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Automatic Level Control for the SP1200/SP2400
SP-DSP1
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Architects’ and Engineers’ Specifications
The SP-DSP1 shall consist of a DSP card and a power sup-
ply expansion card designed to be installed in the SP1200
and SP2400 Program Controller/Amplifier. It shall provide
automatic level control for the program signal, dependent on
the ambient noise level. It shall use a proprietary ambient
noise level sensor algorithm derived from a Normalized Least
Mean Square Adaptive Filter (nLMS).
The SP-Control software shall provide a user interface and
provide control over the digital signal processing parameters
in the SP-DSP1, consisting of the following:
A Minimum Gain control shall provide a gain range from
–40 dB to 0 dB. The Minimum Gain setting shall determine
the normal operating level of the system prior to the action of
the Automatic Level Control.
A Gain Range control shall have a gain range from 0 dB
to +40 dB. The Gain Range setting shall determine the maxi-
mum level of the system after the Automatic Level Control
has been activated.
A Noise Threshold control shall provide a Threshold range
from –80 dB to 0 dB. The Noise Threshold setting shall deter-
mine the noise level above which the Automatic Level Control
begins to operate.
A Noise Range control shall provide a noise range from
+1 dB to +60 dB. The Noise Range setting shall determine
the rate the program level gain changes as a function of the
change in ambient noise level determined by the ambient
noise sensor algorithm.
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Electronic files for this product available at:
www.mackieindustrial.com
This Specification Sheet SPDSP1.PDF
Mackie Designs continually engages in research related to product improvement. New material, produc-
tion methods, and design refinements are introduced into existing products without notice as a routine
expression of that philosophy. For this reason, any current Mackie Industrial product may differ in some
respect from its published description, but will always equal or exceed the original design specifications
unless otherwise stated. ©2002 Mackie Designs Inc. All rights Reserved. and are
registered trademarks of Mackie Designs Inc. Mackie Industrial is a trademark of Mackie Designs Inc.
Part No. 0000759 Rev. A
DSP
SP-DSP1
An Attack Time setting shall provide an attack time range
from 1 second to 300 seconds. The Attack Time setting shall
determine the time for the program gain to increase by 40 dB.
A Release Time setting shall provide a release time range
from 1 second to 300 seconds. The Release Time setting shall
determine the time for the program gain to decrease by 40 dB.
A Program Input Meter shall indicate the input level to the
SP-DSP1 with a range from –60 dB to 0 dB.
A Microphone Input meter shall indicate the ambient
microphone input level to the SP-DSP1 with a range from –60
dB to 0 dB.
A Program Gain meter shall indicate the amount of gain
the algorithm applies to the program input with a range from
–60 dB to 0 dB.
A Program Output meter shall indicate the output level
from the SP-DSP1 with a range from –60 dB to 0 dB.
The SP-DSP1 shall have memory allocated in EEPROM to
store up to ten presets for the adjustable DSP parameters.
An Auto Calibration function shall be provided to compute
the coefficients for the Room Transfer Function (RTF), and opti-
mize the algorithm to reject the music signal and more accu-
rately measure the ambient noise.
The Automatic Level Control shall be a model SP-DSP1
manufactured by Mackie Industrial.
Screen Shots of SP-Control Palm™ Application
