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The MA250 is a high caliber, reasonably priced stereo power
amplifier designed to meet the needs of custom installed systems where
superior sound is a specific requirement.
Knoll engineers designed the MA250 as a plasma TV stereo booster amplifier
with many unique features making it valuable in a wide variety of applications.
One of its most advanced features is the stereo inputs that are directly
connected to the speaker outputs if the amplifier is not powered up. This
allows whole house music from other systems to pass through, and then
be overridden when the local MA250 amplifier is required.
Power on and off can be accomplished by the use of the power switch on
the front panel, a 12-volt trigger input, a video signal or when sound
signals to the amplifier are detected. All controls on the MA250 are rear-mounted,
except for the power button, to ensure there are no maladjustments once
the amplifier is installed.
Key Features:
· Manual and Automatic Power On and Off. The MA250 stereo power
amplifier turns on when a video signal is detected, music or sound is
sensed, the 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 TVs) the
MA250 features amplifier inputs so that whole house music systems can
be heard on the local speakers (without the MA250 being switched on).
When the local source (TV, dish, etc.) needs amplifier power, the whole
house music automatically switches off and the MA250 amplifier switches
on and plays the local source.
· Automatic protection circuitry. Each MA250 channel is individually
and completely protected against low impedance, overheating, overloading,
over voltage and under voltage. The protection circuitry automatically
restores the amplifier channel as soon as its parameter returns to the
safe operating area.
· Individual input gain adjustment. All of the MA250 channels feature
an input gain adjustment pot to adjust each channel for gain and speaker
sensitivity variations. The gain adjustments are on the rear of the amplifier
so installers usually set the gain.
· Stackable 17" chassis. Two MA250’s can fit side-by-side
and be stacked for applications that require more than two amplifier channels.
Specifications:
| Inputs |
Gold RCA input and output jacks with adjustable gain |
| Input impedance |
55,000 ohms |
| Outputs |
Detachable four position plug |
| Output power |
50 watts RMS per channel into 8 ohms
70 watts RMS per channel into 4 ohms |
| Peak output power |
90 watts per channel (8 ohms) |
| Ideal impedance |
4 - 8 ohms (will work at 16 ohms) |
| Frequency response |
10 Hz - 40 kHz +/- 1dB (1w) |
| S/N Ratio |
Over 95 dB A weighted (50 watts) |
| THD distortion |
less than 0.1% 20 Hz to 20 kHz |
| IMD distortion |
less than 0.01% 60 Hz 7 kHz 4:1 (SMPTE) |
| Trigger Control |
12 VDC (35 mA) on a mono 3.5 mm jack |
| Dimensions |
8.5" x 3.5" x 11.5" (432 x 89 x 292 mm) 1/2 width
rack |
| Power |
140 watts at 117 VAC |
| Weight |
8 lbs (3.6 kg) |
Note: Specifications subject to change
without notice.

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