AFS 224 ™ Du a l C h a n n e l A d v a n c e d F e e d b a c k S u p p r e s s i o n P r o c e s s o r User Manual
IMPORTANT SAFETY INSTRUCTIONS WARNING FOR YOUR PROTECTION READ THE FOLLOWING: KEEP THESE INSTRUCTIONS HEED ALL WARNINGS The symbols shown above are internationally accepted symbols that warn of potential hazards with electrical products. The lightning flash with arrowpoint in an equilateral triangle means that there are dangerous voltages present within the unit. The exclamation point in an equilateral triangle indicates that it is necessary for the user to refer to the owner’s manual.
IMPORTANT SAFETY INSTRUCTIONS ELECTROMAGNETIC COMPATIBILITY This device complies with part 15 of the FCC Rules and the Product Specifications noted on the Declaration of Conformity. Operation is subject to the following two conditions: • this device may not cause harmful interference, and • t his device must accept any interference received, including interference that may cause undesired operation. Operation of this unit within significant electromagnetic fields should be avoided.
Service / Warranty AFS 224 ™ Service Contact Info If you require technical support, contact dbx Technical Support. Be prepared to accurately describe the problem. Know the serial number of your device - this is printed on a sticker attached to the chassis. If you have not already taken the time to fill out your warranty registration card and send it in, please do so now. You may also register online at www.dbxpro.com.
AFS 224 ™ Table of Contents Introduction Defining the AFS 224 ���������������������������������������������������������������������������������������������������������������������������������������2 Installation Recommendations �������������������������������������������������������������������������������������������������������������������������3 Connection Recommendations ������������������������������������������������������������������������������������������������������������������������3 Front
Introduction AFS 224 ™ Congratulations on your purchase of the dbx AFS™ 224. The AFS 224 Advanced Feedback Suppression processor was designed to provide state-of-the-art feedback elimination processing, while maintaining a simple and intuitive control interface. From the powerful DSP module to the no-nonsense user interface, the AFS 224 provides all the processing and control necessary for both installation and live use. The AFS 224 is an absolute must for any live sound application.
AFS 224 ™ Introduction and the proprietary, precision AFS filters remove only a fraction of the frequency spectrum. The following graph shows a comparison between AFS filters, the filters available in other feedback eliminators, and conventional graphic EQ filters: Competitor’s Feedback Elimination dbx AFS™ 1/3 Octave EQ For more information regarding dbx Advanced Feedback Suppression (AFS™) technology, please refer to the white paper available online at: www.dbxpro.com.
AFS 224 ™ Front & Rear Panels Front Panel Input Level Bar Graph These four LEDs indicate the input signal level of the AFS 224. Input level LEDs range from -10dBu to +18dBu. NOTE: For maximum performance and proper operation, the average input signal level should consistently light the 0dBu LED, with the +10dBu LED lighting occasionally. Clip LED This LED indicates that there is signal clipping at the input.
AFS 224 ™ Front & Rear Panels Live Filter Lift Button Live Filter Lift provides maximum sonic integrity by removing unnecessary feedback filters. This button is used to select the live filter lift times and are indicated as follows: LED Not Lit Green Yellow Red Lift Time Lift Off 1 Minute 10 Minutes 60 Minutes Mode Button This button is used to select between FIXED MODE (button is green) or LIVE MODE (button is red).
Applications AFS 224 ™ System Connection & Gain Structure The four basic ways to hookup the AFS 224 to your system are as follows: 1. Connected to the insert jack(s) on a microphone channel of a mixer. 2. Connected to the subgroup insert jack(s) of a mixer. 3. Connected to the insert jack(s) on the master outputs of a mixer. 4. Connected inline w/outputs of a mixer (output of mixer to input of 224, output of 224 to amplifiers).
AFS 224 ™ Applications Application 1 – Mixer Channel Inserts This application provides dedicated feedback suppression directly on the microphone channels of a mixing console, thereby leaving other channels unaffected. This application provides two individual channels of feedback suppression with up to 24 filters per microphone channel. 1. Turn off the power to the mixer and amplifiers. 2. Ensure the AFS 224 is configured for dual mono operation (this is the default configuration).
AFS 224 ™ Applications Application 2 – Mixer Subgroup Inserts This setup is ideal for applications that require feedback suppression on certain instruments (such as Output to Power Amp Output to Power Amp microphones) while keeping instruments that desire feedback (such as guitars) separated. This application provides two channels of feedback suppression with up to 24 filters per channel. 1. Turn off the power to the mixer and amplifiers. 2.
AFS 224 ™ Applications Application 3 – Mixer Master Stereo Output Inserts This application provides feedback suppression over the entire mix using the master inserts on the mixing console. This application provides two channels of feedback suppression with up to 24 filters per channel. 1. Turn off the power to the mixer and amplifiers. 2. Ensure the AFS 224 is configured for stereo linked operation. See “Linking Channels” for further information. 3.
AFS 224 ™ Applications Application 4 – In-line Between Mixer & Amp This application is ideal for dedicated feedback suppression on the entire mix, when your mixer does not have master insert connections. This application provides two channels of feedback suppression with up to 24 filters per channel. If your mixer does have master insert connections, it is recommended that you connect the AFS 224 to these master insert jacks as described in Application 3. 1. Turn off the power to the mixer and amplifiers.
AFS 224 ™ Operation Quick Start For best performance, it is recommended that you perform the following: • Ensure you have properly configured the AFS 224 for your application (i.e. dual mono operation or stereo linked operation). See “Linking Channels” for further information. • Ensure that the gain structure has been properly set. See “System Connection & Gain Structure”. Step 1.
AFS 224 ™ Operation Setup Mode The AFS 224 Setup Mode is used to set the total number of AFS filters available and allocate the number of Fixed verses Live filters available in each channel. The number of Live filters is the difference between the total number of filters and the number of Fixed filters (Live Filters = Total Number of Filters - Fixed Filters). Note: If channels are linked, all selections made in Setup Mode will affect both channels.
AFS 224 ™ Operation electing the Number of Fixed Filters S When in Setup Mode, use the channel button(s) to toggle to the Set Number Fixed Filters Menu indicated by the selected channel’s button lighting green. The current setting for the number of Fixed filters is indicated by the number of Filter LED’s lit for each channel. To change the number of Fixed filters, use the selected channel’s button to increment and the button to decrement the number of filters.
AFS 224 ™ Operation Fixed Mode The AFS 224 offers two main modes of operation: Fixed Mode and Live Mode. Fixed Mode is used to detect and remove feedback problems in the system due to microphone placement, room modes, etc.. Once set, these filters are stored in the AFS 224 (even after a power cycle) and are not removed until cleared by the user. The AFS 224 can be put into Fixed Mode by pressing the button until it lights green.
AFS 224 ™ Operation Live Mode Live Mode allows feedback filters to be set and removed based on changes in the environment and is designed to be used during a performance. The AFS 224 can be put into Live Mode by pressing the button until it lights red. Once in Live Mode, if feedback occurs, a filter will be set at the feedback frequency. If there are additional occurrences of feedback, additional notch filters will be set until all the Live filters are used.
Operation AFS 224 ™ Other Functions Clearing Filters o clear the Live filters, press and hold the button on the selected channel for approximately T two seconds. The currently assigned Live filter LEDs will flash. If you wish to clear only the Live filters, release the button at this time. If you wish to clear all filters (Fixed and Live), continue to hold the button an additional two seconds until all filter LEDs are flashing.
AFS 224 ™ Technical Information Factory Hard Reset In the event that you would like to set all parameters back to their factory default state, please perform the Factory Hard Reset procedure outlined below. WARNING! Performing this reset will clear all set filters. Ensure the system’s gain is reduced and amplifiers are off before performing this procedure to ensure the system does not go into feedback once the filters are cleared. Step 1.
Inputs RF Filter Input TYPE IV™ 18 AFS™ 224 User Manual Mode Live Filter Lift Type Bypass CLIP Detect A/D Programmable Logic Micro Processor DSP Input meter Mode Live Filter Lift Type Bypass Filter meter LEDs D/A RF Filter Outputs AFS 224 Block Diagram Technical Information ™ AFS 224 Block Diagram
AFS 224 ™ Technical Information Specifications Analog Inputs: Number of Inputs: Connectors: Type: Impedance: Max input line level: 2 Female XLR and 1/4” TRS Electronically balanced/unbalanced, RF filtered Balanced 50kΩ, Unbalanced 25kΩ +20dBu CMRR: >40dB, typically >55dB @ 1kHz Analog Outputs: Number of Outputs: Connectors: Type: Impedance: Max Output Level: 2 Male XLR and 1/4” TRS Electronically balanced/unbalanced, RF filtered Balanced >120Ω, unbalanced >60Ω +20dBu A/D Performanc
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