(under the class definition) Subject matter where there is an audio transducer and circuitry to protect the transducer from damage due to abnormal operating conditions.
SEE OR SEARCH THIS CLASS, SUBCLASS:
111+, for systems having specific audio transducers.
SEE OR SEARCH CLASS
361, Electricity: Electrical Systems and Devices,
1+, for circuitry to protect other systems and devices in general from damage due to abnormal operating conditions.
