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Radius HP-TWF11 Pro “DDM”


Radius HP-TWF11r DDM 400x300.jpg

Reviewed Jun 2010


Details: World’s first dual-dynamic driver earphone from Japanese audio firm Radius

Current Price: N/A (discontinued) (MSRP: $219.99)

Specs: Driver: Dual Dynamic | Imp: 24 Ω | Sens: 105 dB | Freq: 10-18k Hz | Cable: 3.9’ I-plug

Nozzle Size: 5.5mm | Preferred tips: UE Single-flange (large)

Wear Style: Straight down


Accessories (3.5/5) – Silicone single-flange tips (6 pairs), cleaning cloth, and hard clamshell carrying case with removable cord winder

Build Quality (3.5/5) – The housings are plastic with the inner surfaces rubberized slightly. A thick rubber strain relief protects the cable entry point but doesn’t feel particularly well-integrated. The nylon-sheathed cord is relatively thick and doesn’t kink nearly as much as the Klipsch Custom series cabling. It is terminated with a metal 3.5mm I-plug with a short rubber strain relief

Isolation (2/5) – Quite average due to vented design

Microphonics (3/5) – Fairly bothersome and exacerbated by the fact that the DDM is difficult to wear cord-up

Comfort (3/5) – The DDM is a very tough earphone to get used to. It seems to be designed to maintain stability by virtue of seal alone. The cable exit point keeps me from tucking the driver-containing bulge inside my ear and the nozzle angle is rather odd compared to my other earphones. Though not uncomfortable per se when a proper seal is achieved, the DDM still never feels particularly secure to me. Expect to spend time experimenting with fit to get the most out of these


Sound (8.7/10) – While the ergonomics and aesthetics of the tongue-twisting Radius may leave much to be desired, sound quality is where the funky earphone really shines. By virtue of what I can only imagine is some sort of dark magic, the dual-dynamic-driver HP-TWF11R sounds more coherent than not only most IEMs in its price range, but just about any high-end earphone I’ve heard, period. I’ve said in the past that what a lot of the high-end multiple-BA IEMs do best is dissect a piece of music into the tiniest details to display the most minute intricacies present on the track. The Radius achieves the same result by opposing means – rather than dissecting the music, it presents an exquisitely blended sound that’s refined enough for the tiniest details to make themselves quite obvious. A side effect is that the the DDM takes a bit of getting used to and might not sound entirely natural at first listen. But let’s start from the bottom.


The bass of the HP-TWF11R is the foundation for the robustness of their sound signature. It is very extended, competing with my Monster Turbine Pro Gold and Future Sonics Atrios, and provides a bit of rumble and plenty of impact. Despite being impactful, the HP-TWF11R never loses balance – the bass is rather soft and polite in presentation. Unless a track specifically calls for bass dominance, the low end of the Radius never feels intrusive or aggressive. It keeps up on fast techno and trance tracks and provides the reverb and decay necessary for the proper portrayal of orchestral recordings. Midrange bleed is nonexistent and the midrange itself seems (sounds?) to be the meat of the DDM.


The midrange is fluid and coherent, not at all veiled but not forward as with the ATH-CK100 or thick as with the Ortofon e-Q7. It lacks the absolute transparency of the whimsical Yuin OK1 but still manages to be quite competent in expressing the emotion in vocals. The DDM shines when it comes to reproducing stringed instruments. The rather delicate presentation conveys every nuance of string motion and every intonation of the sound it produces, resulting in a surprisingly detailed sound despite the lack of Etymotic-like forwardness or aggression. The same goes for the treble of the DDM – it is equally polite and very clear but lacks the crispness and energy of the treble produced by certain armature-based earphones (e.g. ATH-CK10, ATH-CK100, TF10). Instead of smacking the listener in the face with detail and clarity the way the CK10 does, the DDM presents detail softly and never leans toward a treble-heavy sound, maintaining a slightly more grounded balance at all times. However, that is not to say that the DDM cannot convey authority – I feel confident in saying that the dynamic range of the earphone is one of widest I have encountered. Despite this, due to the way fine detail is presented, the DDM does not work as well at minimal volume as the Yuin OK1, ATH-CK10, or RE252 – not necessarily a con but simply result of their peculiar dynamics.


In terms of presentation, the DDM is a very airy earphone. The soundstage has very good width and depth and an ‘out of the head’ feel, seemingly compounded by the size of the earphones themselves. Despite the rather large sonic stage, I feel that the DDM works best with conveying the intimacy in recordings rather than spaciousness. Compared to the ATH-CK10, the positioning isn’t quite as precise and imaging isn’t as accurate. The DDM also can’t quite compete with the overall speed of my CK10 or CK90Pro but fares well enough for electronic music. Lastly, the DDM does like being given a bit of extra juice. Depending on the source and/or amp used, giving the DDM some leeway in available power can make it sound more dynamic, more fluid, and even more detailed. Is it a night and day difference? Not exactly, but it is noticeable. I’m not a big proponent of portable amps but if the DDM is your be-all, end-all earphone, a decent amp may be worth the investment.


Value (7/10) – Overall I found the Radius HP-TWF11R to be both incredibly infuriating and undeniably endearing. Their build quality, microphonics, and fit leave much to be desired for me. Granted, I have been spoiled by the ergonomics of the Audio-Technica IEMs along with my Q-Jays and, more recently, the Phiaton PS200, but for me the fit of the DDM is simply irksome. The sound, however, leaves an entirely different impression. Though the signature takes a bit of time to get used to, the DDM is easily one of the most balanced dynamic-driver IEMs I have heard and its sonic characteristics, in a way, make me think of a pyramid – robust, detailed, and consistent bass at the bottom, a voluminous and wonderfully integral midrange in the center, all topped up with a healthy serving of extended and unfatiguing treble – the whole thing in perfect balance (in this analogy the CK10 would be a free-standing upside-down pyramid – unsurprisingly polarizing but quite literally mind blowing under the right conditions). Couple all that with a great dynamic range and I feel confident in saying that the DDM is the best-sounding IEM I have heard in the sub-$200 category. Yes, I require more from an IEM than just sound quality. But if I were to buy an IEM specifically for home use, I’d be hard-pressed to find a better value and a more enjoyable overall listening experience than what the HP-TWF11R provides for the asking price.


Pros: Oh-so-beautiful sound, very nice carrying case

Cons: Finicky fit, mediocre isolation, microphonic





Living in the fast-paced city of Los Angeles, ljokerl has been using portable audio gear to deal with lengthy commutes for the better part of a decade. He spends much of his time listening to music and occasionally writes portable audio reviews across several enthusiast sites, focusing mostly on in-ear earphones.


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