Noise Control & System Protection

Introduction

The AT-1 has been designed to be used in conjunction with the Sentry MK2 environmental control unit. It is a stereo unit and its purpose is to control the volume level of an audio system connected to it. It will control the connected system to the maximum level allowed as defined by the Sentry Mk2. Thus removing the worry of having to continually watch levels so the system is not cut off completely. It does this without affecting the dynamic range of the music being played, and because the control chain is microphone driven the amount of absorption that takes place when a venue is full of people is automatically catered

More that one unit may be connected to the Sentry MK2 to control more than one audio system this is particularly useful, so the house system and a visiting system band etc can be controlled to the same maximum level. The Sentry will automatically control the AT-1 that is in use.

It is in the interests of a visiting band or DJ to connect to the AT-1 so that they do not suffer the embarrassment of being cut off if they play to loud.

In the past this form of control was not available and control systems monitored the signal level passing through a system to control the maximum level available. This approach works fine but the system has to be calibrated to determine the relationship between the signal level and the actual sound pressure level being produced. This makes it impractical to control visiting systems by this method. With the introduction of The AT-1 this has now changed because the control information is derived from a microphone system (i.e. The Sentry) so calibration is no longer required; therefore any system may be connected and controlled, bearing in mind a few common sense points. If the visiting system is not connected to the AT-1 the Sentry switching the available mains power in the usual manner will control it. We feel that this will encourage visiting systems to want to be connected to the AT-1.

Connecting to and using the AT-1

The AT-1 is connected to the Sentry via a simple 4-core control cable.

The unit is fitted with two types of connector ¼" jacks and 3 pin XLR's for its audio connections these may be used as balanced or unbalanced connections. The unit would normally be connected between the mixer or pre amp and the power amplifiers. If the volume of the system were below the warning threshold the AT-1 device does nothing it only attenuates if the threshold is exceeded. If attenuation is taking place a led will illuminate to inform the user of the approximate amount of attenuation. A led is also incorporated to inform the user if the unit is being over loaded and is about to clip.

The Audio performance of the AT-1 is of professional quality. i.e. low distortion and low noise like all Formula Sound audio products.