Rane MP 24z User Manual

Page 8

Manual-6

The front panel switchable LOOP is for stereo devices only,

so consider which eﬀects are connected where. Some proces-

sors, such as delays and reverbs, have only one mono input and

two outputs. This is accommodated automatically by using the

MONO Output of the MAIN EFFECTS LOOP.

The Zone Outputs and the Booth Outputs are the auto-

matic mono/stereo type. If mono is required, simply connect

only to the LEFT OUTPUT. Inserting a plug into the RIGHT

OUTPUT automatically renders it stereo. All of these Output

connectors are unbalanced. Attempting to run TRS balanced on

any of these results in an open leg on the receiving component and

causes problems.

This is a good place to discuss the problems encountered in

connecting the MP 24z to all of the diﬀerent types of cables and

connectors that one ﬁnds when basing a system on consumer

goods (the pieces of equipment with the RCA connectors),

commercial audio products (¼", XLR etc.), and no telling what

else. In consumer audio devices, one rarely ﬁnds ground-lift

capabilities, or any of the other hum prevention devices normally

provided on commercial equipment. Chassis ground and signal

ground are normally the same thing, a situation which may cause

problems when the two species get on the same bus.

The best we can do to try to help you eliminate hum, oscil-

lations, or other stray characters from your system is to tell you

to experiment. If you think lifting the ground on the MP 24z,

crossovers, equalizers or power ampliﬁers might help, go ahead

and try it. There is science involved in de-humming a system,

however it is sometimes faster to just experiment. Occasion-

ally, directly grounding the chassis of the mixer to the power

ampliﬁers with a large gauge wire helps. And by the same token,

isolating the two when they are installed in the same rack may

have a quieting eﬀect. A word of caution: Don’t do anything with

Level controls up, power on, or under any condition that could cause

damage to delicate loudspeakers and ears. Make your changes with

the system oﬀ, then power up carefully to make sure you haven’t

made matters worse. Bring up Level controls slowly and with

great caution. Surprises are nice on birthdays and Christmas,

and rarely any other time.

If hum problems only exist on the Phono Inputs, there is

always a possibility for experimental troubleshooting at this end

also. Experience has shown that just because the manufacturers

put ground wires on them, they are not always connected! Some

turntables even have two ground wires, one for the tone arm and

one for the chassis. Sometimes only one of these should be con-

nected for optimum signal-to-noise, sometimes both, sometimes

none. The rule is: “Whatever works, works.”

MP 24z CONNECTION

Even though the system variations are limitless in most ap-

plications where the MP 24z is used, an installer must follow

some basic interconnect guidelines. Unfortunately, even though

the system and the primary components such as mixers, proces-

sors and ampliﬁers are of commercial grade, most of the source

components, i.e. turntables, disc players, tape decks and so on

are consumer grade, with consumer interconnect limitations.

Therefore, on the input side of the MP 24z, RCA connectors

will prevail with unbalanced lines thereto attached. It is recom-

mended, for no scientiﬁc reason, that the turntable furthest to

the left be connected to Phono 1, and proceed from left to right

with Phono 2 and then Phono 3, if used. See Service Information

on page Manual-9 to convert any PHONO level Input into a

LINE level Input.

When determining which Line Inputs to use for what, the

process becomes a bit more diﬃcult. Obviously, if one of the line

devices feeding the MP 24z is of the commercial variety sport-

ing balanced outputs, use Line 2 for this due to its unique ability

to accept such foreign substances. The rest of the assignments

are pretty much a matter of what you want to appear where on

the source switches. As you can see, Lines 1 through 3 appear

only on Input Channels 1 and 2; Lines 4 through 6 appear only

on Input Channels 3 and 4. So the layout will depend on how

heavily you will use the Phono Inputs and how many line level

devices you will be using.

On the Output side, things are a bit less restrictive. On the

MAIN OUTPUTS you have been given a choice between XLR

balanced and ¼" unbalanced. Which you use should be derived

from some consideration of how far the cable has to run from

the mixer to the next component, how much ambient noise there

is in the local atmosphere (Radio Moscow in the next building,

36,000 SCR controlled light dimmers in the next rack), and any

other possible encumbrance on the quality of the audio inside

the jacket. Most experienced installers and users of commercial

sound equipment have a good handle on which to use in a given

situation. The general rule is: if the Output from the MP 24z is

running longer than 10 feet (3 meters), use balanced cables. If

the input to your system equalizer, crossover, or power ampliﬁer

is balanced, go balanced. If you keep the cable length short and

your destination has unbalanced inputs, you can probably get

away with using the ¼" unbalanced connectors.

The TAPE OUTPUTS are unbalanced RCA connectors;

the assumption being that most readily available tape recording

equipment such as would be used in a club situation would be

of similar type. Simply determine whether you want the signal

processing in the Eﬀects Loops to have an eﬀect on the recording

being made and connect the record inputs (left and right) to the

appropriate PRE-LOOP or POST-LOOP TAPE OUTPUTS.

These Tape Outputs do not contain any signal from the Micro-

phone section. If you need to record the Mic, use the Unbalanced

Main Outputs, Zone Output, or the Booth Output with the

Booth Ducker circuit defeated. (If none of these are available, see

Service Information on page Manual-9 for internal jumper chang-

ing instructions.)