ALTEC LANSING MODEL 1620A ACOUSTIC FEEDBACK SUPPRESSOR

Product Overview

The Altec Lansing Model 1620A is a professional acoustic feedback suppressor designed to automatically detect and eliminate feedback in sound reinforcement systems. By utilizing phase-lock loops and a sophisticated attenuation computer, the unit identifies feedback frequencies and reduces system gain to maintain stability without compromising audio quality. It is housed in a standard 19-inch rack-mount chassis, making it suitable for professional audio installations.

Installation and Setup

The 1620A is designed for standard 19-inch rack mounting and requires 1.75 inches of vertical space. Proper ventilation is essential, with a maximum operating temperature of 55°C (131°F). The unit features balanced input and output connections via XLR-3 connectors or barrier strip terminals. A chassis ground terminal is provided for addressing specific grounding issues in complex system configurations.

Operation

The system operates by monitoring audio for feedback-induced oscillations. When detected, the unit applies attenuation in 3 dB increments up to 28 dB. The front panel provides an LED display to indicate the current level of attenuation. Users can manually reset the unit to unity gain using the front panel button or a remote switch. A bypass relay ensures that the signal path remains intact if power is lost or the unit is switched off.

Technical Specifications

• Frequency Response: ±0.5 dB from 20 Hz to 20 kHz
• THD: Less than 0.05% (100 Hz to 20 kHz)
• Detector Sensitivity: Adjustable from -26 to +4 dBm
• Input Impedance: 15,000 ohms, balanced
• Load Impedance: 600 ohms, balanced
• Signal to Noise Ratio: Better than 90 dB
• Power Requirements: 100/120/200/220/240 Vac, 50/60 Hz, 5W

Maintenance and Safety

The unit is designed for reliable operation in professional environments. The sensitivity control is recessed to prevent accidental adjustment. The capture time control, accessible from the rear panel, is factory-set to lock on feedback oscillations within approximately 2.5 seconds. It is recommended that adjustments to internal controls be performed only by qualified personnel to ensure optimal system performance.