BASS OPTIMIZATION SYSTEM™
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 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 9 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.
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 L to a middle position (10 clicks from a fully clockwise position) and set Level adjustment K 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 Frequency control J 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 K slowly up and down until you have maximized the improvement. If you have really keen ears, you can also have the Bandwidth control L 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
