The ST-GSP1 is a gated-speech preamplifier designed to be used in a variety of situations where it is desired to produce an automatically switched line-level signal from a microphone. This module may be used in conjunction with other RDL modules to configure automatic mixing systems or may be used alone as a voice-operated module. The open-collector output may be used to trigger other equipment or RDL modules. The versatility of ST-GSP1 applications range from complete automatic mixing system design to the addition of automatic mic gating to the inputs of conventional mixers or amplifiers.
The mic input may be wired for balanced or unbalanced operation. A phantom voltage terminal is provided for use with condenser microphones. The phantom inputs accept dc voltages up to 48 Vdc and is internally filtered. Most microphones may run from the same 24 Vdc supply as the ST-GSP1. The audio output may also be wired balanced or unbalanced. Two LED indicators are provided for adjustment. One LED indicates the correct gain setting. The second indicator shows when the module is switched ON. Gain and threshold levels are adjusted using multi-turn precision trimmers.
The mic input gain adjustment has sufficient range to accommodate a wide range of microphones, from low-output dynamic microphones to higher-output condensers. The threshold adjustment permits setting the audio level at which the preamplifier output turns ON. Internal switching is solid-state and uses a soft-switch transition that sounds instantaneous without annoying clicks or edge transitions. The module will mute 2 seconds after the audio level drops below the preset threshold level. In circumstances where a longer delay time is desired, an external capacitor may be connected to extend the delay.
A proprietary RDL circuit provides noise reduction whenever the mic is active. This circuit suppresses ambient noise that permits higher audio levels before feedback and minimizes the audible open-mic effect during the 2 second off delay.
NOTE: Power supply is required.
