Audiophile IEMs with a true wireless form factor - the new Onyx Prime are an exciting addition to the earphone market! The Onyx Prime earbuds have a peculiar square shape design with a thick and wide stompy stem measuring 1.5cm long, 1.3cm wide and 0.5cm thick. Total length of the stem body is 2.5cm long.

The Onyx Prime earbuds are bigger than most true wireless but with good reason. They're equipped with dual drivers (2 drivers per earbud) that includes a balanced armature (BA) driver and a dynamic driver (DD) that create a wider and more detailed sound stage than you get with a pair of true wireless earbuds. The sound separation is very good. Vocals stand out cleanly from the higher and lower tones and, you are also able to hear sub-bass and upper midrange, which makes the audio more dimensional.

The Onyx Prime charging case lid stays upright securely, although it has a weak hinge so, the lid wobbles when moving the charging case around. The narrow oval shape of the charging case makes the base curved so, you cannot lay it upright on a desk unless you plug in the charging cable. The charging case has the word Tronsmart carved onto the top of the lid. The smooth matte coating prevents fingerprint smudges. The Onyx Prime charging case holds 26 hours of additional charge and takes 2 hours to charge to full. The case dimensions are 7cm long, 2.5cm thick and 4.5cm high. Weighs 40 grams.


Despite the bulky look, the Onyx Prime earbuds are very lightweight, weighing just 6.5 grams each. The fit is comfortable too, thanks to the smooth glossy plastic, which doesn't mark easily with fingerprints. Because of the thick nozzle neck, the Onyx Prime earbuds aren't the type that insert deeply inside the ear canal, which is ideal for those with small or sensitive ear canals. If you prefer a more slimline look, check out the Apollo Air earbuds.

 

The fit is secure too, thanks to the rubber wingtips anchoring inside the concha of the ear. There are different size wingtips (and eartips) included with the Onyx Prime earbuds. The Onyx Prime earbuds take 2 hours to re-charge with 7 hours (per earbud) of listening time at 50% volume via SBC codec. Battery life is slightly less (around 6 hours) when listening via aptX or AAC.


The outer side (faceplate) of the Onyx Prime earbuds features the touch control area, ENC microphone and status led indicator, which does not blink when listening to audio. The microphone for calls is located at the tip of the stem. Call quality is loud and clear with very good noise reduction supressing unwanted noise in the background.


Onyx Prime uses a Qualcomm Bluetooth 5.2 chip (QCC3040) that supports absolute bluetooth volume, aptX Adaptive, regular aptX, AAC and SBC audio codecs. Multipoint connection is not supported. Paring the earbuds is easy, although the earbuds have to be taken out of the charging case in order to make the bluetooth connection. 

 

With other earbuds such as the Onyx Free and Onyx Ace, you can keep the bluetooth connecton active while the earbuds remain in the charging case. This is specially convenient when you want to answer a call quickly. Other than a 2 second re-connection delay, switching between earbuds (for mono listening) is seamless without the audio pausing or bluetooth disconnecting.


Touch controls are responsive, requiring only a light tap. Touch controls include play/pause, volume (up/down), skip tracks (next/previous), calls (answer/end/reject), voice assistant and game mode and, they're activated via a series of tap combinations and long presses. There are a lot of functions to remember but you can remap the touch controls via the Tronsmart mobile app and, you can even disable some functions, which is something you cannot do with most app supported earbuds. 

 

The Tronsmart app features a built-in equalizer too with 8 sound presets to choose from. When game mode is activated, you will hear a voice prompt saying "game mode on"/game mode off", although the voice prompt is a bit faint at max volume. Speaking of volume, you will also hear an audible beep when reaching max volume.

The Tronsmart app has a clean user interface which is easy to navigate and displays battery levels for each earbud. An account registration is not required to access the app, which is nice. The only issue experinced with the Tronsmart mobile app was the firmware upgrade, which failed to update.


Onyx Prime come packaged inside a huge hard cardboard box with a removable foam insert protecting the earbuds. The packaging looks and feels premium and, it's very eye-catchy with big bold orange letters. The user guide that comes with the Onyx Prime earbuds also deserves mentioning because it isn't the usual black and white but a glossy full-color user guide.


Accessories include different size bowl-shaped eartips and different size wingtips neatly organized on a tip plastic holder. The eartips are soft and made of thin silicone. They're very comfortable, although you probably may want to use thicker eartips to increase the bass response and passive noise isolation. The charging cable included is a generic USB-C cable. You can buy the Tronsmart Onyx Prime earbuds from Amazon.com and amazon.co.uk when they become available. Check out the review of the Tronsmart Onyx Pure earbuds.