Luxman 308 - Equalization and Filtering Features; Linear Equalizer Functionality; Low Cut and High Cut Filters

The Linear Equalizer:
Although recordings are equalized in accordance with RIAA
standards,
it
is
quite
Common
to
encounter
variations
in
overall
tonal
balance
from
one
recording
to
the
next.
In
addition,
dif-
ferences in listening environment and room acoustics often
require subtle degrees of tonal compensation that conventional
tone controls cannot correct because of their wide range and
overlapping crossover characteristics.
THE LINEAR EQUALIZER control
provides a new form of tonal compen-
sation specifically intended for subtly
augmenting regular tonecontrols. With
the contro! in its mid-position, flat
frequency response is_ achieved.
Switched to either of the two “up-tilt”
positions, the entire response curve is
rotated about a 1KHz fixed axis so as to linearly increase treble
response while simultaneously decreasing bass response. Con-
versely, selection of one of the “down-tilt” positions rotates the
response curve in a clockwise direction, providing a gradual
decrease of treble response and simultaneous increase of bass
response. Degree of slope for either positive or negative settings
has been carefully preset, and the overall response curve
maintains complete linearity from 50Hz to above 10KHz, unlike
the curvature in response normally associated with ordinary tone
controls.
Specifically, when the contro! is turned to the first “up-tilt’
position, it will decrease bass and increase treble by 1.5dB at
100Hz and 10KHz respectively, while selection of the second
“up-tilt’” position will result in a 3dB cut and boost at these same
frequencies. Selection of the first “down-tilt” position will de-
crease treble and increase bass by 1.5dB at the same reference
frequencies, while the second “down-tilt” position provides
3dB of cut (at 100Hz) and boost (at 10KHz).
Combined use of the LINEAR EQUALIZER and conventional
tone controls provides a degree of tonal flexibility which cannot
be achieved with any other tone control arrangement presently
available. Because of the inherently linear nature of this new
circuit, it introduces no increase of harmonic distortion at any of
its settings.
LINEAR EQUALIZER
Linear Equalizer “up-tilt”’
“down-tilt’”’
AG
Low Cut Filter:
When this filter (10) is moved up from the
centre NORMAL position, the low frequencies
you hear are cut off below 7OHz at the rate of
6dB/Octave. When, it is moved down, the low
frequencies are cut off below 20Hz. Thus, it is
useful for removing low frequency noise such as
rumbling of the phono motor. It can also be used
as an auxiliary control for Bass Level! Control.
“, loweut hi
20Hz
High Cut Filter:
When this filter (11) is moved up from the it highcut m
centre NORMAL position, the high frequency : 7KHz dé
range over 7KHz is cut off at the attenuation rate |
of 6dB/Octave. When moved down, the high
frequencies over 12KHz are cut off. Thus, it is
useful for removing scratch or hissing noise and
can also be used as an auxiliary control for Treble
Level Control.
z I2KHz de
Operation of Low Booster
The Tone Controls Switch (9) has two func-
tions: tone defeater and low booster. When this
switch is set at the LOW BOOST position, the
low frequency range below 7OHz is boosted
with a slope of 6dB/Octave in addition to other
tone controls. This circuit, effective only on the
extreme low frequency range, allows flexible and
versatile tone adjustment. For instance, probable
rise-up in a small room of approximately 10m2
in the neighbourhood of 150 to 200Hz can be
subdued with this control by lowering the bass level to the 300Hz
position on the Bass Frequency Selector. This process can sup-
press such unnecessary rise-up without spoiling the response
at the extreme low frequency range. Moreover, when the human
voice sounds unnaturally stout, it can be adjusted to a Clear,
natural voice by switching on this booster and cutting the low
frequency range a small extent with the Bass Level Control.
low boost
tone defeat