---
product_id: 745269336
title: "Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version"
brand: "little bear"
price: "€ 10.60"
currency: EUR
in_stock: false
reviews_count: 4
url: https://www.desertcart.ie/products/745269336-little-bear-b4-x-portable-dual-monovac-tube-headphone-amplifier
store_origin: IE
region: Ireland
---

# 450mW high output power Drives 300Ω headphones 4.5h battery life Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version

**Brand:** little bear
**Price:** € 10.60
**Availability:** ❌ Out of Stock

## Summary

> 🎶 Elevate your sound game with tube-powered precision — don’t just listen, experience!

## Quick Answers

- **What is this?** Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version by little bear
- **How much does it cost?** € 10.60 with free shipping
- **Is it available?** Currently out of stock
- **Where can I buy it?** [www.desertcart.ie](https://www.desertcart.ie/products/745269336-little-bear-b4-x-portable-dual-monovac-tube-headphone-amplifier)

## Best For

- little bear enthusiasts

## Why This Product

- Trusted little bear brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Hi-Fi Tube Warmth:** USA RAYTHEON JAN5899 tubes deliver rich, warm audio that stands out
- • **Portable Powerhouse:** Compact size with 4-4.5 hours of uninterrupted listening freedom
- • **Premium Build Quality:** Gold-plated sockets & original Nichikon capacitors ensure durability & clarity
- • **Versatile Connectivity:** Dual outputs (2.5mm balanced & 3.5mm) fit most premium headphones
- • **Dual Mono Balanced Design:** Independent left/right amplification for pristine sound isolation

## Overview

The Little Bear B4-X is a portable dual mono-balanced tube headphone amplifier featuring independent amplification channels, USA-made JAN5899 tubes, and dual 2.5mm/3.5mm outputs. It delivers 450mW output power, supports headphones up to 300Ω, and offers 4-4.5 hours of battery life with premium components like gold-plated sockets and Nichikon capacitors, making it a must-have for audiophiles seeking warm, high-fidelity sound on the go.

## Description

Product description               Parameter: Tube: USA RAYTHEON JAN5899 x 2 Opamp: NE5532*2 (Upgradable) Lithium battery: 12V, 1000mA Charging time: 2-2.5 hours Working time: 4-4.5 hours Output Power: 450mW SNR:105dB Recommended Load Impedance: 16-300Ω Output: 1 x 2.5 balance jack, 1 x 3.5mm jack Size (L x W x H): 115 x 69 x 23mm / 4.5 x 2.7 x 0.9 inches (Without Knob) Package Includes: 1 x Headphone Amplifier 1 x Power Supply 1 x 3.5mm Audio Cable 2 x Band Note: When you use B4-X on your phone, you can hear "zhi ~ zhi" noise on your headphone. Perhaps interference from cell phones like WIFI or 4G signals, it will strengthen the tube and cause noise. It is normal. Because every tube has a microphone effect. Please keep your phone close to B4-X to avoid this. Q&A: Q: I tried different sources and headphones but the right channel is still still. A: After a long shipping process, the tube contact is insufficient. Open the chassis and adjust the screw near the tube (if you can't find, contact us and we will provide a picture with marked to help you ) The tube may be broken. You can purchase 5899 tube from local shop. If you have any questions please feel free to contact Q: 4 big pops are broken. It doesn't work now. A: Mainly because the battery is running out. Please charge it. If you have any questions, please contact us. Q: If your phone is nearby, the Amp has a lot of electronic feedback/interference. Add a pop to your headphones. A: The vacuum tube will interfere with devices that can transfer signals such as mobile phones, routers, etc. Please keep the amplifier away from the amplifier. Q: Not charging Something loose inside the charger. A: The charger may be broken. Get a new one.                   Directions               1. 携帯電話でB4-Xを使用しているときにヘッドフォンで「zhi~zhi」ノイズが聞こえる場合は、WIFIまたは4G信号からの干渉を避けるために、携帯電話をB4-Xから遠ざけてください。 2. 正しいチャンネルに静電気がある場合、長い出荷後のチューブの接触不良が原因である可能性があります。 聴きながらシャーシを開き、チューブ付近のネジを調整します。 チューブが破損した場合は、地元のショップで5899チューブを購入すると、費用が返金されます。 3. 4つの大きなポップで壊れて動作しない場合は、電力が切れる可能性があるため、バッテリーを充電してください。 4. 電子フィードバック/干渉を避けるために、携帯電話やルーターなどの信号を転送できるデバイスからアンプを遠ざけてください。 5. 充電器が壊れている場合は、新しい充電器を入手するために私達に連絡してください。

## Features

- Difference between B4 and B4-X: 1. The B4-X is a dual mono-balanced version. The left and right channels are amplified by independent components, and the power, tube, and amplifier are all independent and symmetrical. So the sound isolation is higher than B4
- 2. The B4-X uses 2 independent power sources (+12 V and -12 V) to support 2 optics amplifiers, with less interactivity, and can drive 300 ohm headphones. 3. This circuit adopts dual opire amp parallel output, providing high output power. ④ The B4-X has two output interfaces of 3.5mm and 2.5mm, suitable for most balanced standard headphones
- Mini Size and Unique Design: Built-in tube with one hand handheld tube amplifier, convenient to carry and enjoy HiFi music anywhere. Full, delicate and soft sound: warmer than transistors, independent opamp and power supply disturb SNR and isolation, low interplay and high sound quality
- Built-in Battery Protection Circuits: Battery provides hours of listening feast Cannot be turned on while charging. Automatically turns off after charging and the charging LED turns green
- High-end manufacturing materials and technology: Uses gold-plated socket, original nichikon electrolytic capacitors, original DALE resistors, precision ring resistors. Fast and careful customer service

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Item model number | 7545884688 |
| Is Discontinued By Manufacturer | No |
| Color Name | Upgrade Version Black |
| Compatible Devices | 3.5mm audio output device |
| Connector | 2.5mm, 3.5mm |
| Material Type | Gold Plated |
| Output Wattage | 0.45 Watts |
| Battery type | Lithium |
| Power Source | Battery Operated |

## Product Details

- **Brand:** Little Bear
- **Color:** Upgrade Version Black
- **Material:** Gold Plated
- **Style:** 首回り
- **Model Name:** Little Bear B4-X

## Images

![Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version - Image 1](https://m.media-amazon.com/images/I/71NgP4S28HL.jpg)
![Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version - Image 2](https://m.media-amazon.com/images/I/71iR4k88a1L.jpg)
![Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version - Image 3](https://m.media-amazon.com/images/I/713YafzsNaL.jpg)
![Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version - Image 4](https://m.media-amazon.com/images/I/71WGaUkxSJL.jpg)
![Little Bear B4-X Portable Dual Monovac Tube Headphone Amplifier Mini Balance Audio Headphone Amplifier B4 Upgrade Version - Image 5](https://m.media-amazon.com/images/I/71OoX1HF79L.jpg)

## Questions & Answers

**Q: Why mine which is brand new stopped working and makes a loud hissing/banging noise?**
A: Charge it. It’s just outta power

**Q: Does this B4-X works while charging? without any limiter like "for safety reason"**
A: Hello. Sorry B4-X still has the limitation.

**Q: best place to buy op amps**
A: Amazon.

**Q: Mine stopped holding a charge, can the batteries be replaced?**
A: Yes you can, easy todo

## Customer Reviews

### ⭐⭐⭐⭐⭐ 良い方の当たり品？
*by K***様 on February 23, 2023*

安いですが、ちゃんと真空管っぽい音がします！しかも、ボリューム最大でもホワイトノイズ無しの当たり品でした。ポータブルの管球で避けられないハウリングですが、シリコンリングでの制振が凄まじく効きました。おすすめのシリコンリングは内径10mmの3mm幅品です。もはや必需品で良いのでは?外部の電波ノイズを結構拾います。BTを受信している機器が近くにあると、可聴域のノイズが乗りました。アンプケースの内側に銅テープを貼るだけでもソコソコ効果が有りましたのでオススメです。あとは、OPA交換で楽しめるのがポイント高いです。最初から付いているOPAでも楽しめるレベルなので、イイ感じのバランスだと思います。

### ⭐⭐⭐⭐⭐ オーディオ生活を豊かに
*by ジ***ョ on August 23, 2023*

DAPとヘッドホン・イヤホンを繋いで音楽を楽しんでいます。通常タイプのヘッドホンアンプは、けっこう買い揃えてありましたが、あのちょっとリバーブがかかったようでぬるい音響を自分のコレクションに取り込みたくて購入しました。艶っぽい中音域が伸びやかであり、透明感もあっていいですね。バッテリ駆動時間が十分とは言えないので、お出かけのお供には足りないですが、お部屋使いなら問題はないでしょう。初期には時折ノイズが乗ったりしましたが、使っている内になくなりました。真空管らしい音響が気に入ったので、ローテーションに積極的に入れて、オーディオ生活を豊かにしています。

### ⭐⭐⭐⭐ 真空管の,明かりがとても、、goodです。
*by 8***3 on October 17, 2023*

opeアンプを、交換したりしがら、自分の音を、自分なりにさがし、求めて、,行きたいと、思います。

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*Product available on Desertcart Ireland*
*Store origin: IE*
*Last updated: 2026-03-07*