OMNITRONIC MP 250 Mixing Amplifier User Manual

: July 21, 2024
: OMNITRONIC

Table of Contents

OMNITRONIC MP 250 Mixing Amplifier User Manual
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OMNITRONIC MP 250 Mixing Amplifier User Manual

MP 60 | 120 | 180 | 250 PA Amplifier

PA mono mixing amplifier with 60-250 watts power

The amplifiers of the MP series have been specially designed for the use in 100 V PA systems. PA speakers with 70 V and 100 V audio transformers or 4-16 Ω speakers can be connected. It is possible to connect three microphones and three units with line level to the six inputs which can be mixed with each other. Microphone channel 3 is equipped with an adjustable priority function which reduces the volume of the other signal sources in case of an announcement. A chime can be released prior to an announcement. For connection to units with line level (e.g. mixer) an additional stereo RCA output is available.

Overview of all features

PA outputs for 70 V or 100 V PA speakers or for low-impedance speakers (4-16 ohms)
3 microphone inputs (6.3 mm jack) with separate level controls
Microphone input 3 with adjustable priority circuit
3 line inputs (stereo RCA) with separate level controls
1 line output (stereo RCA)
Chime, switchable
Treble and bass control for the output signal
7-fold LED level display
Master control for the output signal
Fan-cooled
Protection circuits with LED indication: over current, short circuit, turn-on delay
Rack installation

For product updates, documentation, software and support please visit www.omnitronic.de. You can find the latest version of this user manual in the product’s download section.

© 2024 OMNITRONIC. All rights reserved.
No part of this document may be reproduced in any form without the written permission of the copyright owner. The contents of this document are subject to revision without notice due to continued progress in methodology, design, and manufacturing.

All trademarks mentioned herein are the property of their respective owners.

Introduction

Welcome to Omnitronic! Thank you for choosing one of our products. This user manual will show you how to install and operate the PA amplifier. Users of this product are recommended to carefully read all warnings in this manual and on the unit in order to protect yourself and others from damage.

This user manual is valid for item numbers: 80709610, 80709620, 80709630, 80709640. Please save this document for future needs and pass it on to further owners.

Safety Instructions

CAUTION!

Keep this device away from rain and moisture!

CAUTION!

Be careful with your operations. With a dangerous voltage you can suffer a dangerous electric shock when touching the wires!

HEALTH HAZARD!

By operating speaker systems with an amplifier, you can produce excessive sound pressure levels that may lead to permanent hearing loss.

This PA system has left our premises in absolutely perfect condition. In order to maintain this condition and to ensure a safe operation, it is absolutely necessary for the user to follow the safety instructions and warning notes written in this user manual.

Damages caused by the disregard of this user manual are not subject to warranty. The dealer will not accept liability for any resulting defects or problems.

Unpacking

Please make sure that there are no obvious transport damages. Should you notice any damages, do not take the device into operation and immediately consult your local dealer.
Save the package and all packing materials. In the event that a fixture must be returned to the factory, it is important that the fixture be returned in the original factory box and packing.

Protection Class

This device falls under protection class I. The power plug must only be plugged into a protection class I outlet. The voltage and frequency must exactly be the same as stated on the device. Wrong voltages or power outlets can lead to the destruction of the device and to mortal electrical shock.

Power Cord

Always plug in the power plug least. The power plug must always be inserted without force. Make sure that the plug is tightly connected with the outlet.
Never let the power cord come into contact with other cables! Handle the power cord and all connections with the mains with particular caution! Never touch them with wet hands, as this could lead to mortal electrical shock.
Never modify, bend, strain mechanically, put pressure on, pull or heat up the power cord. Never operate next to sources of heat or cold. Disregard can lead to power cord damages, fire or mortal electrical shock.
The cable insert or the female part in the device must never be strained. There must always be sufficient cable to the device. Otherwise, the cable may be damaged which may lead to mortal damage.
Make sure that the power cord is never crimped or damaged by sharp edges. Check the device and the power cord from time to time.
The occupation of the connection cables is as follows:

The earth has to be connected! If the device will be directly connected with the local power supply network, a disconnection switch with a minimum opening of 3 mm at every pole has to be included in the permanent electrical installation. The device must only be connected with an electric installation carried out in compliance with the IEC standards. The electric installation must be equipped with a Residual Current Device.

Liquids

There must never enter any liquid into power outlets, extension cords or any holes in the housing of the device. If you suppose that also a minimal amount of liquid may have entered the device, it must immediately be disconnected. This is also valid, if the device was exposed to high humidity. Also if the device is still running, the device must be checked by a specialist if the liquid has reduced any insulation. Reduced insulation can cause mortal electrical shock.

Foreign Objects

There must never be any objects entering into the device. This is especially valid for metal parts. If any metal parts like staples or coarse metal chips enter into the device, the device must be taken out of operation and disconnected immediately. Malfunction or short-circuits caused by metal parts may cause mortal injuries.

Ambient Conditions

The ambient temperature must always be between -5° C and +45° C. Keep away from direct insulation (particularly in cars) and heaters. The relative humidity must not exceed 50 % with an ambient temperature of 45° C.
This device must only be operated in an altitude between -20 and 2000 m over NN.
Never use the device during thunderstorms. Over voltage could destroy the device. Always disconnect the device during thunderstorms.
This device must never be operated or stockpiled in surroundings where splash water, rain, moisture or fog may harm the device. Moisture or very high humidity can reduce the insulation and lead to mortal electrical shocks.
When using smoke machines, make sure that the device is never exposed to the direct smoke jet and is installed in a distance of 0.5 meters between smoke machine and device.

Installation

Do not shake the device. Avoid brute force when installing or operating the device. When choosing the installation spot, please make sure that the device is not exposed to extreme heat, moisture or dust. There should not be any cables lying around. You endanger your own and the safety of others!
Never install the amplifier next to highly sensitive devices like pre-amplifiers or tape decks, as the strong magnetic field of the amplifier can produce hum in these devices. The magnetic field is strongest directly above or below the amplifier. If a rack is used, the amplifier should be installed at the bottom and the highly sensitive devices at the top.

Commercial Use

Operating an amplification system in public or industrial areas, a series of safety instructions have to be followed. The operator must therefore inform himself on the current safety instructions and consider them.

Setup

Operate the device only after having familiarized with its functions. Do not permit operation by persons not qualified for operating the device. Most damages are the result of unprofessional operation!
Before the unit is switched on all faders and volume controls have to be set to zero or minimum position. Turn the amplifier on last and off first! Only connect the device when the power switch is off. Never connect output to output. Never connect the inputs or outputs to any power source (batteries, etc.)

Cleaning and Service

Disconnect from mains before cleaning! Never use solvents or aggressive detergents in order to clean the device! Rather use a soft and damp cloth.
There are no serviceable parts inside the device except for the fuse. Maintenance and service operations are only to be carried out by authorized dealers! Should you need any spare parts, please use genuine parts.

Modifications and Guarantee

Never remove the serial barcode from the device as this would make the guarantee void.
Please consider that unauthorized modifications on the speaker system are forbidden due to safety reasons!
If this device will be operated in any way different to the one described in this manual, the product may suffer damages and the guarantee becomes void. Furthermore, any other operation may lead to dangers like short-circuit, burns, electric shock, etc.

Maximum Power

The given maximum power of the speaker system describes short-term peaks the system can handle as a maximum. The correspondent RMS power is – as of all comparable systems (also from other manufacturers) – significantly lower. The maximum power of the speaker system must never be exceeded. When operating the speaker system, please make sure that the loudspeakers always sound well. When distortions can be heard, either the amplifier or the loudspeaker is overloaded. Overloads can quickly lead to amplifier or speaker damage. In order to avoid damage, please reduce the volume immediately when distortions can be heard. When speaker systems are destroyed by overload, the guarantee becomes void.

Batteries

Do not try to short-circuit, recharge, disassemble or heat batteries (danger of explosion!). Remove the batteries if the device is not used for a longer period of time. Damaged/leaking batteries may cause harm to your skin–use safety gloves.

Intended Use

The PA mono mixing amplifiers of the MP series have been specially designed for the use in 100 V PA systems.

Operating Elements and Connections

This user manual describes the MP-250 as a reference. The other models are similar in construction.

Front Panel

Rear Panel

Installation

This amplifier is built for 483 mm racks (19″). This rack should be a double- door rack where front panel and rear panel can be opened. The rack should be provided with a cooling fan. When mounting the amplifier into the rack, please make sure that there is enough space around the device so that the heated air can be passed on. Steady overheating will damage your device.

You can fix the amplifier with four screws M6 in the rack. If several devices are to be installed, make sure that you leave 1 unit (1 U) space between the devices. Be careful when mounting the amplifier into the rack. Put the heaviest devices into the lower part of the rack. Be aware that fastening the amplifier with four screws on the front panel is not enough. In order to ensure safety, additional fastening by using ground and side bars is necessary.

If racks are to be transported or used for mobile use, fasten the devices additionally by connecting the rear brackets with the side or ground bars of the rack. Thus, the amplifier cannot be pushed backwards. The front panel alone is not designed to absorb acceleration forces occurring during transportation.

Connections

Speakers

DANGER TO LIFE!

High voltage at terminals when using PA systems. Installation by skilled personnel only! Turn off amplifier before connecting.

Either PA speakers with 70 V and 100 V audio transformers or 4-16 Ω speakers or speaker groups can be connected.

Connect PA speakers to the terminals COM (negative pole) and 70V or 100V (positive pole).
Connect low-impedance speakers to the terminals COM (negative pole) and 4-16 Ω (positive pole).
When connecting, observe the correct polarity (positive and negative connections). The positive connection of the speaker cables is always specially marked.

The total load must not exceed 60 WRMS (MP-60), 120 WRMS (MP-120), 180 WRMS (MP-180) or 250 WRMS (MP-250), otherwise the amplifier may be damaged by overload.

Notes

The input impedance of the speaker systems should at least be the same or even higher than the output impedance of the amplifier. Refer to this example for the calculation number of speakers/impedance:

Choosing appropriate speaker cables

Speaker systems must only be connected via sufficiently dimensioned cables. Thin cables lead to cable heatup or enormous power loss and loss in sound quality. For all speaker systems up to 400 Watts, we recommend a cable diameter of 2.5 mm², for all other speaker cables 4 mm².
A high damping factor of your amplifier supplies a clear sound reproduction. Unnecessarily long and thin cables will influence the damping factor and thus the low frequencies in a negative way. In order to safeguard good sound quality, the damping factor should lie around 50. The longer a cable has to be, the thicker it should be. In this respect, a damping factor of 200 will be reduced to 47 (8 ohms) when using a 10 m long, 2.5 mm² speaker cable. The power loss at 8 ohms is 1.63 %, at 4 ohms 3.25 % and at 2 ohms even 6.5 %.The maximum cable length is 30 meters.

General information on installing cables

Always treat cables carefully and protect them from damages during transportation.
Install cables always in a structured way and protect them from damage.
Cables must be installed in a way that no person can stumble over them. Always fix cables with an appropriate tape.
Cables should be installed directly (no loops, S-shaped overlengths).
Always install cables far away from power cables (never closely parallel).
Never put heavy objects like speaker systems, flightcases etc. on cables.
Never operate cables wound up.

Line output

For connection to units with line level (e.g. mixer, amplifier) the stereo RCA output LINE OUTPUT can be used.

Microphones

Three inputs are available for connecting dynamic microphones via unbalanced 6.3 mm jacks: two via the rear inputs MIC 1 INPUT and MIC 2 INPUT, and one via the front input PRIORITY MIC 3. Input PRIORITY MIC 3 is equipped with an adjustable priority function.

Units with line level

Three audio units with line level can be connected to the stereo RCA inputs LINE 1 to 3.

Connection with the mains

Finally connect the device to a mains outlet (230 V AC, 50 Hz ~) with the mains cable.

Operation

To prevent loud switching noise, first switch on all other units of the PA system.
Prior to switching on, turn the master control LEVEL and the level controls of the input channels to zero to avoid a high volume at the beginning. Then switch on the unit with the power switch. The power indicator lights up.
Turn up the master control LEVEL so that the mixing ration of the signal sources can be adjusted in an optimum way.
Adjust the desired volume ratio with the level controls of the channels LINE 1 to 3 and MIC 1 to 3. Turn the controls of the inputs not used to zero.
To improve the audibility of an announcement microphone channel PRIORITY MIC 3 is equipped with an adjustable priority function: In case of an announcement via the channel PRIORITY MIC 3 the level of the other channels is attenuated–depending on the rear control PRIORITY LEVEL. After the announcement, the level of the other channels slowly returns to the original level.
Adjust the desired sound with the tone controls. By adjusting the tone controls, the high frequencies (control TREBLE) and the low frequencies (control BASS) can be boosted or attenuated. With the controls in mid-position, the frequency response is not affected.
Adjust the definite level of the total volume with the master control LEVEL. The 7-step LED row shows the output level: the 0 dB LED must not light permanently. Otherwise slightly turn back the master control.
To release the chime prior to an announcement, press the button CHIME. Then also the level of the channels is attenuated–depending on the rear control PRIORITY LEVEL.

Notes

When operating the amplifying system, please make sure that the loudspeakers always sound well. When distortions can be heard, either the amplifier or the loudspeaker is overloaded. Overloads can quickly lead to amplifier or speaker damage. In order to avoid damage, please reduce the volume immediately when distortions can be heard. When speaker systems are destroyed by overload, the guarantee becomes void. Always check the sound pressure level with a meter in order to keep to the threshold.

Protective circuits

The protective circuits prevent damage to the speakers and the amplifier. If activated, the speakers are electrically separated from the amplifier and the LED FAULT lights up:

for a few seconds after switching-on until the speaker outputs are ready for operation
in case of a short-circuit at a speaker output
in case of over current

If the red LED FAULT lights up during operation or if it does not go out after switching on, the amplifier has to be switched off and the cause of the fault has to be removed.

Problem Chart

Cleaning and Maintenance

We recommend a frequent cleaning of the device. Please use a soft lint-free and moistened cloth. Never use alcohol or solvents! There are no serviceable parts inside the device except for the fuse. Maintenance and service operations are only to be carried out by authorized dealers. Should you need any spare parts, please use genuine parts. If the power supply cable of this device becomes damaged, it has to be replaced by a special power supply cable available at your dealer. Should you have further questions, please contact your dealer.

Replacing the fuse

If the fine-wire fuse of the device fuses, only replace the fuse by a fuse of same type and rating. Before replacing the fuse, unplug mains lead.

Procedure:

Step 1: Open the fuseholder on the rear panel with a fitting screwdriver.
Step 2: Remove the old fuse from the fuseholder.
Step 3: Install the new fuse in the fuseholder.
Step 4: Replace the fuseholder in the housing.

Technische Daten

Specifications are subject to change without notice due to product improvements.

Protecting the Environment

Disposal of old equipment

When to be definitively put out of operation, take the product to a local recycling plant for a disposal which is not harmful to the environment. Devices marked with this symbol must not be disposed of as household waste. Contact your retailer or local authorities for more information. Remove any inserted batteries and dispose of them separately from the product.

You as the end user are required by law (Battery Ordinance) to return all used batteries/rechargeable batteries. Disposing of them in the household waste is prohibited. You may return your used batteries free of charge to collection points in your municipality and anywhere where batteries/ rechargeable batteries are sold. By disposing of used devices and batteries correctly, you contribute to the protection of the environment.

MP SERIES

D00124776
Version 1.5

Omnitronic is a brand of Steinigke Showtechnic GmbH
Andreas-Bauer-Str. 5
97297 Waldbüttelbrunn, Germany