Bose 901 Series III - Manual (Page 16)

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VI. Living with your BOSE 901 Speakers
A. ADJUSTING YOUR EQUALIZER CONTROLS
The 901 Series 111 equalizer has been completely redesigned
wiih new control features, allowing greater flexibility in opera­
tion and speaker placement. These controls are particularly
useful in establishing the overall balance of the speaker system
with your lisler^ing room acoustics. Generally speaking, adjust­
ing the frequency contour controls near the midposition will
provide the best performance characteristics of the 901 system
for most listening rooms. However, you are encouraged to ex­
periment with different settings of the equalizer controls and
your tone controls as these controls must ultimately be set
according to your own listening tastes.
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MID BASS FREQUENCY CONTOUR CONTROL. The perform­
ance of any speaker system Is affected by ttie acoustics of the
listening room—in particular, the mid-bass region, which can be
dramatically affected by the speaker s placement. The BOSE
901 Series III Active Equalizer addresses this problem with a
unique new control called the “Mid-bass Frequency Contour”
control This continuously variable slider control adjusts the
spectral respronse of the 80- to 260-Hz range II the speakers
are placed close to the reflecting wall, the midbass response
will increase Reducing the mid-bass control will then restore
proper
peiformance Similarly, placing the speakers further
away from ihe reflecting wall will cause a decrease in the mid­
bass response of Ihe speaker system Increasing the mid-bass
control will then restore proper balance
TREBLE FREQUENCY CONTOUR CONTROL. The Treble
Frequency Contour” control is also a continuously variable
slider control that contours the response of the speaker system
upwards from 4.000 Hz to beyond audibility This compensates
for the general reverberant characteristics of your listening
room, personal listening tastes, and high-frequency variations
in program material (see SECTION C).
You may find that placing your speakers in front of curtained
walls may require a higher setting of the treble control Similar­
ly. if your room is excessively bright sounding, you may find a
lower setting of the treble control provides a more pleasing
sound
BELOW 40 CONTROL. The Active Equalizer features a newly
designed "Below 40 Contour” control. The "Below 40" switch
can be used to reduce the lowest octave of bass (30-60 Hz)
energy without affecting the mid-bass response. The "Below 40”
switch is also useful in reducing turntable or record rumble.
901 III EQUALIZEH CONTROL RESPONSE
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