dbx AFS2 Advanced Feedback Suppression Processor User Manual

1. Introduction and Overview

The dbx AFS2 Advanced Feedback Suppression Processor is engineered to eliminate audio feedback in live sound and installed audio systems. This unit features a powerful Digital Signal Processing (DSP) module, providing comprehensive control and processing capabilities. It offers up to 24 filters per channel, with filter Qs as precise as 1/80 of an octave, ensuring effective feedback elimination without significantly impacting audio quality.

Key features include:

• Easy-to-read Display: A full LCD display facilitates menu navigation, interaction with the AFS2 Wizard, and adjustment of settings.
• Versatile Connections: Equipped with XLR and 1/4-inch TRS connections for compatibility with various professional audio equipment.
• Input Signal Meters: Five-segment LED meters per channel, including a red clip indicator, provide accurate monitoring of input signal levels.
• Wizard Function: An intuitive setup Wizard simplifies the configuration process for users of all experience levels.
• Advanced Filtering: 24 programmable filters per channel with corresponding LED metering, offering application-specific filter types (speech and music: low, medium, and high).

2. Setup

Proper setup of the dbx AFS2 is crucial for optimal performance. Follow these steps to integrate the processor into your audio system.

2.1 Unpacking and Inspection

Carefully remove the AFS2 unit from its packaging. Inspect the unit for any signs of damage that may have occurred during shipping. Ensure all components listed in the packing material are present.

2.2 Front Panel Overview

The front panel provides access to all operational controls and visual feedback. It includes the main LCD display for menu navigation, input signal meters for monitoring audio levels, a rotary encoder for parameter adjustment, and dedicated buttons for the Wizard function and channel bypass. The filter section displays active feedback filters via LED indicators.

2.3 Rear Panel Connections

The rear panel houses all audio input and output connections, as well as the power inlet and a USB port for firmware updates. Each channel (Channel 1 and Channel 2) features balanced XLR and 1/4-inch TRS input and output jacks. A switch for selecting +4 dBu or -10 dBV operating level is also present for each channel.

This detailed view of a single channel's connections illustrates the flexibility of the AFS2. Ensure that the input and output levels (+4 dBu or -10 dBV) are correctly matched to the connected equipment to prevent signal clipping or excessive noise.

2.4 Audio Connections

1. Power Off: Before making any connections, ensure all audio equipment, including the AFS2, is powered off.
2. Input Connection: Connect the output of your mixer or pre-amplifier to the INPUTs of the AFS2 using either XLR or 1/4-inch TRS cables.
3. Output Connection: Connect the OUTPUTs of the AFS2 to the inputs of your power amplifier or powered speakers using either XLR or 1/4-inch TRS cables.
4. Level Matching: Set the +4 dBu / -10 dBV switch on the rear panel to match the nominal operating level of your connected equipment. For most professional gear, +4 dBu is appropriate.
5. Power Connection: Connect the supplied AC power cord to the AFS2's power inlet and then to a suitable AC power outlet.

3. Operating Instructions

The AFS2 is designed for straightforward operation, especially with its integrated Wizard function.

3.1 Powering On and Initial Boot

After all connections are made, power on your audio system, with the AFS2 being one of the last devices to power on. The unit will display a boot-up sequence on the LCD screen.

3.2 Using the Wizard Function

The Wizard function simplifies the initial setup and calibration of the AFS2. Press the illuminated WIZARD button on the front panel to activate it. The LCD display will guide you through a series of steps to analyze your audio environment and automatically set up the feedback suppression parameters. This process typically involves generating test tones and listening for feedback to identify problematic frequencies.

Follow the on-screen prompts provided by the Wizard. It will help you configure settings such as the number of filters, filter type (fixed or live), and overall system gain. The Wizard is particularly useful for new installations or when setting up in a new venue.

3.3 Manual Operation and Filter Control

Beyond the Wizard, the AFS2 allows for manual adjustment of parameters. Use the large rotary encoder and the MENU/BACK and SELECT buttons to navigate through the LCD menus. You can manually adjust filter settings, recall presets, and monitor system performance.

• Filter Types: The AFS2 offers various filter types, including "Speech" and "Music" modes, with low, medium, and high Q settings. Select the appropriate type based on your audio source.
• Filter Metering: The 24 LED indicators per channel visually represent the active feedback filters. When a filter is engaged, its corresponding LED will illuminate, indicating that a specific frequency is being attenuated to prevent feedback.
• Bypass Function: Each channel has a dedicated BYPASS button. Pressing this button will temporarily disable the feedback suppression for that channel, allowing for A/B comparison or troubleshooting.

3.4 Input Signal Monitoring

The input signal meters (LEDs) on the front panel provide real-time visual feedback of the audio input level for each channel. Aim for signal levels that illuminate the green and yellow LEDs consistently, avoiding the red "CLIP" LED, which indicates signal overload and potential distortion.

4. Maintenance

The dbx AFS2 is designed for reliable operation with minimal maintenance. Adhering to these guidelines will help ensure its longevity and performance.

• Cleaning: Use a soft, dry cloth to clean the exterior of the unit. Avoid abrasive cleaners, solvents, or harsh chemicals, as these can damage the finish or internal components.
• Ventilation: Ensure that the ventilation slots on the unit are not obstructed. Adequate airflow is essential to prevent overheating.
• Environmental Conditions: Operate the AFS2 in a dry environment, away from direct sunlight, excessive heat sources, and moisture. Avoid extreme temperature fluctuations.
• Firmware Updates: Periodically check the dbx official website for any available firmware updates. Updates can improve performance, add features, or resolve known issues. The USB port on the rear panel is used for this purpose.

5. Troubleshooting

This section addresses common issues you might encounter with the dbx AFS2.

5.1 No Audio Output

• Check Connections: Verify that all audio cables (inputs and outputs) are securely connected to the correct jacks on the AFS2 and other equipment.
• Bypass Status: Ensure that the channel's BYPASS button is not engaged, which would disable processing.
• Power: Confirm the AFS2 is powered on and receiving power.
• Level Settings: Check the +4 dBu / -10 dBV switch on the rear panel to ensure it matches the nominal operating level of your connected equipment.

5.2 Persistent Feedback

• Run Wizard Again: If feedback persists, re-run the Wizard function to recalibrate the system to the current acoustic environment.
• Gain Staging: Ensure proper gain staging throughout your audio chain. Excessive gain before the AFS2 can overwhelm its feedback suppression capabilities.
• Microphone Placement: Adjust microphone placement to minimize proximity to speakers and monitors.
• Filter Count: Verify that enough filters are allocated and active for the problematic frequencies. The AFS2 can utilize up to 24 filters per channel.

5.3 Display Issues or Unit Unresponsive

• Power Cycle: Turn off the unit, wait a few seconds, and then power it back on.
• Firmware: Ensure the unit has the latest firmware. Refer to the dbx website for instructions on updating firmware via the USB port.

6. Specifications

7. Warranty and Support

For warranty information and technical support, please refer to the official dbx website or contact Harman Music Group directly. Warranty terms and conditions may vary by region and purchase date. It is recommended to register your product upon purchase to facilitate any future support needs.

Manufacturer: Harman Music Group

For the most current support resources, including FAQs, software downloads, and contact information, please visit the official dbx website: www.dbxpro.com