Connecting The MPL 1502 - General Suggestions
The actual connections you’ll make to and from the MPL 1502 will vary accord- ing to the environment you use it in and the particular equipment you have.
In the “MPL 1502 Applications” sections at the rear of this manual, you’ll find some suggested setups. Here are a few basic rules concerning MPL 1502 connections that will apply in most situations:
•In general, it’s best to make all connections with the MPL 1502 and any connected power amplifiers turned off. If you must make connections with the power on, make sure that the Main gain control is completely down (turn the knob fully counterclockwise). Whenever powering down, turn the Main gain control completely down and turn off the main power amps first. Wait a few seconds for their power supplies to discharge and then turn off all connected equipment, turning the MPL 1502 off last.
•Try to use balanced connectors and cabling wherever possible. These kind of connections do a better job of rejecting extraneous noise and hum and generally provide a cleaner signal. Although the MPL 1502 will accept unbalanced connectors throughout, it specifically provides electronically balanced inputs for all mono line inputs (channels 1 - 5) and for its main outputs. The wiring diagram below shows how 1/4” TRS (Tip/Ring/Sleeve) connectors should be wired for use with these inputs and outputs:
SLEEVE
TIP
RING
TIP +
GROUND RING -
Unbalanced cables use standard 1/4” phone connectors, wired as follows:
| + SIGNAL |
+ SIGNAL |
|
GROUND | GROUND |
•Make one connection at a time and then monitor the incoming signal. If you hear a distinct hum or buzz, you may have a grounding problem with that particular device. See the section in this manual entitled “Grounding Techniques” for information on how to avoid grounding problems.
•NEVER connect a microphone and line level input to the same channel simultaneously— use one or the other. You can have some channels connected to microphones and others to line level signals (for example, you might want to plug mics into channels 1 - 3 and line level signals into the remaining channels)— just don’t have both kinds of inputs connected to the same channel. The diagram below shows how your mic connectors should be wired:
3 - SIGNAL
1 GROUND 
TO MIXER 2 + SIGNAL
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