Review: oBravo Ra C Cu – Top of the line



In this topic I’ll be describing the Ra C Cu how it sounds at its very best. That means in Single Ended mode hooked up to the Audiovalve Solaris in OTL mode and the Comply Foam T500 tips. And in that case the oBravo Ra is one of the most impressive universal inears in the world.

With this combo, Ra sounds incredible and I haven’t heard a single other universal monitor sound like this. Where I would normally say the naturalness, dynamics or precision is really good, it’s of the chart here. And it does that for so many things, that the only way to describe it is: Heavenly. The sound is so realistic and rich and it’s presented in a smooth and warmer way, it’s to die for. The copper Ra has great extension and the decay is very impressive to say the least. You from top to bottom get top level clarity and a very clean sound.

No this isn’t a neutrally tuned IEM, but it’s a realistic and natural one. Ra give you all the detail there possibly is, and it combines it with the perfect speed, spaciousness and airiness. And of course it does all of this in a very musical way without ever getting lost in too many details or anything else. The sound stage is wide and deep, layering is exemplary. There’s nothing bad about it, it’s jaw dropping.

When you’re listening to this setup you can exactly pinpoint the instruments and their location. You’re not listening to IEMs, and the sound is everywhere. It’s like sitting in a perfectly quiet, sound treated room where you’re listening to the best possible speaker setup. The presentation is open and Ra immerses you in a sea of perfect sound. Too much? Well sorry then, but it’s just so darn good.

The bass body is bigger than neutral but bass is extremely well done with great depth and detail. The impact is definitely there but bass at the same time will never take over the mids or become overpowering. If you’re a fan of hardcore trance or anything like that you might prefer a faster and even tighter kind of bass, but I really can’t complain about how oBravo tuned the bass. If I would really have to point out something, I’d probably say it rolls off a tad early but that’s really nit-picking there. It really is top notch bass, and I usually describe it as listening to bass from high end speakers, only right next or in your ear. Impressive bass, that’s for sure.

The mids, which perfectly connect to the bass, are just as rich, layered, spacious and natural as the bass is. Underpower it however and the mids will sound very dark, muffled even. Get it right and you’ll smile like never before. I can’t remember who ever started using the word “rhythmicity” in reviews, but the mids are just that!

The treble section is very extended and lively. I really like my treble – I must be getting older – but I can see the Ra C Cu being a tad hot for some of you, especially when hooked up to a source with less synergy. I guess that’s also where the tubes come in as they perfectly keep the treble section enjoyable. No that doesn’t do it justice, with the right source treble is extended, rich and has perfect decay. Treble is energetic and lively ad it blends in perfectly with the mids and bass section.

With the right amp/source, you simply get an incredible level of sound. With a less synergetic one, the results will be different. So let’s dive into the different combos!

Amplification & Sources

I’ll split up this section in five different topics : Desktop amps, portable amps, DAC/AMP combos, portable players and others.

Desktop amps

If you skipped the review to this section you will have missed me saying the Audiovalve Solaris in Single ended mode with the OTL setting is my favorite source for the Ra C Cu. You get the best possible bass, richest mids and most energetic treble. To me it’s the best all-round performer and the Solaris gives it a very natural sound, presented in a smooth and lush way, where musicality and richness are the key words. This setup (without DAC) sets you back around $15K already, but man is it good! See above for more details.

Another high-end tube amplifier in my main setup is the Auris Audio Headonia which we reviewed just a few weeks ago. The Headonia has a less smooth and warm character compared to the Solaris, and it has a more neutral presentation of sound. With the Ra C Cu, the Headonia sounds best with the impedance set at 80 and 150 but it’s completely different from before. The combo here misses clarity and precision and you get a dark presentation where the bass is undefined and the mids sound muffled. Treble is very soft and not sparkling at all. This combination just doesn’t work, it’s a shame really as the Headonia is a great 2A3 amp for full sized headphones.

The solid state Violectric V281 is a powerful amplifier and it up to today still is one of my favorite ss amps. The synergy with the Ra is excellent and you get great clarity, top level detail and all that in a clean yet warmer and musical way. The music sounds powerful and especially the decay, left/right balance and extension is impressive. You don’t get the same immersive experience as with the Solaris but this is a top quality sound. The sound stage width in this combo is excellent but it isn’t as deep. Layering is good but not exceptional. The bass is tight, mids rids and treble playful, I could live with this setup each and every day.

The Astell&Kern Acro L1000 is an amplifier I’ve been using and enjoying daily at my day job. It’s a beautifully designed amp and its tuning is all about clarity and precision and the delivery is more neutral. It plays great with most of full sized headphones and my customs in balanced mode but with the Ra C Cu it sounds best in single ended mode. It doesn’t reach the level of the V281 but it’s still very good. Clarity is even better, bass is tighter and the pace is faster. Bass is also lighter though, the mids are a bit leaner and the treble is extra clear. All-in-all a flatter presentation where the focus is on detail, where the Violectric’s is at warmth and musicality.

One of the latest additions to my tube amp collection is the Felix Audio Euforia. I’ve been really enjoying it with the 7236 power tubes. Euforia is always dead silent and it’s the case with the oBravo as well. Actually only Ra only picks up noise from the Headonia. Anyway, the synergy with the Euforia is good but the focus here is on the bigger bass. Unfortunately it isn’t as tight or fast. Treble is excellent though. All in all the sound isn’t as wide, layered or deep as it is with the Solaris but what bugs me most are the darker mids. Once you know how they can sound, it’s hard to not want it again. Conclusion: an acceptable combo, but not the very best.

The Cayin Ha-1A mk2 is a dark and warm sounding tube amp, which is a perfect match for many Audeze’s and other full sized headphones. I don’t really like it as much with inear monitors and it’s no different with the oBravo Ra C Cu. The sound has a good pace but it becomes overly dark in the mids with too soft and flat treble. Bass is impressive but because of the effect the amp has on mids and treble, it overpowers them. The Ra also picks up some noise from the circuit and that for me is a fun killer. This is a no go.

The Auris Audio Ha 2 SE is one of those amps that can easily “do” a whole lot of ear- and headphones. Compared to its big brother it is warmer, smoother and more romantic sounding with a wide series of headphones. The Ra C Cu sounds best on the HA2 SE with the 80 and 150Ohm setting and I personally prefer it most with the 80 one, as it brings out the clarity, upper mids and treble most. For me the Ra matches better with the HA2 SE than it does with the Headonia but I’m still missing some clarity in the mids and treble region. You get a slower, warmer sound that is thick down under but to me it’s mostly the mid clarity which is missing here. Doable but not the best.

Conclusion: it’s a picky IEM! My 2 favorite Ra-proof amps are the V281 and the Solaris, that’s for sure.

Portable amps

For the selection of portable amps I have only selected my favorite, best performing ones. That means we’ll be looking at several CypherLab units, The PlusSound Cloud Nine and the Meier Audio Quickstep.

First up is one of my all-time favorite portable amps: the CypherLabs Duet. And it doesn’t let me down this time either, as the synergy with the Ra is really good. Even in low gain, the Duet drives it with authority and you get pure clarity and excellent pace. You get the same powerful sound as with the full sized V218 amp but at a lower level. This still is very good sounding however, with fast, tight bass, rich musical mids and energetic and happy treble. A really great setup for on the go, and even a desktop setup. Excellent combo.

More on amps and Sound on the NEXT PAGE

3.8/5 - (44 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 May 16, 2018

    Dave Hutchinson

    I guess a couple of good comparisons might have been the Audeze LCD-i4 or the Shure KSE-1500?
    Of course, they aren’t the same price but they are TOTL IEMs and with the law of diminishing returns it would be a very interesting comparison.

  • Reply June 18, 2018

    Guy Lamaar

    If you look at the price delta between the Ra-C-Cu and the “standard” Ra-C, that’s some pretty expensive copper. I think I’ll wait until oBravo release the -Pt or -Au variants; hopefully, they’ll be priced a little more realistically …

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