Knoll MR1250A - User Manual

12 Channel
Power Amplifier
Version 2.4
OPERATION
MANUAL
MR1250a
MR1250f
2
Congratulations and thank you for choosing the Knöll
MR1250a power amplifier. The MR1250a is designed to
meet the amplifier needs of multi-zone systems where
high quality sound is a specific requirement.
Key Features:
1. Size efficiency. The MR1250a consists of a total of
12 power amplifiers in one 3-1/2" high enclosure. Each
power amplifier channel can deliver 50 watts RMS.
2. Automatic protection circuitry. Each MR1250a
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.
3. 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 MR1250a so
installers normally set the gain.
4. External power on/off. The MR1250a can be
turned off and on by external controllers such as the
MR640. To activate external power on, apply a 12VDC
current to the trigger jack (the MR1250a power switch is
in the off position for external power control).
5. Stackable 17" chassis. Optional RK1250 rack kit.
6. Link Feature. Certain installations require that some
or all of the stereo channels play the same content.
Instead of using Y cords, "link" cascades any or all of
channels 2-6 to channel 1 (l/r).
7. Optional fan version. For installations that require
a lot of "heavy" use we recommend the MR1250F with an
internal fan. A fan will help to avoid early protection
system distortion.

Summary

Key Features

Size Efficiency

The MR1250a is a 12-channel amplifier in a 3-1/2" high enclosure, with each channel delivering 50 watts RMS.

Automatic Protection Circuitry

Each channel is individually protected against low impedance, overheating, overloading, and voltage issues, restoring automatically.

Individual Input Gain Adjustment

Each channel features a rear-panel gain adjustment pot to match sensitivity variations.

External Power On;Off

The amplifier can be turned on/off by external controllers using a 12VDC trigger signal.

Stackable Chassis and Link Feature

Features stackable 17" chassis and a link feature to cascade channels for stereo content.

Optional Fan Version

An optional fan version (MR1250F) is recommended for heavy use to prevent distortion.

Installation and Specifications

Cooling and Rack Mounting

Proper cooling requires 3-5" space above. Rack installations benefit from 3-1/2" blanks between units.

Connection Guidelines

Use quality RCA cables for inputs and 16-gauge copper wire for speakers. Avoid loads less than 4 ohms.

Trigger and Power Setup

Connect trigger to a 12VDC source. Ensure AC power outlet supplies at least six amps.

Amplifier Specifications

Details input/output specs, power output, frequency response, distortion, dimensions, and weight.

Troubleshooting

Power Issues

Diagnoses issues with the power LED not lighting or the unit not turning on.

Audio Output Problems

Addresses sound cutting out, distorted sound, or the unit not turning off.

Trigger and Speaker Pops

Troubleshoots trigger not working and speaker pops upon amp turn on/off.

Rear Panel Overview

Input;Output Connections

Details the placement and function of input jacks, output binding posts, and link controls.

Trigger Input and Power

Explains the 12VDC trigger input and the AC power connection specifications.

Limited Warranty

Knoll MR1250A Specifications

General

Brand	Knoll
Model	MR1250A
Category	Amplifier
Language	English