Boult Audio K40 TWS Earbuds

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  • Bluetooth version 5.3
  • Low Latency Gaming
  • Fast Charging
  • IPX5 water resistance
  • Quad Mic AI-ENC
  • BoomX tech
  • Multicolor options
  • Touch controls


Boult Audio K40 Quick Features Review

Boult Audio continues to shake up the budget audio game, and their K40 true wireless earbuds caught my attention with promises of booming bass and marathon battery life. As a seasoned tech reviewer, I decided to put them through their paces.

Build and Design: Functional, Not Frills

The K40s sport a classic in-ear design with short stems. They come in various colors, but the all-plastic construction won’t be mistaken for premium. Thankfully, they feel sturdy enough for the price. The included silicone ear tips in multiple sizes should ensure a snug and comfortable fit, even for extended periods.

Audio: All About the Low-End

Let’s be clear: if you’re a bass addict, the K40s might be your new best friend. Their 13mm drivers and Boult’s BoomX technology deliver a punchy, bass-forward sound experience. Hip-hop, electronic music, and action movies will rumble to life. Mids and highs aren’t totally lost, but they take a backseat to the low-end emphasis. This might not be everyone’s cup of tea, especially if you prefer a more balanced sound signature.

Calling: Decent in Quiet Spaces

The K40’s “ZEN” Environmental Noise Cancellation (ENC) and quad-microphone array aim to improve call clarity. In my tests, they performed well enough during calls in quieter environments like your home or office. Busy streets or crowded cafes will overwhelm noise reduction, leading to less than ideal call quality.

Gaming: Stay in Sync

Mobile gamers and video enthusiasts will appreciate the K40’s low-latency mode (45ms). This significantly reduces the annoying audio delay often present with wireless earbuds. Whether it’s the gunfire in your favorite FPS or the dialogue in a movie, the audio syncs up nicely for a more immersive experience.

Battery Life: Endurance Champion

Boult wasn’t kidding about the K40’s battery endurance. They promise a staggering 48 hours of total playtime (including the charging case). I consistently got near those numbers, making these a great choice if you hate frequent recharges. Even if you do run low, a mere 10 minutes of charging gives you 100 minutes of playback – perfect for those on-the-go power boosts.

Connectivity: Stable Basics

The K40s feature Bluetooth 5.3, providing a generally smooth and reliable connection in my testing. Range was decent, but walls and other interference can cause the occasional hiccup. They don’t support higher-end audio codecs like aptX, which audiophiles might miss, but the average listener likely won’t notice the difference.

Other Features

  • IPX5 Water Resistance: Handle workouts and light rain without worry.
  • Touch Controls: While responsive, they are limited to basic functions – play/pause, answer calls, and switching between low-latency and normal modes.


  • Powerful, bass-driven sound that will please bassheads
  • Truly impressive battery life
  • Fast charging is incredibly convenient
  • Affordability makes them a great value
  • Comfortable and secure fit, even for extended sessions


  • Sound signature is heavily bass-focused, potentially overpowering for some
  • Call quality is decent but struggles in very noisy environments
  • Lack of active noise cancellation (ANC)
  • Build quality feels functional, not luxurious


The Boult Audio K40 truly delivers on its core promises: big bass and epic battery life at a budget-conscious price. These are an excellent pick for those who want a fun, bass-heavy sound signature and don’t want to constantly worry about recharging. If you prioritize a balanced audio profile or absolute call clarity, other options might suit your needs better.


  • Q: Can I use one K40 earbud independently? A: Yes, they support single earbud use.
  • Q: Are they compatible with both Android and iOS? A: Yes, they’ll pair with most Bluetooth-enabled devices.
  • Q: Is there an app for customization? A: Unfortunately, no dedicated app is available.

Price History


Additional information

Specification: Boult Audio K40 TWS Earbuds

General Details
Model Name

Boult Audio K40

Water Protection Details


Connectivity Specs
Bluetooth Version


Other Connectivity Details

Bluetooth, Google Fast Pair

Charging Details
Charging Port

Type C Charging Port

Fast Charging

10 min charge = 100 min playback time

Audio Features
Driver Size


Audio Features

13mm Bass Driver, BoomX Technology

Battery Features Details
Single Earbud Battery Life

Upto 7 hours

Total Battery Life with Case

Upto 48 hours

Battery Capacity Details

Gaming Features
Gaming Specs Details

Combat Gaming Mode

Latency Specs

45ms Low Latency

Calling Specifications

4 Mics

Other Calling Specs

AI Powered Zen Quad Mic ENC

Controls Details

Gaming Mode, Next/Previous, Play/Pause, Reject/Answer Calls

Touch Control


Noise Cancellation Features
Active Noise Cancellation(ANC)


Noise Cancellation Features

Environmental Noise Cancellations(ENC)

More Features
Other Features

AI Voice Assistant, BoomX Drivers

Launch Date

December 2023

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