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THE DELTAMAX™ SYSTEM
Operation
PICTORIAL 1 — DMC-1152B Front Panel Diagram
OPERATION
FRONT PANEL INDICATORS AND CONTROLS
(refer to pictorial 1)
1.
INPUT LEVEL INDICATORS: Three LEDs
show the drive level at the input of the control-
ler. Levels are calibrated in dBu (-20, 0, + 16)
NOTE:
Do not allow the 16-dB input-level
indicator to stay on continuously.
If the 16-dB
indicator is allowed to stay on for long periods,
the input circuit will clip. The input signal
should be reduced until the 16-dB indicator
lights only on loud instantaneous peaks.
GAIN REDUCTION INDICATORS: Three
LEDs show how much gain reduction is occur-
ring in the compressor at the input of the con-
troller. The display is calibrated in relative dB
(3, 6, 12). Gain reduction occurs only when the
maximum temperature, excursion and amplifier
capabilities are exceeded for either the woofer
or compression driver. The Output-Limits dis-
play indicates which limits are being exceeded
when gain reduction occurs.
NOTE: Do not allow the 12-dB-gain-reduction
indicator to stay on continuously. If the 12-dB
indicator is allowed to stay on for long periods,
the speaker may be damaged. The input
signal should be reduced until the 12-dB
indicator lights only on loud passages.
3.
OUTPUT LIMIT INDICATORS:
A. TEMPERATURE LIMIT: These LED's
light when the temperatures of the woofer
or compression-driver voice coils
approach their maximum allowable limit.
Under this condition, gain reduction will
occur at the input of the controller so that
the maximum-temperature limits will not
be exceeded for either the woofer or
compression driver.
B.
EXCURSION LIMIT: These LED's light
when the excursion of the woofer cone or
compression-driver diaphragm approach
their maximum allowable limit. Under this
condition, voltage clamping will occur at
the output of either the low- or high-
frequency section so that the maximum-
excursion limits will not be exceeded for
either the woofer or compression driver.
C. AMPLIFIER LIMIT: These LED's will
provide status information for the high-
and low-frequency power amplifiers if the
controller has been calibrated to the
amplifiers. (See the AMPLIFIER/
CONTROLLER CALIBRATION section.)
With the Cal/Clip-Limit switch pressed in,
the LED's will signal the occurence of
amplifier clipping. With the switch in the
outward position, the LED's indicate that
gain reduction in the form of hard limiting
is occurring at the input of the controller to
prevent the amplifiers from clipping.
OUTPUT LEVEL CONTROLS:
A.
LF: This control adjusts the level of the
low-frequency output signal. The control
range is from -12 dB to +12 dB.
NOTE: The gain has been structured within
the DMC-1152B controller so that DML-1152A
loudspeaker will have a flat frequency re-
sponse (as shown in Figure 3) in an anechoic
environment with the output levels of the
controllers set in the 0-dB-detent position and
with the amplifier channels having identical
gain driving the LF and HF sections of the
speakers.
page 8
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