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THE DELTAMAX™ SYSTEM
OPERATION (continued)
has three LED's to indicate loudspeaker thermal-
protection activation, loudspeaker excursion protec-
tion activation and amplifier clipping (or amplifier
clipping prevention). In addition, there is an LED
display to indicate the amount of long-term overall
gain reduction occurring due to loudspeaker ther-
mal protection and amplifier clipping prevention.
(The instantaneous loudspeaker excursion voltage-
clamping protection is not reflected in the overall
gain-reduction display.)
In very high-powered applications, the detailed dis-
plays on the DMC controllers provide the user with
information to make adjustments or changes to the
system (if desired) to eliminate the protection and
increase the acoustic output. For example:
e If an excessive amount of low-frequency protec-
tion is occurring, selective equalization can be
used ('/s-octave-band equalizer, parametric
equalizer, etc.) to reduce the level in the fre-
quency range that is causing the excessive ex-
cursion, allowing the overall level to be turned
up. If the desired amount of high-level low-
frequency response still cannot be obtained,
subwoofers (or additional subwoofers) should be
added to the system.
e
If an excessive amount of loudspeaker thermal
protection is occurring in any frequency band,
more speaker systems are generally needed. If
the program material has a lot of energy concen-
trated in a relatively small frequency range, se-
lective equalization may serve as an effective
compromise.
Operation
e If excessive amplifier clipping (or amplifier clip-
ping prevention) is occurring without excessive
loudspeaker thermal protection or excursion pro-
tection, larger power amplifiers should be used.
* |f excessive loudspeaker thermal protection and
excursion protection is occurring, more speakers
should be used.
* |fexcessive overall gain reduction is occurring,
more speakers should be added.
e Ifthe 12-dB-gain-reduction LED is on for any sig-
nificant portion of time, the level should be
turned down. Levels driven beyond this point
may exceed the protection capability of the pro-
tection circuitry.
When multiple controllers are used (such as in a
stereo system) the control voltages should be
slaved together as detailed in the INSTALLATION
section. The gain of all of the controllers will then
track whenever gain reduction occurs due to loud-
speaker thermal protection or amplifier clipping pre-
vention, regardless of which loudspeaker or
amplifier was exceeding its limit. This will prevent
acoustic image shifting at very high levels. When a
DMC-2181S/DML-2181A subwoofer system is
used with a full-range DeltaMax™ system (such as
a DMC-1152B/DML-1152A) the control voltages
should be slaved together to prevent spectral bal-
ance shifting at high levels when gain reduction oc-
curs for loudspeaker thermal protection or amplifier
clipping prevention. The loudspeaker excursion
voltage-clamping protection will still operate inde-
pendently in each frequency band in each controller
when the control voltages are slaved.
page 11
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