OPERATION Table I. Control ond Indica tor Functions
CO NTROLS AND INDICAT O RS
The pilot indica tor and al l operating controls ar e on the front
pan e l (see Figure 6). Thei r function s are descri bed in Table
I. A hinged cover preve nts inad vertent control changes.
When the hinged co ver is secured, onl y the BYPASS switch
and pilo t indicator are exposed.
Use of Equalizer Con trols
Although the filter controls are continuously variab le slide
potentiometers, they are det e nted in increment s of 1-1/2 dB.
ALTEC strong ly recommends that onl y the det ented pos itions
be used to guarantee prec ision resetting of the con trols.
Typica I sound system response curves before an d after equa 1-
izat ion are shown in Figures 7 and 8. A convenient method
of recording filter contro l se tt ings for future resetting of con-
tro ls for different installati ons or application s is show n in
Figur e 9.
On ly one pushbutto n at a ti me should be pressed on the HIGH
PASS se lector or LOW PASS selector. Two pushbuttons wiII
lock in for ei ther selector but an error in filt er frequency
inser tion wiII resu It.
The first attempt to smooth the house cur ve shou ld be limited
to one or two of the greate st peaks or va Ileys. After th is
initial smoothing, run a new house cur ve to check resu lts.
Continue adjusting one or two sections at a time, rep lot ting
the frequency response each time, un til the desired unifo rmit y
of response is achieved or unti I the correct ion capabi Iity of
the 9860A is exceeded.
After the best obtainab le house cur ve is achie ved with the
9860A fi lter controls, adjust the GA iN control to provide an
equa lized output leve l as high as the unequalized input
leve l. The GAIN control is detented in increm ents of 2 dB
and has a reinsertion range of +20 dB.
Nam e
Filter Controls
HIGH PASS Se lector
LOW PASS Se lector
GA IN Contro l
BYPASS Switch
Pilot Indicator
1/~ OCTAVf CENT ER FReQueNCV·H I
Function / Description
Twent y six detent e d, lin ear slide con-
tro ls, continuous ly variab le, gradu-
ated from O to - 15 dB. Each control
adjusts a 1/3-oct a ve band-rejection
filter. ISO cent er frequencies range
from 40 to 12,50 0 Hz. Fi Iter depth is
-15 dB on each center frequency,
combining with ad jacent filters at - 7
dB.
Four interlocked pushb utton switches
for OFF , 40 Hz, 80 Hz and 160 Hz.
Selects high pass filter to shape low-
frequenc y audio spectrum. Inserts -18
dB/ octa ve rolloff a t the selected cor-
ner frequency.
Four interlocked pushbutton switches
for OFF, 6 kHz, 12.5 kHz and 16
k Hz . Selects low pass filter to shape
high-frequency au d io spectrum. In-
serts -18 dB/ octa ve rolloff at the se-
lected corner freq uency.
De tented, lin ear sl ide contro l, con-
tinuous ly var iable over a 20 dB range.
Adju sts leve l of eq ua lized program to
match level of unequalized program.
Pushbutton switch for A/ B comparison
or bypassing 9860A . Options of mo-
mentar y action or pus h-and- lock.
Light-emitting dio de . Continuousl y
Iit when equa Iize r is in operation.
Periodicall y flashe s in bypass mode.
on ,,,
-- - -- - ----- - ------ - -- - - - - -~
-------- - -- - - - - - - - - ------_ ,
------------ - - -- - -- - - -----·
----------- - -- - -------- - --·
----- - ------ - - -----------_,,
----------- - - - - -----------··
Figure 6. Front View 9860A, Hinged Pane l Cover Open
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