User manual ART PRO VLA

[. . . ] PRO VLA PROFESSIONAL TWO CHANNEL VACTROL/TUBE LEVELING AMPLIFIER USER'S GUIDE TABLE OF CONTENTS Introduction Registration Features Overview Setting Up Unpacking AC Power Hookup Audio Connections Installation Safety Precautions Powering Up Front Panel Controls and Indicators Power Threshold Control Ratio Control Output Level Control VU Meter Input/Output Switch Attack Time Switch Release Time Switch Bypass Switch Stereo Link/Dual Mode Switch Gain Reduction Meter VU Level Meter Rear Panel Connections Input Output Applications Tube Replacement Warranty Information Service Information PRO VLA Specifications On-line Information 2 2 3 4 5 5 5 5 5 6 6 6 6 7 7 8 8 8 8 9 9 10 10 10 11 11 11 12 12 13 14 14 212-5004-101 1 Introduction Thank you for purchasing Applied Research and Technology's PRO VLA. Offering a superb level of sound quality, the PRO VLA has a unique design which will enhance the sonic textures of your audio system for years to come. Registration If you haven't done so already, please take the time to fill out the User Registration Card for your purchase. Having you in our data base allows us to keep you informed of updates, application notes, and new product introductions. [. . . ] If the unit still fails to operate properly, turn it off and unplug it. Then consult your dealer or A R T's Customer Service department. 6 7 Output Control The Output control sets the output gain of the PRO VLA. When the control is fully counterclockwise, the output level of the PRO VLA is attenuated by -83dB. Turning the control clockwise adds gain (sometimes called "make-up" gain). Since levels can be decreased when compression is applied, the PRO VLA has the ability to apply gain to bring the processed signal back up to unity (same as input level). To properly set the output level, adjust the Output Control while switching between Active and Bypass. When these two levels are equal in volume, the output control is set properly. VU Meter - Input/Output Switch The VU Meter Input/Output Switch toggles the VU meter between displaying either input or output signal levels. The Input setting is the signal entering into the PRO VLA. The Output setting is the signal (post-process) leaving the PRO VLA. In stereo applications, place one switch in the Input position and one switch in the Output position. This enables you to see both levels at a single glance of the meters. Note: The Zero ("0") level of the VU meter is calibrated at +4dBm when using the XLR connectors into a 600 Ohm load or - when using the 1/4" outputs into a high impedance load. Attack Time Switch The position of the Attack Time switch selects the attack characteristics for the channel of the PRO VLA. Attack Time refers to how quickly compression is added after the input signal rises above the Threshold. Since different signals have different attack characteristics, it is important for a compressor to have different settings which allow the action of the compressor to sound more natural. The "out" position is the "Auto" setting. The Auto setting is a program dependant attack time with 20ms being the slowest the PRO VLA will take to achieve 20dB of compression. In other words, the Attack Time circuitry in the PRO VLA is designed to "adapt" to the signal characteristics of the signal you are processing. The "in" position is the "Fast" setting. This setting has a fixed attack time of 2ms. The Fast setting is ideal for punchy, repetitive signals. [. . . ] Put the packaged unit in another box for shipping. Print the RA number clearly on the outside of the shipping box. Print your return shipping address on the outside of the box. 5) Include with your unit: a return shipping address (we cannot ship to a P. O. [. . . ]