Specifications

Chapter 30: Surround Concepts 501
Calibrated Surround Monitoring
One of the most important things you can do is
to calibrate not only Pro Tools, but also your
monitoring system and other equipment.
For example, many post production facilities
calibrate their Pro Tools audio interfaces for
–20 dB = 0 VU. Once Pro Tools hardware has
been calibrated to unity gain, the monitoring
system can be adjusted to account for anomalies
in the room acoustics, speaker placement, and
other variables.
Calibrating your Pro Tools system involves at-
tenuating the input and output stages of your
system. Settings and reference level vary accord-
ing to the applicable standards of the current
project.
Calibrating Your Studio The first task for sur-
round mixing should be getting your monitor
speakers in proper position, alignment and cali-
bration for accurate listening and mixing.
Speaker position and alignment will vary ac-
cording to each installation, and is very specific
for different speakers, manufacturers, and for
each surround format. Instructions for optimal
speaker location should have been provided
with the speaker and monitor system, so consult
the documentation provided by its manufac-
turer.
Proper speaker calibration ensures that your sys-
tem plays back at accurately balanced levels.
This lets you compensate for any variances in
speaker position, alignment, or performance.
Formats and Terminology
Some multichannel mixing formats are referred
to numerically (such as 5.1 and 7.1). These num-
bers describe the number and type of output
(speaker) channels required for that format.
Other formats are referred to by their track lay-
out (such as LCRS and LCR).
Surround formats are referred to by their devel-
oper and product name, such as Dolby Surround
(or Pro Logic), Dolby Digital, DTS, Dolby Sur-
round EX, and others. Each surround format re-
quires you to mix in a compatible mixing for-
mat. For example, both Dolby Digital and DTS
are “5.1 surround formats.”
The standards for each format include more
than just the number of speakers. Formats also
may require specific track layout and filtering
for the various channels. For example, the sur-
round channel in Dolby Surround is band lim-
ited from 100 Hz to 7 kHz.
Surround formats also increase the importance
of phase, balance, and sound placement due to
the various ways in which multichannel mixes
can be encoded, decoded, compressed, ma-
trixed, or downmixed. Many publications are
available on these subjects. For a listing of sev-
eral sources of surround format information, see
“Where to Get More Information on Surround
Technology” on page 504.
Instructions for calibrating a Pro Tools
192 I/O audio interface are included with
the 192 I/O documentation.