a full set of measurements of the LS3…

In this frequency response chart taken from GoldenEars, we see that the “peaks & valleys” nature of the TWFK is in full effect here in the midrange and treble.

LS4:
Not bad for a “bass-driven” BA CIEM. Well, it’s not that it’s a bass monster, but I found the bass to be more of a factor than the midrange, which seemed a bit more laid back in comparison. I really like the way the highs are presented, in a present, but not overbearing manner, and it sits very well in with the pleasant mids, which are nicely detailed but, as alluded to earlier, placed just a bit too far away for my personal tastes. Bass speed is quite good, due to the dual DTEC lows, which are probably the most speedy-sounding BA “woofers” from Knowles that I’ve heard. The low/mids are delivered by a CI driver, which is commonly known as a woofer (like the way it’s used in the LS2 and LS3) but can also deliver pleasant, warmish mids when expropriated in the correct manner. Upper mids and highs are delivered by an ED driver, which are the de facto standard for extended, but not overly bright highs in a multi-BA setting.

Update: A frequency response printout for the LS4…

Frequency Response Curve of the Rooth LS4. Note: QC graphs are not necessarily indicative of the actual response; they may be conducted to perform one last left/right channel matching test, or to identify any large errors.

LS-X5:
The X5 began life as a customer request to make a specific upgrade to their old UE Super.Fi 5EB. They began the project as just a remold plus driver upgrade project, but it developed and developed until Rooth believed it had a product that could stand on its own with its own dynamic drivers and BA drivers. As a five-driver IEM with the only dynamic lows of the bunch, the LS-X5 is definitely the most ‘excitement’ oriented of the Rooth lineup. While I haven’t heard the UM Merlin myself, you can be assured that the internals are completely different; in fact, the LS-X5 is a triple-bore affair — it shares more with the basic sound of the Rooth LS8+ than anything else, and is the most U-shaped of all the Rooth monitors, as well as intimate mids. Bass is big and dynamic, but not really overbearing. It doesn’t feel bassy at first, but then you realize how bassy it can get. Since I’m not really the type to get into big bass, I don’t find the LS-X5 as engaging as other may feel. For me, it’s fun for the first 20 min. then it gets sort of annoying — not merely because of the bass, but because it’s easily the one Rooth model with the most perceived  sibilance. Keep in mind, though, that these impressions were made with demo earphones, the experience of which can differ drastically from the real thing. I usually find that the full-on custom will, due to better isolation, a more secure fit, and lack of unpredictable canal resonances, give better perceived bass extension, a deeper and wider soundstage, and less peaky treble. The LS-X5 will actually be the one Rooth model available as both a custom IEM and a universal IEM; apparently, the universal version is still undergoing revisions, and my hope with the LSX5 is that the final mold for the universal version will be different and more reflective of a less peaky sound on the top end. I do actually think the treble peakiness I heard in the demo would be mitigated with a full-custom mold, but if the LSX5 is indeed going to be universalized, it should definitely try to have less of that treble peak, especially when silicone tips tend to amplify unwanted ear resonances. Overall, though, I definitely think the LSX5 has a place for other people; it’s quite well-tuned and cohesive from top to bottom, but just has a bit too much stimulation for me.

LS6:
For me, the LS6 seemed to be the star of the Rooth lineup (your opinion may very well differ) — it’s very, very refined sounding; bass is only a tiny bit boosted above ER4 levels, basically perfect for my tastes. The highs are quite good, mostly neutral with hints of gentle sparkle, a vestige of the WBFK-esque sound that makes it quite loud at the 6-8k range; in my view, cymbals are still just ever so slightly too present and shimmery for a true “neutral” stance, but definitely not overdone and very, very well-controlled. It’s one of the flatter-sounding CIEMs I’ve heard thus far, flatter than my Heir Audio 4.A, flatter than the JH13 (non-FreqPhase demo), flatter than the FitEar Private C435 and 333. To me, it’s a beautiful blend of a neutral, analytical sound that doesn’t bore (at least for me). For others who crave more exaggeration, it can probably be slightly boring, but that’s exactly what helps it stay in my ears for the longest time out of the entire lineup of Rooth CIEMs.

LS8+:
Those looking for that little extra bit of excitement over the LS6 without going overboard with the LS-X5, will love the LS8+. It’s fully deserving of the ‘flagship’ moniker. While design-wise, it shares more in common with the LS-X5 (similar mid and high drivers in a triple bore configuration, except the LS8+ stratifies the low-mids and the lows with two pairs of dual drivers instead of the single dynamic driver), but it actually takes the basic LS6 sound and adds some pizzaz to both the low and high ends. It’s more airy, and more hefty in the bass. Refined, yet sparkly at the same time, the LS8+ retains all of the detail of the LS6. I believe that it has the most potential of “wowing” people on first listen, as it has a wide, airy soundstage that is almost reminiscent of those of electrostatics (grain of salt). Halo products should be that way, and I think Rooth did a good job in tuning it in a way that makes the sound exciting, yet refined at the same time. In the end, it doesn’t stay in my ears as much as the LS6 (call me boring, it’s okay), but it’s very, very nice, and deserving of consideration to be in the collections of enthusiasts nevertheless.

Update: GoldenEars has done a full set of measurements on the LS8+…

The frequency response chart for the LS8+ — looks a bit disjointed, but it sounds a lot better than it looks.

LS8:
The LS8 is surprisingly the most monitor-like of the bunch, though not quite the quintessential monitor sound. It’s warm in the mids, and reminds me of my 4.A with a little more bass and slightly less lower midrange presence. It definitely had a sound that was familiar to me, so it’s very pleasant, but while auditioning, I detected a partially-faulty DTEC driver on the left side that made a weird buzzing/vibrating sound so I don’t know if I was hearing it at its full potential. It has less noticeable sibilance than the LS8+ (though I wouldn’t say that the LS8+ is necessarily sibilant), at about the same level as the LS6, but has less clarity than both as well, even though it’s not really lacking in clarity, either. Unfortunately, it’s not really as airy as I’d hoped, which was surprising. All in all, it kept reminding me of my 4.A. Personally, the LS8 is a teeny bit too similar to my 4.A for me to go with it, but I’m sure the LS8 has its own set of suitors, namely those looking for a slightly warmer, more grounded, and more intimate sounding environment than the LS8+. With both the LS8 and LS8+ being offered at the same price, I think Rooth was wise to offer two different flagships for people with different tastes.

For more information on Rooth and its products, please visit HFI International and contact Tomo. As mentioned before, Rooth is undergoing a developmental overhaul, including a new website yet to be finished.

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Special Thanks to Tomo of HFI and Jason of JM-Plus