Atlas Sound AA200PHD-CE mixer-amplifier is a professional grade product has been designed from the ground up to include the important features that professional installation personnel require to meet or exceed their customers expectations. Small, compact, and engineered for reliability, the Atlas Sound AA200PHD-CE will provide years of service and flexibility in todays background music and paging applications.Ideal ForThe Atlas Sound AA200PHD-CE is the perfect choice for distributed business paging and background music BGM systems, small to medium speech privacy systems, and in applications where music on hold MOH plus paging is required.PHD SwitchThe AAPHD Series features a patent-pending Amplifier Diagnostic System. The PHD Push Here Diagnostic is simple to use and very effective in testing the speaker wiring and load impedances on 100V speaker systems to assure the proper load is applied to the amplifier.VOX Mute Sensitivity ControlInput 1 signal can be used to trigger or activate a mute command. When an input is set to Mute Receive via the corresponding DIP switch, the input associated with the switch will be muted when a signal is applied to Input 1. The VOX Mute Sensitivity Control adjusts how sensitive the mute circuitry from Input 1 reacts. Setting the control fully counter-clockwise will lower the sensitivity, where a higher amplitude signal will be required at Input 1 to trigger the mute send circuits. Fully clockwise will raise the sensitivity of the mute circuits, where a lower amplitude signal will trigger a mute send. Calibration of this control in conjunction with the microphone to be used is very important to assure the proper amount of signal from the mic is enough to trigger the mute circuits. If it is not calibrated properly, the mute may not be triggered when a weak voice vs a strong voice uses the mic.