Artifact: Audio Center Equipment (ACE), Apollo Command Module, Block II

Audio Center manufactured by Collins Radio Co, Cedar Rapids Iowa. The 7.9 pound unit, measuring 4.7 by 4.56 by 8.65 inches is a 28-volt, 20 watt gasket-sealed box enclosing three identical headset amplifiers, one for each Astronaut audio station on the Apollo Command Module. It enabled communications among astronauts, between astronauts and launch personnel, and post-landing recovery frogmen; via the external communications links (Unified S-Band and VHF) to JSC Houston and the Lunar Module, as well as routing of audio to the Data Storage Equipment (DSE) for recording of audio signals.

The ACE consists of three electrically identical sets of circuitry which provide parallel selection, isolation, gain control and amplification of all voice communications. Each set of circuitry contains isolated pad, diode switch and gain control for each receiver input, and intercom channel along with isolation pad and diode switch for each transmitter modulation output and intercom channel; an earphone and microphone amplifier and voice-operated relay (VOX) circuitry with externally controlled sensitivity. The equipment operates with three remote control panels to form three audio stations, each providing an astronaut with independent control of all common functions.