DOUKAUDIO

Introduction

The VU2 is a multi-functional VU meter and audio splitter box originally designed by Douk Audio. It offers versatile functionality for audio enthusiasts and professionals alike.

As an Analog VU Meter:

• Features wired stereo RCA input and wireless microphone inputs.
• Pairs well with common audio devices like mobile phones, computers, CD players, and speakers.
• Ideal for home, office, or studio systems to dynamically enhance the auditory experience.

As a 4-Way Audio Splitter Box:

• 4-IN-1-OUT Mode: Compare sound quality from different audio sources (e.g., mobile phone, tablet, TV, CD player, DAC).
• 1-IN-4-OUT Mode: Contrast different audio outputs (e.g., preamp, headphone amplifier, power amplifier, active speakers).
• Eliminates the need for repeated cable plugging and unplugging, preventing wear on socket contact points.
• Allows simultaneous input from 4 channels to mix different audio sources.
• Enables simultaneous output from multiple channels for monitoring or recording purposes.

Warm Tips

1. All 4 channels can work simultaneously (input or output), but this function is set by pressing the four channel buttons on the front panel, not via remote control.
2. In 4-IN-1-OUT mode, it is not recommended to operate all 4 channels in parallel if their output levels differ, as this may cause distortion.
3. Avoid powering the VU2 from the USB interface of audio source devices to prevent potential noise generation.

Instructions for Use

Delay Knob:

Adjusts the beating speed of the pointer. Set a slower speed for slow-tempo music and a faster speed for fast-tempo music to enhance visual enjoyment. Settings are displayed in real-time, referencing the input audio signal. Ensure an audio signal is present when adjusting.

Gain Knob:

Sets the gain of the input signal. This is adjusted digitally via a microcontroller, without physical contact with the audio signal, thus not affecting audio quality. It controls the beating range of the pointer. Increase gain for small input signals and decrease for large ones to optimize the pointer's swing. For recording, the 0dB position can be set conveniently for monitoring recording volume.

Input Selection:

The device has both microphone and line inputs. Use LINE input for accurate display and microphone input when cable connection is inconvenient.

Dynamic Acceleration and Deceleration Damping Mode:

This mode (default ON) enhances the pointer's beating rhythm. To toggle: press and hold the MUTE button, then press the ACG/DB button. The LED indicator for ACG/DB will flash to confirm the change. Press MUTE again to exit. For best results during setting, play music and set Delay and Gain knobs to at least 50%. A fast-beating pointer indicates the mode is ON; a slower beat indicates it is OFF.

Notice

1. During sensitivity setting, music input is required for the pointer to swing and display the effect of the current setting. A slight delay upon selection is normal due to program design.
2. When using the microphone input, adjust the gain knob according to speaker volume or distance from the speaker for optimal display effects.
3. Common ground noise may occur in some audio systems when multiple inputs are connected due to common ground connections. Consider using an audio isolation module between the audio source and VU2 to mitigate this.
4. In mute mode, the pointer continues to swing in 1-IN-4-OUT mode but stops in 4-IN-1-OUT mode.
5. The backlight brightness on the dark version can be adjusted by accessing the adjustable resistors on the left and right channels inside the chassis.

Front Panel Overview

The front panel features:

• A. Delay Knob: Adjusts pointer sensitivity (beating speed).
• B. Function Button:
  • Single Click: Starts the VU2 (if off) or selects signal input between microphone and line (if on).
  • Double Click: Switches between ACG and DB gain modes.
  • Long Press (3 seconds): Shuts down the VU2.
• C. Gain Knob: Adjusts input signal gain (pointer swing range).
• D. Input Channel Button:
  • Short Press: Selects a channel to work independently.
  • Long Press: Adds a channel to work with the currently selected channels.

Diagram shows the front panel with labels for Delay Knob (A), Function Button (B), Gain Knob (C), 4 Channel Select Button (D), Infrared receiver, Line Input Indicator (Red), Mic Input Indicator (Green), ACG Mode Indicator (Red), and DB Mode Indicator (Green).

Instructions of ACG and DB Display Mode

ACG Mode:

The VU meter uses a dynamic square root audio compression algorithm. The relationship between input volume and pointer swing is not proportional. Lower input volumes result in larger swings, while higher volumes produce smaller swings. This mode provides good display effects across a wider input range without constant gain adjustments. The pointer will react even to small volumes and won't always reach maximum swing with large volumes. It's recommended to set GAIN so the pointer swings close to 70% (0dB). Due to the compression algorithm, this mode does not accurately reflect the actual input volume level and is not suitable for professional recording. However, it aligns with typical human hearing habits.

DB Mode:

The VU meter's light beam movement is driven by standard AD conversion. The data is unprocessed, meaning the pointer's swing is directly proportional to the input signal. This mode is suitable for situations requiring accurate music level monitoring, such as in recording studios or when testing specific sound levels.

Diagrams illustrate the relationship between input voltage and pointer swing range for both ACG mode (non-linear, curved) and DB mode (linear, straight).

Parameters

• Brand: Douk Audio
• Model: VU2
• VU Meter Color: Light (yellow) / Dark (black) / Blue
• Audio Input: Stereo RCA / Microphone
• Audio Output: 4 groups of stereo RCA
• Switcher Working Mode: 1-IN-4-OUT / 4-IN-1-OUT
• Sensitivity Adjustment: Supported
• Gain Adjustment: Supported (DB mode / ACG mode)
• Working Voltage: Micro USB DC 5V
• Working Current: 0.5A (dark version) / 1.5A (light version)
• Backlight Voltage: DC / AC 6-12V
• Backlight Current: 10mA (dark version) / 100mA (light version)
• Dynamic Acceleration/Deceleration Damping Modes: Supported
• Power On/Off Function: Supported
• Settings Saved After Shutdown: Supported
• Mute Function: Supported
• Dimensions (W*D*H): 280*122*80 mm (11.02*4.08*3.15 in)