Наушники — Koss CS340BT QZ

The CS340BT QZ is a wireless on-ear communication headset from Koss, the Milwaukee maker that launched the first stereophone, the SP/3, in 1958. Koss introduced it on 26 September 2022 and aims it at offices, call centres, telehealth and education, where a boom microphone and background noise control count for more than hi-fi features. Active noise cancellation sits alongside environmental noise cancellation for the microphone, and the list price is USD 99.99 with a one-year warranty.

Key specs that matter

Koss quotes a response of 20 Hz to 20,000 Hz and an impedance of 36 ohms. The link is Bluetooth 5.0 with a stated range of more than 9 m. Battery life reaches 30 hours on Bluetooth alone and falls to 22 hours once ANC is switched on. The cell is a 3.7 V lithium-ion pack of 420 mAh, or 1.6 Wh, charged through a USB-C port at 5 V and 250 mA, and a full charge takes three hours. Koss does not publish driver size, sensitivity or mass for the CS340BT QZ.

Engineering and use context

Voice pickup uses two microphones processed by cVc 8.0, an environmental noise cancellation algorithm meant to strip room noise from the outgoing call. The microphone sits on a pivoting arm, and the headset folds flat for storage in a bag. Leatherette cushions rest on the ear, and Koss frames them for hours of daily wear. Controls are on the earcup, and a status LED reports each state - three blue flashes at power on, one red flash at power off, a blue pulse every two seconds when connected, steady red while charging and steady blue when charging is done. A separate blue indicator shows whether ANC is active. First pairing starts by holding the power button for at least five seconds, after which the headset reconnects on its own to the last device. An integrated 3.5 mm audio jack lets the headset carry on as a wired unit when the battery runs low. The operating temperature range is 0 to 45 degrees C.

Pairing

As a Bluetooth headset it links directly to phones, tablets and laptops and needs no amplifier or DAC. For softphone and video call work on a laptop the wireless link frees the user from the desk within the stated range. The cable input suits a computer or player with a mini-jack output and keeps the headset usable even with an empty battery. Users who spend long shifts on calls can leave ANC off to reach the longer battery figure, then switch it on in louder rooms.

Alternatives

The Koss QZ99 is a wired over-ear model with passive noise reduction, a 60 ohm rating and a volume control on the earcup, listed at USD 64.99.