Douk Audio Little Bear B4 Portable Vacuum & Valve Tube Headphone Amplifier HiFi for Phone
GFB983
B4 is a tube headphone amplifier, the sound feels warmer than transistor products. It has built-in battery protection circuit. It powers off automatically after fully charged , and the charger LED will turns to green.
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Description
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B4 is a tube headphone amplifier, the sound feels warmer than transistor products. It has built-in battery protection circuit. It powers off automatically after fully charged , and the charger LED will turns to green. Can realize the use of human intelligence. Else . When you charging the battery. This B4 amplifier can not turn ON until you pull out charger interface. because we design it work like that, just make battery safe.
Direction for use:
1. .Ipod / Cellphone / MP3: connect to B4 INPUT socket by 3.5 to 3.5 audio cable.
2. .Switch & volume control share the same knob: Please rotate the VOL Knob to the left, then plug in your Headset / earplugs to HEADPHONE socket.
3. .Turn on your media player, and tune VOL knob from left to right till the volume is suitable.
4 .Turn off: When you do not want to listen, please take off the headphone, turn down the volune till the machine is powered off.
Notice:
when you using B4 with your cellphone, if you fell some "zhi ~ zhi" noise into your headphone That's usually the cellphone effect it Sometimes, it's cellphone WIFI, or 4G signal effect the tube Then the noise into the sound... . That's normal. Because all tube with some microphone effect case. Solve way is. just move your cellphone as far as possible from the B4.
Performance parameters:
Frequency response range: 0-100K-0.1dB
Gold-plated input / output socket
NE5532 OP chip (you can upgrade it to a other better brand OP chip. Like BB or Muse)
Original nichicon electrolytic capacitor
TOP HiFi Original DALE resistors.
Precision rings resistance.
Battery: Lithium batteries, voltage: 12V, 1000mA
Charging time: 2-2.5 hours to charging full the battery
Working time: 4-4.5 hours
Output power: 450mW
SNR: 99dB
Suggest load impedance: 16-400Ω
Size: 115 * 69 * 23 mm1 (Length XWidth X Depth) (The measurement does not include the knob size.)
Reference data for 5899:
(A type Amplified state):
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