Altec 1608 a owners manual

Page 1

OPERATION
CONTROLS AND INDICATORS

All normal operating controls are on the
front panel. Installation and service ad-
justments include an Acousta-Volcing
pad at rear of chassis, a tone control in-
\ out switch on the preamplifier board and
. a power driver balance control on the
power driver board. Control and indicator
functions are described in Table II.

WRITE-IN BLOCKS

The write-in blocks above the six gain
controls may be marked with a soft lead
pencil to identify use. To remove writing,
use a damp cloth - never use a pencil
eraser or other abrasive material because
the writing surfaces will become
unusable.

NORMAL GAIN SETTINGS

For average input signals, the MASTER
gain control should be set to approxi-
mately 14 dB. This allows maximum flex-
ibility in setting individual mixer gain
controls (MIX 1, MIX 2, MIX 3, MIX 4 and
MIX 5) to the desired operating level for
respective input channels. If one input is
unusually low, it may be necessary to
increase the MASTER gain control set-
ting and operate the other inputs at a
proportionately lower gain setting. A
recommended procedure Is to divide the
losses equally between the MASTER and
MIX gain controls.

SOUND PRODUCTS DIVISION

VU METER ACCESSORY

The 1608A output may be indicated in VU
with the VU meter accessory. The range
of the meter ls selected with the VU
METER switch. The VU meter accessory
is operated by switching the VU METER
switch from OFF to the desired range;
+40 VU, +43 VU, +46 VU, or +49 VU.

The upper scale of the VU meter Is cali-
brated in VU from «20 VU to +3 VU, A
value In VU of the 1608A output is
obtained by adding the range setting to
the meter indication. Example: An Indica-
tion of -2 VU on the meter with a range
setting of +46 VU means the 1608A out-
put is +44 VU.

The VU meter gives direct indication of
sine wave output. A value of +46 VU
indicates an output of 40 watts and a
value of +52 VU indicates an output of
160 watts.

VU meter indications are approximately
10 dB below peak output of voice and
music program material because the
meter cannot follow such rapidly chang-
ing signal peaks. Thus, for an indication
of +43 VU, the output may be assumed
to have peaks of 200 watts.

The relationship between indicated VU
and output power in watts (with normal
settings of MIX and MASTER gain con-
trols) is shown in Table I. Approximate
output of the 1608A can therefore be set
in accordance with the listed values.

1608A
MIXER/POWER AMPLIFIER

OPERATING
INSTRUCTIONS

COMPRESSOR ACCESSORY

Excessively high input-signal peaks may
be controlled with the compressor acces-
sory. The compression threshold to
which the signal must rise before com-
pression begins is selected with the
COMPRESSION THRESHOLD switch.
The Compressor accessory is operated by
switching the COMPRESSION THRES-
HOLD switch from OFF to the desired
threshold; +40 VU, +43 VU, +46 VU or
+49 VU.

A family of amplifier performance curves
is presented in Figure 1 for the different
compressions. With no compression
(switch in OFF position), amplifier per-
formance follows the 0 dB COMPRES-
SION curve. Performance of the 1608A

Table I. Wattage Outputs for VU Values

VU Values Peak Level
Meter Output for
Indication Voice & Music

Plus Range Average Program
Settings) Output Material
+ 40 VU 10W 100W
+ 43 VU 20W 200W
+ 46 VU 40W 400W
+ 49 VU 80W 800W"
+ 52 VU 160W 1600W"

*Additional values within those listed
may be found by linear interpolation.

"Amplifier overload indicator may be
expected to illuminate. Optimum area
of operation for typical program
material is 41-42 VU.

§
E
E

Figure 1. Compression Characteristics of
14678A Compressor Assembly

Specificatiom and components subject to change WllhOIAZ

notice. Overall performance will he maintained or improved.

1515 5. Manchester Ave., Anaheim, Calif. 92803

Copyright © 1976, Altec Corporation

42-02-042516-06
LITHO IN U.S.A. CP-177-2K