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Sound optimisation
At the completion of installation, some
time spent fine-tuning the DSP amplifier
settings can bring benefits to the sound
of the installed system.
Filtering / equalisation
The basic limiter and filter settings listed
in the ‘Planning the Installation’ setting
must always be in place.
Amina also publishes optimisation files
which can provide an excellent starting
point for equalisation depending on the
acoustic environment.
Additional filtering should be primarily
subtractive in nature since large boosts
in low frequencies have the potential
to override power limiting settings or
reduce the overall sensitivity of the
subwoofer.
Phase
When setting up any speaker system
that includes the ALF100SM, it is
advisable to experiment with connecting
the ALF100SM in reverse phase with
respect to the other system speakers.
• To do this, take a seat in a good
listening position and play a short
passage of music which includes
some bass energy.
• Reverse the + and - wires where they
connect to the amplifier, or use DSP to
reverse the phase.
• Repeat the listening test with the
same passage of music.
Reverse-phase connection can
sometimes result in better integration
and slightly higher sound pressure
level through the “cross-over” region.
• Repeat the listening test until you can
determine the best phase setting.
Using pink noise can be a good way
of judging the difference between
the in-phase and reverse-phase
connections.
Time alignment
In multi-channel audio systems with
loudspeakers and subwoofers at different
distances from the main listening
position, sound from each channel will
arrive at the listening position at slightly
different points in time.
The standard method for improving
system synchronisation and ultimately
intelligibility is with the use of time
delays. This can be achieved by using
DSP settings to slightly delay the sound
from sources of sound closer to the
listening position so that the time of
arrival at the main listening position
matches that from the furthest sound
source.
A one meter difference will require
approximately 2.92ms of delay (0.029 ms
per cm), and one foot of difference will
require 0.89 ms of delay (0.075 ms per
inch). The speed of sound varies slightly
with temperature and elevation - these
examples are given at room temperature,
at sea level.