1. Introduction
Thank you for choosing the Douk Audio EQ5 PRO Mini 5-Band EQ Preamp Stereo Bluetooth Equalizer. This device is designed to enhance your audio experience by providing precise frequency control, a pre-amplification stage, and convenient Bluetooth connectivity. Its vintage VU meters offer a dynamic visual display of your audio signal, making it a stylish and functional addition to any home or desk audio setup.
2. Important Safety Information
- Read all instructions carefully before operating the device.
- Keep the device away from water, moisture, and extreme temperatures.
- Do not open the casing; refer all servicing to qualified personnel.
- Use only the specified DC 5V power supply (not included) and ensure it provides at least 500mA.
- Avoid sharing the power supply with audio sources to prevent common ground noise.
- Ensure proper ventilation around the unit.
3. Package Contents
Please check the package for the following items:
- 1x EQ5 PRO Equalizer Unit
- 1x USB Cable (Type-C)
- 1x Bluetooth Antenna
Note: A DC 5V power adapter is not included and must be purchased separately.
4. Product Overview
Familiarize yourself with the controls and connections of your EQ5 PRO unit.
4.1 Front Panel Controls
- VU Meter (L/R): Displays the audio signal level for left and right channels.
- Volume Knob: Adjusts the overall output volume.
- Power Switch: Turns the unit ON/OFF.
- 5-Band EQ Adjustment Knobs (100Hz, 400Hz, 800Hz, 4KHz, 10KHz): Adjusts the gain for specific frequency bands.
- Balance Adjustment Knob: Compensates for left/right channel balance.
- EQ / Bypass Select Switch: Engages or bypasses the equalizer pre-amplification.
- Bluetooth / AUX Input Select Switch: Selects between Bluetooth and AUX (RCA/3.5mm) inputs.
4.2 Rear Panel Connections
- ANT: Connection point for the Bluetooth antenna.
- RCA IN (L/R): Stereo RCA audio input.
- 3.5mm AUX IN: 3.5mm stereo audio input.
- RCA OUT (L/R): Stereo RCA audio output.
- 3.5mm AUX OUT: 3.5mm stereo audio output.
- DC 5V IN (Type-C): Power input port.
5. Setup Instructions
Follow these steps to set up your EQ5 PRO:
- Connect Bluetooth Antenna: Screw the provided Bluetooth antenna onto the 'ANT' connector on the rear panel.
- Power Connection: Connect the supplied USB Type-C cable to the 'DC 5V IN' port on the rear panel. Connect the other end to a dedicated DC 5V power adapter (not included, ≥500mA). Important: Do not use USB ports from computers or share power with other audio sources to avoid noise.
- Audio Input Connection:
- RCA Input: Connect your audio source (e.g., CD player, media player) to the 'RCA IN' ports using an RCA cable.
- 3.5mm AUX Input: Connect your audio source (e.g., phone, tablet) to the '3.5mm AUX IN' port using a 3.5mm audio cable.
- Bluetooth Input: Ensure the input select switch is set to 'BT'.
- Audio Output Connection:
- RCA Output: Connect the 'RCA OUT' ports to your amplifier, headphone amplifier, or active speakers using an RCA cable.
- 3.5mm AUX Output: Connect the '3.5mm AUX OUT' port to your amplifier, headphone amplifier, or active speakers using a 3.5mm audio cable.
- Initial Power On: Ensure all connections are secure. Turn the volume knob to its minimum position. Flip the Power Switch to 'ON'.
6. Operating Instructions
6.1 Input Selection
Use the 'BT / AUX' switch on the front panel to select your desired input source:
- AUX: For RCA or 3.5mm wired inputs.
- BT: For Bluetooth wireless input.
6.2 Bluetooth Pairing
When 'BT' input is selected, the unit will automatically enter pairing mode. Search for 'EQ5 PRO' on your Bluetooth device and connect. Once connected, you can stream audio wirelessly.
6.3 Equalizer Adjustment
The EQ5 PRO features five independent frequency bands for precise sound customization:
- 100Hz: Controls the very low bass frequencies.
- 400Hz: Adjusts the mid-bass and lower midrange.
- 800Hz: Affects the central midrange frequencies.
- 4KHz: Controls the upper midrange and lower treble.
- 10KHz: Adjusts the high treble frequencies.
Rotate the respective knobs to increase or decrease the gain (±5dB) for each frequency band. Experiment to find your preferred sound profile.
6.4 Balance Adjustment
Use the 'BALANCE' knob to fine-tune the left and right channel output levels. This helps to prevent the sound field from deviating from the center position, especially useful in uneven listening environments.
6.5 Bypass Mode
The 'EQ / PASS' switch allows you to bypass the equalizer pre-amplification. In 'PASS' (Bypass) mode, the audio signal passes directly from input to output without any processing, allowing you to enjoy the original, unaltered sound. In this mode, the VU meters will not function.
6.6 VU Meters
The dual 45mm VU meters dynamically display the level of the audio signal in real-time, adding a vintage aesthetic and visual feedback to your audio experience. They are driven by a dedicated VU driver chip for accuracy.
7. Maintenance
- Cleaning: Use a soft, dry cloth to clean the exterior of the unit. Do not use liquid cleaners or solvents.
- Storage: When not in use for extended periods, store the unit in a cool, dry place, away from direct sunlight and dust.
- Ventilation: Ensure the unit has adequate ventilation to prevent overheating. Do not block any ventilation openings.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound output | Unit not powered on; Incorrect input selected; Cables loose/faulty; Volume too low; EQ in Bypass mode. | Check power connection and switch; Select correct input (BT/AUX); Ensure cables are securely connected; Increase volume; Switch EQ to 'EQ' mode. |
| Humming or noise | Common ground noise; Poor cable shielding; Interference. | Use a separate, dedicated USB power supply for the EQ5 PRO; Ensure high-quality, shielded audio cables are used; Move unit away from other electronic devices. |
| VU meters not working | Unit in Bypass mode; No audio signal. | Switch EQ to 'EQ' mode; Ensure an audio signal is playing through the unit. |
| Bluetooth connection issues | Antenna not connected; Input not set to BT; Device too far; Interference. | Ensure Bluetooth antenna is connected; Select 'BT' input; Keep device within range; Reduce interference sources. |
| Distorted sound | Input signal too strong; EQ settings too high; Volume too high. | Reduce volume of audio source; Adjust EQ knobs to lower gain; Lower the main volume. |
| RCA and 3.5mm AUX inputs not working correctly | Both inputs connected simultaneously. | Only connect one AUX input (either RCA or 3.5mm) at a time to avoid signal mixing. |
9. Specifications
| Feature | Specification |
|---|---|
| Audio Input | Bluetooth / Stereo RCA / 3.5mm AUX |
| Audio Output | Stereo RCA / 3.5mm AUX |
| Gain | ±5dB |
| EQ Bands | 100Hz / 400Hz / 800Hz / 4KHz / 10KHz |
| Bypass Function | Supported |
| Balance Adjustment (L/R) | Supported |
| Input Impedance | 50KΩ |
| Output Impedance | 15Ω |
| Frequency Response | 5Hz-20KHz |
| THD (Total Harmonic Distortion) | 0.003%@1KHz |
| Working Voltage | DC 5V (≥500mA) |
| Power Interface | USB (Type-C) |
| Diameter of VU Meter | 45mm |
| Dimensions (W*D*H) | 164*108*82mm / 6.46*4.25*3.23in |
| Net Weight | 730g / 1.61lb |
| Package Weight | 1.0kg / 2.20lb |
| Certification | CE |
10. User Tips
- Experiment with EQ: Don't be afraid to experiment with the 5-band EQ knobs. Small adjustments can make a big difference in tailoring the sound to your personal preference, room acoustics, or specific music genres.
- Dedicated Power: Always use a dedicated 5V USB power adapter for the best performance and to avoid potential noise issues.
- Cable Quality: Invest in good quality, shielded audio cables to minimize interference and ensure optimal signal transmission.
11. Warranty and Support
Douk Audio products are designed for reliability and performance. For any technical support or warranty inquiries, please contact your retailer or the official Douk Audio support channels. Keep your purchase receipt as proof of purchase.