Nobsound VU3PRO Audio Selector Speaker Switcher User Manual

1. Introduction

The Nobsound VU3PRO is an advanced 2-input, 2-output audio selector and speaker switcher designed to enhance your audio experience. It features large VU meters for visual feedback, supports high power output up to 350W, and includes dedicated protection for vacuum tube amplifiers. This manual provides detailed instructions for setup, operation, and maintenance of your VU3PRO unit.

Figure 1: Nobsound VU3PRO with 2-input, 2-output configuration. Two speaker groups can operate simultaneously.

2. Setup

2.1 Package Contents

• 1 x VU3PRO Audio Selector Speaker Switcher
• 1 x Power Adapter
• 1 x Remote Control (batteries not included)
• 1 x USB Cable (Type-C)

Figure 2: Included accessories and the VU3PRO unit.

2.2 Connections

Ensure all audio equipment is powered off before making connections.

1. Amplifier Input: Connect your amplifiers (e.g., Amplifier A and Amplifier B) to the corresponding "AMPLIFIER" input terminals on the rear panel of the VU3PRO. Use high-quality speaker cables.
2. Speaker Output: Connect your speaker sets (e.g., Speaker 1 and Speaker 2) to the corresponding "SPEAKER" output terminals. Ensure correct polarity (+ to + and - to -).
3. Power Connection: Connect the provided power adapter to the DC 5V input (Type-C) on the rear panel and then to a power outlet.

Figure 3: Detailed connection diagram for amplifiers and speakers.

The VU3PRO supports high power output up to 350W per channel and is compatible with various amplifier types including BTL, Class A, Class D, and vacuum tube amplifiers. Pure copper speaker terminals and AC250V 5A relays are used for reliable high-current transmission.

Figure 4: High-quality speaker terminals and 350W power handling capability.

3. Operating Instructions

3.1 Front Panel Controls

• Power Switch / MIC Mode: Press to power on/off. Long press to activate/deactivate microphone pickup mode for the VU meters.
• Amplifier A/B Switch: Selects between Amplifier A and Amplifier B inputs.
• Speaker 1/2 Switch: Selects between Speaker 1 and Speaker 2 outputs. Both outputs can operate simultaneously.
• GAIN Knob: Adjusts the sensitivity of the VU meters (20 levels).
• SENS Knob: Adjusts the response speed and swing range of the VU meters (30 levels).

3.2 Remote Control Operation

The included remote control allows convenient operation from a distance. Ensure batteries are inserted (not included).

• Power Button: Turns the unit on or off.
• MIC Button: Toggles microphone pickup mode.
• COLOR Button: Cycles through 35 backlight colors for the VU meters.
• LIGHT Button: Adjusts the brightness of the VU meter backlight (5 levels).
• A/B Button: Switches between Amplifier A and Amplifier B inputs.
• 1/2 Button: Switches between Speaker 1 and Speaker 2 outputs.
• 1+2 Button: Activates both Speaker 1 and Speaker 2 outputs simultaneously.

Figure 5: Using the remote control for convenient operation.

3.3 VU Meter Customization

The VU3PRO features large 85mm VU meters with extensive customization options:

• Backlight Colors: Choose from 35 different backlight colors to match your mood or environment.
• Brightness Levels: Adjust the backlight brightness with 5 available levels.
• Gain Adjustment: Fine-tune the meter's sensitivity with 20 levels to accurately reflect your audio signal.
• Sensitivity Adjustment: Control the needle's response speed and swing range with 30 levels. Turning the SENS knob counter-clockwise increases the swing range by slowing the needle's return speed.

Figure 6: Customizable VU meters with multiple backlight colors.

Figure 7: 20-level gain adjustment for precise meter calibration.

Figure 8: 30-level sensitivity adjustment for meter response.

Figure 9: 5-level brightness adjustment for the VU meter backlight.

Figure 10: 35 backlight color options for personalized aesthetics.

4. Features

• Space-Saving Design: Compact unit (26.8cm width) allows easy integration into existing audio setups, providing flexibility to switch between multiple amplifiers and speakers without re-cabling.
• High Power Compatibility: Supports up to 350W per channel, ensuring stable operation with modern high-end amplifiers (e.g., TPA3255) and large floor-standing speakers. Compatible with BTL, Class A, Class D, and other amplification methods.
• Visual Audio Feedback: Large 85mm VU meters with 35 backlight colors and 5 brightness levels provide dynamic visual representation of your audio.
• Microphone Pickup Function: Built-in microphone allows the VU meters to visualize sound levels even without direct speaker connection, useful for monitoring subtle audio cues like record needle drops.
• Vacuum Tube Amplifier Protection: A patented HL current sensor prevents overload. A specialized dummy load circuit automatically generates an 8Ω virtual load if the switch is left on without speakers, protecting valuable vacuum tube amplifiers from no-load damage and transformer overheating.
• Long-Term Reliability: Features pure copper speaker terminals and AC250V 5A relays to prevent contact welding during high current transmission, ensuring over 10 years of reliable performance. The circuit board is coated with a moisture-proof layer to prevent performance degradation in humid environments.
• Professional-Grade Accuracy: Meets broadcast industry standards with a frequency response of 30Hz-20kHz ±1dB, ensuring precision for both hobbyist and professional applications.

5. Maintenance

To ensure the longevity and optimal performance of your Nobsound VU3PRO, follow these maintenance guidelines:

• Cleaning: Use a soft, dry cloth to clean the exterior of the unit. Avoid using liquid cleaners or abrasive materials, as they may damage the finish or internal components.
• Placement: Place the unit in a well-ventilated area, away from direct sunlight, heat sources, and excessive moisture. Ensure there is adequate space around the unit for proper airflow.
• Connections: Periodically check all cable connections to ensure they are secure. Loose connections can lead to signal loss or degraded audio quality.
• Power Off: Always power off the unit and disconnect it from the power source before performing any cleaning or maintenance.

6. Troubleshooting

• No Sound Output:
  • Check if the VU3PRO is powered on.
  • Verify that the correct amplifier input (A or B) and speaker output (1 or 2, or 1+2) are selected.
  • Ensure all audio cables are securely connected to both the VU3PRO and your audio components.
  • Confirm that your amplifiers and speakers are powered on and functioning correctly.
• VU Meters Not Moving or Moving Minimally:
  • In wired input mode, if the audio signal has low bass components or is at a low volume, the VU meter needle movement may be less pronounced. This is normal behavior.
  • Adjust the GAIN knob clockwise to increase the meter's sensitivity.
  • Adjust the SENS knob counter-clockwise to increase the meter needle's swing range.
  • Ensure the MIC mode is off if you are using wired input.
• Remote Control Not Working:
  • Check if batteries are inserted correctly and are not depleted. (Batteries are not included in the package).
  • Ensure there are no obstructions between the remote control and the VU3PRO's IR receiver.
• Distorted Audio:
  • Ensure that the total power output of your amplifier does not exceed the VU3PRO's 350W per channel limit.
  • Check all cable connections for proper seating and integrity.
  • Reduce the volume level from your amplifier or source device.

7. Specifications

8. Warranty and Support

The Nobsound VU3PRO comes with a 1-year manufacturer's warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use.

For technical support, troubleshooting assistance, or warranty claims, please contact Nobsound customer service through the retailer where you purchased the product or visit the official Nobsound website for contact information.

Please retain your proof of purchase for warranty validation.