Portable Dual-Mono Vacuum Tube Headphone Amplifier for Little Bears

The B4-X Headphone Amplifier: A Compact Tube Powerhouse

Parameters: Tube: 2x USA RAYTHEON JAN5899 Op Amp: 2x NE5532 (upgradable) Lithium Battery: 12V, 1000mA Charging Time: 2-2.5 hours Working Time: 4-4.5 hours Output Power: 450mW SNR: 105dB Suggested Load Impedance: 16-300Ω Outputs: 1x 2.5mm Balanced Jack, 1x 3.5mm Jack Dimensions (LWD): 1156923 mm / 4.52.70.9 in (without knobs)

Packing List: 1x Headphone Amplifier 1x Power Supply 1x 3.5mm Audio Cable 2x Bands

Notice: When using the B4-X with your cellphone, you may hear a "zhi ~ zhi" noise in your headphones. This is likely caused by interference from your cellphone's WIFI or 4G signal, which can interfere with the tube circuitry. This is normal, as tubes are susceptible to microphone effects. To avoid this, keep your cellphone away from the B4-X.

Q&A: Q: The right channel has static, even with different sources and headphones. A: The tube may have poor contact after shipping. Open the chassis and adjust the screw near the tube while listening. If the issue persists, the tube may be broken, and you can purchase a replacement 5899 tube locally. We will refund the cost.

Q: The amp suddenly stopped working with loud pops. A: This is likely due to the battery running out of power. Please charge the device. If the issue remains, contact us.

Q: The amp has a lot of electronic feedback/interference when a cellphone is nearby, causing popping in the headphones. A: Vacuum tubes are susceptible to interference from devices that can transfer signals, such as cellphones and routers. Keep the amp away from these devices to avoid interference.

Q: The amp cannot be charged, as something is loose inside the charger. A: The charger may be broken. Please contact us to receive a replacement.

The Difference between B4 and B4-X: 1. The B4-X is a dual-mono balanced version, with independent components, power supply, tubes, and op amps for the left and right channels, resulting in higher sound separation. 2. The B4-X has independent +12V and -12V power supplies for the op amps, reducing mutual effects and allowing it to drive 300Ω headphones. 3. The B4-X has a dual op amp parallel output, providing higher output power. 4. The B4-X offers both 3.5mm and 2.5mm balanced outputs, suitable for most balanced and standard headphones.

The B4-X's compact, unique design with a built-in tube allows you to enjoy a tube-driven HiFi experience on the go, with a full, delicate, and warm sound signature. The independent components and power supplies enhance the signal-to-noise ratio and channel separation, delivering superior sound quality. The built-in battery protection circuit ensures worry-free listening sessions without time limitations.

product information: