User manual RME OCTAMIC

[. . . ] User's Guide OctaMic / OctaMic D Portable Professional Mic Preamp 8-channel Microphone / Line Preamp with Line Outputs Universal Power Supply Input Optional 8-Channel 192 kHz 24 Bit ADC AES-3 24 Bit Interface Contents Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. 1 Analog. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. 2 ADC Modul. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] As interesting as this is ­ you don't need to think about it. 96 kHz capable ADAT hardware, like all current RME digital interfaces, re-combine the data automatically. The user (and the DAW software) does not see any split data, but just single channels at the expected double sample rate. At frequencies not higher than 48 kHz (Single Speed), the outputs MAIN and AUX operate simultaneously and carry the same audio data. With this it is possible to distribute the output signal to two devices (2 x ADAT splitter). Up to 96 kHz (Double Speed), the ADAT outputs can be used in parallel to the AES outputs. In Quad Speed mode (128 kHz up to 192 kHz), the ADAT outputs are operated synchronously at Single Speed sample clock, but do not provide any audio data. The ADAT optical outputs of the ADC Module are fully compatible to all ADAT optical inputs. ADAT Main Interface for the first or only device receiving an ADAT signal from the OctaMic. When sending a Double Speed signal, this port carries the channels 1 to 4. In Quad Speed mode ADAT MAIN carries an empty but synchronous ADAT signal. When sending a Double Speed signal, this port carries the channels 5 to 8. In Quad Speed mode ADAT AUX carries an empty but synchronous ADAT signal. User's Guide OctaMic © RME 10 9. Word Clock 9. 1 Operation and Technical Background Correct interpretation of digital audio data is dependent upon a definite sample frequency. Digital signals can only be processed or transferred between devices if these share the same clock. Otherwise the signals are misinterpreted, causing distortion, clicks/crackle or dropouts. AES/EBU, SPDIF and ADAT are self-clocking, so an additional line for word clock could be considered redundant. In practice however, using several devices at the same time can cause problems. For example, if devices are connected in a loop without there being a defined `master' device, self-clocking may break down. Besides, the clocks of all devices must be synchronized from a single source. Devices without SPDIF inputs (typically playback devices such as CD players) cannot be synchronized via self-clocking. In digital studios, synchronization requirements can be met by connecting all devices to a central sync source. [. . . ] In most cases, it will switch off when being fed Professional-coded data. The table shows that a Professional-coded signal would lead to malfunctions for copy prohibition and emphasis, if being read as Consumer-coded data. This actually happened in former times, but if found today then it was implemented to force the costumer to buy a more expensive device. Nowadays many devices with SPDIF input can handle Professional subcode. [. . . ]