Subwoofer Spl Adjustment - Linear Acoustic AERO.qc User Manual

Linear Acoustic AERO.qc User Guide
Using a sound pressure level (SPL) meter set to "C-weighted" and "Slow Response" adjust
the Center channel power amplifier to the desired SPL. Typical industry levels range from
78-79dB/C/Slow for near field television mixing to 85dB/C/Slow for far-field film mix-
ing. It is important to note that while an overall reference level is very important, it is more
important to ensure that all main channels are set to the same SPL.
If the power amplifier or powered speaker is adjusted as low as possible and the desired
target SPL cannot be reached, use the Center channel output trim on the AERO.qc to ad-
just to the desired SPL. This adjustment can be found under the Speaker Output -> Cali-
bration -> Levels menu.
Repeat this procedure for all of the main audio channels, again making sure that the
AERO.qc volume control remains at reference (green LED on). This allows the "return to
reference" function to support any desired volume setting while mixing, and a simple re-
turn to the calibrated SPL during final mixing or mastering.
5.1.2

Subwoofer SPL Adjustment

For 5.1 channel mixing, the subwoofer is required to apply 10dB of gain to the signal ap-
plied to it. This means that if the reference SPL of the main channels is set to 79dBSPL,
then the subwoofer is set to 89dBSPL. This is based on the long-standing practice in film
to allow an extra 10dB of headroom in the Low Frequency Effects (LFE) channel and was
originally required by optical and magnetic tracks that could not pass high-level low fre-
quency information without severe overload. Modern 5.1 systems no longer have a head-
room issue, but for compatibility with industry practice and legacy material, the increased
reproduction level of the subwoofer is maintained.
It is strongly recommended that this adjustment be made with the real-time analyzer (RTA)
built into the AERO.qc and not an SPL meter due to constraints in low frequency response
performance of typical meters. The procedure is simple: after calibrating the level of the
main channels, apply pink noise to the Center channel and note the average level. Next,
apply pink noise though the LFE channel to the subwoofer and adjust its level so that it
has about 10dB of additional mid-band level as compared to the Center channel.
The desired relationship between Center and Subwoofer is shown below
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Monitor Setup