Front Panel
1. 'SST POWER' switch The front panel label 'SST POWER', is a touch sensitive membrane switch used to apply or remove a/c line power to the soft start circuitry. Push firmly the center of the switch until the power-up sequence begins. Push again and the amplifier will power-down. ( Note: the rear circuit breaker must be on for the amplifier to power-up) 2. LED Indicator The 7B SST has an LED indicator to monitor the following conditions: UNLIT indicates the amplifier has no power. RED indicates the amplifier is muted (power-up) GREEN indicates the amplifier operation is normal. FLASHING RED - indicates the amplifier clipping. ORANGE indicates channel thermal shutdown. Power up sequence After pushing the 'SST POWER' switch, the LED will turn from unlit to red (mute). When the power supply has stabilized the amplifier will come out of mute and the LED will change to green (normal operation). Unlit LED ( No power ) The 7B SST LED when unlit indicates no A/C mains power is present and the amplifier probably needs only to be powered on or the rear panel circuit breaker is switched off. Clipping ( flashing red ) Clipping occurs when the channel output level no longer can follow the level increase at the input (Overdriven input condition). When the 7B SST is driven into clipping the LED will change from green to red then back to green when the level is reduced ( Flashing Red ). Momentary clipping can be tolerated, however it indicates that maximum un-distorted power has been surpassed and potential speaker damage may result if overload conditions persist. Any amplifier that is constantly operated into clipping indicates a more powerful amplifier is needed for that application. Thermal Shutdown ( orange ) The 7B SST has thermal shutdown circuitry to prevent damage due to overheating. Should thermal shutdown occur, the amplifier will mute, and the LED will turn orange indicating this condition. When the amplifier has cooled to a safe operating condition the 7B SST will return to normal operation. Persistent Thermal shutdown indicates steps need to be taken to increase airflow across the heat sink. ( Also see installation section on ventilation ).
