oBravo RA C Cu

The price to hear the God of the Sun!

PROS: unique hybrid design, solid build, the only IEM with AMT tweeter, super transparent crisp sound, luxurious accessories.

CONS: price, sound dependency on source pair up, modified oB-mmcx connector.

The product was provided to me free of charge for the review purpose in exchange for my honest opinion.

Manufacturer website: oBravo, available for sale on Audio Sanctuary.


My first experience with oBravo was a year ago when I reviewed ERIB-1C, their 2-way hybrid flagship featuring Dynamic Driver (DD) and Planar Magnetic Driver (PMD). After the review, I received questions with some people still arguing who was the first to implement PMD in IEMs, but the fact remains that oBravo was an early adopter of PMD drivers in IEMs since 2015. Also, at the time of ERIB-1C review, I didn’t even scratch the surface of their other exclusive AMT tweeter design where oBravo took “ribbon” technology of Air-Motion Transformer drivers found in floor speakers, and scaled it down to fit into IEMs of their EAMT series. While others now feature PMD drivers in their IEM designs, as far as I know – AMT is still exclusive to oBravo.

The company continued their R&D work until the next gen AMT-II driver saw the light of day, but unlike the original AMT tweeter used in various EAMT-1 through EAMT-5 models, this driver is exclusive to EAMT-0 only which became their new flagship under the name of RA. Furthermore, while ERIB and EAMT series feature aluminum body main shell with a choice of ceramic, wood, or aluminum nozzles (front of the shell chamber part), oBravo added 2 new options for RA with Copper and Titanium main shell body and a ceramic nozzle, each one with a different sound characteristic. As I mentioned in my ERIB-1C review, going through oBravo catalog feels like building a custom UIEM where you choose either PMD or AMT tweeter, pick the size of DD, select main shell material, and then finalize a nozzle.

But this premium technology comes at a premium price. When I attended CanJam NYC early this year, there was a lot of buzz surrounding RA where many wanted to see $10k IEM. The buzz wasn’t centered as much around how it sounds or the exclusive tech behind AMT-II drivers, but rather about the price which raised people’s expectations. And on top of that, many visited oBravo table with their iPhones and portable underpowered DAPs. For example, I had WM1Z DAP with me, and even that wasn’t the best pair up, while later I discovered SP1000 SS having a much better synergy with RA (to my ears). At least in the follow up audio shows and meets, I noticed (from their social media pictures) oBravo table is now filled with a variety of more powerful sources to drive RA to its full potential.

Furthermore, while working on this review, I talked to a few audiophiles with exotic 2 channel systems and others who use high end flagship electrostatic and planar magnetic full-size headphones with some expensive desktop amps and pricey cables (for both the audio and the power). I wanted to understand why they invest so much money into audio gear setups which are not even portable, and many replied back with the same explanation of looking for a specific sound signature and willing to pay premium to reach their goal. As they say, to each their own. And I think it’s great to see oBravo attending more international audio shows where people can audition RA and other IEMs, try it with different sources, and search for IEM equivalent of their desktop setup. Or if you are close to any of the oBravo distributors, it’s a good idea to setup an appointment to hear it firsthand.

But for others who can’t make it to the shows and curious about the sound tuning or the technology behind RA-C-Cu IEM, I hope my review will be able to shed some light on it. Perhaps, I won’t be able to answer the burning question about its premium price, but I certainly would like to share with you what I hear and how I hear it.


Unboxing and Accessories.

Considering the ultra-flagship status and pricing of RA model, oBravo decided to take the unboxing experience and the quality of accessories to a whole new level. Many people ask me why I even bother to include Unboxing section in all my reviews. In my opinion, manufacturers put a lot of effort to make their product more presentable, and in case of RA you can certainly sense that.

You start off with a rather large pressed cardboard container that feels like it’s made from a recycled material which probably carries a message of environmental awareness. It’s a large box, like a plant container, and when you lift the lid up – you see the top layer of secure foam cutout with RAs, 6.3mm adapter, and 2 storage boxes. I have used the term “jewelry box” in many of my previous reviews, while here you can find a real jewelry box, 6″ x 6″ x 2 3/4″ dark stained wood jewelry box with a shiny lacquer finish, metal latches, push button lock, and foam/velour insert for RA storage and display showcasing.

In addition, you have another carry box which is more transportable than jewelry box above, and has a natural wood finish, solid metal hinges, and a magnetic lock. Inside you have a removable wooden spool to wind a cable for storage and two cutouts with straps to secure RA shells. This particular box is smaller in size, about 3 1/4″ x 3 1/4″ x 1 3/4″, but still not exactly pocket friendly, only transportable. I can imagine that oBravo didn’t want to cheapen the look of the accessories, but I think there is no harm to include a pocket friendly slick leather case. Maybe they can consider it in the future.

When the top layer of foam insert is removed, the bottom foam tray insert has a cleaning/wipe clothe, a set of Comply T500 (blue foam) S/M/L eartips, a set of generic silicone S/M/L eartips, and a 3.5mm SE cable with oB-mmcx connectors. oBravo offers to their customers these oB-mmcx connectors by request so you can use them for custom cables.


oBravo IEM comes with a proprietary mmcx connector which has an interlocking design. Though it comes with mmcx based connector, there is a little notch on the cable side and the extended collar on the shell side where a cutout interlocks with a notch, preventing cable from rotation. There is no denial, mmcx connectors are more prone to issues, in comparison to 2pin, because the cable is not fixed from rotation, the dirt and moisture can get inside causing loss of contact and oxidation, and in general you get faster wear’n’tear. This modified connector solution addresses most of these issues. But at the same time, many audiophiles already have various 2pin and mmcx replacement cables which they won’t be able to take advantage of, though you can use oBravo cable with any standard mmcx connector IEM.

The provided OFC cable looks basic, with a gold plated straight 3.5mm TRS plug in a slim laser etched aluminum housing and a nice strain relief. Y-splitter has a matching design, no chin-slider. The earpiece connectors also match the headphone plug and y-splitter finish, and have a color-coded Red (right side) and Blue (left side) rings for ID. Depending on how you wear RA with a cable up/down, you can switch between L/R sides and the color rings are the only indicators of which side is which. The cable jacket has a neat tight nylon braiding, making the cable look like a shoestring, but be aware those are usually susceptible to more wear after a while of use. Plus, due to a tight braiding and the selection of the material – there is a noticeable microphonics effect. A balanced cable also available, and it’s identical in build and design, only the jacket is white and it uses 2.5mm balanced connector.

Since oBravo offers oB-mmcx connectors to customers who want to consider an alternative cable, I contacted PlusSound with a request for an aftermarket cable solution for RA. Due to a very small diameter of the connector, they suggested to consider X-series slim single conductor cables, and try Gold Plated Copper (GPC) wires which have a transparent sound and should add some body with an improvement in resolution.

PlusSound X-series GPC (gold plated copper)

PlusSound X-series cable features a Type 6 Litz configuration where wires have 6 enamel-coated groups with multiple strands to decrease electrical anomalies (such as skin and proximity effect causing microphonics), to minimize oxidation (preventing wires turning green), and to improve conductivity (electric signal usually travels on the surface of the wire, thus multiple thin strands will have a better conductivity and a smaller resistivity). Also, these wires are cryogenically treated for strengthening purpose to enhance their reliability and longevity. Furthermore, the wires itself are UP-OCC manufactured, referring to Ultra-Pure Ohno Continuous Casting process developed and patented by Professor Ohno of CIT in Japan.

X-series PlusSound cable doesn’t look like a traditional multi-braided heavy cable. It’s part of their ultra-portable series which is lightweight, flexible, using thin 26AWG gauge wires with only 2 twisted cables. Due to a small diameter of oB-mmcx connectors, it’s impossible to use multi-braided wires, and this wire fits perfectly. One important thing to keep in mind when you are ordering custom cables for oBravo IEMs, makes sure to request a cable without memory wires or pre-shaped flexible earhook so you can use the cable wire up or down. The transparent shielding and clear chin-slider and the golden tone of the wires, along with custom slim bronze y-splitter, matched the tone of RA copper shell nicely. There are many ways to customize the cable, just talk to your cable manufacturer to find out all the available options.

But this specific PlusSound GPC cable doesn’t just improve the looks and the ergonomics, I was also able to hear some improvements in sound performance.

Stock (OFC, bal) vs PS X-series (GPC, bal) – Stock OFC cable has a little smoother and a little warmer tonality. With PlusSound GPC cable I hear the improvement in transparency – the sound is not as warm, less colored, more transparent and more resolving, even with some improvement in retrieval of details without making the sound harsher.

I thought it would have been ironic to mate RA with EA Horus cable considering both names associated with Egyptian mythology, but I was afraid that EA Horus cable will not be a good pair up due to its brighter revealing tonality which can make RA sound harsher.


Page 2 – AMT Technology, Design, and Eartips selection.

Page 3 – Sound analysis, Front vent tape mod, and Comparison.

Page 4 – Pair up and Conclusion.

3 thoughts on “oBravo RA C Cu

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