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INFINITY ALPHA 1200S
Infinity’s Bass Optimization System is a simple-to-use,yet
sophisticated,low-frequency calibration system.Each Interlude
subwoofer contains a parametric equalizer that you can adjust
following the directions below.By following these instructions,
you can improve the sound of your system.
The Bass Optimization System Goal
It is a fact of audio that what we hear at low frequencies is
determined as much or more by the listening room than by the
loudspeaker itself.Placement of the loudspeakers and listeners
and the acoustical characteristics of the room surfaces are all
important determinants of bass quantity and quality.In most
practical situations,there is little that can be done about this,
except for patient trial-and-error repositioning of the
loudspeakers and listeners.Usually,the practical constraints of
a living space and the impracticality of massive acoustical
treatment mean that equalization is the only practical solution.
Professional sound engineers routinely employ sophisticated
measurement systems and equalizers to optimize speakers to the
installation.This was never practical for the home audiophile.
This is why the Bass Optimization System was created.It
enables you to identify the dominant low-frequency response
characteristic of your room.Once you know the problem,the
Bass Optimization System provides the tools needed to optimize
the low-frequency characteristics of the speakers to the room
they are in,exactly as the professional sound engineers do it.
Preparations
Before beginning the bass tests,please check the following:
• Make sure all three Bass Optimization System controls on the
subwoofer are turned fully clockwise.
• Make sure the loudness contour (if any) on your receiver/
processor/preamp is turned off.
• Set the receiver’s/processor’s tone controls (Bass and Treble)
to their center or flat positions.
• Bypass all surround and effects features of your receiver/
processor/preamp or set to Stereo Bypass.
• If you are using a multichannel surround processor or
receiver,make sure all bass-management features are properly
set.The Audio channels should all be set to “Small”or “High-
Pass” and the subwoofer set to “On.”
• Set the Bass Optimization System Selector
ᕡ to “On.”
For best results,it is recommended that all major furnishings
are in place and that all doors and windows in the listening
area are in their normal positions.That is,if you normally listen
to music with all doors closed,then this is how they should be
during this procedure.
BASS OPTIMIZATION SYSTEM
™
To solve a problem,it helps to first identify whether you have one
and,if so,what it is.First,play a variety of music and films with
energetic bass sounds,like bass guitar,kick drum,keyboards,
etc.A kick drum should produce a tight “thump”, not a flabby
“boom.”Bass melody or harmony lines should have notes that are
about equally loud.If some notes disappear, or stand out
because they are consistently too loud,there is a problem.
Disappearing notes have to be handled by moving the listening
position,or the loudspeakers,to slightly different locations.
Often,but sadly not always,this will be enough. Excesses in bass
tend to be most annoying,and energetic resonances that cause
“boomy”or “lumpy”bass can be truly aggravating over a period
of time.Infinity’s Bass Optimization System can fix this.
So,the first step is to exercise your music collection,and listen
for low-frequency problems that crop up in several different
recordings.Something that only happens in one recording is
likely to be a problem in the recording – it happens! If you
identify something that is consistently wrong,select a record that
shows it very clearly,and put your CD/DVD player into a repeat
mode (A-B repeat is especially helpful,because you can isolate a
short musical passage).
Set the Bass Optimization System Bandwidth Adjustment Control
ᕤ
to a middle position (10 clicks from a fully clockwise
position) and set the Level adjustment ᕣ for a –6dB (8 clicks
from a fully clockwise position).Then,while the music is playing,
sit in your favorite chair and have somebody else slowly adjust
the Center-Frequency control ᕢ from fully clockwise to fully
counter-clockwise.At a certain frequency,you should hear the
problem lessen and the overall bass performance improve.When
you are satisfied that you have found the best frequency,have
your assistant vary the Level
ᕣ slowly up and down until you
have maximized the improvement.If you have really keen ears,
you can also have the Bandwidth Adjustment control
ᕤ
adjusted
for maximum benefit.
While the Bass Optimization System allows the listener to fine-
tune the bass response to sound best in a particular room,some
listeners don’t have the skill or desire to adjust their system by
ear.In order to facilitate quicker and more accurate results,
Infinity has developed an optional test and measurement kit that
allows the user to perform a series of measurements and aids
him/her in properly setting the Bass Optimization System
controls.With the addition of this kit,the Bass Optimization
System becomes truly room-adaptive.The kit consists of the
following: a test CD,a sound-level meter that is specifically
calibrated for low frequencies,and something we call a “Q-Finder,
”
a device to help find the width of the measured curve and,
finally,a measurement template.It works as follows.The listener