Douk Audio VFD253 Audio Spectrum Analyzer User Manual

1. Introduction

The Douk Audio VFD253 is a versatile desktop device that combines an audio spectrum analyzer, a Bluetooth 5.0 receiver, a 3.5mm AUX audio selector, and a high-precision home desk clock. It is designed to enhance your audio experience with visual feedback and provide convenient timekeeping. This manual provides detailed instructions for setup, operation, and maintenance of your VFD253 unit.

2. Key Features

• Multi-functional Device: Integrates an audio spectrum analyzer, Bluetooth 5.0 receiver, 3.5mm AUX selector, and a high-precision desk clock.
• VFD Display: Utilizes a dedicated green VFD (Vacuum Fluorescent Display) screen with 25 × 15 high resolution for accurate frequency band representation.
• Multiple Audio Inputs: Supports microphone pickup, Bluetooth 5.0, and two 3.5mm AUX inputs (IN1, IN2) for connection to various audio sources like phones, PCs, game players, amplifiers, and speakers.
• Audio Output: Features one 3.5mm AUX output.
• High-Precision Clock: Equipped with an RX8025T built-in crystal oscillator, offering a clock accuracy of ±3ppm (year error within 1 minute).
• Wide Frequency Range & AGC Display: 80Hz-16KHz frequency sweep with a special AGC (Automatic Gain Control) algorithm and customized output curve to ensure optimal visual effects across varying input signal levels.
• Adjustable Display Effects: Customizable settings for gain, brightness (5 levels + auto), main light column falling speed, peak holding time, and peak falling speed.
• Display Modes: Offers 5 music spectrum display modes and 2 clock display modes.
• Power-Off Memory: All settings are saved automatically and retained after power cycling.
• Convenient Control: Includes a remote control for easy adjustment of all settings.
• Premium Design: CNC machined aluminum and transparent acrylic case provide a solid, beautiful, and compact design.

3. Package Contents

Please check the package for the following items:

• 1 × VFD253 Audio Spectrum Analyzer
• 1 × USB Cable (Type-C)
• 1 × Remote Control (Note: Batteries are not included for safe shipping. Requires 2*AAA batteries.)
• 2 × Anti-slip Pads (to stick to the bottom of the unit)
• 1 × User Manual (this document)

4. Controls and Ports

Familiarize yourself with the physical controls and connection ports on your VFD253 unit:

Front Panel:

• Mode -: Decreases the selected mode/setting.
• Mode +: Increases the selected mode/setting.
• Audio Source Selection / Power Switch: Short press to cycle through audio input sources (MIC, Bluetooth, AUX IN1, AUX IN2). Long press to power the unit on/off.

Rear Panel:

• 3.5mm AUX Output: Connects to external audio devices like headphones or speakers.
• Microphone Pickup: Built-in microphone for ambient sound spectrum analysis.
• 3.5mm AUX Input (IN1): First 3.5mm auxiliary audio input.
• 3.5mm AUX Input (IN2): Second 3.5mm auxiliary audio input.
• DC IN (Type-C): Power input port (5V DC).

5. Initial Setup

1. Power Connection: Connect the provided USB Type-C cable to the DC IN port on the rear of the VFD253 and plug the other end into a 5V DC power adapter (not included).
2. Remote Control Batteries: Open the battery compartment of the remote control and insert two AAA batteries (not included), ensuring correct polarity.
3. Placement: Apply the two anti-slip pads to the bottom of the unit to ensure stability on your desk.
4. Power On: Long press the 'Audio Source Selection / Power Switch' button on the front panel to turn on the unit.
5. Audio Input: Connect your desired audio source to one of the input options:
   • Microphone: The built-in microphone will pick up ambient sounds.
   • Bluetooth: Select Bluetooth input, then pair your device (e.g., smartphone, PC) with the VFD253.
   • AUX IN1/IN2: Connect an audio cable from your source device's output to either the 3.5mm AUX IN1 or AUX IN2 port.
   Note: Only one audio source channel (MIC / Bluetooth / IN1 / IN2) can be active at a time. 3.5mm AUX1 and 3.5mm AUX2 cannot input simultaneously.
6. Audio Output (Optional): If you wish to output audio from the VFD253 to another device, connect an audio cable from the 3.5mm AUX Output port to your external speakers or headphones.

6. Operating Modes

The VFD253 offers various operating modes, which can be selected and configured using the front panel buttons or the remote control.

6.1. Work Modes

The unit supports two primary work modes:

• Auto Mode: The VFD253 will display the music spectrum when an audio input is detected. If no music input is present, it will automatically switch to display the clock mode.
• Clock Display Mode (Always): The unit will continuously display the clock, regardless of audio input.

6.2. Display Items

• Music Spectrum Display: Visualizes the frequency components of the audio input. There are 5 different music spectrum display styles available.
• Clock Display: Shows the current time. There are 2 different clock display styles available.

7. Adjustments and Settings

The VFD253 allows for various adjustments to customize the display and performance. These settings can be accessed and modified via the remote control.

• Gain Adjustment: Adjusts the input sensitivity of the audio signal. There are 5 levels of gain adjustment.
• Brightness Adjustment: Controls the intensity of the VFD display. There are 5 brightness levels, plus an auto-adjustment feature.
• Main Light Column Falling Speed: Adjusts how quickly the main bars of the spectrum fall.
• Peak Holding Time: Sets the duration for which the peak level indicators remain visible.
• Peak Falling Speed: Controls how quickly the peak level indicators descend after their holding time.
• Music Display Mode: Selects between 5 different visual styles for the music spectrum.
• Clock Display Mode: Selects between 2 different visual styles for the clock.
• AGC (Automatic Gain Control): The unit features a special AGC algorithm and customized output curve to ensure ideal visual effects, preventing no display with low input and full display with high input.

8. User Tips

• Remote Control Batteries: Remember to purchase and install 2 AAA batteries for the remote control, as they are not included in the package.
• Simultaneous AUX Inputs: The VFD253 can only process one audio input source at a time. If you have devices connected to both AUX IN1 and AUX IN2, ensure only one is actively playing or select the desired input via the source selection button.
• Bluetooth as Input: The Bluetooth function on the VFD253 acts as an audio input for the spectrum analyzer. You can connect your smartphone or other Bluetooth-enabled device to the VFD253 via Bluetooth to display its audio spectrum, even if your smartphone is simultaneously connected to a DAC via USB-C for audio output. The VFD253 will analyze the audio stream it receives via Bluetooth.

9. Specifications

10. Troubleshooting

• No Power: Ensure the USB Type-C cable is securely connected to both the VFD253 and a working 5V DC power source. Try a different power adapter or USB port.
• No Audio Spectrum Display:
  • Check if an audio source is properly connected and playing.
  • Ensure the correct audio input source (MIC, Bluetooth, AUX IN1, AUX IN2) is selected.
  • Adjust the gain settings if the input signal is too low.
  • If in 'Clock Display Mode (Always)', switch to 'Auto Mode' or 'Music Spectrum Display' mode.
• Remote Control Not Working:
  • Verify that 2 AAA batteries are correctly inserted with the proper polarity.
  • Replace old batteries with new ones.
  • Ensure there are no obstructions between the remote and the VFD253.
• Incorrect Time Display: Refer to the user manual for instructions on how to set the clock using the remote control.
• No Sound Output: If using the 3.5mm AUX Output, ensure your external speakers or headphones are properly connected and powered on, and their volume is adjusted.

11. Maintenance

• Cleaning: Use a soft, dry cloth to clean the unit. Do not use liquid cleaners or abrasive materials, as they may damage the VFD screen or acrylic case.
• Storage: Store the unit in a cool, dry place away from direct sunlight and extreme temperatures.
• Handling: Handle the unit with care to avoid dropping or physical impact, which could damage internal components or the display.

12. Warranty and Support

For any issues not covered in this manual, or for warranty claims, please contact the seller or manufacturer directly. Keep your purchase receipt as proof of purchase. The product is certified with CE standards.