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Nu Republic Cyberstud X4 Firefly specifications and in-depth review

Nu Republic Cyberstud X4 Firefly

Manufacturer: Nu Republic

The Nu Republic Cyberstud X4 Firefly are true wireless in-ear earbuds that come equipped with RGB lighting and a four-microphone setup, making them a feature-rich option within the wireless earbuds category. They ship with a travel bag and offer ambient sound mode alongside mute functionality, giving users reasonable control over their listening environment without reaching for a phone.

On the technical side, the Cyberstud X4 Firefly uses a 13 mm driver unit covering a frequency range of 20 Hz to 20,000 Hz, paired with both active noise cancellation and passive noise isolation. Connectivity runs through Bluetooth 5.3 with a maximum range of 10 m and a rated audio latency of 40 ms, while the USB Type-C charging port supports fast charging that brings the earbuds to full capacity in 1.5 hours. Total battery endurance reaches up to 72 hours when combining the 8-hour earbud playback time with the 64-hour capacity of the included charging case.

Pros
  • Both active noise cancellation and passive noise reduction are present, offering two layers of sound isolation
  • The charging case extends total battery endurance to 64 hours, which suits extended use without frequent recharging
  • Fast charging support reduces downtime when the earbuds need a top-up
  • A four-microphone array with noise-canceling capability makes for cleaner voice pickup during calls
  • Ambient sound mode allows users to stay aware of their surroundings without removing the earbuds
  • A travel bag is included in the box, adding practical portability out of the package
Cons
  • No water resistance rating means the earbuds offer no protection against sweat or rain
  • Wireless charging is not supported, requiring a wired connection every time
  • No in/on-ear detection means playback does not pause automatically when the earbuds are removed
  • The Bluetooth connection lacks support for high-quality codecs such as LDAC, aptX, or AAC, limiting audio transmission options
  • No find-device feature is available, making misplaced earbuds harder to locate
  • Fast pairing and NFC pairing are both absent, making the initial connection process more manual
Who is this for?

The Cyberstud X4 Firefly suits users who want a fully wireless, cable-free listening experience with an extended total battery life of up to 72 hours, making it a practical choice for frequent travelers or those who dislike charging their earbuds daily. The combination of active noise cancellation and ambient sound mode makes it a reasonable fit for commuters or office users who need to switch between focused listening and staying aware of their surroundings. Those who take regular calls will also benefit from the four-microphone noise-canceling setup, which supports cleaner voice transmission in moderately noisy environments.

Who is this NOT for?

Users who work out or exercise outdoors will find the lack of any water or sweat resistance a meaningful drawback, as the earbuds offer no protection against moisture. Audiophiles or listeners who prioritize high-fidelity wireless audio will be limited by the absence of advanced codecs such as LDAC, aptX, or AAC, meaning audio transmission quality is constrained to standard Bluetooth delivery. The earbuds are also a poor match for users who want a seamless, modern pairing experience, since neither fast pairing nor NFC pairing is available, and there is no find-device feature for those prone to misplacing their earbuds.

Design:

Fit In-ear
water resistance None
has no wires or cables ✓
are neckband earbuds ✕
wingtips included ✕
has RGB lighting ✓
has stereo speakers ✓
has UV light ✕
Has a display ✕

The Nu Republic Cyberstud X4 Firefly adopt a true wireless, in-ear design with no cables or neckband, keeping the form factor compact and uncluttered. They feature RGB lighting and stereo speakers, adding a visual element alongside their audio output. Wingtips are not included, there is no display or UV light, and the earbuds offer no water resistance rating.

Sound quality:

has active noise cancellation (ANC) ✓
has passive noise reduction ✓
driver unit size 13 mm
lowest frequency 20 Hz
highest frequency 20000 Hz
supports spatial audio ✕
has Dolby Atmos ✕
has Dirac Virtuo ✕
has a neodymium magnet ✕

The Cyberstud X4 Firefly handles noise management through both active noise cancellation (ANC) and passive noise reduction, offering two layers of isolation from ambient sound. Audio is delivered via a 13 mm driver unit covering a frequency range of 20 Hz to 20,000 Hz. The earbuds do not include a neodymium magnet, and there is no support for spatial audio, Dolby Atmos, or Dirac Virtuo processing.

Power:

Battery life 8 hours
Battery life of charging case 64 hours
charge time 1.5 hours
has wireless charging ✕
Has a solar power battery ✕
has a battery level indicator ✓
has a rechargeable battery ✓

The Cyberstud X4 Firefly is equipped with a rechargeable battery that delivers 8 hours of playback per charge, with the charging case extending total endurance to 64 hours. A full charge takes 1.5 hours, and a battery level indicator is included to help track remaining power. Wireless charging and solar battery options are not supported.

Connectivity:

has fast pairing ✕
Has USB Type-C ✓
Bluetooth version 5.3
has LDAC ✕
has LDHC ✕
has Bluetooth LE Audio ✕
has aptX Adaptive ✕
has aptX Low Latency ✕
has aptX HD ✕
has aptX ✕
has aptX Lossless ✕
audio latency 40 ms
has aptX Voice ✕
has Auracast ✕
maximum Bluetooth range 10 m
supports Bluetooth pairing using NFC ✕
Can be used wirelessly ✓
has AAC ✕

The Cyberstud X4 Firefly connects wirelessly via Bluetooth 5.3, with a maximum range of 10 m and an audio latency of 40 ms. Charging is handled through a USB Type-C port, though wireless charging is not available. The earbuds do not support fast pairing, NFC pairing, AAC, LDAC, LDHC, Auracast, or any variant of the aptX codec family, including aptX, aptX HD, aptX Adaptive, aptX Low Latency, aptX Lossless, and aptX Voice. Bluetooth LE Audio is likewise absent.

Features:

has ambient sound mode ✓
has in/on-ear detection ✕
has find device feature ✕
Supports fast charging ✓
can read notifications ✕
has a mute function ✓
can be used as a headset ✓
control panel placed on a device ✓
Has voice prompts ✓
travel bag is included ✓
Has an in-line control panel ✕
Has a temperature sensor ✕
Has a built-in camera remote control function ✕

The Cyberstud X4 Firefly includes ambient sound mode, a mute function, voice prompts, and fast charging among its core features, and it can function as a headset with controls managed through a device-side control panel. A travel bag is included in the box. The earbuds do not offer in/on-ear detection, a find-device function, notification reading, an in-line control panel, a body temperature sensor, or a built-in camera remote.

Microphone:

number of microphones 4
has a noise-canceling microphone ✓

The Cyberstud X4 Firefly features a four-microphone setup with noise-canceling microphone support, allowing for cleaner voice pickup during calls or voice input by reducing unwanted background sound.

Final Verdict

The Nu Republic Cyberstud X4 Firefly positions itself as a feature-packed true wireless option for everyday users who value extended battery endurance and versatile noise management. Its combined 72-hour battery system, dual-layer noise handling through both active cancellation and passive isolation, and a four-microphone setup make it a capable daily companion for commuters and remote workers alike. That said, the absence of water resistance, high-fidelity codec support, and seamless pairing features means it falls short for more demanding listeners or active users. Overall, the Cyberstud X4 Firefly is a well-rounded everyday wireless earbud that delivers on core usability without catering to audiophile or fitness-oriented needs.