Nobsound MC403

Nobsound Little Bear MC403 Mini 4-IN-3-OUT Audio Selector Box User Manual

Model: MC403

Introduction

Thank you for purchasing the Nobsound Little Bear MC403 Mini 4-IN-3-OUT Audio Selector Box. This device is designed to provide flexible audio routing for your home audio system, allowing you to switch between multiple audio sources and outputs. It features 3.5mm AUX, RCA, and Bluetooth inputs, with 3.5mm AUX and RCA outputs. Please read this manual carefully before use to ensure proper operation and to maximize the performance of your device.

Safety Information

  • Do not expose this device to rain, moisture, or extreme temperatures.
  • Avoid placing the device near heat sources or in direct sunlight.
  • Do not open the casing; there are no user-serviceable parts inside.
  • Use only the provided power adapter or one with identical specifications (5V DC, 200mA).
  • Ensure all connections are secure before powering on any connected audio equipment.
  • Keep out of reach of children.

Package Contents

Please check the package for the following items:

  • 1 x Nobsound Little Bear MC403 Audio Selector Box
  • 1 x Power Adapter (for Bluetooth function)
  • 1 x Bluetooth Antenna

Product Overview

Front Panel

Front view of the Nobsound Little Bear MC403 Audio Selector Box
Figure 1: Front Panel Overview. This image shows the front of the Nobsound Little Bear MC403. It features two large rotary knobs, one for input selection (labeled 1-4) and one for output selection (labeled A-C). A red "MUTE" button is located between the knobs. Below the knobs are a 3.5mm input jack (labeled 4) and a 3.5mm output jack (labeled A). The device name "ONE Little Bear MC403" is printed above the mute button.
Diagram of the Nobsound Little Bear MC403 front panel controls
Figure 2: Front Panel Control Diagram. This diagram highlights the functions of the front panel. The left knob is the Input Selector, allowing selection between inputs 1, 2, 3, and 4 (Bluetooth/3.5mm AUX). The right knob is the Output Selector, choosing between outputs A (3.5mm AUX), B (RCA), and C (RCA). The red button is the Mute function. Input 4 is a 3.5mm jack, and Output A is also a 3.5mm jack.
  • Input Selector Knob: Selects between 4 audio inputs (1, 2, 3, or 4). Input 4 corresponds to the front 3.5mm jack and Bluetooth.
  • Output Selector Knob: Selects between 3 audio outputs (A, B, or C). Output A corresponds to the front 3.5mm jack.
  • MUTE Button: Press to mute/unmute the audio output.
  • 3.5mm Input Jack (Input 4): For connecting 3.5mm audio sources.
  • 3.5mm Output Jack (Output A): For connecting 3.5mm audio devices like headphones or speakers.

Rear Panel

Rear view of the Nobsound Little Bear MC403 Audio Selector Box
Figure 3: Rear Panel Overview. This image displays the rear panel of the Nobsound Little Bear MC403. On the left are RCA output jacks (C and B). In the center, there is a DC IN 5Vdc:200mA power port, a Bluetooth antenna connector, and an ON/OFF switch. On the right are RCA input jacks (3 and 2).
Diagram of the Nobsound Little Bear MC403 rear panel connections
Figure 4: Rear Panel Connection Diagram. This diagram labels the rear connections. Outputs C and B are RCA stereo pairs. The DC IN port accepts 5Vdc power for Bluetooth and indicator LED functionality. The ON/OFF switch activates/deactivates Bluetooth. The Bluetooth antenna port is for the included antenna. Inputs 2 and 3 are RCA stereo pairs.
  • RCA Inputs (2 & 3): For connecting RCA audio sources.
  • RCA Outputs (B & C): For connecting RCA audio devices like amplifiers or active speakers.
  • DC IN (5Vdc, 200mA): Power input for the Bluetooth function and indicator LED. A standard cellphone charger can be used.
  • Bluetooth Antenna Port: For attaching the included Bluetooth antenna.
  • ON/OFF Switch: Activates or deactivates the Bluetooth function.

Setup

  1. Attach Bluetooth Antenna: Carefully hold the black part of the antenna upright. Screw the antenna onto the Bluetooth antenna port on the rear panel until it is securely fastened. Do not twist the entire antenna to tighten the screw.
  2. Connect Power (Optional for Bluetooth): If you intend to use the Bluetooth function, connect the provided 5V DC power adapter to the "DC IN" port on the rear panel. Plug the adapter into a power outlet.
    Nobsound Little Bear MC403 with power adapter connected
    Figure 5: Power Adapter Connection. This image shows the MC403 with its power adapter connected to the DC IN port on the rear.
  3. Connect Audio Sources:
    • For RCA sources (e.g., CD player, DVD player), connect them to the "INPUT 2" or "INPUT 3" RCA jacks on the rear panel.
    • For 3.5mm AUX sources (e.g., smartphone, tablet, laptop), connect them to the "INPUT 4" 3.5mm jack on the front panel.
    • Bluetooth is also an input option (Input 4).
  4. Connect Audio Outputs:
    • For RCA outputs (e.g., amplifier, active speakers), connect them to the "OUTPUT B" or "OUTPUT C" RCA jacks on the rear panel.
    • For 3.5mm AUX outputs (e.g., headphones, small active speakers), connect them to the "OUTPUT A" 3.5mm jack on the front panel.
Connection diagram for the Nobsound Little Bear MC403 Audio Selector Box
Figure 6: Typical Connection Diagram. This diagram illustrates how to connect various audio devices to the MC403. An MP3 player or phone can connect to the 3.5mm input (Input 4). A CD player can connect to RCA inputs (Input 2 or 3). Outputs can go to a headphone amplifier, active speakers, or a power amplifier. The Bluetooth antenna is shown connected to the rear.

Operating Instructions

  1. Power On: If using Bluetooth, ensure the power adapter is connected and the ON/OFF switch on the rear panel is set to "ON".
  2. Select Input: Rotate the Input Selector Knob on the front panel to choose your desired audio source (1, 2, 3, or 4).
  3. Select Output: Rotate the Output Selector Knob on the front panel to direct the audio to your desired output device (A, B, or C).
  4. Mute Function: Press the red MUTE button to temporarily silence the audio output. Press it again to unmute.
  5. Passive Operation: The RCA and 3.5mm AUX inputs/outputs function passively without power. Power is only required for Bluetooth functionality and the indicator LED.

Bluetooth Pairing

To use the Bluetooth receiver function:

  1. Ensure the power adapter is connected and the Bluetooth ON/OFF switch on the rear panel is set to "ON".
  2. Turn on the Bluetooth function on your mobile phone or other Bluetooth-enabled device.
  3. Search for available Bluetooth devices.
  4. Locate and select the device named "WIN-668". No pairing code is required.
  5. Once paired, you can play music from your mobile device via Bluetooth through the MC403.

Note: The Bluetooth receiver output power is 20mW. It can directly drive headphones with an impedance of 12-120 ohms. Ensure your mobile phone's volume is set appropriately.

Maintenance

  • Clean the device with a soft, dry cloth. Do not use liquid cleaners or aerosols.
  • Keep the device free from dust and debris.
  • When not in use for extended periods, disconnect the power adapter.

Troubleshooting

ProblemPossible CauseSolution
No audio output.
  • Incorrect input/output selected.
  • Mute function is active.
  • Cables are not connected properly.
  • Connected devices are off or volume is too low.
  • Verify input and output selections.
  • Press the MUTE button to unmute.
  • Check all audio cable connections.
  • Ensure connected audio sources and output devices are powered on and their volume levels are adequate.
Bluetooth not connecting or "WIN-668" not found.
  • Power adapter not connected or Bluetooth switch is OFF.
  • Device is too far from the MC403.
  • Interference from other wireless devices.
  • Connect the 5V power adapter and ensure the Bluetooth ON/OFF switch on the rear is "ON".
  • Move your Bluetooth device closer to the MC403.
  • Try to minimize interference from other 2.4GHz devices.
Humming or buzzing noise.
  • Ground loop issue.
  • Poor quality audio cables.
  • Interference from power cables.
  • Try connecting all audio equipment to the same power strip.
  • Replace audio cables with shielded, higher-quality ones.
  • Ensure audio cables are not running parallel to power cables.
Bluetooth antenna feels wobbly.Antenna not properly secured or overtightened.When installing, hold the black part of the antenna and only twist the base to tighten. Do not force the entire antenna. If it's already wobbly, avoid further twisting to prevent internal damage.

Specifications

FeatureDetail
ModelMC403
Inputs2 x RCA, 1 x 3.5mm AUX, 1 x Bluetooth
Outputs2 x RCA, 1 x 3.5mm AUX
Bluetooth Version4.0 (Stereo Audio Receiver)
Bluetooth Output Power20mW (for headphones 12-120 ohms)
Power SupplyDC 5V, 200mA (for Bluetooth and LED)
Dimensions (W x D x H)150mm x 105mm x 68mm (approx.)
Weight485g (approx.)
Connector Type3.5mm Jack, RCA
Compatible DevicesDVD-Player, Television, Laptop, Smartphone, Tablet
Dimensions of the Nobsound Little Bear MC403 Audio Selector Box
Figure 7: Product Dimensions. This image shows the approximate dimensions of the MC403: 150mm width, 105mm depth, and 68mm height.

Support

Nobsound is committed to providing the highest level of customer service. If you encounter any issues or have questions regarding your Little Bear MC403 Audio Selector Box, please contact us via email. We aim to respond within 24 hours.

For further assistance, please visit the official Nobsound store: Nobsound Store

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