PreSonus MP20 User Manual

MP20

TWO CHANNEL MICROPHO NE

PRE - AMPLIFIER

USERS MANUAL

Version 1.1

? 1999,2001, PreSonus Audio Electronics, Incorporated.

All rights reserved.

WARRANTY

PreSonus Limited Warranty

PreSonus Audio Electronics Inc. warrants this product to be free of defects in material and
workmanship for a period of one year from the date of original retail purchase. This warranty is
enforceable only by the original retail purchaser. To be protected by this warranty, the purchaser
must complete and return the enclosed warranty card within 14 days of purchase. During the
warranty period PreSonus shall, at its sole and absolute option, repair or replace, free of charge,
any product that proves to be defective on inspection by PreSonus or its authorized service
representative. To obtain warranty service, the purchaser must first call or write PreSonus at
the address and telephone number printed below to obtain a Return Authorization Number and
instructions of where to return the unit for service. All inquiries must be accompanied by a
description of the problem. All authorized returns must be sent to the PreSonus repair facility
postage prepaid, insured and properly packaged. PreSonus reserves the right to update any unit
returned for repair. PreSonus reserves the right to change or improve the design of the product
at any time without prior notice. This warranty does not cover claims for damage due to abuse,
neglect, alteration or attempted repair by unauthorized personnel, and is limited to failures arising
during normal use that are due to defects in material or workmanship in the product. Any implied
warranties, including implied warranties of merchantability and fitness for a particular purpose,
are limited in duration to the length of this limited warranty. Some states do not allow limitations on
how long an implied warranty lasts, so the above limitation may not apply to you. In no event will
PreSonus be liable for incidental, consequential or other damages resulting from the breach of
any express or implied warranty, including, among other things, damage to property, damage
based on inconvenience or on loss of use of the product, and, to the extent permitted by law,
damages for personal injury. Some states do not allow the exclusion of limitation of incidental or
consequential damages, so the above limitation or exclusion may not apply to you. This warranty
gives you specific legal rights, and you may also have other rights, which vary form state to state.
This warranty only applies to products sold and used in the United States of America. For
warranty information in all other countries please refer to your local distributor.

PreSonus Audio Electronics, Inc.
7257 Florida Blvd.
Baton Rouge, LA 70806
[phone]

[e-mail]

? 2001, PreSonus Audio Electronics, Incorporated. All rights reserved.

TABLE OF CONT ENTS

1 Overview

1.1 Introduction 4

1.2 Features 4

2 Controls & Connections

2.1 Front Panel Basic Layout 8

2.2 Preamplifier Section 9

2.3 Master Channel 11

2.4 Back Panel Basic Layout 11

2.5 Power Supply 13

3 Operation

3.1 Dynamic Microphones 14

3.2 Phantom Powered Microphones 14

3.3 Instrument Input 14

3.4 Inserting Compressors, EQ’s, etc. 14

3.5 Using Return as Line In 15

3.6 Aux Input – Cascading Mixes 15

4 Technical

4.1 Specifications 16

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1 OVERVIEW

1.1 INTRODUCTION

Thank you for purchasing the PreSonus MP20 Two Channel
Microphone / Instrument Preamplifier with Stereo Bus. This pre-amp
was designed using state of the art components to deliver crystal
clear audio for an infinite period of time. We believe the MP20 to be
an exceptional sounding unit and an exceptional value. Feel free to
contact us at 1-800-750-0323 anytime for any reason whatsoever.
We value your suggestions and your comments. PreSonus Audio
Electronics is committed to constant product improvement and feel
the best way to accomplish this task is by listening to the experts on
our gear, our valued customers. We appreciate the support you have
shown us through the purchase of our products.

Please pay close attention to how you connect your MP20 to your
system. Improper grounding is the most common cause of noise
problems found in studio or live sound systems. We urge you to
scan this manual before hooking up your MP20 to become familiar
with its features and various applications.

Good luck and enjoy your MP20!

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OVERVIEW

1.2 FEATURES

The following is a summary of your MP20’s features:

? FET, Class A Discrete Input Buffers. Each channel of

your MP20 contains a Class A discrete input buffer
followed by a dual servo gain stage. This provides ultra
low noise and wide gain control. This allows the MP20
user to boost desirable signal without increasing
unwanted background noise (NO capacitors! )

? 48 Volt Phantom Power. Each channel of the MP20 has

48V Phantom power available. When the Phantom
power switch is engaged, power is supplied at a constant
rate whether one or both channels are utilized. This
assures optimum performance of your condenser
microphone(s) and that it will be free of distortion
associated with insufficient power.

? Polarity Reverse. A phase reverse switch is provided on

each channel. This switch enables the user to invert the
phase of a microphone when phase cancellation is noted.
The phase reverse switch allows the operator to avoid
phase cancellation when identical microphones are used
in close proximity to one another. The phase reverse
switch also can compensate for different XLR connector
hook-ups where pin connections have been inverted.

? 20 dB Pad. A 20 dB pad is available on each channel for

reducing the in-coming signal level. This pad provides a
more manageable signal from high output devices giving
the operator greater control over the in-coming signal and
a much reduced chance of over-driving the input and
thereby avoiding distortion.

? +28 dB Headroom. The MP20 has +28 dBu of

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OVERVIEW

headroom on each channel. This feature gives you a very
wide dynamic range and excellent transient response
characteristics.

? Rumble Filter. A Rumble filter is provided on each

channel for eliminating low frequency noise. This lets you
greatly reduce background noise such as air conditioners
or wind noise with the flick of a switch without effecting the
desired frequencies.

? Microphone or Instrument Input. Each channel of the

MP20 has a separate XLR microphone input on the rear of
the unit and a female 1/4” instrument input jack located on
the front panel.

? High Quality Transformer with IDSS Control. The

MP20 offers a high quality transformer on each channel.
These feature an IDSS control (this control adjusts the
drain current on the input FET amplifier altering the even
harmonic levels of the signal being passed) with an
adjustment range of 0% to 100%. The 0% position
passes a pure signal. As the control is rotated to the
100% position, the signal’s even harmonic series is
boosted giving the signal “warmth” very much like a
vacuum tube or similar to the sound of analog tape
saturation. This remarkable effect gives you the sound of
a tube without the headache of uneven performance often
encountered with vacuum tube devices ( no tube to pick­up RF or to age and become “microphonic”)

? Mix Bus. The MP20 has a stereo summing bus for

combining the input signals assigned to the bus using the
L/R function switch on the front panel of the MP20. A pan
knob allows the placement of the selected signal
anywhere in the stereo array of the stereo summing bus
out-going signal (i.e.- left; left-center; center; right-center or

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