3d. OptiProtect® Speaker Overload Protection
Within OptiProtect® the AM-77 has an in-built speaker protection circuit. Unlike common protection systems which are in series with the speaker output and where the music signal always passes through the protection circuit, the AMR speaker protection system acts as a crowbar circuit shorting across the output - hence it is separate from the audio circuitry and does not affect the sound quality unless it is engaged.
This is mainly a final safeguard against equipment failure and/or extreme levels of over-driving the amplifier and speakers. When the display shows:
S p e a k e r P r o t e c t i o n
E n g a g e d !
This indicates that the AM-77 has detected an output condition that could potentially damage the speakers connected to it.
Normally switching the AM-77 off, waiting 20 seconds and switching it back on will reset the protection circuit if the cause was for example, excessive signal levels. In the extremely rare event that an internal malfunction of the AM-77 is the cause for the protection circuit to engage, the protection will re-engage on switch-on, indicating the need for the AM-77 to be serviced.
