Test Tone Generator - Focal ASTRAL 16 Manuel D'utilisation

ASTRAL 16
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Test Tone Generator

Astral 16 includes a highly configurable test tone
generator which can be used to help manually
calibrate channels.
1. Generator
Click this button to turn on the tone generator. It
will automatically start with Group 1. The channels
outputting sound will be highlighted in green.
2. Setup
Unlike traditional generators, Astral 16 will not
strictly play tones one channel at a time. Click
Setup to assign channels to groups. Each group
may contain one or more channels. For example,
if you have 2-way active loudspeakers, you
may wish to group the high frequency and low
frequency component of each into one group.
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3. Noise Selection
Choose the type of noise or tone created by the
generator.
• Sine: Generates a sine wave at the frequency
specified.
• Pink Noise: Generates full bandwidth pink
noise
• Pink Noise 400-4kHz: Generates pink noise
band limited to one decade. This is particularly
useful when setting relative levels between
channels with dramatically different useful
bandwidths. Remember SPL meters measure
not only sound pressure but also bandwidth.
• External: it is possible to use an external
noise generator connected to one of Astral
16 defined input. This is usually required
when using an external room calibration tool
providing its own stimuli (Room EQ Wizard is
one of them, see "REW integration").
4. Gain
The gain figure can be set so that the noise
generator operates at a level at or below that of
a normal source playing at 0dBFS. Default is 0.1
(-20dBFS).
5. Group
When the noise generator is active, use this
function to play the noise through different
groups defined in "2. Setup".
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6. RTA
When a USB microphone (such as the optional
Theater Acoustic Diagnostic Kit) is connected to
Astral 16, you can use the Real Time Analyzer to
visualize the response of loudspeaker groups in
the room. Note that the built in RTA is not accurate
enough to use for calibration, but is useful for
getting a good idea of the approximate response
of the system. Maximum level of the capture can
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be set by adjusting Mic Ref Level. Graph vertical
scale can be changed from Logarithmic (default)
to Linear.
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7. Dirac
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See "Dirac Live" for use of Dirac Live Calibration
Tool.
8. Volume Reference
It is good practice when calibrating systems to
always work at a reference level such as 85dB
C-weighted. Before activating the noise generator,
make sure the master volume is at a low level. Set
and recall a reference master volume value. Click
SET once you have dialed the value you'd like
to store. Click RECALL to quickly return to that
value.
Individual Channel Adjustments
Once your theater is defined, each channel can
be individually fine tuned. The theater can also
be renamed, and a child theater can be created
which enables stereo left, right, or mono audio to
be routed to existing channel assignments.
9. Channel Status
Each channel is enabled by default. If for some
reason this channel needs to be disabled, click the
ON button. It will turn to OFF and audio will no
longer be routed to that channel. Note that audio
will not be re-routed to other channels. Channel
status is set per Theater / Zone and is not stored
as part of a profile.
10. EQ
Each channel can have up to 20 filters cells
configured selecting the wheel icon. Channel
EQ can be bypassed by selecting ON/OFF. See
"Channel EQ" for detailed EQ options. EQ settings
are stored as part of profiles.
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11. Signal
Indicates which signal is routed to this output.
Should you desire to remap signal routing, you
can do so with Output Mapping. See "Output
Mapping" for details.
12. Channel Name
Customizable name to easily identify each
channel. By default, these are named for the
signal sent to each channel. You may decide
to change these to speaker model or another
unique identifier. Maximum allowable character
count is 25.
13. Size / Filter
Identify each channel as either Large, Small, or
Large and Sub. When a channel is set to Large,
no bass is redirected from this channel to the
subwoofer. Use this setting when the loudspeaker
has sufficient bandwidth and output capability to
reproduce sufficient bass. When a channel is set
to Small, bass in this channel is redirected to the
subwoofers according to the Frequency and Slope
for that channel. Large and Sub is a special case
that not only allows that channel to reproduce
full bandwidth audio, but also duplicates bass in
that channel to the subwoofer(s) according to the
Frequency and Slope for that channel.
Subwoofer channels have specific settings. By
definition, subwoofers have limited bandwidth
and some are more limited than others.
• Low Pass LFE: When this is set to ON, the
subwoofer channel has a low pass filter applied
according to that channel's Frequency and
Slope. This is designed to limit the channel's
ability to reproduce the upper portion of the
bass spectrum. This is usually done to prevent
the subwoofer from contributing midrange
distortion.
• Subsonic SUB: When this is set to ON, a
high pass filter is applied to the channel
which restricts the subwoofer's ability to
reproduce very deep bass according to the
frequency and slope defined for that channel.
Many subwoofers, especially smaller models
do not have the amplifier power or driver
displacement required to accurately reproduce
very deep bass. By actively filtering very deep
bass away from the subwoofer, it is better able
to reproduce bass within it's useful bandwidth.
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