oBravo RA C Cu

Sound analysis.

I spend many hours analyzing RA sound performance across different sources, with different eartips, and playing variety of my favorite test tracks, such as: Agnes Obel “The curse”, Avicii “Lonely together”, C-Bool “Never go away”, Ed Sheeran “Shape of you”, Galantis “Hunter”, Iggy Azalea “Black widow”, Indila “Boite en argent”, Robin Schultz “Oh child”, David Elias “Vision of her”, Michael Jackson “Dirty Diana”, and Counting Crows “Big yellow taxi”. Also, considering hybrid design of RA with 16mm dynamic driver, I let it burn in for 150hrs, though without any noticeable sound changes, before getting deep into sound analysis.

RA has a mid-forward sound signature with a crisp sound and a super transparent neutral tonality, courtesy of the fast AMT-II tweeter. Tonality usually defines the color of the sound, and due to a more neutral nature of the bass and mid-forward signature of the tuning, the perception of RA sound is skewed toward a brighter side. If you focus on how RA renders the sound, especially the vocal tracks with natural non-synthesized instruments, you realize how neutral and transparent the sound is. If you analyze its FR response (I measured and ran multiple sweeps), you will hear 2k peak which gives the sound its crunchy characteristics, 4k peak which gives you a fast edge while avoiding the sibilance peak, and 12k peak which gives you that extra vivid clarity and high definition. This tuning results in a retrieval of details on micro-detail level with a clarity that picks up some very fast nuances in the sound.

But you need to keep in mind, due to analytical nature of the sound, it will not be as forgiving and it will also be very picky about source pair up, the latter one also having a lot to do with a design of the driver and its synergy with different sources. In cases with bad pair ups, synergy was ruined by making treble sound harsher and thinner. I’m not gonna deny, it took some experimenting with various sources, different eartips, and trying a new custom cable until I reached the sweet spot of RA sound. And then, when I taped the front DD vent, I was in for a big surprise when I heard the bass slam of RA’s mighty 16mm driver. But in my main sound analysis, the focus will be on the original tuning.

In more details, bass of RA is extended, goes deep, but stays neutral in quantity. It does come more alive in tracks where it’s called upon and hits harder in EDM tracks, but still maintains its neutral quantity with a very articulate and multi-layered quality. Mid-bass is faster than I expected from DD, not as fast attack like you would hear in BA drivers, but certainly with a short decay and overall very tight performance.

Lower mids are lean, thus don’t expect too much of a full body in here, while upper mids are very transparent, layered, micro-detailed, a little on a colder side, approaching analytical level without being harsh. Here you can hear a nice separation between the sounds, with air between the layers. This tuning is not for someone who wants a smoother or more natural/organic warmer sound. This sound is a bit raw and more revealing.

Treble extends far, very crisp and sparkly, super resolving with a vivid definition thanks to its 12k peak, but it’s not sibilant or harsh or fatigue. As I mentioned before, treble can get a bit out of hand with a bad pair up or a poor seal. Thus, I recommend taking your time to find the best pair up synergy before jumping to any conclusion about the sound.

Of course, I saved the best for last. The soundstage expansion was another shining star of RA tuning, with nearly an open back type of holographic expansion that paved the way to an impressive imaging with a very accurate positioning of instruments and vocals. We are talking about 3D imaging within holographic soundstage expansion. Here, the only limiting factor is your source.


Front vent tape mod.

The discovery of this mod came by accident. As I was going through tip rolling and finally settled on blue Comply eartips included with RA, I noticed a roll of blue masking tape in the kitchen (my kids were using it for some project). The combination of blue eartips and blue masking tape triggered a thought of covering up a pinhole vent in the ceramic part of the shell nozzle. Plus, masking tape doesn’t leave a sticky residue which could clog the vent.

After this mod, the quantity of the bass went up, and it also turned the mid-forward signature of RA-C-Cu into a more balanced sig with a warmer tonality and fuller body, while keeping the transparency and resolution of the mids and the sparkle of the treble. This truly unleashes the power of 16mm NDD, like a bass switch with a narrow bandwidth filter which only affects and scales up the quantity and the impact of sub-bass and mid-bass.

The bass becomes fuller, sub-bass rumble goes up in quantity, and the punch of mid-bass impact hits harder. Bass is still tight and articulate, but with a little slower speed and more analog texture. As a result of this mod, the sound now has more body and gains deeper bass impact I was craving for. I know, we are talking about TOTL IEM to walk around with a piece of tape, but I think it’s very cool to be able to go back’n’forth between two complementary sound signatures.


The following comparison was done using RA with and without a tape mod, and I volume matched each pair for consistency.

RA vs 64 Audio Fourte (Redcore cable, Symbio tips) – RA opens the sound wider, while both have the same depth in soundstage. As a result, Fourte soundstage is oval while RA has a holographic expansion. Without a mod, Fourte has a deeper and more elevated sub-bass rumble and stronger mid-bass punch in comparison to a more neutral RA, but once the tape mod applied, all bets are off because RA low end scales up with bass being a little more elevated than Fourte, but also tighter and more articulate. RA lower mids are leaner, more neutral than Fourte. Upper mids of RA are a little brighter and more transparent in comparison to a smoother and more organic upper mids of Fourte. Treble is where you hear the biggest difference where Fourte treble is brighter, more forward, more exaggerated in comparison to RA which has as much crunch and as vivid, but presented in a more transparent and more controlled way. Tape mod here only affects the bass, so with or without it, mids/treble remains the same.

RA vs 64 Audio U18t (Horus cable, M20 apex filter) – RA soundstage is wider, while both have the same depth with more out of your head (in a natural controlled way) stage expansion. Without a mod, U18t bass has more sub-bass and mid-bass quantity while in comparison RA has great extension but a lot more neutral quantity. With a mod, RA bass has a little more rumble and stronger mid-bass impact, but not by a whole lot. One thing to note here, even with a mod, U18t bass still feels faster and more BA in comparison to a little slower analog textured bass of RA. Both have a very articulate and layered bass characteristic. Lower mids are leaner in RA, while more neutral with a little extra body in U18t. The same with upper mids where RA is more revealing, more micro-detailed, and a little more analytical in comparison to a smoother and still detailed upper mids of U18t. Treble differs here as well, except now RA has an upper hand with more sparkle and crunch, while U18t has a good treble definition and sparkle, but smoother and under more control. Overall, RA has more transparency and a little more resolution. Also, with a tape mod, the bass of RA gains more impact and more analog quality, but sound becomes less coherent in comparison to U18t.

RA vs UM Mason V3 – Mason soundstage is a little narrower, while soundstage depth is very similar. With dB-Go bass off in Mason, it still has a little more sub-bass rumble and a touch more mid-bass impact, but after applying the tape mod – RA bass just explodes and has more impact, and more articulation than Mason with dB-Go bass on, though the bass speed is the same between these two. Lower mids in Mason are more neutral and smoother, with more body, while RA is leaner in comparison. Upper mids are more revealing, more micro-detailed, with a better layering and separation in RA, while Mason is smoother and more organic. With treble, both have a well-defined vivid crisp treble, but RA treble just sounds cleaner and more focused.

RA vs oBravo ERIB-1C – Both have a similar soundstage depth, while RA sounds wider and a little more open in staging. I’m not comparing with/without tape mod because I have a feeling if I tape ERIB, it could yield a similar increase in bass impact. When compared the bass, RA is more neutral, more articulate, tighter, and even a little faster, while ERIB bass is a little warmer, has more quantity, and a little less articulate in comparison. Lower mids of RA are leaner while ERIB-1C is more neutral and has a little more body. Upper mids in ERIB are smoother, a little warmer, while RA is brighter, more analytical, more layered, more micro-detailed. Both have a rather transparent mids, and even with ERIB being smoother, it doesn’t color sound as much. RA treble has more sparkle, higher definition. Both have a great treble extension, but RA has more airiness in comparison. In this comparison, you can certainly hear the effect of higher resolution of AMT driver vs PMD driver.



Page 4 – Pair up and Conclusion.

2 thoughts on “oBravo RA C Cu

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