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Radius HP-TWF21

Radius HP-TWF21 Review

Radius HP-TWF21
Reviewed Mar 2011

Details: Radius’s follow-up to the world’s first dual-dynamic driver earphone
Current Price: $250 from (MSRP: $298)
Specs: Driver: Dual Dynamic | Imp: 24 Ω | Sens: 107 dB | Freq: 10-20k Hz | Cable: 4’ I-plug
Nozzle Size: 5.5mm | Preferred tips: Stock single-flanges
Wear Style: Straight down

Accessories (3.5/5) – Silicone single-flange tips (6 pairs), cleaning cloth, L-plug adapter, and hard clamshell carrying case with removable cord winder
Build Quality (3.5/5) – Overall build quality is very similar to the old DDM – the housings are completely plastic and the cord is nylon-sheathed for durability. The thin-stem design of the TWF21 does mean that the earphones probably won’t survive being stepped on the way higher-end Audio-Technica or Ortofon models might but for general use they should last if treated well. The nylon-sheathed cable is flexible and tangle-resistant and features a sliding rubber cinch. The metal-jacketed 3.5mm I-plug has a short rubber strain relief, same as the original DDM
Isolation (2/5) – Being a half-in-ear design with a rear vent, the TWF21 really doesn’t isolate much more than the original DDM did
Microphonics (3.5/5) – Less bothersome than with the original DDM but exacerbated by the fact that the TWF21 is very difficult to wear cord-up
Comfort (4/5) – With my average-sized ears, the fit of the new Radius is much more pleasant than that of the old earphone. The earbud-like design is reminiscent of the mid-range Phiaton models and Audio-Technica’s CKS series and fits perfectly into my outer ear. I especially like the way the cable exit point is positioned away from the antitragus – makes the earphones very comfortable for prolonged listening sessions. However, as is usually the case with earbud-style IEMs, over-the-ear wear without swapping channels is nearly impossible. I do also wish a larger selection of tips was included but other than that I have absolutely no problems with the fit

Sound (8.8/10) – The promotional materials for the new Radius claim that the earphone has been “carefully tuned” to provide more modest lows and clearer highs compared to the TWF11. Both of these claims are true to a degree but there is no mistaking the TWF21 for an analytical earphone. The bass, for one, is still enhanced. Low end extension is very good, competing with the likes of the Monster Turbine Pro Gold and Future Sonics Atrio. Sub-bass rumble is plentiful and there should be enough impact for all but the most unreasonable bass lovers. It is only the lack of a pronounced mid-bass hump that keeps the TWF21 from become a total bass monster. The reasonably level bass prevents the low end from becoming dominant over the rest of the signature. For an earphone with such impressive bass presence, the TWF21 is surprisingly soft-footed and polite with most of my test tracks – a far cry from the aggressive, hard-hitting bass of earphones like the Fischer Audio Eterna. It is not the sprightliest of earphones but it performed better than I expected with the Exaile album I’ve been listening to lately. At the same time, the attack and decay times are natural enough for realistic portrayal of the instruments in my classical and jazz recordings.

Because the bass of the TWF21 is so linear, midrange bleed is fairly low even next to the other top-tier bass-heavy dynamics. The midrange is warm, smooth, and slightly thick. To my ears it is neither forward nor recessed but otherwise reminds me of the HiFiMan RE262. Not a bad job by Radius as the 262 is one of the most technically capable dynamic-driver earphones I’ve ever heard. Detail and clarity are likewise very close to those of the best dynamics. Like that of the original DDM, the midrange of the TWF21 is fluid and oddly delicate. It is not as transparent as that of the Yuin OK1 or certain BA-based earphones but doesn’t lag too far behind, either. The treble, similarly, is smooth and polite. Like the original DDM, the TWF21 is quite laid-back at the top and leans towards the darker side of things when it comes to tone. Comparatively speaking, I feel that the TWF21 has just a bit more treble presence than the TWF11 but still lacks the effortlessness and extension of the Sennheiser IE8 or RE262. Similarly, the treble crispness and energy characteristic of many armature-based earphones is nowhere to be found. The detail, for the most part, is still there but it is presented softly and unassumingly. As a result, I’ve found myself turning the volume up a little higher than usual on a number of occasions.

The presentation of the TWF21 is spacious and engrossing. Personally, I think presentation is where the new and old Radius models most differ. Since I switch earphones very often, I never quite managed to get used to the way the original DDM presented music – the oddly intimate feel, combined with the thickness and sweetness of the earphones, never really sounded right when switching to the DDM from any other earphone. No such problems with the TWF21 – the soundstage is still just as wide and deep as that of the old earphone but is no harder to get used to than that of my Sennheiser IE7 or Xears TD-III. Actually, the presentations of the TWF21 and TD-III share several characteristics aside from large size – both earphones are good at presenting intimacy and neither has the pinpoint-accurate positioning of a high-end BA-based earphone such as the ATH-CK10 or Westone 4. Similarly, both earphones fare better than average when it comes to dynamics and accurate portrayal of timbre; in the case of the TWF21 – significantly better than average. Lastly, the TWF21 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. Not a night-and-day difference, but it can be noticeable.

Value (6.5/10) – Considering the overwhelmingly positive reception of the sound of the original DDM, it is no surprise that the signature of the new Radius HP-TWF21 strays little from that of its predecessor. There are minor tweaks to the bass and treble but the biggest difference for me is in the presentation – the original DDM really took a bit of getting used to but the new one consistently puts a smile on my face within the first few minutes of listening. Similarly, while the day-to-day usability of the original Radius DDM was at best a mixed bag, the new earphone is easier to live with. The isolation and build quality have not undergone significant improvement but the new earbud-style housings fit me much better and the cable noise is less noticeable. Whether the improvements are worth the extra ~$120 over the TWF11 is a personal choice but for those who, like me, were never quite happy with the fit of the original, the revision brings about a welcome leveling of sound quality and functionality – not a bad deal at all considering how well the W-series earphones perform to start with.

Pros: Oh-so-beautiful sound, very nice carrying case, comfortable half-in-ear form factor
Cons: Mediocre isolation, significantly pricier than TWF11 PRO model





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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