1. Introducció
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. Característiques clau
- Dispositiu multifuncional: Integrates an audio spectrum analyzer, Bluetooth 5.0 receiver, 3.5mm AUX selector, and a high-precision desk clock.
- Pantalla VFD: Utilizes a dedicated green VFD (Vacuum Fluorescent Display) screen with 25 × 15 high resolution for accurate frequency band representation.
- Múltiples entrades d'àudio: 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, amplificadors i altaveus.
- Sortida d'àudio: 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.
- Modes de visualització: Offers 5 music spectrum display modes and 2 clock display modes.
- Memòria d'apagada: All settings are saved automatically and retained after power cycling.
- Control convenient: Includes a remote control for easy adjustment of all settings.
- Disseny Premium: CNC machined aluminum and transparent acrylic case provide a solid, beautiful, and compact design.

3. Contingut del paquet
Si us plau, comproveu el paquet per veure si hi ha els elements següents:
- 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 × Manual d'usuari (aquest document)

4. Controls i ports
Familiarize yourself with the physical controls and connection ports on your VFD253 unit:

Panell frontal:
- 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.
Panell posterior:
- 3.5mm AUX Output: Connects to external audio devices like headphones or speakers.
- Recollida del micròfon: 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. Configuració inicial
- Connexió d'alimentació: 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).
- Bateries de control remot: Open the battery compartment of the remote control and insert two AAA batteries (not included), ensuring correct polarity.
- Col·locació: Apply the two anti-slip pads to the bottom of the unit to ensure stability on your desk.
- Encès: Long press the 'Audio Source Selection / Power Switch' button on the front panel to turn on the unit.
- Entrada d'àudio: Connect your desired audio source to one of the input options:
- Micròfon: 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.
- Sortida d'àudio (opcional): 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. Modes de funcionament
The VFD253 offers various operating modes, which can be selected and configured using the front panel buttons or the remote control.
6.1. Modes de treball
The unit supports two primary work modes:
- Mode automàtic: 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.
- Visualització del rellotge: 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.
- Ajust de guany: Adjusts the input sensitivity of the audio signal. There are 5 levels of gain adjustment.
- Ajust de brillantor: 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.
- Mode de visualització del rellotge: Selects between 2 different visual styles for the clock.
- AGC (control automàtic de guany): 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. Consells d'usuari
- Bateries de control remot: 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. Especificacions
| Característica | Especificació |
|---|---|
| Pantalla de visualització | VFD (Vacuum Fluorescent Display) |
| Resolució | 25 × 15 |
| Frequency Range Supported | 80Hz-16KHz |
| Mostra elements | Music Spectrum / Clock |
| Entrada de senyal d'àudio | MIC / Bluetooth 5.0 / 2 groups of 3.5mm AUX |
| Sortida de senyal d'àudio | 1 group of 3.5mm AUX |
| Modes de treball | Auto mode (spectrum/clock) / Clock display mode (always) |
| Clock Display Styles | 2 tipus |
| Music Spectrum Display Styles | 5 tipus |
| Music Display Mode | AGC + customized output curve (Real output / Smooth output) |
| Adjustable Items | Main light column falling speed / Peak holding time / Peak falling speed |
| Ajust de brillantor | 5 levels + auto adjustment |
| Ajust de guanys | 5 nivells |
| Funció de memòria d'apagada | Admet |
| Control remot | Admet |
| Voltage | DC 5V |
| Dimensions (W*D*H) | 184*75*66mm / 7.24*2.95*2.60in |
| Pes net | 322 g / 0.71 lliures |
| Pes del paquet | 500 g / 1.10 lliures |
| Canals | 2 (2.0) |
| Certificació | CE |
10. Solució De Problemes
- Sense energia: 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.
- El control remot no funciona:
- Verify that 2 AAA batteries are correctly inserted with the proper polarity.
- Substituïu les piles velles per unes de noves.
- Ensure there are no obstructions between the remote and the VFD253.
- Visualització de l'hora incorrecta: Refer to the user manual for instructions on how to set the clock using the remote control.
- Sense sortida de so: 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. Manteniment
- Neteja: 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.
- Emmagatzematge: Guardeu la unitat en un lloc fresc i sec, allunyat de la llum solar directa i de temperatures extremes.
- Manipulació: Handle the unit with care to avoid dropping or physical impact, which could damage internal components or the display.
12. Garantia i Suport
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.





