Trigger does not 1. Measure trigger voltage with a voltmeter. It
work needs to be 11-16 volts DC to work (current is
about 35mA total per amp). See page 5 for details.
Speaker pops 1. Speaker may need resistor placed across terminal.
when MA252 is Suggest 2000 ohm 1/4 watt. This discharges the
turned on or off speaker internal capacitor if it has one.
Warranty
Knoll Systems warrants MA252 amplifiers sold in the USA and Canada by authorized Knoll
dealers to be free of defects in materials and workmanship. This warranty extends for three
full years from the date of purchase by the original consumer. Any products returned to
Knoll Systems and found to be defective by Knoll Systems within the warranty period will be
repaired or replaced at Knoll Systems decision, at no charge. Knoll Systems will not be
responsible for the actual cost of installation or removal of the product, nor for any
incidental or consequential damages. Some states do not allow the exclusion or limitation of
incidental or consequential damages, so the above limitation may not apply to you. This
warranty gives you specific legal rights. You may have additional legal rights that vary from
state to state.
Specifications:
Line level inputs /outputs
50 watts RMS per channel (8 ohms)
100 watts per channel (8 ohms)
10 Hz - 40 kHz +/- 1dB (1w)
over 95 dB A weighted (50 watts)
less than 0.1% 20 Hz to 20 kHz
less than 0.01% 60 Hz 7 kHz 4:1 (SMPTE)
12 VDC 35mA on 3.5mm mono jack
17" x 3.5" x 11.75" (431.8 x 89 x 298mm)
175 watts at 117 VAC or 230 VAC
Note: Specifications subject to change without notice.
Knoll Systems
145 Tyee Drive Point Roberts, WA 98281
12140 Horseshoe Way, Richmond, BC V7A 4V4
Tel: (604) 272 4555, fax (604) 272 5595
Made in Canada
MA252
Stereo Amplifier
Installation Instructions v1.0
Warning: To be installed and/or used in accordance with appropriate
electrical codes and regulations.
Description: Designed primarily for custom installations, the MA252 is
used to power stereo speakers, usually in a single room. Each channel
has a gain control. The MA252 can be turned on and off using the front
panel power switch, composite video detection, when music is sensed
or the 12 VDC trigger. A special feature of the MA252 is that whole
house music from another amplifier can be heard on the speakers
connected to the MA252. When the local source needs amplifier power
the MA252 senses this, disconnects the other amplifier and amplifies
the local source. The MA252 amplifier is designed to meet the amplifier
needs of custom installed systems where high-quality sound is a
specific requirement.
Key Features:
Manual and Automatic Power On and Off. The MA252 stereo
power amplifier is designed to be turned on when a video signal
is detected, music inputs are sensed, a 12-volt trigger is
activated or the front panel power switch is pushed on. Power
off is automatic in all modes except the front panel power
button.
Whole house music override. In homes, yachts, businesses
and motor home applications (typically with plasma or large
screen TV's) the MA252 features amplifier inputs so that whole
house music system can be heard on the local speakers (without
the MA252 turned on). When the local source (TV, dish, etc.)
needs amp power, the whole house music switches off
automatically and the MA252 amplifier plays the local source.
Automatic protection circuitry. Each MA252 channel is
individually and fully protected against low impedance,
overheating, overloading, overvoltage and undervoltage. The
protection circuitry automatically restores the amplifier channel
as soon as its parameter returns to the safe operating area.
Individual input gain adjustment. Each channel features an
input gain adjustment pot to adjust each channel for gain and
speaker sensitivity variations. The gain adjustments are on the
rear of the MA252 so installers normally set the gain.
(4 pages)
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