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THE DELTAMAX™ SYSTEM
Amplifier/Controller Calibration/installation
AMPLIFIER CALIBRATION PROCEDURE
(continued)
The HF section of the controller is now calibrat-
ed. The HF Output Level trimpot may be ad-
justed as necessary for the desired frequency
spectrum balance without affecting calibration.
12. Remove the shorted '/4-inch phone plug
from the Gain Control Bus jack and set the
Cal/Clip Limit switch to the Limit position (out).
Set the HF and LF Output Level controls to
their center-detent position (or as desired).
13. Turn the amplifier off and connect the speaker
cables to the output of the amplifier. Make cer-
tain that the "lows" are wired to the woofer and
that the "highs" are wired to the compression
driver. In addition, be sure to observe polarity
when making speaker connections.
NOTES:
A.
The Amplifier Calibration trimpots may be
adjusted during use with program material
to set the desired amount of amplifier
limiting. The limiter in the controller will
allow some fast transient peaks through,
allowing some amplifier clipping to occur
on signal peaks after the calibration
procedure. The limiter circuit will,
however, prevent long-term amplifier
clipping when adjusted properly.
B. The Cal/Clip Limit switch may be left in the
recessed Cal/Clip position (in) if the power
amplifier has an internal limiter, or if clip
protection is not desired., When left in the
Cal/Clip position, the Amplifier Output
Limiter indicators on the front panel of the
controller will indicate when the amplifier
is self-limiting or clipping.
C. Iftwo or more speakers are connected in
parallel to an amplifier output, most
amplifiers will exhibit a drop in clipping
voltage due to the lower load impedance.
This will require that the Amplifier
Calibration trimpot be set to a value
slightly lower than the value obtained in
the "no-load" calibration test.
Note that the result of this is that, even
when multiple speakers are paralleled on
an amplifier channel, the Amplifier
Calibration trimpot will always end up
pointing at the maximum amount of power
(on the calibrated markings on the front
panel) that the amplifier is capable of
delivering to each individual driver no
matter how many drivers are connected in
parallel.
D. Do not change the amplifier gain, or
recalibration will be necessary.
Use the
LF and HF Output Level controls on the
controller to change power amplifier drive
levels. The Output Level controls do not
affect controller calibration
INSTALLATION
AMPLIFIER REQUIREMENTS
Professional power amplifiers with the following
ratings are recommended for use with the
DMC-1152B/DML-1152A system:
LF: 400-800 watts continuous into eight ohms
HF: 125-250 watts continuous into eight ohms
The use of amplifiers with lower power ratings is
acceptable, however, the full-power capabilities of
the system will not be realized. The use of amplifi-
ers with significantly higher power ratings is waste-
ful and may endanger the loudspeakers; it is
generally not recommended.
Under certain circumstances, however, higher rated
power amplifiers are acceptable. It is acceptable to
drive the DML-1152A speaker with a stereo power
amplifier having the recommended LF power rating,
utilizing one channe! to drive the low frequencies
and the other channel to drive the high frequencies.
For an extra degree of protection when operating in
this configuration, the user may want to set the HF
Amplifier Calibration level to the 250-watt position
to limit excessively high power levels from reaching
the compression driver.
DML-1152A speakers may be paralleled with other
DML-1152A speakers if the amplifier is capable of
delivering adequate power to each speaker at the
lower impedance. Under no circumstances should
DML-1122A and DML-1152A speakers be paral-
leled on the same amplifier channels.
NOTE: For proper operation of the protection
circuitry, the power amplifiers must be
calibrated to have a voltage gain between
27 and 35 dB (32 dB is optimum). See the
AMPLIFIER/CONTROLLER CALIBRATION
section.
CONNECTOR AND CABLE REQUIREMENTS
Controller Connections
The DeltaMax™ controllers have 3-pin XLR-type
connectors for signal input and output. The input is
electronically balanced and has a female connector
with pin 1 as a referenced ground, pin 2 high (+)
and pin 3 low (-). The outputs are transformer bal-
anced and have male connectors with pin assign-
ments identical to the input. Figure 13 illustrates
the preferred interconnection between the controller
and the power amplifier. When driving unbalanced
lines, pin 3 should be shorted to ground.
page 13
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