Backup Audio Interface. The EVB-BA-100 provides a means to switch in a backup amplifier in the event of a primary amp failure. One backup amp can be provided in reserve for several primary amps. Amplifier outputs are connected at TB2, and speaker field wiring at TB1. Supervisory and 24 VDC power inputs are provided at TS1. The LED onboard activates when the backup amp has been switched in. All wiring is power-limited. Mounts to snaptrack or insulating nylon standoffs. The EVB-BA-100 is compatible with both 25VRMS and 70VRMS audio signals.