Bose Direct / Reflecting 901 Series 4 - Manual (Page 15)

B. ADJUSTING THE LOW AND HIGH FREQUENCY SOURCE
AND ROOM COMPENSATION CONTROLS
1. Select a well-recorded familiar record with a full orchestral
passage or a record with a large number of diverse musical
instruments that span the entire frequency range. Select a
recorded passage that has sustained music over several
seconds so you can observe the effects of the controls.
2. Preset the HIGH FREQUENCY Control in the center.
3. Move the LOW FREQUENCY Control back and forth
several times over the extremes of the control's range and
carefully listen to its effect. You will notice a dramatic
change in the basic fullness or body of the sound without
changing the deep bass or midrange. Starting with the con­
trol at the extreme left, slowly move the knob until the
balance of the sound is rich and full, but without excessive
heaviness.
4. Next, replay the same passage again and move the HIGH
FREQUENCY Control over the extremes of the range
several times, listening to its effect. Starting with the con­
trol set at the extreme left, slowly move the knob until the
sound fills with instrumental detail clarity, and presence.
Note that since no room is typical, it will be rare that the
center setting of both controls is used. Accordingly, it is
important to realize that it is your adjustment of these
controls that will result in the speakers optimum perfor­
mance.
LOW FILTER CONTROL
The 901 Active Equalizer features a newly-designed LOW
FILTER Control. The LOW FILTER Switch can be used to
reduce the lowest two octaves of bass energy without affec­
ting the mid-bass response. This control is most useful in
removing record or turntable rumble.
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FREOUEMCV IN СГС1БЗ PER SECOND
901 IV EQUALIZER CONTROL RESPONSE
C. SPEAKER PLACEMENT
Several options are possible regarding placement of your 901
in your listening room. Shelving that is deep enough to provid*
the necessary distances behind and to the side of the speake
system can be used. Make certain the shelving is substaniig
and not the same shelf used to hold your turntable, as possibi
acoustic feedback can occur.
Many people choose the attractive pedestals available wit
the 901 Series IV System. If you choose this method of suppor
instructions are provided with the pedestals for connectin
and mounting the speaker system, using the four predrille
holes (A) in the speaker bottom.
Another placement idea is to suspend the speaker syster
from the ceiling (see Figure 1). This placement method i
particularly attractive if wall surfaces are interrupted by wir
dows or doorways or if floor placement is difficult due t
furniture or the presence of children.
15