Altec 19 Walnut - Speaker System Usage and Maintenance; Electrical Connections; Grille Removal and Installation; Frequency Control Adjustments

Electrical Connections
Two terminals at the underside of the
cabinet connect leads from the amplifier.
If more than one Studio Monitor Speaker
System is connected to the amplifier(s),
be sure to observe polarity so that proper
acoustic phasing is achieved.
Removal of Grilles
‘Push-and-lock’ fasteners secure each
grille to the cabinet. To remove a grille,
simply grasp the upper corners and pull
firmly outward. To put the grille back on,
align it with the cabinet and press each
corner until firmly seated. For the Model
15, also press the center of the grille,
just below the horn area, to engage the
central fastener.
Frequency Controls
Two frequency controls are located on the
network/equalizer assembly, behind the
grille (lower grille for the Model 19. When
the controls are positioned in the OPTI¬
MUM area of adjustment, a ‘flat’ fre¬
quency response Is obtained for most
acoustic environments. Figure 2 shows a
typically ‘flat’ response of the Model 19
when both frequency controls are set in
the OPTIMUM area of operation.
When the HF LEVEL control is turned
counterclockwise from the OPTIMUM
area, the higher frequencies are ‘rolled
off’ or reduced in volume. This enhances
the bass and mid-range frequencies.
When the MF LEVEL control is turned
counterclockwise from the OPTIMUM
area, the mid-range frequencies are atten¬
uated, producing a ‘dip’ in the mid-range
portion of the audio spectrum. This
enhances the bass and treble frequencies.
Turning the control clockwise from the
OPTIMUM area enhances the mid-range
frequencies.
Figure 3 shows effects to the audio
spectrum when the two controls are
turned fully ‘up’ or ‘down’. With both
controls ‘up’ (solid line), both mid-range
and treble frequencies are enhanced. With
both controls fully ‘down’ (broken line),
the same frequencies are attenuated,
which enhances the bass frequencies.
Figure 4 shows effects to the audio
spectrum when the controls are turned to
extreme opposites to one another, with
HF Al
MD MF CON
TROLS n
4 OPTIML
IM AREA
10 20 50 100 200 500 1000 2000 5000 10000 20000
FREQUENCY IN HERTZ
Figure 2. Typical Response of Model 19 with
Optimum Control Settings
10 20 50 100 200 500 1000 2000 5000 10000 20000
FREQUENCY IN HERTZ
SOLID LINE = HF AND MF CONTROLS FULLY CLOCKWISE
BROKEN LINE = HF AND MF CONTROLS FULLY COUNTERCLOCKWISE
Figure 3. Typical Response of Model 19 with
Controls at Maximum and Minimum Positions
10 20 50 100 200 500 1000 2000 5000 10000 20000
SOLID LINE = HF CONTROL FULLY COUNTERCLOCKWISE,
= MF CONTROL FULLY CLOCKWISE
BROKEN LINE = HF CONTROL FULLY CLOCKWISE,
= MF CONTROL FULLY COUNTERCLOCKWISE
Figure 4. Typical Response of Model 19 with
Controls at Opposite Maximum and Minimum Positions
one control fully ‘up’ and the other con¬
trol fully ‘down’. With the HF control
‘down’ and the MF control ‘up’ (solid
line), mid-range frequencies are enhanced
and treble frequencies are attenuated.
With the HF control ‘up’ and the MF con¬
trol ‘down’ (broken line), mid-range fre¬
quencies are attenuated and treble fre¬
quencies are enhanced.
Maximum range of the two controls is
nominally 14 dB. Upon inspection of the
curves shown in Figures 3 and 4, some
interaction is seen between the two con¬
trols. This control interaction prevents
extreme imbalance between mid to high
response, and assures minimum phase
shift through the crossover network. Con¬
trols for the Model 15 function in a
similar manner.
By experimenting with these controls, you
may determine which particular settings
produce the most pleasing effects for
your acoustic environment.
SERVICE INFORMATION
Speaker system components may be
detached from the cabinet by removing
appropriate mounting screws. The low-
frequency loudspeaker and the network
assembly each mount to the cabinet with
four screws (see Figure 5). The Model
19 horn/driver assembly is mounted to
the upper part of the cabinet with six
bolts, which are accessible when the
acoustic damper pad is removed. The
Model 15 horn/driver assembly is mounted
with four bolts. The driver and interfacing
gasket are attached to the horn with two
nuts and two washers (see Figure 6).
Electrical connections are made in
accordance with the schematic diagram
of Figure 7.
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