Bose 901 Owner's guide - Page 12

conventional

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position, it reduces turntable rumble and other low frequency disturbances in a manner that has much less effect upon music than that caused by conventional rumble filters. This is achieved, as shown in Figure 4, by a unique filter design which provides a uniform attenuation below 40 Hz while causing no audible amplitude or phase deviations above 50 Hz. TREBLE LEVEL AND TREBLE CONTOUR - The combination of these two switches provides a wide range of control over the reproduction of notes in the higher octaves of the musical scale. It has long been recognized that the better speaker is more sensitive to the quality of program material and the more selective the listener must be in choosing his recordings. The purpose of these switches is to extend the excellent performance attainable with good recordings to an extremely wide range of commericial recordings and to enable you to exercise personal taste with respect to music reproduction in your particular listening room. When the TREBLE LEVEL control is in the dot position, the high frequency response of the system may be varied by moving the TREBLE CONTOUR switch. The highs may be either increased or decreased as shown in Figure 4. When the TREBLE LEVEL switch is in the DECREASE position, the system reduces the response in the midrange and highs. The degree of reduction obtained may be selected by the TREBLE CONTOUR switch. Unlike ordinary tone controls, the response of the system remains at a fixed level for high frequencies and does not continue to fall, as shown in Figure 5. This enables a reduction of response in the midrange (such as the sound of violins) without destroying the timbre of the instruments and without eliminating the very high frequencies (affecting percussion, for example). •

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position,
it
reduces
turntable
rumble
and
other
low
frequency
distur-
bances
in
a
manner
that
has
much
less
effect
upon
music
than
that
caused
by
conventional
rumble
filters.
This
is
achieved,
as
shown
in
Figure
4,
by
a
unique
filter
design
which
provides
a
uniform
attenuation
below
40
Hz
while
causing
no
audible
amplitude
or
phase
deviations
above
50
Hz.
TREBLE
LEVEL
AND
TREBLE
CONTOUR
-
The
combination
of
these
two
switches
provides
a
wide
range
of
control
over
the
reproduc-
tion
of
notes
in
the
higher
octaves
of
the
musical
scale.
It
has
long
been
recognized
that
the
better
speaker
is
more
sensitive
to
the
quality
of
program
material
and
the
more
selective
the
listener
must
be
in
choosing
his
recordings.
The
purpose
of
these
switches
is
to
extend
the
excellent
performance
attainable
with
good
recordings
to
an
extremely
wide
range
of
commericial
recordings
and
to
enable
you
to
exercise
personal
taste
with
respect
to
music
reproduction
in
your
particular
listening
room.
When
the
TREBLE
LEVEL
control
is
in
the
dot
position,
the
high
frequency
response
of
the
system
may
be
varied
by
moving
the
TREBLE
CONTOUR
switch.
The
highs
may
be
either
increased
or
de-
creased
as
shown
in
Figure
4.
When
the
TREBLE
LEVEL
switch
is
in
the
DECREASE
position,
the
system
reduces
the
response
in
the
midrange
and
highs.
The
degree
of
reduction
obtained
may
be
selected
by
the
TREBLE
CONTOUR
switch.
Unlike
ordinary
tone
controls,
the
response
of
the
system
remains
at
a
fixed
level
for
high
frequencies
and
does
not
continue
to
fall,
as
shown
in
Figure
5.
This
enables
a
reduction
of
response
in
the
midrange
(such
as
the
sound
of
violins)
without
destroying
the
timbre
of
the
instruments
and
without
eliminating
the
very
high
frequencies
(affecting
percussion,
for
example).
•