Description

With built-in battery protection circuit: battery lets your listening feast without time limitation. It can't be turned on during charging and will power off automatically after fully charged, and charger LED will turn to green. Add to Favorites Seller Join newsletter New Arrival Ending Soon View Feedback About Us Contact Us View All Categories Nobsound & Douk Audio Add-on Items US Warehouse UK Warehouse DE Warehouse AU Warehouse Digital Amplifier Tube Amplifier Audio Amplifier Preamp & Phono Stage Headphone Amplifier DAC & Audio Adapter Audio Splitter/Switcher Audio Processor Audio Player Music Spectrum & Clock Empty Chassis Record Player & Turntable Part Power Supply Vacuum Tubes Hi-Fi Speakers Hi-Fi Cable Transformer Radio Communication Audio Accessories Other Home Feedback Save Seller New Listed Ending Soon Contact us Store Category Nobsound & Douk Audio Add-on Items US Warehouse Add-on Items Amplifier Preamp & Phono Stage Headphone Amplifier DAC & Audio Adapter Audio Splitter/Switcher Music Spectrum & Clock Audio Accessories Other UK Warehouse Add-on Items Digital Amplifier Tube Amplifier Hi-Fi Amplifier Preamp & Phono Stage Headphone Amplifier DAC & Audio Adapter Audio Splitter/Switcher Audio Processor Music Spectrum & Clock Record Player & Turntable Part Audio Board & DIY Kit Audio Accessories Other DE Warehouse Add-on Items Digital Amplifier Tube Amplifier Hi-Fi Amplifier Preamp & Phono Stage Headphone Amplifier DAC & Audio Adapter Audio Splitter/Switcher Audio Processor Music Spectrum & Clock Aluminum Chassis Record Player & Turntable Part Audio Board & DIY Kit Radio Communication Audio Accessories Other AU Warehouse Add-on Items Amplifier Preamp & Phono Stage Headphone Amplifier DAC & Audio Adapter Audio Splitter/Switcher Music Spectrum & Clock Audio Accessories Other Digital Amplifier Multi-Function Mono Channel 2.0 Channel 2.1 Channel 4.0 Channel 5.1 Channel Tube Amplifier DIY Kit Hybrid Amplifier Mini Tube Amplifier EL34 Tube Amplifier KT88 Tube Amplifier 300B Tube Amplifier Other Tube Amplifier Audio Amplifier Mini Amplifier Integrated Amplifier Power Amplifier Audio Board & DIY Kit Preamp & Phono Stage Tube Preamp Digital Preamp Phono Preamp Passive Preamp Audio Board & DIY Kit Headphone Amplifier Mini Headphone Amp Desktop Headphone Amp Portable Headphone Amp Tube Headphone Amp DAC & Audio Adapter Audio Adapter USB DAC Bluetooth Receiver/Transmitter Digital Interface Audio Board & DIY Kit Audio Splitter/Switcher Speaker Switcher Bluetooth & XLR & MIC 2 Way 3 Way 4 Way Multiple Way Audio Processor Guitar Effects Equalizer Audio Mixer Noise Isolator Audio Player Digital Player Record Player CD Player Portable Player Music Spectrum & Clock Analog VU Meter Tube Sound Level Meter LED Sound Level Meter VFD Audio Spectrum LED Clock Nixie Tube Clock VFD Tube Clock IPS Nixie Clock Oscilloscope Tube Clock Board & DIY Kit Other Empty Chassis Small-sized Medium-sized Large-sized Personalized Record Player & Turntable Part Set-up Transformer Record Weight & Clamp Cleaning Kit Scale Gauge Platter Mat Dust Cover Needle Other Power Supply Linear Power Supply Switching Power Supply Power Supply Filter USB Charging Hub Board & DIY Kit Vacuum Tubes Shuguang Tube PSVANE Tube Tube Socket Tube Tester Probe Hi-Fi Speakers Frequency Divider Speaker Unit Hi-Fi Cable RCA Audio Cable 1/8 & 1/4 Stereo Jack Cable Speaker Cable USB Cable Optical Fiber Cable Conversion Cable Dock Cable Other Transformer Toroidal transformer Output Transformer Other Radio Communication Tesla Coil Transmitter & Receiver Signal Generator Antennas & Tuners Shortwave Radios Ham Amateur Radio Audio Accessories Volume Controller Mount Stand Bracket Feet & Pads Op Amp Headphone Current Meter Other Other Join Our Newsletter Receive our email newsletters about new items and special promotions! Sign Up Now ! Little Bear B4-X Portable Dual-Mono Vacuum Tube Headphone Amplifier Balanced Amp Item description Warm tips: Because the device contains the battery, the parcel to USA will be deliveried by DHL (shipping fee 15USD) To other countries will be deliveried via standard Air mail (Free shipping) Features Mini size and unique design: built-in tube makes you have a tube amplifier which can be held by one hand, convenient to carry and can enjoy HiFi music everywhere. With built-in battery protection circuit: battery lets your listening feast without time limitation. It can't be turned on during charging and will power off automatically after fully charged, and charger LED will turn to green. Full, delicate and soft sound: warmer than transistors, independent op amp and power supply inhance the SNR and degree of separation, less interplay and higher sound quality. High-end making material and craft: using gold-plated socket, original nichicon electrolytic capacitor, original DALE resistors and precision ring resistance. The difference between B4 and B4-X 1. B4-X is a dual-mono balanced version. Its left and right channel are amplified by independent components, and power supply, tubes, and op amp are all independent and symmetric. So the degree of sound separation is higher than B4. 2. B4-X adopts 2 groups of independent power supply(+12V and -12V) for 2 op amps, less mutual effects and can drive 300Ω headphones. 3. The circuit adopts dual op amp parallel output, with higher output power. 4. B4-X has 3.5mm and 2.5mm 2 kinds of output interface, suitable for most of balanced and standard headphones. If you want more information about B4, please click: LINK and the best matched 3.5mm AUX cable please click: LINK Parameters Tube: USA RAYTHEON JAN5784×2 Op amp: NE5532*2 (can be upgraded ) Lithium Battery: 12V, 1000mA Charging time: 2-2.5 hours Working time: 4-4.5 hours Output power: 450mW SNR: 105dB Suggest load impedance: 16-300Ω Output: 2.5 balanced Jack*1, 3.5mm Jack *1 Size: 115 * 69 * 23 mm (L*W*D) (does not include the knob) Packing List 1× headphone amplifier 1× power supply 1× 3.5mm audio cable 2× band Notice: when using B4-X with your cellphone, if you heard some "zhi ~ zhi" noise in your headphone. Probably it is the inteference from your cellphone such like WIFI or 4G signal, which intefers the tube and cause noise. That's normal. Because there are microphone effect with all tubes. To avoid it, please keep your cellphone far away from B4-X. Q&A Q: Tried different source and headphones, but the right channel still has static. A: Maybe the tube has a poor contact after long shipping process, open the chasis and adjust the screw near the tube while listening (if you cannot find it, contact us and we will give you a photo with marks to help you). Maybe the tube is broken, you can buy a 5899 tube in local shops. And we will refund you the cost. Q: It broke just now four loud pops and it's doesn't work now. A: Mainly because the battery is run out of power. Please charge it. If no help, please contact us. Q: The Amp has a lot of electronic feedback/interference when a cellphone is nearby. It creates popping in the headphones. A: Vacuum tubes are easy to be interfered by devices that can transfer siganl like cellphones, routers. Please keep the amp away from them. Q: It cannot be charged, something is loose inside the charger. A: Maybe the charger is broken. Contact us to get a new one please. Payment Delivery details Return Policy About us Contact us Payment Safe and secure payment by PayPal. Delivery details Please leave VALID TELEPHONE NUMBER which is necessary and very important. Customs Clearance We are NOT responsible for any customs duties fee. We are NOT responsible for any import tax or customs delay. Most item will be shipped within 2 working days. For package less than 2KG, we use Airmail (10-25 days to most countries) and for package over than 2KG we use Expedited Service such as DHL, UPS and FEDEX (5-8 days to most countries). Return Policy Free Return Within 30 Days We provide return within 30 days for all items you bought on eBay, full refund and return shipping will be provided. 1-year warranty is provided for all items( Excluding: 1. Man-made damage or misuse. 2. Audio accessories and consumables such as vacuum tubes). If you are satisfied with our products and service please leave a 5-star . Feedback is very important to us just like our lives, please DO contact us before you leave a neutral or negative feedback, we will provide better solutions until you are satisfied. About us Douk Audio / Nobsound Studio was founded in 2013 in Shenzhen CHINA, we own several brands including Douk Audio / Nobsound / Little Bear etc. As a professional audio company, we are dedicated to design and produce the best products at the lowest prices to make HiFi affordable. We will spare no efforts to bring great products and service for customers and extremely to improve our customers’ listening experience. Contact us Please don't hesitate to contact us if you have any questions or comments about our items. And our working time is from Monday to Friday between 9:00 am to 06:00 pm(Beijing Time), which means we can keep on-line at: Working time Beijing(CN) Monday-Friday 09:00 AM - 18:00 AM New York(US) Sunday to Thursday 08:00 PM - 05:00 AM London(UK) Monday-Friday 01:00 AM - 10:00 AM Paris(FR) Monday-Friday 02:00 AM - 11:00 AM During holiday, please allow us to response you early next week. Please don't leave any negative / neutral feedback or make dispute/claim on our non-working time, thank you for your understanding and cooperation. Home Feedback Save Seller New Listed Ending Soon Contact us