AJA FS1 Installation and Operation Guide

FS1 Audio Level
Choices Pro or
Consumer
FS1 Installation and Operation Manual — Cabling the System
Since the FS1 handles both digital and analog audio and can convert between the two,
it provides settings via the Parameter Menus and the remote web browser that allow
you to control the relationship between audio level in analog versus the same audio
level in the digital domain. The FS1 offers four settings to accommodate these
different audio relationships in both professional and consumer audio applications.
The audio levels listed in the following table are defined in reference to 0 dBFS (where
FS = full scale), which is the maximum level that can be represented digitally.
Note: the measurements mentioned here are made using a 1kHz sine wave.
FS1 Professional Audio Level Settings
FS1 Audio Setting Meaning
+24 dBu analog = 0 dBFS SMPTE standard With digital audio at maximum possible level
(before clipping), the expected analog audio
input level is +24 dBu, and the output will be
scaled to this level.
+18 dBu analog = 0 dBFS EBU standard With digital audio at maximum possible level
(before clipping), the expected analog audio
input level is +18 dBu, and the output will be
scaled to this level.
+15 dBu analog = 0 dBFS With digital audio at maximum possible level
(before clipping), the expected analog audio
input level is +15 dBu, and the output will be
scaled to this level.
FS1 Consumer Audio Level Setting
FS1 Audio Setting Meaning
+12 dBu analog = 0 dBFS. With digital audio at maximum level (before
clipping), the analog audio input level will be
+12 dBu, and the output will be scaled to
this level.
These levels are provided for consumer
equipment that outputs audio at levels lower
than the professional levels.
Note: In the consumer audio world, units are
often given in terms of dBV, so +12.2dBu is
equivalent to +10dBV. The standard
operating level then corresponds to -10dBV
(-7.8dBu). The "+12dBu" FS1 setting
provides consumer audio levels with
headroom.
How Do Audio Level Settings Relate to Nominal Levels?
Most users refer to audio levels at the Standard Operating Level for the U.S. and
Alignment Level for the EU—a level not at maximum level, but rather at some lower
point to allow headroom for audio to become louder without clipping.
In the U.S. most users use +4 dBu as their Standard Operating Level. This
corresponds to -20dBFS in the digital domain (20 dB of headroom, per SMPTE
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