Samson Musical Instrument MPL 1502 User Guide

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Introduction  
Congratulations on purchasing the Samson MPL 1502 stereo mixer! Although  
this unit is designed for easy operation, we suggest you first take some time to  
go through these pages so you can fully understand how we’ve implemented a  
number of unique features.  
In this manual, we’ll provide you with an overview of the MPL 1502 features,  
followed by a guided tour of its front and rear panels. Then we’ll describe how  
the MPL 1502 should be connected to your existing equipment (including wiring  
diagrams) and talk about the important topics of gain structure and grounding  
techniques. Next, we’ll cover a number of specific MPL 1502 features (such as  
panning, equalization, auxiliary sends and returns, and channel inserts) in detail.  
Finally, we’ll wrap things up with a series of applications notes describing how  
you can use the MPL 1502 for both live performance and recording. You’ll also  
find a warranty card enclosed—please don’t forget to fill it out and mail it so that  
you can receive online technical support and so we can send you updated  
information about other Samson products in the future.  
SPECIAL NOTE: Should your unit ever require servicing, a Return Authorization  
number (RA) is necessary. Without this number, the unit will not be accepted.  
Please call Samson at 1-800-372-6766 for a Return Authorization number prior  
to shipping your unit. Please retain the original packing materials and, if  
possible, return the unit in its original carton and packing materials.  
MPL 1502 Sys te m Fe ature s  
MPLstands for Microphone/Program/Lineand the name describes the broad  
range of signals which can be handled by this powerful stereo mixer. In fact, the  
compact design of the MPL 1502 belies an extraordinary versatility. Add excel-  
lent sound quality to the equation, and youve got a product which is equally  
useful as a live performance mixer, keyboard submixer, or even for simple  
recording purposes (youll find descriptions of each of these applications at the  
conclusion of this manual). Here are some of the MPL 1502s main features:  
Fifteen input channels, including five stereo channels. The five monophonic  
channels provide electronically balanced inputs that can be used for micro-  
phone or line-level input, and the five stereo channels are ideal for line-level  
sources such as outboard signal processors; CD players; tape or cassette  
recorders; stereo drum machines; and keyboards and MIDI tone modules.  
An electronically balanced main stereo output for connection to a power  
amplifier.  
A dedicated tape input/output that allows direct recording of a live  
performance and playback of prerecorded material.  
Two auxiliary sends and two stereo auxiliary returns (which can be used as  
four monophonic returns). Both sends are post-fader and post-equalizer.  
1
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Introduction  
Independent 3-band equalization for each channel, with 15 dB of cut or boost  
for low (80 Hz) and high (10 kHz) frequencies, and 12 dB of cut or boost for  
the mid-range (800 Hz) frequency.  
Constant level pan controls for placing each monophonic channel in the left-  
right stereo spectrum, as well as balance controls for each stereo channel  
and Aux return that allow you to blend the relative levels of stereo inputs.  
Channel inserts are provided for each of the 5 monophonic input channels,  
enabling you to use outboard signal processors such as outboard  
equalizers, compressor/ limiters, or noise gates in a standard effect loop.”  
Input trims for each channel are continuously adjustable from +4 to -50 dB,  
making it possible to use the MPL 1502 with a wide variety of signal sources  
and outboard equipment.  
Center detents for all gain, pan, balance, and EQ controls, making it easy to  
use the MPL 1502 even in low-light situations such as live performance.  
Peak input LEDs for each channel, showing you when an input signal is  
overloading or near overloading (these illuminate -5 dB prior to distortion).  
The provision of 48v phantom power makes it possible to plug high-quality  
condenser microphones directly into the MPL 1502, without the need for  
expensive and cumbersome external power supplies.  
A seven-segment front-panel meter that allows you to view at a glance the  
continuous main stereo output level.  
An independent front-panel headphone jack with dedicated volume control.  
With accessory rack ears, the MPL 1502 can be mounted in any standard  
19rack (taking six rack spaces), making it easy to integrate into any exist-  
ing system.  
Last but certainly not least, affordability. The MPL 1502 has been designed  
from the ground up to provide versatility and excellent sound quality at a  
cost-conscious price.  
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Guide d Tour - Ove rvie w  
The following illustration shows an overview of the front panel of the MPL 1502:  
1
2
3
5
6 / 7  
8 / 9  
10 / 11  
12 / 13  
14 / 15  
4
MIC INPUT (BALANCED -50dB TO +4dB)  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
2
1
2
1
2
1
2
1
2
1
3
3
3
3
3
S A M S O N  
15 CHANNEL  
STEREO MIXER  
LINE INPUT (BALANCED 10K-30dB TO +4dB)  
MPL 1502  
LINE INPUT (BALANCED 10K-40dB TO +4dB  
RIGHT  
RIGHT  
10  
RIGHT  
10  
RIGHT  
10  
RIGHT  
10  
10  
10  
10  
10  
10  
10  
MPL 1502  
0
0
0
0
0
0
+4  
0
0
0
0
15 CHANNEL STEREO MIXER  
+4  
-50  
+4  
-50  
+4  
-50  
+4  
-50  
+4  
-50  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
0
0
+2 +6  
+2 +6  
-20 -10 -6 -2  
-20 -10 -6 -2  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
LEFT  
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
RIGHT  
PHANTOM  
POWER  
-15  
-15  
+15  
-15  
-15  
+15  
-15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
TAPE IN  
ON  
OFF  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
+15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
CHANNEL 14 / 15  
0
0
0
0
0
0
0
0
0
0
0
L
R
BALANCE  
−∞  
−∞  
AUX 1  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
AUX 1  
+10  
−∞  
+10  
+10  
+10  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+20  
−∞  
AUX 1  
AUX 1  
AUX 1  
AUX 1  
AUX 1  
AUX 1  
AUX 1  
AUX 1  
AUX 1 LEVEL  
0
0
0
0
0
0
0
0
0
0
0
L
R
+10  
AUX 2  
+10  
AUX 2  
+10  
−∞  
+10  
AUX 2  
−∞  
+10  
AUX 2  
+10  
AUX 2  
+10  
AUX 2  
+10  
AUX 2  
+10  
AUX 2  
+10  
AUX 2  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
+20  
AUX 2 LEVEL  
−∞  
AUX 2  
BALANCE  
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
0
10  
PAN  
0
PAN  
0
PAN  
0
PAN  
0
PAN  
0
BALANCE  
BALANCE  
BALANCE  
BALANCE  
BALANCE  
HEADPHONE  
LEVEL  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
0
0
0
0
0
0
+15  
+15  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
+15  
−∞  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
−∞  
−∞  
−∞  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
1
2
3
4
5
6 / 7  
8 / 9  
10 /11  
12 /13  
14 /15  
MAIN  
Mono channels  
Stereo channels  
Main section  
3
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Guide d Tour - Mono and Ste re o Channe ls  
1: Mic inputs (1 - 5) - Provided in monophonic channels only. Use these electronically balanced  
1
XLR jacks to connect microphones to any of the MPL 1502s five mono channels (channels 1 - 5).  
These are intended to accept signal from low-level, low-impedance mics but can also be used for  
signal from other sources (such as direct injection boxes) if the channels Trim control is turned  
down. WARNING: Do not turn Phantom power on if signal sources other than microphones are  
connected to any of these inputs. Also, do not connect a channels microphone input if you  
already have something connected to its line input; each channel is designed to accept only one  
source or the other.  
2
1
1
3
2
3
10  
0
2: Line inputs (1 - 15) - Use these standard 1/4jacks to connect line-level sources such as  
synthesizers, drum machines, CD players, tape decks, or effects processors to any of the MPL  
1502s fifteen mono or stereo channels. The line input jacks for monophonic channels (channels  
1 - 5) are electronically balanced, so you should use balanced three-conductor cabling and  
Tip/Ring/Sleeve (TRS) plugs wherever possible (unbalanced two-conductor plugs can also be  
inserted into these inputs, but youll get better signal quality and less outside noise and hum if you  
use balanced lines). The line input jacks for stereo channels (channels 6 - 15) are unbalanced.  
When connecting only one monophonic signal to stereo channels, use the left (even-numbered)  
input; the MPL 1502 will then treat that channel as if it is a mono channel, allowing the signal to  
be panned (using the Balance control)see the Using Pan/Balancesection on page 18 for  
more information. The Connecting The MPL 1502section on page 10 provides more informa-  
tion on how best to use channel inputs. WARNING: Do not connect a channels line input if you  
already have something connected to its microphone input; each channel is designed to accept  
only one source or the other.  
+4  
-50  
TRIM  
0
-15  
+15  
HIGH  
0
4
-15  
-15  
+15  
MID  
0
+15  
LOW  
0
+10  
AUX 1  
−∞  
5
6
0
+10  
−∞  
AUX 2  
3: Trim (black) - This knob determines the input level of the connected mic or line signal.  
In stereo channels, it determines the input level of both the left and right inputs. Continuously  
adjustable from +4 dB to -50 dB (for mono channels) or +4 dB to -30 dB (for stereo channels), the  
input trim is at unity gain (no boost or cut) when set to the 0(9 oclock) position. The input  
signal is boosted when the trim is turned to the right of 0and attenuated when turned to the left  
of 0.For information on how to properly set this for each channel, see the section on page 14  
entitled Setting The Correct Gain Structure.”  
L
R
PAN  
0
PEAK  
8
9
+15  
−∞  
GAIN  
1
4: Equalizer (blue) - These knobs determine the amount of boost or attenuation in each of three  
frequency areas. The high and low frequency knobs provide 15 dB of cut or boost at 10 kHz and  
80 Hz, respectively, while the mid frequency knob provides 12 dB of cut or boost at 800 Hz.  
The low and mid frequency controls utilize a resonant (bell) peaking curve, while the high  
frequency control utilizes a shelving curve. In stereo channels, EQ settings affect both the left  
and right inputs, although the signals remain separate. A center detent in each knob (at the 0”  
position) indicates no boost or attenuation (that is, flat response). As each knob is turned  
clockwise from the 0position, the frequency area is boosted; as it is turned counterclockwise  
from the 0position, the frequency area is attenuated. For more information on the application of  
EQ, see the Using Equalizationsection on page 19.  
5: Auxiliary sends (light gray) - These knobs allow you to route signal to either or both of the  
MPL 1502s two monophonic Auxiliary outputs. These are typically used to create submixes (for  
example, a headphone cue mix) and to feed signal from single or multiple channels to outboard  
effects devices. At the 0(2 oclock) position, the signal is routed with unity gain (that is, no  
boost or attenuation). As each knob is turned clockwise from the 0position, the signal is  
boosted; as it is turned counterclockwise from the 0position, it is attenuated. Both Aux send 1  
and Aux send 2 are post-fade; that is, the level of the signal is determined by the channels input  
trim, its EQ settings, and the position of its gain control.  
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Guide d Tour - Mono and Ste re o Channe ls  
6: Pan (white) - Provided in mono channels only. This knob allows you to place the input signal  
14 / 15  
anywhere in the left-right stereo spectrum, while keeping the overall signal level constant. When  
the knob is placed at its center (detented) position, the signal is sent equally to both left and right  
outputs. When moved left of center, less signal is sent to the right output (making the sound  
appear left of center) and when moved right of center, less signal is sent to the left output  
(making the sound appear right of center). To route a signal hard left or right, place the pan  
knob either fully counterclockwise or fully clockwise.  
LEFT/MONO  
2
3
RIGHT  
7: Balance (dark gray) - Provided in stereo channels only. When both inputs (even-numbered  
and odd-numbered) are connected to a stereo channel, the even-numbered input signal is auto-  
matically panned hard left and the odd-numbered input signal is automatically panned hard right.  
In this case, the Balanceknob controls the relative levels of the paired input signals. When the  
knob is placed at its center (detented) position, both signals are at equal strength. When moved  
left of center, the even-numbered channel remains at the same strength but the odd-numbered  
channel is attenuated; when the knob is moved right of center, the odd-numbered channel  
remains at the same strength but the even-numbered channel is attenuated. When placed fully  
counter-clockwise, only the even-numbered channel is heard (panned hard left); when placed  
fully clockwise, only the odd-numbered channel is heard (panned hard right).  
10  
0
+4  
-30  
TRIM  
0
-15  
+15  
HIGH  
0
4
-15  
+15  
MID  
0
-15  
+15  
LOW  
In stereo channels where only the even-numbered input is connected, the Balance knob func-  
tions the same as a mono channel Pan control; see #6 above for details. For more information,  
see the Using Pan/Balancesection on page 18.  
0
−∞  
+10  
AUX 1  
5
7
0
+10  
AUX 2  
−∞  
8: Peak LED (red) - This warning light indicates an overload situation. It lights whenever a  
channels signal is 5 dB short of clipping. To stop it from lighting (and eliminate the accompanying  
sonic distortion), turn down the channels Trim knob (see #3 above) or reduce the amount of  
equalization boost. See the Setting the Correct Gain Structureand Using Equalization”  
sections in this manual (pages 14 and 19) for more information.  
L
R
BALANCE  
PEAK  
8
9
0
−∞  
+15  
9: Gain (green) - In mono channels (or in stereo channels where only the odd-numbered input  
is connected), this knob determines the signal level being sent to the main output as well as  
affecting the signal level being sent to both Aux send. In stereo channels, this knob simultane-  
ously controls the level of both the even-numbered and odd-numbered inputs (the relative levels  
of the two can be adjusted with the Balance knob, as described above). In practice, you will use  
the channel gain controls to continuously adjust the levels of the various signals being blended  
together by the MPL 1502. The center-detented 0position of the knob indicates unity gain (no  
level attenuation or boost). Moving the knob counterclockwise from the 0position (towards  
-) causes the signal to be attenuated (at the very bottom, it is attenuated infinitelyin other  
words, there is no sound). Moving it clockwise from the 0position (towards +15) causes the  
signal to be boosted by as much as 15 dB.  
GAIN  
14 /15  
For best signal-to-noise ratio, all gain controls for channels carrying signal should generally be  
kept at or near the 0position. Channels that are unused should have their gain controls kept  
fully counterclockwise at their -(minimum) level. See the Setting the Correct Gain Structure”  
section on page 14 for more information.  
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Guide d Tour - Main Se ction  
MPL 1502  
15 CHANNEL STEREO MIXER  
0
0
+2 +6  
+2 +6  
-20 -10 -6 -2  
-20 -10 -6 -2  
LEFT  
1
RIGHT  
PHANTOM  
POWER  
2
3
TAPE IN  
ON  
OFF  
CHANNEL 14 / 15  
0
L
R
+20  
−∞  
AUX 1 LEVEL  
BALANCE  
4
6
5
0
L
R
+20  
AUX 2 LEVEL  
−∞  
BALANCE  
7
8
0
10  
HEADPHONE  
LEVEL  
0
+15  
−∞  
MAIN  
1: Meter - This seven-segment bar meter shows the continuous output level of  
the main stereo output. For optimum signal-to-noise ratio, try to adjust all levels  
so that program material is usually at or around 0 VU, with occasional but not  
steady excursions to the red +2 or +6 segments. See the Setting the Correct  
Gain Structuresection on page 14 for more information.  
2: Meter LEDs - These show the status of various conditions within the MPL  
1502. The left LED (labeled Phantom) lights steadily red when phantom power  
is being supplied to all 5 mic inputs (see the Guided Tour - MPL 1502 Rear  
Panelsection on page 8 for more information). The right LED (labeled Power)  
lights steadily red when the MPL 1502 is powered on.  
3: Tape In / Channel 14/15 switch - When pressed in (the onposition), the  
signal arriving at the rear panel tape inputs is automatically routed to stereo  
channel 14/15, with the signal connected to the channel 14/15 line inputs  
disconnected and the channel 14/15 Trim control made inactive (the tape input  
signal is automatically given unity gain). When this switch is out (the off”  
position), channel 14/15 operates normally and the tape input signal is not heard.  
6
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Guide d Tour - Main Se ction  
4: Stereo Auxiliary Return Level (gray) - These knobs determine the input  
level of signal arriving via the MPL 1502s two stereo Auxiliary returns. Each  
return is at unity gain (no boost or attenuation) when set to the 0(2 oclock)  
position. The input signal is boosted when the knob is turned to the right of 0”  
and attenuated when turned to the left of 0.For information on how to properly  
set these, see the sections in this manual entitled Setting the Correct Gain  
Structureand Using the Aux Sends and Returns(pages 14 and 20).  
5: Stereo Auxiliary Return Balance (white) - These knobs determine the  
relative levels of the left and right input signals connected to the MPL 1502s two  
stereo Auxiliary returns. When the knob is placed at its center (detented)  
position, both left and right input signals for that Aux return are at equal strength.  
When moved left of center, the left input signal remains at the same strength but  
the right input signal is attenuated; when the knob is moved right of center, the  
right input signal remains at the same strength but the left input signal is  
attenuated. When placed fully counter-clockwise, only the left input signal is  
heard (panned hard left); when placed fully clockwise, only the right input signal  
is heard (panned hard right). These radicalpositions are useful when you are  
using a stereo Aux return as two mono returnssee the Using the Aux Sends  
and Returnssection on page 20 for more information.  
When only the left input of an Aux return is connected, its Balance knob  
functions as a constant level Pan control, allowing you to continuously place the  
incoming signal anywhere in the left-right stereo field.  
6: Headphone Level (blue) - This knob sets the level of the signal sent to the  
headphone jack (see #7 below). WARNING: To avoid possible damage to con-  
nected headphones (or, worse yet, to your ears!), always turn this all the way off  
(to the fully counterclockwise 0position) before plugging in a pair of head-  
phonesthen raise the level slowly while listening. The Headphone Level has  
no effect on the final Main Mix output level.  
7: Headphone jack - Connect any standard stereo headphones to this jack (via  
a standard 1/4TRS plug) for private monitoring of the main stereo output. The  
built-in MPL 1502 headphone preamp delivers 150 mw at 30 ohms.  
8: Main Mix (green) - This knob determines the final output signal levelyou  
can think of this as being the master fader.Signals from all channels and  
Auxiliary returns are routed here just before leaving the MPL 1502 via its left and  
right main output jacks. The center detented 0position of the knob indicates  
unity gain (no level attenuation or boost). Moving the knob counterclockwise  
from the 0position (towards -) causes the signal to be attenuated (at the  
very bottom, it is attenuated infinitelyin other words, there is no sound).  
Moving it clockwise from the 0position (towards +15) causes the signal to be  
boosted by as much as 15 dB. For more information, see the Setting The  
Correct Gain Structuresection on page 14.  
7
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Guide d Tour - Re ar Pane l  
1
2
POWER  
PHANTOM  
TIP RING SLEEVE  
AVIS:  
ON  
CAUTION  
MPL 1502  
RISQUE DE CHOC ELECTRIQUE  
NE PAS OUVRIR  
15 CHANNEL STEREO MIXER  
S A M S O N  
TIP  
RING  
+
-
!
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
SAMSON TECHNOLOGIES CORP., HICKSVILLE, NEW YORK  
OFF  
DO NOT EXPOSE THIS EQUIPMENT  
TO RAIN OR MOISTURE  
SLEEVE GND  
48V  
FUSE RATING  
TAPE OUT  
(600+4dΒ)  
5
4
3
2
1
1
RIGHT  
LEFT  
2
RIGHT  
LEFT/MONO RIGHT LEFT/MONO  
0.3A/250V(115V)  
0.15A/250V(230V)  
L
VOLTAGE SELECTOR  
2
1
230V  
115V  
R
SERIAL NUMBER  
MAIN OUT  
AUX SEND  
AUX RETURN  
CHANNEL INSERT - TIP RETURN - RING SEND  
(BALANCED 600 +4dB) (UNBALANCED 2K+4dB)  
(UNBALANCED 2K+4dB)  
TAPE IN  
(10K-10dB)  
~115/230V,50/60Hz 23W  
ASSEMBLED IN R.O.K.  
3
4
5
6
7
8
9
1: Power on-off switch - As you may have guessed, this is what you use to  
turn the MPL 1502 on and off. To avoid potential damage to your speakers, turn  
the mixer on before you turn on any connected power ampsand turn it off after  
the power amps are turned off.  
2: Phantom switch - When this switch is turned on, the MPL 1502 delivers 48  
volts of phantom power to pins 2 and 3 of all XLR microphone connectors (mono  
channels 1 - 5). WARNING: Only turn this on or off with the MPL 1502 powered  
down. Use phantom power only when one or more condenser microphones are  
connected to the MPL 1502 (these microphones will correctly load the input in  
order to drain offthe phantom power voltage). Before turning phantom power  
on, be sure to disconnect all non-microphone signal sources (such as direct  
injection boxes) from the XLR mic jacks. Phantom power will generally have no  
adverse affect on connected dynamic microphones; however, we strongly  
recommend that you refer to the owners manual of your microphone to  
determine whether or not it requires 48 volts phantom power. We cannot  
assume responsibility if you damage a mic by incorrectly applying  
MPL 1502 phantom power. If youre not sure that one or more connected mics  
require 48 volts phantom power, leave this switch OFF.  
3: AC input - Connect the supplied standard 3-pin EECplug here.  
4: Voltage selector - Set this to the left (115 V) position for operation in the  
United States and Canada. Set this to the right (230 V) position for operation  
in other countries. This will normally be preset correctly at the factory and will  
require no adjustment unless you use the MPL 1502 in a country other than the  
one in which you purchased the unit.  
8
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Guide d Tour - Re ar Pane l  
5: Main out (L, R) - These are the MPL 1502s main outputs. Youll usually use  
these to connect the MPL 1502 to a power amp and speakers. The Main out  
jacks are electronically balanced, so you should use balanced three-conductor  
cabling and TRS plugs wherever possible (unbalanced two-conductor plugs can  
also be inserted into these outputs, but youll get better signal quality and less  
outside noise and hum if you use balanced lines). See the Connecting the MPL  
1502section on page 10 for more information.  
6: Aux Sends (1, 2) - These unbalanced 1/4outputs allow you to route signal  
from each of the two discrete Aux Sends to external devices such as effects  
processors. Both Aux sends are post-fade and post-EQ. See the Using the  
Aux Sends and Returnssection on page 20 for more information.  
7: Tape In/Out (L, R) - Use these two sets of dual RCA input jacks to connect  
the inputs and outputs of a tape player to the MPL 1502. When the front panel  
Tape In / Channel 14/15switch is pressed in, the input signal connected here  
appears at stereo channel 14/15, at unity gain (during this operation, the channel  
14/15 trim control has no effect). From there, it can be equalized if necessary  
and routed to either or both Aux sends. The tape output signal is a duplicate of  
the Main output, at unity gain. See the section in this manual entitled Guided  
Tour - MPL 1502 Main Section(page 6) for more information.  
8: Aux Returns (1, 2) - These unbalanced 1/4inputs allow you to route signal  
from external devices such as effects processors to either of the two stereo Aux  
Returns. See the Using the Aux Sends and Returnssection on page 20 for  
more information.  
9: Channel inserts (1 - 5) - Use these to insert an external effects processor  
(such as outboard equalizer, compressor/limiter or noise gate) into any of the  
MPL 1502s five mono channels in an effects loopconfiguration. These jacks  
accept 1/4TRS plugs, with the ring carrying the send signal and the tip carrying  
the return signal. Normally, this will be connected to a Y-cord; see the  
Connecting The MPL 1502section on page 10 for more information and a  
wiring diagram.  
9
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Conne cting The MPL 1502 - Ge ne ral Sugge s tions  
The actual connections youll 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 Applicationssections at the rear of this manual, youll find  
some suggested setups. Here are a few basic rules concerning MPL 1502  
connections that will apply in most situations:  
In general, its 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 1/4TRS (Tip/Ring/Sleeve)  
connectors should be wired for use with these inputs and outputs:  
SLEEVE  
RING  
TIP +  
TIP  
GROUND  
RING -  
Unbalanced cables use standard 1/4phone connectors, wired as follows:  
+ SIGNAL  
GROUND  
+ SIGNAL  
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  
Techniquesfor information on how to avoid grounding problems.  
NEVER connect a microphone and line level input to the same channel  
simultaneouslyuse 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 dont 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  
2 + SIGNAL  
TO MIXER  
10  
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Conne cting The MPL 1502 - Ge ne ral Sugge s tions  
For single-fader control over a pair of matched signals (i.e. the left-right out-  
puts of a stereo effects processor, keyboard, drum machine, tone generator,  
CD player, or tape recorder), use the MPL 1502s stereo input channels (6/7,  
8/9, 10/11, 12/13, and 14/15). The Balance control in these channels will  
allow you to adjust the relative levels of the two inputs, and you can also  
equalize the stereo signal, with the same EQ settings applied to both inputs.  
6 / 7  
8 / 9  
10 / 11  
12 / 13  
14 / 15  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LINE INPUT (BALANCED 10K-30dB TO +4dB)  
RIGHT  
RIGHT  
RIGHT  
RIGHT  
RIGHT  
LEFT/MONO  
LEFT/MONO  
RIGHT  
RIGHT  
There are two more hidden(or at least not so obvious) stereo inputs to the  
MPL 1502; these are the Auxiliary returns. Use these whenever you want to  
bring in a stereo signal that will not need to be equalized. Also bear in mind  
that the two stereo Auxiliary returns can also be used as four monophonic  
returns, with the Aux Balance controls giving you the ability to adjust the  
relative levels of the left/right inputs. If youre using the MPL 1502 in live  
performance to drive a mono PA system, you may not need to take the  
stereo returns from outboard effects processors.  
1
2
AUX RETURN  
(UNBALANCED 2K+4dB)  
When connecting only one monophonic signal to a stereo channel, always  
use the left (even-numbered) input. When only the left input is connected in  
a stereo channel, the MPL 1502 treats that channel as if it is a mono channel  
and the signal can then be panned (using the Balance control). See the  
Using Pan/Balanceand Using the Aux Sends And Returnssections in  
this manual (pages 18 and 20) for more information.  
6 / 7  
8 / 9  
10 / 11  
12 / 13  
14 / 15  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LINE INPUT (BALANCED 10K-30dB TO +4dB)  
Use even-numbered inputs when  
connecting monophonic signal to a  
stereo channel.  
RIGHT  
RIGHT  
RIGHT  
RIGHT  
RIGHT  
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Conne cting The MPL 1502 - Ge ne ral Sugge s tions  
Signals that are likely to require in-lineprocessing (such as  
compression/limiting or expansion/noise gating) should be connected to  
channels 1 - 5, since these channels provide an insert connection.  
Insert cables (sometimes called Y-cords) should terminate in standard 1/4”  
TRS jacks (ring to send and tip to return), wired as follows:  
SLEEVE  
RING  
TIP RETURN  
GROUND  
RING SEND  
TIP  
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Se tting Up and Us ing The MPL 1502  
Setting up your MPL 1502 is a simple procedure which takes only a few minutes:  
1. Remove all packing materials (save them in case of need for future service)  
and decide where the unit is to be physically placedit can be used on a table-  
top or optionally mounted in any standard 19rack, requiring six rack spaces.  
MAIN OUT  
(BALANCED 600 +4dB)  
RIGHT  
LEFT  
2. Before even plugging the unit into an AC socket, begin by connecting the  
MPL 1502 main outputs into a power amp and the amp into loudspeakers. It is  
never a good idea to power up any amplifier that is not connected to loud-  
speakers.  
3. Next, make the signal input connections to the mic or line inputs of the vari-  
ous channels. WARNING: Do not connect a channels line input if you already  
have something connected to its microphone input, or vice versa; each channel  
is designed to accept only one source or the other.  
S
A
M
S
O
N
SERVO - 240  
4. Turn all channel trim and gain controls as well as the Main gain control fully  
counterclockwise, to their -setting. Then connect the EEC main power cord  
and plug the MPL 1502 into any grounded AC socket.  
5. Turn on the rear panel Power switchthe PowerLED in the meter section  
will light up.  
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Se tting the Corre ct Gain Structure  
Youre now ready to establish the correct gain structurethe key to getting the  
best performance from the MPL 1502, or from any mixer, for that matter. This is  
a simple procedure that ensures optimum input and output levels so that no  
unnecessary noise (caused by too low a signal) or overload distortion (caused by  
too high a signal) is created. Heres a step-by-step description of how to do so:  
a. With all connections made (as described above) but with the power amplifier  
and MPL 1502 off, start by setting the power amplifier volume to minimum. On  
the MPL 1502, turn all channel gain controls fully counterclockwise (to their -”  
position), and then set the Main gain control to its 0position.  
b. Set all channel input trim knobs to their fully counterclockwise (+4) position.  
c. Set all channel equalizer and pan/balance knobs as well as both Aux return  
balance knobs to their center detent 0positions.  
d. Set all channel Aux send knobs and both Aux return level knobs to their fully  
counterclockwise (-) position.  
e. Turn on all devices connected to channel line inputs and Aux returns and set  
their level controls to unity gain or, if there is no unity gain indicated on their out-  
put control, to maximum. If youve got outboard effects processors connected to  
Aux returns, make sure they are sending completely wet(processed) signal,  
with no dry(unprocessed) signal mixed in.  
f. If any condenser microphones are connected to the MPL 1502, turn on the  
rear-panel Phantom switch.* Then turn on the MPLs rear-panel Power switch—  
the Power LED in the meter section will light up. Finally, turn on the power  
amplifier.  
g. Play an instrument connected to one of the MPL 1502s line inputs** and,  
while doing so, slowly raise the corresponding channel gain control to the center  
detented 0positionyou should see the MPL meter begin to move. Now  
carefully adjust the input trim control for that channel so that the 0segment in  
the meter lights frequently and the +2segment lights only occasionally. If the  
incoming signal seems too hot even with the input channel trim all the way at its  
minimum (+4) setting, you may need to lower the output level of the instrument,  
though this will rarely occur. Conversely, if the signal is too low even with the  
input channel trim all the way up, somethings definitely wrong: in all likelihood,  
the connecting audio cable is faulty.  
h. Once youve set the optimum level in step (g) above, continue playing the  
instrument and slowly raise the power amplifier volume until you reach the level  
you want to hear.  
i. Repeat step (g) above for each instrument connected to the MPL 1502  
channel line inputs.  
* CAUTION: Before turning phantom power on, be sure to disconnect all non-  
microphone signal sources (such as direct injection boxes) from the mic jacks.  
** If you’re using an instrument such as electric guitar or bass, we recommend  
that you connect it to the MPL 1502 with a direct injection box to ensure correct  
impedance.  
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Se tting the Corre ct Gain Structure  
j. The procedure for setting optimum microphone levels is virtually identical; sing  
or speak into the mic at the level you expect to use in performance while slowly  
raising the gain control for that channel to its center detented 0position. Then  
carefully adjust the input trim control for that channel while watching the meter,  
until the 0segment lights frequently and the +2segment lights only occasion-  
ally. You should expect that microphone inputs will require rather more in the  
way of input trim boost than line inputs.  
k. If you have any outboard signal processors connected to the Aux send and  
return jacks on the rear panel, follow this step. Because outboard effects  
processors can sometimes be quite noisy, its particularly important to maximize  
the amount of signal being sent to them via the MPL 1502 Aux sends. The idea  
is to drive these devices as hot as possible (short of overloading them) and then  
to use the corresponding Aux return level to carefully adjust the amount of  
processed signal being blended with the dry signal. To set optimum Aux send  
levels, use a channel that has already had its gain structure adjusted in step (g)  
or (j) above. Turn both Aux send knobs for that channel to their 0(unity gain)  
position and then play the instrument (or sing into the microphone) connected to  
that channel. Adjust the input levels of connected outboard effects processors  
so that their meter shows incoming signal normally in the 0 vu range (with only  
occasional higher excursions). Then its time to optimize the Aux return levels.  
While continuing to play your instrument (or continuing to sing into the micro-  
phone), slowly raise each Aux return level control until you hear the desired  
amount of processed signal added to the dry signal. For more information, see  
the Using the Aux Sends and Returnssection on page 20.  
l. The gain structure is now correctly setyouve optimized the level of all  
signals coming into and out of the MPL 1502, and the end result will be minimum  
noise and distortion and maximum clean sound. Youll now find that the majority  
of your mixes can be accomplished with most channel gain controls at or near  
their center detented 0(unity gain) position and that the channel peak LEDs  
rarely if ever light (remember, if they do light, it means that something is  
distorting!). If you need to make adjustments to the overall level, use the level  
control of your power amplifier.  
If you encounter difficulty with any aspect of setting up or using your MPL 1502,  
you can call Samson Technical Support (516-932-1062) between 9 AM and 5  
PM EST.  
15  
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Grounding Te chnique s  
Hum and buzz are the biggest enemies you face when interconnecting a large  
number of different pieces of equipment to a central audio mixer. This is  
because each piece of equipment may operate at a marginally different voltage  
(this difference is called potential) and, when two devices at slightly different  
potential are physically connected with audio cabling, the end result can be  
nasty, extraneous noise (mind you, connecting two devices at very different  
potential can result in a major electrical shock!).  
However, there are several steps you can take to avoid grounding problems.  
First, assuming you have an isolated electrical circuit that can handle the  
electrical demands of your mixer and all connected audio equipment (these  
needs will usually be modest), you should always plug your mixer and all  
connected equipment into the same circuit. If possible, nothing else but this  
equipment should be connected to that circuit. If you cant do this, at least avoid  
plugging your mixer and audio equipment into the same circuit that is already  
powering things like heavy machinery, air conditioners, heaters, refrigerators,  
washing machines, neon signs or fluorescent light fixtures. One particular culprit  
that will almost certainly create problems is the standard light dimmer (the kind  
that uses silicon controlled rectifiers). Where low-level lighting is desired, use  
incandescent fixtures with autotransformer-type dimmers (sometimes called  
Variacs) insteadthese cost considerably more than the standard dimmer youll  
find at your local hardware store, but are well worth the extra expense.  
Three-prong plugs (such as the one used by the MPL 1502) should always be  
used as is; dont use adapters to lift the ground (unless youre using a star  
ground network”—see below). If you hear hum or buzz from a device that uses  
a two-prong plug (or an external two-prong AC/DC adapter), you can try revers-  
ing the plug in the socket. If that doesnt work, you may need to physically  
ground that devices chassis by connecting a wire (called a strap) from it to a  
grounded piece of metal such as rack ears. Some pieces of equipment have a  
screw-type ground post to which the strap can be connected; if not, you can  
attach some kind of metallic binding post to the case itself. If you are using rack-  
mounted audio devices and are experiencing hum or buzz, theres a simple test  
to determine the source of the problem: while keeping all devices powered on  
and connected with audio cabling, physically remove each device, one by one,  
from the rack. If the hum disappears when a particular device is removed, youll  
know that device is the culprit.  
We also recommend that you use balanced audio cabling and connectors  
wherever possible. The MPL 1502 provides electronically balanced inputs for all  
line channel inputs and for its main outputs. The wiring diagram in the  
Connecting The MPL 1502section of this manual (page 10) shows how 1/4”  
TRS (Tip/Ring/Sleeve) connectors should be wired for use with these inputs and  
outputs.  
In addition, you can minimize possible interference by planning your audio,  
electrical, and computer cable runs so that they are as far apart from one  
another as possible and so they dont run parallel to one another. If they have to  
cross, try to ensure that they do so at a 90° angle (that is, perpendicular to one  
another). In particular, try to keep audio cabling away from external AC/DC  
adapters.  
16  
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Grounding Te chnique s  
If youre using the MPL 1502 in a fixed location such as a recording studio, you  
may want to invest the time and money into creating a star ground network. This  
is by far the best technique for avoiding grounding problems. It involves using a  
formidable ground source such as a cold water pipe or a copper spike driven into  
the earth. A thick grounding cable is connected to that source and then brought  
to a central distribution point; from there, individual cables are connected to each  
piece of equipment. This setup also requires that you lift the ground plug of all  
three-prong AC connectors, so there is the possibility of danger if it is done incor-  
rectly. We strongly recommend that you contract with a qualified professional to  
carry out this or any kind of electrical work.  
Another, less common problem you may encounter is that of oscillation (a ringing  
tone), which, apart from being annoying, is potentially dangerous to your  
speakers. This is generally caused either by poor outside wiring or by returning  
a signal out of phase (most commonly from an outboard signal processor). If  
audible oscillation occurs, try isolating each input signal by turning down all other  
inputs. If one signal alone is causing the problem, you should be able to elimi-  
nate the oscillation by reversing that signals phase (many signal processors  
have a switch that allows you to do this).  
17  
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Us ing Pan/ Balance  
The final Main output of the MPL 1502 is stereothat is, there are two discrete  
output jacks, labeled leftand right,which will normally be routed to two  
discrete speakers.* Because of this, you will usually be working with a stereo  
field that ranges from hard left to hard right. The Pan control in each mono  
channel (and the Balance control in each stereo channel, when only the left  
[even-numbered] input is connected) allows you to place each individual sound  
at any point within this left-right field, while keeping the overall level constant.  
L
R
PAN  
You can use stereo panning creatively in a variety of ways: For example, you  
might want to have guitars coming from one speaker and keyboards from  
another, or you might use panning to spreadthe signal from a piano miked with  
two microphonesone over the bass notes (panned left) and the other over the  
treble notes (panned right). By turning a Pan knob while a signal is present, the  
sound appears to move in space (a process known as dynamic panning)this  
can be particularly effective when applied to sound effects.  
L
R
BALANCE  
In live performance, you may want to resist the temptation to pan anything  
completely hard left or right, since some members of the audience not seated in  
the center of the venue may miss some signal altogether. In these circum-  
stances, youre best to use modest panning, with signals routed no further than  
the 9 oclock and 3 oclock positions.  
In stereo channels where both inputs are connected, the even-numbered input  
signal is automatically panned hard left and the odd-numbered input signal is  
automatically panned hard right. The Balance knob in these channels controls  
the relative levels of the two input signals. When the knob is placed at its center  
(detented) position, both the even-numbered and odd-numbered channels are at  
equal strength. When moved left of center, the signal of the even-numbered  
channel remains the same but the signal of the odd-numbered channel is attenu-  
ated; when the knob is moved right of center, the the signal of the odd-numbered  
channel remains the same but the signal of the even-numbered channel is atten-  
uated. When placed fully counter-clockwise, only the even-numbered channel is  
heard; when placed fully clockwise, only the odd-numbered channel is heard.  
In the stereo Aux return section, the Balance control works in a similar fashion.  
When both inputs are connected, the left signal is automatically panned hard left  
and the right signal is automatically panned hard right. The Balance knob con-  
trols the relative levels of the two signals. When the knob is placed at its center  
(detented) position, both the left and right signals are at equal strength. When  
moved left of center, the left input signal remains the same but the right input sig-  
nal is attenuated; when the knob is moved right of center, the right input signal  
remains the same but the left input signal is attenuated. When placed fully  
counter-clockwise, only the left input is heard (panned hard left); when placed  
fully clockwise, only the right input is heard (panned hard right).  
If you connect different monophonic devices (such as effects processors) to both  
the left and right inputs of an Aux return, you can use the Aux Balance control to  
blend the relative contribution of each. If you turn the Balance knob fully coun-  
terclockwise, youll hear only the device connected to the left Aux input; if you  
turn it fully clockwise, youll hear only the device connected to the right Aux input.  
For more information, see the Using Aux Sends and Returnssection on page  
20.  
* You can, of course, also use the MPL 1502 monophonicallysimply route the  
same signal to both the left and right outputs.  
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Us ing Equalization  
One of the most exciting aspects of using a mixer such as the MPL 1502 is the  
ability to shape a sound, using a process called equalization. But there are few  
areas of sound engineering more misunderstood than equalization, and, just as  
good EQ can really help a sound, bad EQ can really hurt it, so read on...  
0
Every naturally occurring sound consists of a broad range of pitches, or  
frequencies, combined together in a unique way. This blend is what gives every  
sound its distinctive tonal color. The EQ section in a mixer allows you to alter a  
sound by boosting or attenuating specific frequency areas. The MPL 1502  
provides independent three-band equalization controls for each of its five mono  
and five stereo input channels. Each EQ knob is labeled with the maximum  
amount of cut or boost provided (± 15 dB in the case of the high and low  
frequencies and ± 12 dB in the case of the middle frequency).  
-15  
+15  
HIGH  
0
-15  
+15  
MID  
0
We provided these particular frequency areas because they have maximum  
impact on musical signalsthats why they are sometimes known as sweet  
spots.When an EQ knob is in its center detented position (0), it is having no  
effect. When it is moved right of center, the particular frequency area is being  
boosted; when it is moved left of center, the frequency area is being attenuated.  
The high EQ control employs what is known as a shelving curve, where only  
frequencies above the specified area are affected. The low and mid frequency  
controls employ what is known as a peaking resonant curve (sometimes known  
as a bell curve), where frequencies both above and below the specified area are  
affected.  
-15  
+15  
LOW  
In most instances, the best way to approach equalization is to think in terms of  
which frequency areas you need to attenuate, as opposed to which ones you  
need to boost (boosting a frequency area also has the effect of boosting the  
overall signal; too much EQ boost can actually cause overloadwith the  
accompanying Peak LED warning!). Be aware of the phenomenon of masking,  
where loud sounds in one frequency range obscure softer sounds in the same  
range; by cutting EQ notchesin a loud signal, you can actually make room for a  
softer one to shine through. And try not to think of EQ as a miracle workerno  
amount of equalization can put a singer in tune or remove the distortion from an  
overloaded input signal! The key is to get the signal right in the first place, by  
using correct gain structure and mic placement.  
Although the specific EQ you will apply to a signal is very much a matter of  
personal taste, here are a few general suggestions: Boosting the low frequency  
of instruments such as bass drums or bass guitar will add warmth and make the  
sound fatter; conversely, you may want to attenuate the low frequency compo-  
nent of instruments such as cymbals, high-hats, and shakers so as to thinthem  
out. The mid-range control is particularly effective for vocalsattenuating it can  
give a vocal performance more of an FM-radiofeel, while boosting it can help a  
vocal cut through dense instrumentation. Be careful not to boost high frequen-  
cies too much or you risk adding hiss to the signal, though just a touch can help  
add shimmerto an acoustic guitar, ride cymbal, or high-hat. Finally, because  
the MPL 1502 high EQ utilizes a shelving curve, attenuated settings can be used  
to reduce hiss (which is composed almost exclusively of high frequencies).  
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Us ing Aux Se nds and Re turns  
The MPL 1502s two Auxiliary sends allow you to combine the signal from  
0
multiple channels and send the resulting mix to external devices such as effects  
processors. When an Aux send knob is at the 0position, the signal is routed  
with unity gain (that is, no boost or attenuation). As it is turned clockwise from  
the 0 position, the signal is boosted; as it is turned counterclockwise from the 0  
position, it is attenuated. Both Aux sends are post-fade; that is, the level of the  
signal is determined by the input trim, the EQ settings, and the position of the  
channel gain control. In other words, raising or lowering the input level of the  
channel will affect the send level as well.  
−∞  
−∞  
+10  
AUX 1  
0
+10  
AUX 2  
The MPL 1502 also provides two stereo Auxiliary returns. These allow you to  
return signal from outboard devices, either in stereo pairs or monophonically  
(many popular effects processors provide a single mono input but have two  
stereo outputs). In practice, youll probably want to use the Auxiliary returns to  
bring in signal from connected effects processors. If the effects processors have  
stereo outputs, they should be connected to both the left and right Auxiliary  
return inputs so that their stereo integrity is retained. If they have mono outputs,  
you can route them to either the left or right inputs and then use the Auxiliary  
return Balance control to adjust the relative level of each paired signal. In this  
way, you can actually connect up to four monophonic devices to the MPL 1502s  
Aux return section.  
0
L
R
+20  
AUX 1 LEVEL  
−∞  
BALANCE  
0
L
R
+20  
AUX 2 LEVEL  
−∞  
BALANCE  
Each of the stereo Auxiliary returns is somewhat similar to a stereo channel,  
except that a signal being brought into to a stereo channel can be equalized if  
necessary and optionally sent on to other outboard devices (via Aux sends or  
channel inserts).  
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Us ing Channe l Ins e rts  
In addition to using Auxiliary sends and returns to access outboard devices, the  
MPL 1502 also provides channel inserts for the first five (mono) input channels.  
These should be used when you want to affect just one channels signal, as  
opposed to signal from several channelsmost often, this will be for dynamic  
processing purposes (such as outboard equalization, compression/limiting, or  
noise gating). You can also use the channel insert sends as post-eq (but  
pre-fade) direct outputs, if you need to route a single monophonic signal to an  
external device such as a tape deck.  
5
4
3
2
1
CHANNEL INSERT - TIP RETURN - RING SEND  
The channel insert jacks on the rear panel accept 1/4TRS plugs, with the ring  
carrying the send signal and the tip carrying the return signal; this will normally  
be connected to a Y-cord (see the Connecting The MPL 1502section in this  
manual for a wiring diagram). This configuration is sometimes known as an  
effects loop,since the signal is sent and returned over the same cable.  
If nothing is plugged into the channel insert jacks, they have no effectbut if you  
connect them to a passive device like a patchbay, youll need to normal (perma-  
nently connect) or half-normal (connection is made unless overriden by a patch  
cord) the send to the return. The insert signal is returned just before the channel  
fader. For this reason, youll have to be careful to set the output of external  
devices connected this way to unity gain.  
21  
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Applications  
Here are four suggested applications for the MPL 1502; bear in mind that your particular circumstance may dictate  
changes in these suggested signal connections and routings.  
Application 1 - Us ing The MPL 1502 As A Main Live Mixe r  
The main connections here involve routing the MPL 1502s Main output to the input of a power amplifier, and, from there,  
to PA speakers. Microphones and monophonic line level signals requiring insert processing are connected to mono  
channel inputs, while stereo line level signals are connected to stereo channel inputs. A tape deck is connected to the  
rear panel tape in/outs (making it easy to record the gig) and, for playback, the signal is returned to stereo channel 14/15  
by setting the Tape In / Channel 14/15to the onposition (pressing it in). Signal processors are connected to Aux  
send 2 (and either or both Aux returns) and to channel inserts as required. A submix from Aux send 1 is connected to  
the input of a second power amplifier driving onstage monitor speakers so that performers can receive a monitor mix  
independent of the house mix.  
L
R
S
A
M
S
O
N
SERVO - 240  
POWER  
PHANTOM  
1
2
3
4
5
6
/
7
8
/
9
10  
/
11  
12  
/
13  
14 15  
/
TIP RING SLEEVE  
AVIS:  
ON  
CAUTION  
MIC INPUT (BALANCED -50dB TO +4dB)  
MPL 1502  
15 CHANNEL STEREO MIXER  
RISQUE DE CHOC ELECTRIQUE  
S A M S O N  
TIP  
RING  
+
-
!
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
NE PAS OUVRIR  
DO NOT EXPOSE THIS EQUIPMENT  
TO RAIN OR MOISTURE  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
OFF  
SAMSON TECHNOLOGIES CORP., HICKSVILLE, NEW YORK  
SLEEVE GND  
2
1
2
1
2
1
2
1
2
1
48V  
FUSE RATING  
TAPE OUT  
(600+4dΒ)  
3
3
3
3
3
1
RIGHT  
LEFT/MONO  
RIGHT LEFT/MONO  
5
4
3
2
1
RIGHT  
LEFT  
2
S A M S O N  
0.3A/250V(115V)  
0.15A/250V(230V)  
L
VOLTAGE SELECTOR  
LINE INPUT (BALANCED 10K-30dB TO +4dB)  
15 CHANNEL  
STEREO MIXER  
MPL 1502  
2
1
115V  
230V  
R
SERIAL NUMBER  
MAIN OUT  
(BALANCED 600  
AUX SEND  
+4dB) (UNBALANCED 2K+4dB)  
AUX RETURN  
(UNBALANCED 2K+4dB)  
CHANNEL INSERT  
-
TIP RETURN RING SEND  
-
LINE INPUT (BALANCED 10K-40dB TO +4dB  
RIGHT  
RIGHT  
10  
RIGHT  
10  
RIGHT  
10  
RIGHT  
TAPE IN  
(10K-10dB)  
~115/230V,50/60Hz 23W  
10  
10  
10  
10  
10  
10  
10  
MPL 1502  
ASSEMBLED IN R.O.K.  
0
0
+4  
0
0
0
0
+4  
0
0
0
0
15 CHANNEL STEREO MIXER  
+4  
-50  
+4  
-50  
+4  
-50  
+4  
-50  
+4  
-50  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
-30  
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
Ring  
SIGNAL PROCESSOR  
Tip  
-20 -10 -6 -2  
-20 -10 -6 -2  
0
0
+2 +6  
+2 +6  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
LEFT  
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
RIGHT  
S
A
M
S
O
N
+15db  
+15db  
PHANTOM  
POWER  
0
0
-15db  
+15db  
-15db  
+15db  
-15  
-15  
+15  
-15  
-15  
+15  
-15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
0
0
TAPE IN  
ON  
-15db  
-15db  
OFF  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
+15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
CHANNEL 14 15  
/
R L  
0
0
0
0
0
0
0
0
0
0
0
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
L
R
BALANCE  
SIGNAL PROCESSOR  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+20  
LEVEL  
−∞  
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
1
0
0
0
0
0
0
0
0
0
0
0
+10  
+10  
−∞  
+10  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+10  
L
R
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
+20  
LEVEL  
−∞  
AUX  
2
2
2
2
2
2
2
2
2
2
2
BALANCE  
L
R
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
0
10  
PAN  
0
PAN  
0
PAN  
0
PAN  
0
PAN  
0
BALANCE  
BALANCE  
BALANCE  
BALANCE  
BALANCE  
L
HEADPHONE  
LEVEL  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
0
0
0
0
0
0
CASSETTE or DAT  
+15  
+15  
−∞  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
1
2
3
4
5
6
/
7
8
/
9
10 /11  
12 /13  
14 /15  
MAIN  
R
L
R
L
MIDI TONE GENERATOR  
DRUM MACHINE  
S
A
M
S
O
N
SERVO - 240  
MIDI KEYBOARD  
R
L
22  
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Applications  
Application 2 - Us ing The MPL 1502 As An Ons tage Monitor Mixe r  
Here, the MPL 1502 is receiving monophonic signal into its line inputs from the direct channel outputs of a main live  
mixer. Its Main output is connected to an outboard signal processor (typically an equalizer) prior to being routed to an  
amplifier and onstage monitors. This allows the overall mix to be adjusted in order to eliminate feedback and ringing  
problems.  
L
R
S
A
M
S
O
N
SERVO - 240  
L
R
SIGNAL PROCESSOR  
R
L
S
A
M
S
O
N
+15db  
+15db  
0
0
-15db  
+15db  
-15db  
+15db  
0
0
-15db  
-15db  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
0
0
0
0
0
0
0
0
0
0
0
0
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
0
0
0
0
0
0
0
0
0
0
0
0
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
0
0
0
0
0
0
0
0
0
0
0
0
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
0
0
0
0
0
0
0
0
0
0
0
0
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
0
0
0
0
0
0
0
0
0
0
0
0
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
0
0
0
0
0
0
0
0
0
0
0
0
0
0
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
POWER  
PHANTOM  
1
2
3
4
5
6
/
7
8
/
9
10  
/
11  
12  
/
13  
14  
/
15  
TIP RING SLEEVE  
AVIS:  
ON  
MIC INPUT (BALANCED -50dB TO +4dB)  
CAUTION  
MPL 1502  
S A M S O N  
15 CHANNEL STEREO MIXER  
RISQUE DE CHOC ELECTRIQUE  
TIP  
RING  
+
-
!
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
LEFT/ONO  
LEFTONO  
LEFT/MONO  
LEFT/MONO  
LEFT/ONO  
NE PAS OUVRIR  
DO NOT EXPOSE THIS EQUIPMENT  
TO RAIN OR MOISTURE  
OFF  
SAMSON TECHNOLOGIES CORP., HICKSVILLE, NEW YORK  
SLEEVE GND  
2
1
2
1
2
1
2
1
2
1
48V  
FUSE RATING  
3
3
3
3
3
TAPE OUT  
(600+4dΒ)  
5
4
3
2
1
RIGHT  
LEFT  
2
1
RIGHT  
LEFT/MONO  
RIGHT LEFT/MONO  
S A M S O N  
0.3A/250V(115V)  
0.15A/250V(230V)  
L
VOLTAGE SELECTOR  
LINE INPUT (BALANCED 10K-30dB TO +4dB)  
15 CHANNEL  
STEREO MIXER  
MPL 1502  
2
1
115V  
230V  
R
SERIAL NUMBER  
MAIN OUT  
(BALANCED 600  
AUX SEND  
+4dB) (UNBALANCED 2K+4dB)  
AUX RETURN  
(UNBALANCED 2K+4dB)  
CHANNEL INSERT  
-
TIP RETURN  
-
RING SEND  
LINE INPUT (BALANCED 10K-40dB TO +4dB  
RIGHT  
RIGHT  
10  
RIGHT  
10  
RIGHT  
10  
RIGHT  
TAPE IN  
~115/230V,50/60Hz 23W  
10  
10  
10  
10  
10  
10  
10  
(10K-10dB)  
MPL 1502  
0
0
+4  
0
0
0
0
+4  
ASSEMBLED IN R.O.K.  
0
0
0
0
15 CHANNEL STEREO MIXER  
+4  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
-30  
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
-20 -10 -6 -2  
-20 -10 -6 -2  
0
0
+2 +6  
+2 +6  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
LEFT  
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
RIGHT  
PHANTOM  
POWER  
-15  
-15  
+15  
-15  
-15  
+15  
-15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
TAPE IN  
OFF  
ON  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
+15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
CHANNEL 14 15  
/
0
0
0
0
0
0
0
0
0
0
0
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
L
R
BALANCE  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+20  
−∞  
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
1
LEVEL  
0
0
0
0
0
0
0
0
0
0
0
+10  
+10  
−∞  
+10  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+10  
L
R
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
+20  
LEVEL  
−∞  
AUX  
2
2
2
2
2
2
2
2
2
2
2
BALANCE  
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
0
10  
PAN  
0
PAN  
0
PAN  
0
PAN  
0
PAN  
0
BALANCE  
BALANCE  
BALANCE  
BALANCE  
BALANCE  
HEADPHONE  
LEVEL  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
0
0
0
0
0
0
+15  
+15  
−∞  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
1
2
3
4
5
6
/
7
8
/
9
10 /11  
12 /13  
14 /15  
MAIN  
23  
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Applications  
Application 3 - Us ing The MPL 1502 As A Ke yboard Submixe r  
Here, various keyboards and MIDI tone generators are connected to the mono and stereo line inputs of the MPL 1502.  
Signal processors are connected to Aux sends and returns and to channel inserts as required. The Main output can then  
be routed to a stereo input channel of a live performance or recording mixing console, with the performer having  
complete control over the blend of signals being provided to the sound engineer.  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
-10  
MIDI TONE GENERATOR  
0
0
0
0
0
0
0
0
0
0
0
0
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
+4  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
-30  
0
0
0
0
0
0
0
0
0
0
0
0
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
0
0
0
0
0
0
0
0
0
0
0
0
L
R
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
-12  
+12  
0
0
0
0
0
0
0
0
0
0
0
0
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
-12  
-15  
+12  
0
0
0
0
0
0
0
0
0
0
0
0
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
MIDI TONE GENERATOR  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
PFL (SOLO)  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
+15  
0
0
0
0
0
0
0
0
0
0
0
0
0
0
L
R
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
db  
SIGNAL PROCESSOR  
L
R
POWER  
PHANTOM  
TIP RING SLEEVE  
AVIS:  
ON  
CAUTION  
MPL 1502  
S A M S O N  
15 CHANNEL STEREO MIXER  
RISQUE DE CHOC ELECTRIQUE  
TIP  
RING  
+
-
!
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
NE PAS OUVRIR  
DO NOT EXPOSE THIS EQUIPMENT  
TO RAIN OR MOISTURE  
OFF  
SAMSON TECHNOLOGIES CORP., HICKSVILLE, NEW YORK  
SLEEVE GND  
48V  
FUSE RATING  
TAPE OUT  
(600+4dΒ)  
RIGHT  
LEFT  
2
1
RIGHT  
LEFT/MONO  
RIGHT LEFT/MONO  
5
4
3
2
1
0.3A/250V(115V)  
0.15A/250V(230V)  
L
VOLTAGE SELECTOR  
2
1
115V  
230V  
R
SERIAL NUMBER  
MAIN OUT  
(BALANCED 600  
AUX SEND  
+4dB) (UNBALANCED 2K+4dB)  
AUX RETURN  
(UNBALANCED 2K+4dB)  
CHANNEL INSERT  
-
TIP RETURN RING SEND  
-
TAPE IN  
~115/230V,50/60Hz 23W  
(10K-10dB)  
ASSEMBLED IN R.O.K.  
SIGNAL PROCESSOR  
R
L
1
2
3
4
5
6
/
7
8
/
9
10  
/
11  
12  
/
13  
14 15  
/
MIDI KEYBOARD  
MIC INPUT (BALANCED -50dB TO +4dB)  
LEFT/ONO  
LEFTONO  
LEFT/ONO  
LEFT/ONO  
LEFT/MONO  
2
1
2
1
2
1
2
1
2
1
3
3
3
3
3
S A M S O N  
LINE INPUT (BALANCED 10K-30dB TO +4dB)  
15 CHANNEL  
STEREO MIXER  
MPL 1502  
LINE INPUT (BALANCED 10K-40dB TO +4dB  
RIGHT  
RIGHT  
10  
RIGHT  
10  
RIGHT  
10  
RIGHT  
10  
10  
10  
10  
10  
10  
10  
MPL 1502  
0
0
+4  
0
0
0
0
+4  
0
0
0
0
15 CHANNEL STEREO MIXER  
+4  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
-30  
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
-20 -10 -6 -2  
-20 -10 -6 -2  
0
0
+2 +6  
+2 +6  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
LEFT  
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
RIGHT  
PHANTOM  
POWER  
-15  
-15  
+15  
-15  
-15  
+15  
-15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
TAPE IN  
OFF  
ON  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
+15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
CHANNEL 14 15  
/
0
0
0
0
0
0
0
0
0
0
0
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
L
R
BALANCE  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+20  
−∞  
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
1
LEVEL  
0
0
0
0
0
0
0
0
0
0
0
+10  
+10  
−∞  
+10  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+10  
L
R
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
+20  
LEVEL  
−∞  
AUX  
2
2
2
2
2
2
2
2
2
2
2
BALANCE  
MIDI KEYBOARD  
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
0
10  
PAN  
0
PAN  
0
PAN  
0
PAN  
0
PAN  
0
BALANCE  
BALANCE  
BALANCE  
BALANCE  
BALANCE  
HEADPHONE  
LEVEL  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
0
0
0
0
0
0
+15  
+15  
−∞  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
1
2
3
4
5
6
/
7
8
/
9
10 /11  
12 /13  
14 /15  
MAIN  
24  
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Applications  
Application 4 - Us ing The MPL 1502 For Re cording  
You can also use the MPL 1502 for making simple recordingsfor example, when recording a rehearsal or practice  
session direct to open-reel two-track, cassette, or DAT recorder. Connect the MPL 1502 tape outputs to the inputs of the  
two-track tape recorder, and connect the Main outputs to a power amplifier driving the control room speakers. The two  
tape recorder outputs are then returned to the MPL 1502 tape inputs. Microphones and monophonic line level signals  
requiring insert processing are connected to mono channel inputs and stereo line level signals are connected to stereo  
channel inputs. Signal processors are connected to Aux send 2 (and either or both Aux returns) and to channel inserts as  
required. A submix from Aux send 1 is connected to the input of a second power amplifier driving cue headphones so  
that performers can receive a headphone mix independent of the main control room mix.  
L
R
S
A
M
S
O
N
SERVO - 240  
POWER  
PHANTOM  
1
2
3
4
5
6
/
7
8
/
9
10  
/
11  
12  
/
13  
14 15  
/
TIP RING SLEEVE  
AVIS:  
ON  
CAUTION  
MIC INPUT (BALANCED -50dB TO +4dB)  
MPL 1502  
15 CHANNEL STEREO MIXER  
RISQUE DE CHOC ELECTRIQUE  
S A M S O N  
TIP  
RING  
+
-
!
RISK OF ELECTRIC SHOCK  
DO NOT OPEN  
NE PAS OUVRIR  
DO NOT EXPOSE THIS EQUIPMENT  
TO RAIN OR MOISTURE  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
LEFT/MONO  
OFF  
SAMSON TECHNOLOGIES CORP., HICKSVILLE, NEW YORK  
SLEEVE GND  
2
1
2
1
2
1
2
1
2
1
48V  
FUSE RATING  
TAPE OUT  
(600+4dΒ)  
3
3
3
3
3
1
RIGHT  
LEFT/MONO  
RIGHT LEFT/MONO  
5
4
3
2
1
RIGHT  
LEFT  
2
S A M S O N  
0.3A/250V(115V)  
0.15A/250V(230V)  
L
VOLTAGE SELECTOR  
LINE INPUT (BALANCED 10K-30dB TO +4dB)  
15 CHANNEL  
STEREO MIXER  
MPL 1502  
2
1
115V  
230V  
R
SERIAL NUMBER  
MAIN OUT  
(BALANCED 600  
AUX SEND  
+4dB) (UNBALANCED 2K+4dB)  
AUX RETURN  
(UNBALANCED 2K+4dB)  
CHANNEL INSERT  
-
TIP RETURN RING SEND  
-
LINE INPUT (BALANCED 10K-40dB TO +4dB  
RIGHT  
RIGHT  
10  
RIGHT  
10  
RIGHT  
10  
RIGHT  
TAPE IN  
(10K-10dB)  
~115/230V,50/60Hz 23W  
10  
10  
10  
10  
10  
10  
10  
MPL 1502  
ASSEMBLED IN R.O.K.  
0
0
+4  
0
0
0
0
+4  
0
0
0
0
15 CHANNEL STEREO MIXER  
+4  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
-30  
+4  
-30  
+4  
-30  
+4  
-30  
-30  
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
TRIM  
0
Ring  
SIGNAL PROCESSOR  
Tip  
-20 -10 -6 -2  
-20 -10 -6 -2  
0
0
+2 +6  
+2 +6  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
LEFT  
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
HIGH  
0
RIGHT  
S
A
M
S
O
N
+15db  
+15db  
PHANTOM  
POWER  
0
0
-15db  
+15db  
-15db  
+15db  
-15  
-15  
+15  
-15  
-15  
+15  
-15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
-15  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
MID  
0
0
0
TAPE IN  
OFF  
-15db  
-15db  
ON  
+15  
-15  
+15  
-15  
+15  
-15  
+15  
+15  
-15  
+15  
+15  
-15  
+15  
-15  
+15  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
LOW  
CHANNEL 14 15  
/
R L  
0
0
0
0
0
0
0
0
0
0
0
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
L
R
BALANCE  
SIGNAL PROCESSOR  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+20  
LEVEL  
−∞  
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
AUX  
1
AUX  
1
0
0
0
0
0
0
0
0
0
0
0
+10  
+10  
−∞  
+10  
−∞  
+10  
−∞  
+10  
+10  
+10  
+10  
+10  
+10  
L
R
−∞  
−∞  
−∞  
−∞  
−∞  
−∞  
+20  
LEVEL  
−∞  
AUX  
2
2
2
2
2
2
2
2
2
2
2
BALANCE  
L
R
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
0
10  
PAN  
0
PAN  
0
PAN  
0
PAN  
0
PAN  
0
BALANCE  
BALANCE  
BALANCE  
BALANCE  
BALANCE  
L
HEADPHONE  
LEVEL  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
PEAK  
0
0
0
0
0
0
CASSETTE or DAT  
+15  
+15  
−∞  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
+15  
−∞  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
GAIN  
1
2
3
4
5
6
/
7
8
/
9
10 /11  
12 /13  
14 /15  
MAIN  
R
L
R
L
MIDI TONE GENERATOR  
HEADPHONE AMP  
DRUM MACHINE  
MIDI KEYBOARD  
R
L
25  
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Spe cifications  
1. Frequency Response (0 dB = 1.0 V RMS)  
17 Hz to 30 kHz ± 1.5 dB at +4 dB  
2. Equivalent Input Noise  
Ch. 1 - Ch. 5 Mic input  
-128 dB (A filter, 150 shorted)  
-131 dB (A filter, input shorted)  
Ch. 1 - Ch. 15 Line input  
3. THD+N (unity gain, 20 Hz - 20 kHz)  
Less than 0.03 %  
4. Input Level  
Ch. 1 - Ch. 5 Mic input  
Ch. 1 - Ch. 15 Line input  
-50 dBV to +4 dB (10 k, balanced XLR)  
-40 dBV to +14 dB  
(10 k, balanced stereo phone jack)  
+4 dB (47 k, unbalanced phone jack)  
Aux return 1 - 2  
5. Maximum Input Level  
Ch. 1 - Ch. 5 Mic input  
Ch. 1 - Ch. 15 Line input  
+17 dB  
+27 dB  
6. Trim gain range  
0 dB to +54 dB  
+15 dB to -80 dB  
+10 dB to -75 dB  
7. Channel fader range  
8. Aux send gain range  
9. Crosstalk  
Ch-to-Ch (1 kHz)  
Stereo Ch L/R (1 kHz)  
-80 dB  
-65 dB  
10. Standard Output Level  
Main Out  
+4 dBV (balanced, 600 loaded)  
+4 dBV (unbalanced, 2.2 kloaded)  
150 mW (30 loaded)  
Aux Out  
Headphones  
11. Maximum Output  
Main Out  
+22 dBV (balanced, 600 loaded)  
+22 dBV (unbalanced, 2.2 kloaded)  
+22 dBV (unbalanced, 600 loaded)  
Aux Out  
Tape Out  
12. Tone Control  
High  
Mid  
Low  
10 kHz ± 15 dB  
800 Hz ± 12 dB  
80 Hz ± 15 dB  
13. Dimensions  
14. Weight  
13.8 in (w) x 10.4 (d) x 3.2 (h)  
350 mm (w) x 264 (d) x 82 (h)  
7.7 lbs 3.5 kg  
26  
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