Line input analog audio received via the min-XLR inputs is immediately digitized at 24 bit
per sample at a 48KHz sample rate. Microphone level audio inputs are routed via an adjustable gain pre-amplifier before digitization, no gain adjustment is available for Line level inputs.
Reference Line Input level (0dB) is 0.775v. Microphones with an output sensitivity ranging between -30dB and -60dB can be accommodated by the pre-amplifier, which provides user adjustable amplification over the range of +22dB to +54dB with minimal signal degradation.
Due to the significantly higher precision and dynamic range of 24 bit sampling, input stage limiters or AGC’s are not provided by the RED-ONE camera. The digitized audio data can be considered as high dynamic range RAW sound information that is complimentary
to the high dynamic range RAW video information.
Just as linear response RAW video data is converted to REC 709 for metering, the linear response audio data is converted to Log Base 10 data for metering. A color coded 4 channel audio meter is provided in the lower section of the camera GUI. This information is visible in the RED-EVF, RED-LCD and HDMI (DVI) monitor outputs.
The goal for optimal quality recording is to place the audio reference level at an appropriate location in the digital range, providing sufficient headroom above the reference level to prevent clipping, while maintaining the sound quality of lower volume sources such as dialog.
A 0dB reference voltage level of 0.775V provides approximately 8dB of headroom above reference. Microphone pre-amplifier gains should be adjusted accordingly (i.e. 8dB lower)
e.g. With an Azden SGM X1 microphone rated at -41dB sensitivity, set the microphone
pre-amplifier to (41 – 8) = 33dB for optimal recorded signal quality.