Review: Radius HP-TWF41 – All for the music

Disclaimer: The review sample of the Radius HP-TWF41 was donated to us by AudioNext from German. AudioNext is the official Radius seller in Germany. Big shout-out to them for doing this with us.


Radius is a brand that isn’t always known to the general public but the Japanese based company has been making some really great sounding universal inear monitors. If you’re into IEMs and keep track of the latest developments and new technologies then I’m sure you’re come across Radius before.

While Radius in the beginning was really serving a niche market, their products quickly gained popularity. That resulted in the brand becoming more known in US an EU markets and they keep getting more popular each day. A big reason for that is the HP-TWF41 we’re looking at today but Radius is not just about that IEM. Radius actually was founded in 1996 already and they are active in the development and sales of audio products, accessories for smart phones, Blue-ray discs, DVDs and memory cards for consumer markets.

Radius offers a whole range of IEMs (click HERE) but they also developed a music app which is called the NePLAYER app, and they advise suing that app for High-Res Audio playback.


I first heard (of) the Radius HP-TWF41 when I was visiting the AudioNext booth at the European Canjam festival in Essen. I quickly listened to it as I was on my way out of the building and at that time it didn’t impress. They guys insisted however that I’d take one home with me and now I am glad they did. Of course the HP-TWF41 isn’t a new IEM and it’s been around since late 2016 already (I think) but it deserves a full review on HFN, even after all that time. This IEM is often called the W n°4 as well.

The Radius HP-TW41 has a very sexy Burgundy(Red) color and a very unique look. Like the Sennheiser HD800 they have this backward kind of design that messes with your mind. What you think you need to plug in your right ear actually goes in to your left ear and vice versa. This design is called “Deep Mount” and it should deliver a tight fit to the ear canals, resulting in a rich bass reproduction. The best way to “wear” these IEMs is the cable down way, although it is possible to wear the cable over ear. When worn ear down, the cable exits at the front of the unit and not on the back, as is the case with most universals.

“Newly designed Deep Mount earpiece. Its’ unique shape provide tight fit to the ear canals providing a rich bass reproduction.”

The cable of the HP-TWF41 is terminated with MMCX connectors and as a result can be changed if you find one with recessed connectors. I however quite like the sleeved thin cable the Radius HP-TWF41 comes with. It’s comfortable, doesn’t suffer from too much friction noise and sounds great so I don’t see why I should change it. On the other end the IEM is finished with a gold-plates 135° 3.5mm plug. The technology used in the special IEM is remarkable as well. Radius uses something that is called DDM. DDM stands for Dual Diaphragm Matrix and the monitor actually uses two individual drivers they love to describe as: “Tweeter in front and Woofer in back”. 

The coaxial structure, having two drivers placed on the same axis, is a Radius own appropriately technology. Because of applying beryllium coating to the woofer’s diaphragm the frequency response is extended. Together with ceramic tweeter the transient response has been improved. The energy of low and midrange that is launched from the rear driver and comes out through the holes on the piezo driver, fuses with the high range energy on the same axis.

In short: beryllium coated 13mm dynamic driver + piezo ceramic driver for the highs


The Radius HP-TWF41 comes in a basic box and like so many other IEMs comes with a limited number of accessories. Included are a nice leather carrying case, 4 sets of ear caps (XS/S/M/L), one cleaning cloth and the manual/warranty. It isn’t the most generous set of accessories but that’s just the way it is.


The Radius HP-TWF41 sets you back around between $/€399 – $/€549 depending on where you get it. Looking at its plastic finish and the more limited number of accessories, that seems a little on the higher side. You get a unique design, the latest technology, good sound and an overall musical experience in return. There are other IEMs on the market with more drivers but they won’t sound like the unique HP-TWF41.


Driver Type Dynamic + Piezo
Driver Size Dynamic 13mm +Piezoφ12mm(Dual diaphragm)
Output Sound Pressure Level 108±3dB/mW
Frequency Range 10Hz〜45000Hz
Max. Input 20mW
Impedance 32Ω
Connector Φ3.5mm gold plated stereo mini plug
Cable Length Approx. 120cm (Y Type)
Weight Approx. 18g (includes cable)



The Radius HP-TWF41 is vented, you’ll find a mini vent on the inside of the unit, right where the type name is printed. The big advantage is that there is no pressure build-up inside the enclosure which is good for the driver/sound and some might even say your listening comfort, the only disadvantage is that music will leak out and noise will leak in to the monitor. While I do like using these IEMs on the way home in the train, they of course don’t isolate like customs do. They isolate enough however to clearly hear and enjoy your music but you will still hear people talking. I’ve on several occasions asked people if my music was audible for them but that never was the case.

Because of the vent, these IEMs do sound reasonably open sound-wise. When I first listened to them however in the noisy Canjam Europe building I was far from convinced. Because of bad sealing tips, the fit was extremely bad and the sound was thin and without any bass. When I got home I tried the silicone tips again that came with the unit but my ears simply don’t like these. Ever since I have been using Comply T-400 tips (if I’m not mistaken) and those not only isolate are extremely comfortable very well, they also bring out really good bass and mids. My point is that you should make sure to use the good tips for your ears, but that’s always the case when using universal IEMs. You’d be surprised how bad fitting tips can alter your IEM’s sound.

Sound continues on Page 2 after the click HERE or below

4/5 - (24 votes)

Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.


  • Reply April 7, 2017


    Check out on the black version TWF-31 for more balance sounding… I own TWF-31.
    Please don’t change the stock ear-tips… I tried with SpinFit, Comply, JVC Spriral Dot… all these tips makes the soundstage collapsed, no layering depth… Thanks

    • Reply October 26, 2018


      I agreed. I own TWF-41 and tired with SpinFit,Spiral dot, Sony Hybrid, Acoustone aet07, Comply all these tips soundstage collapsed and some tip make bass blur 🙁

  • Reply July 14, 2017


    Just got them – source is AK 70 and I use an Ifi micro BL but even without the Ifi is the sound incredible. Voices, bass, warmth, mood, soundstage – sweet. Against my Shure 535 it´s like night and day and I like them even more than the Audioquest Nightowl.

  • Reply August 9, 2017


    tried this one, one impression I had about it was that it sounds quite relaxed with good bass decay and relaxed mids… one stuck on my mind is the unique sounding highs though, Dunno how I should put my finger on it, the highs just sounds different form any other gears I listen the music on (is that the piezo driver working its magic?), I know it because I’ve been listening to it for testing gears for quite a while, and I don’t know whether to say I prefer the change or not. I did manage to swap the tips into a Spinfit which I had at the time, I prefer the Spinfit vastly.

    Just, at that moment, it doesn’t manage to wow me with my Sony XBA A3 at the side, the Sony just hit that much harder with sound sig I’ve known for long

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