AES42
AES42 referred to in the sound technology a standard for a digital audio - Interface for microphones . AES42 is based on the digital standard AES3 (colloquially AES / EBU ) of the A udio E ngineering S ociety / E uropean B roadcasting U nion .
An AES42 microphone converts the sound directly into a digital PCM bit stream. The resolution is up to 24 bit / 192 kHz. The processing chain impedance converter - microphone preamplifier - A / D converter is integrated in the microphone housing. The sound characteristics of the microphone are not influenced by any external preamplifier and are therefore always the same.
The connection is made via an XLR connector, the electronics are supplied with power via phantom power (Digital Phantom Power (DPP), 10 V, max. 250 mA). By modulating the phantom voltage by 2 V, such microphones can be operated remotely, for example to set low-cut filters or directional characteristics .
This interface can have advantages in practice, for example due to the compact integration in the mobile area, due to the remote control in large studio rooms and due to the always the same sound characteristics due to the completely integrated signal processing chain. Even with long cable runs, capacities or electromagnetic interference cannot have a direct effect on the audible microphone signal.
However, digital signal transmission can also lead to signal mutilation with long and inferior cables: If the receiver can no longer reconstruct the bit stream 100% using the checksum , the signal will deteriorate. It manifests itself in a loss of amplitude resolution (dynamics) and temporal desynchronization ( glitch ). The signal may then sound rough and be interrupted by crackling. In this case, a remedy is provided by higher-quality cables that are specified for digital transmission (characteristic impedance of 110 ohms) and avoiding adapters and extensions in the digital signal path.
literature
- Thomas Görne: Microphones in theory and practice. 8th, new, revised and expanded edition. Elektor-Verlag, Aachen 2007, ISBN 978-3-89576-189-8 .
