Samson MPL 1502 User Manual
Introduction 1
MPL 1502 Features 1
Guided Tour 3
Overview 3
Mono and Stereo Channels 4
Main Section 6
Rear Panel 8
Connecting The MPL 1502 - General Suggestions 10
Setting Up and Using the MPL 1502 13
Setting the Correct Gain Structure 14
Grounding Techniques 16
Using Pan/Balance 18
Using Equalization 19
Using Aux Sends and Returns 20
Using Channel Inserts 21
Applications Notes 22
Using The MPL 1502 As A Main Live Mixer 22
Using The MPL 1502 As A Monitor Mixer 23
Using The MPL 1502 As A Keyboard Submixer 24
Using The MPL 1502 For Recording 25
Specifications 26
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 System Features
“MPL” stands for “Microphone/Program/Line” and 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 excellent sound quality to the equation, and you’ve got a product which is equally
useful as a live performance mixer, keyboard submixer, or even for simple
recording purposes (you’ll find descriptions of each of these applications at the
conclusion of this manual). Here are some of the MPL 1502’s main features:
• Fifteen input channels, including five stereo channels. The five monophonic
channels provide electronically balanced inputs that can be used for microphone 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
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 leftright 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
19” rack (taking six rack spaces), making it easy to integrate into any existing 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.
2
Guided Tour - Overview
The following illustration shows an overview of the front panel of the MPL 1502:
3
123
2
1
3
MIC INPUT (BALANCED -50dB TO +4dB)
2
3
2
1
3
LINE INPUT (BALANCED 10KΩ -40dB TO +4dB RIGHT RIGHT RIGHT RIGHT RIGHT
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
−∞
AUX 1
+10
−∞
AUX 2
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
−∞
AUX 1
+10
−∞
AUX 2
-50+4
+10
-50+4
0
+10
0
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
0
−∞
+10
AUX 1
0
+10
−∞
AUX 2
4
6 / 75 8 / 9 10 / 11 12 / 13 14 / 15
LEFT/MONOLEFT/MONOLEFT/MONOLEFT/MONOLEFT/MONO
2
1
-50+4
3
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
0
−∞
AUX 1
0
−∞
AUX 2
2
1
-50+4
0
+10
0
+10
3
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
−∞
AUX 1
−∞
+10
AUX 2
1
LINE INPUT (BALANCED 10KΩ -30dB TO +4dB)
10
0
TRIM
0
-15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
−∞
AUX 1
+10
−∞
AUX 2
-30+4
+10
-50+4
0
+10
0
10
0
-30+4
TRIM
0
-15 +15
+15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
0
−∞
+10
AUX 1
0
+10
−∞
AUX 2
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
0
−∞
AUX 1
0
+10
−∞
AUX 2
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
−∞
AUX 1
+10
−∞
AUX 2
-30+4
+10
-30+4
0
+10
0
10
0
-30+4
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
0
−∞
+10
AUX 1
0
+10
−∞
AUX 2
SAMSON
MPL 1502
MPL 1502
15 CHANNEL STEREO MIXER
-20 -10 -6 -2
LEFT
RIGHT
-20 -10 -6 -2
PHANTOM POWER
0
0
−∞
AUX 1 LEVEL
−∞
AUX 2 LEVEL
0
+20
0
+20
TAPE IN
ON
OFF
CHANNEL 14 / 15
15 CHANNEL
STEREO MIXER
0+2+6
0+2+6
RL
BALANCE
RL
BALANCE
LR
PAN
PEAK
0
−∞
GAIN
+15
LR
PAN
PEAK
0
−∞
GAIN
+15
LR
PAN
PEAK
0
−∞
GAIN
+15
LR
PAN
PEAK
0
−∞
GAIN
+15
LR
PAN
PEAK
0
−∞
GAIN
+15
LR
BALANCE
PEAK
0
−∞
GAIN
+15
LR
BALANCE
PEAK
0
−∞
GAIN
+15
LR
BALANCE
PEAK
0
−∞
GAIN
+15
LR
BALANCE
PEAK
0
−∞
GAIN
+15
LR
BALANCE
PEAK
0
−∞
GAIN
14 /1512 /1310 /118 / 96 / 754321
010
HEADPHONE
LEVEL
+15
0
+15
−∞
MAIN
Main sectionStereo channelsMono channels
Guided Tour - Mono and Stereo Channels
1: Mic inputs (1 - 5) - Provided in monophonic channels only. Use these electronically balanced
XLR jacks to connect microphones to any of the MPL 1502’s 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 channel’s 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 channel’s 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: Line inputs (1 - 15) - Use these standard 1/4” jacks to connect line-level sources such as
synthesizers, drum machines, CD players, tape decks, or effects processors to any of the MPL
1502’s 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 you’ll 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/Balance” section on page 18 for
more information. The “Connecting The MPL 1502” section on page 10 provides more information on how best to use channel inputs. WARNING: Do not connect a channel’s line input if you
already have something connected to its microphone input; each channel is designed to accept
only one source or the other.
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 o’clock) position. The input
signal is boosted when the trim is turned to the right of “0” and 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.”
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 “0” position, the frequency area is boosted; as it is turned counterclockwise
from the “0” position, the frequency area is attenuated. For more information on the application of
EQ, see the “Using Equalization” section on page 19.
5: Auxiliary sends (light gray) - These knobs allow you to route signal to either or both of the
MPL 1502’s 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 o’clock) position, the signal is routed with unity gain (that is, no
boost or attenuation). As each knob 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 send 1
and Aux send 2 are
post-fade; that is, the level of the signal is determined by the channel’s input
trim, its EQ settings, and the position of its gain control.
4
1
2
3
10
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
−∞
AUX 1
−∞
AUX 2
LR
PAN
PEAK
0
−∞
GAIN
1
1
1
2
-50+4
3
4
0
+10
0
+10
5
6
8
9
+15
Guided Tour - Mono and Stereo Channels
6: Pan (white) - Provided in mono channels only. This knob allows you to place the input signal
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.
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 automatically panned hard left and the odd-numbered input signal is automatically panned hard right.
In this case, the “Balance” knob 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).
In stereo channels where only the even-numbered input is connected, the Balance knob functions the same as a mono channel Pan control; see #6 above for details. For more information,
see the “Using Pan/Balance” section on page 18.
8: Peak LED (red) - This warning light indicates an overload situation. It lights whenever a
channel’s signal is 5 dB short of clipping. To stop it from lighting (and eliminate the accompanying
sonic distortion), turn down the channel’s Trim knob (see #3 above) or reduce the amount of
equalization boost. See the “Setting the Correct Gain Structure” and “Using Equalization”
sections in this manual (pages 14 and 19) for more information.
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 simultaneously 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 “0” position of the knob indicates unity gain (no
level attenuation or boost). Moving the knob counterclockwise from the “0” position (towards
“-∞”) causes the signal to be attenuated (at the very bottom, it is attenuated infinitely—in other
words, there is no sound). Moving it clockwise from the “0” position (towards “+15”) causes the
signal to be boosted by as much as 15 dB.
For best signal-to-noise ratio, all gain controls for channels carrying signal should generally be
kept at or near the “0” position. 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.
5
14 / 15
LEFT/MONO
2
RIGHT
10
3
4
5
7
8
9
0
TRIM
0
-15 +15
HIGH
0
-15 +15
MID
0
-15 +15
LOW
−∞
AUX 1
+10
−∞
AUX 2
LR
BALANCE
PEAK
0
−∞
GAIN
14 /15
-30+4
0
+10
0
+15
Guided Tour - Main Section
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 Structure” section 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
Panel” section 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 “on” position), 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
15 CHANNEL STEREO MIXER
MPL 1502
-20 -10 -6 -2
1
LEFT
RIGHT
-20 -10 -6 -2
PHANTOM POWER
0+2+6
0+2+6
2
TAPE IN
LEVEL
ON
OFF
CHANNEL 14 / 15
0
+20
0
+20
BALANCE
BALANCE
0
RL
5
RL
7
3
−∞
AUX 1 LEVEL
4
−∞
AUX 2 LEVEL
6
010
HEADPHONE
8
−∞
+15
MAIN
Guided Tour - Main Section
4: Stereo Auxiliary Return Level (gray) - These knobs determine the input
level of signal arriving via the MPL 1502’s two stereo Auxiliary returns. Each
return is at unity gain (no boost or attenuation) when set to the “0” (2 o’clock)
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
Structure” and “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 1502’s 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 “radical” positions are useful when you are
using a stereo Aux return as two mono returns—see the “Using the Aux Sends
and Returns” section 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 connected headphones (or, worse yet, to your ears!), always turn this all the way off
(to the fully counterclockwise “0” position) before plugging in a pair of headphones—then 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 1/4” TRS 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 level—you
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 “0” position of the knob indicates
unity gain (no level attenuation or boost). Moving the knob counterclockwise
from the “0” position (towards “-∞”) causes the signal to be attenuated (at the
very bottom, it is attenuated infinitely—in other words, there is no sound).
Moving it clockwise from the “0” position (towards “+15”) causes the signal to be
boosted by as much as 15 dB. For more information, see the “Setting The
Correct Gain Structure” section on page 14.
7
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