McIntosh MQ108, Руководство пользователя, Страница: 7 / 20

The MQ108 is a programmable seven band equalizer. There are two filter bands for each
channel, making a total of 14. Each filter can be programmed for frequency, bandwidth and
amplitude boost or cut. It has 1/3 octave selectivity capability. The MQ108 connects to a stereo
system between a preamplifier or control center and the power amplifier.
The MQ108 is designed to correct for frequency response problems created by standing
waves and resonances in the listening room. The required programming is accomplished by
first measuring the frequency response of the loudspeakers in the listening room with a 1/3
octave analyzer to determine the frequency ranges that need to be compensated. Then
capacitors of the proper size to affect each of the needed frequency ranges and channels
are inserted into the socket pins provided in the MQ108. Adjustments are then made with
the level control for each band to achieve the desired results. Refer to the section HOW TO
PROGRAM THE MQ108 for details.
The MQ108 was designed to be used in a stereo system to correct for problems caused
by the room acoustics. Although the equalizer is not designed to correct specific loudspeaker
problems or limitations, it can be helpful in improving the sound of any loudspeaker system
in a typical listening room. The best results will always be achieved if a loudspeaker system
of the highest quality is used.
Loudspeaker performance is affected by the listening room in the following ways.
• The position of the loudspeakers in the room.
• The position of the listener in the room.
• The dimensions of the room.
• The wall, floor and ceiling covering.
• The stiffness or flexibility of the room surfaces.
• Reflections from furniture or substructures in the room.
All these factors can affect the sound balance. Standing waves or room resonances occur
due to reflections of the sound from wall to wall, from floor to ceiling and from any other
room structures. The acoustic characteristics of a typical listening room can affect loudspeaker
performance usually at frequencies below 1000Hz. The most pronounced effects are at fre-
quencies below 250Hz and can alter frequency response as much as ± 15dB.
These frequency response variations are the greatest in a square room with equal dimen-
sions from wall to wall and floor to ceiling. A high quality loudspeaker with the ability to radiate
perfectly uniform frequency response can have its sound characteristics changed drastically
by a room with severe standing waves. In most every case the change will degrade the listen-
ing. The most common effect is one or more peaks in the bass frequency range. These bass
peaks tend to mask the high frequencies which do not normally create standing waves due
to their shorter wavelengths. There can also be dips in the bass response at certain frequency
bands. Although dips in bass frequency response are undesirable, they generally are less
objectionable than bass peaks.
A multiband equalizer, properly programmed, can make dramatic improvements in the sound
of a high quality stereo system. Since the response peaks and dips can occur over a very
narrow range of frequencies, 1/3 octave measurement and corrective equalization is essential.
Both left and right loudspeakers in a stereo system must be equalized independently. Since
the loudspeakers are in different positions in the room, each speaker will drive the room to
5
INTRODUCTION
ROOM ACOUSTICS