Headphones — JBL JR310BT

The JR310BT is a Bluetooth on-ear headphone that JBL designed for children, sitting in the brand's Jr range next to the corded JR310. It dates from 2020, and the product is built around JBL Safe Sound, a volume ceiling set so that output is designed never to pass 85 dB. A set of reusable stickers comes in the box, letting a child decorate the outer cups.

Key specs that matter

Each cup contains a 32 mm dynamic driver specified for 20 Hz to 20 kHz, with an impedance of 32 ohm and sensitivity of 90 dB SPL at 1 kHz and 1 mW. Maximum SPL is 80 dB. The headphone weighs 115 g. Its lithium-ion polymer battery is rated 400 mAh at 3.7 V and delivers 30 hours of music with Bluetooth on, recharging from empty in under 2 hours through a USB Type-C port fed at 5.0 V and 1.0 A. A 5 minute top-up gives about 2 hours of listening. The ear cups are 6.5 cm high and 6.5 cm wide on the outside, with a 3 x 3 cm opening inside and a depth of 1.6 cm, dimensions chosen for small heads.

Engineering and use context

Because the level limit is part of the design rather than a setting in an app, a parent does not need to configure anything before handing the headphones over. The control buttons sit on the ear cups and are sized so that children can work them on their own. Comfort relies on a soft padded fabric headband and cushioned ear pads, and the frame folds flat into a compact shape for a school bag or travel. A built-in microphone with a sensitivity of -40 dBV plus or minus 3 dB lets the wearer talk with family or join a lesson with a teacher. JBL gives a maximum operating temperature of 45 degrees C. The package contains the headphones, a USB charging cable of about 0.2 m, the stickers, a quick start guide and warranty and warning cards.

Pairing

The link uses Bluetooth 5.0 with A2DP 1.3, AVRCP 1.5 and HFP 1.6 profiles, transmitting in the 2.4 to 2.4835 GHz band at under 4 dBm with GFSK, pi/4 DQPSK and 8DPSK modulation, and JBL states a wireless range of up to 15 m. Multi-point connection is also supported. Typical sources are a tablet, a phone or a laptop used for school, and since the headphones contain their own receiver and amplifier, nothing else is needed between source and ears.

Alternatives

JBL's JR310 is the wired counterpart for kids, using the same driver and volume limit with an anti-tangle cable, inline mic and remote at 105 g.