Genther MPAII User manual

MPAII
Installation and
Operations Manual

© Copyright 1997 Gentner Communications Corporation. All rights reserved. No part of this manual may be
reproduced in any form or by any means without written permission from Gentner Communications Corporation.
Printed in the United States of America. Original version, 3/95. Gentner Communications Corporation reserves
specification privileges. Information in this manual is subject to change without notice.
MPAII Installation and Operations Manual
Gentner Part No. 800-111-001 (Rev. 2.00)
January 1997
Manual Development: Bill Kilpack
Artwork and Illustrations: Mike Greenhalgh, Bill Kilpack
Copyright
Information
Gentner Communications Corporation is committed to protecting the environment
and preserving our natural resources.
This manual has been printed entirely on recycled paper.
This equipment complies with the requirements of the EU guidelines:
89/336/EEC “Electromagnetic Compatibility”
73/23/EEC “Electrical operating material for use within specific
voltage limits”
Conformity of the equipment with the above guidelines is attested by the CE mark.

Contents
MPAII Installation and Operations Manual Page iii
Introduction 1
Warranty Registration 1
Unpacking 1
Features and Benefits 2
Applications 2
Audioconferencing and Videoconferencing 2
Courtrooms and Public Meetings 2
Distance Learning 2
Hotels and Government Meetings 2
Houses of Worship 3
Talk Shows 3
Product Description 3
MPAII 3
Front-Panel Controls 4
Back-Panel Connectors 5
Before You Install 6
Room Planning 6
Microphone Selection 8
Microphone Placement 8
Power Requirements 9
PC Option 9
Auxiliary Equipment 9
Equipment Placement 9
Environmental Requirements 9
Installation 10
Completed Installation 10
Step 1 — Voltage Input Selection 10
Step 2 — Back-Panel Connections 11
Step 3 — Phantom Power Configuration 12
Step 4 — Auto Mix Switches 13
Step 5 — Baud Rate 13
Step 6 — Setting Levels 13
Program Setup 14
Factory Default Programs 14
User-Configuration Programs 14
Default Program Description 15
Custom Programming 17
Running the MPAII Programmming Software 17
Understanding the Main Screen 18
Programming Functions 19
Program Parameters 21
Specifications 24
Warranty 26
FCC Part 15 Compliance 26
Safety Information 27
Appendix A: Glossary 27
Appendix B: Connector Pinouts 28
Appendix C: Programming Tutorial 29
Appendix D: Applications 35
Appendix E: MPAII Block Diagram 40
Appendix F: Schematics 41
Technical orSetupAssistance
Telephone:[phone] (USA)or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com

Page iv MPAII Installation and Operations Manual
List of Tables
Table 1. Default Program Parameters 16
Table 2. RS232 COM Port Pinout 28
Table 3. Logic Output Pinout 28
List of Figures
Figure 1. Equipment diagram 1
Figure 2. MPAII front-panel controls 4
Figure 3. MPAII back-panel connectors 5
Figure 3a. MPAII back-panel connectors 6
Figure 4. Room acoustics diagram 7
Figure 5. Conference room block diagram 8
Figure 6. Microphone isolation diagram 9
Figure 7. Completed MPAII installation 10
Figure 8. Voltage-input selection 10
Figure 9. MPAII power module 11
Figure 10. MPAII back-panel connectors 11
Figure 11. MPAII COM port connector 11
Figure 12. MPAII logic output DB15 connector 11
Figure 13. MPAII speaker connectors 11
Figure 14. MPAII PA Input female XLR connector 11
Figure 15. MPAII PA Output/Master Output connector 11
Figure 16. MPAII back-panel connectors 12
Figure 17. MPAII Microphone male XLR connector 12
Figure 18. MPAII auxiliary input/output RCA connector 12
Figure 19. MPAII phantom-power dip switches 12
Figure 20. MPAII front-panel controls 13
Figure 21. MPAII auto-mix switches 13
Figure 22. MPAII baud-rate dip switches 13
Figure 23. MPAII control norm position 13
Figure 24. MPAII front-panel controls 14
Figure 25. MPAII programming software title screen 18
Figure 26. MPAII programming software main screen 18
Figure 27. Adaptive ambient diagram 21
Figure 28. Decay rate diagram 22
Figure 29. Hold time diagram 23
Figure 30. Off attenutation diagram 23
Figure 31. PA adaptive mode diagram 24
Figure 32. Programming screen 30
Figure 33. Configuration programming screen 32
Figure 33a.Configuration programming screen 33
Figure 34. MPAII teleconferencing block diagram 35
Figure 35. MPAII talk show application block diagram 36
Figure 36. MPAII distance-learning block diagram 37
Figure 37. MPAII courtroom application block diagram 38
Figure 38. MPAII convention-center block diagram 38
Figure 39. MPAII house of worship block diagram 39
Technical orSetup Assistance
Telephone:[phone] (USA) or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com

MPAII Installation and Operations Manual Page 1
Technical orSetup Assistance
Telephone:[phone] (USA) or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com
Congratulations on purchasing the MPAII Mixer/Power Amplifier II. This eight-
channel, PC-controlled, automatic microphone mixer and power amplifier is a
proven solution for distance learning, panel discussions, audioconferencing and
videoconferencing applications, broadcast studios, courtrooms, hotels and
government meetings.
The MPAII contains commonly requested features such as an RS232 connection
for PC control, logic output and user-programmable gated microphone operation.
The latter allows you select which microphones and how many you wish to gate
or not to gate; this reduces noise and increases intelligibility. The MPAII also
comes equipped with several factory-designed programs and user-changeable
programs to compliment any environmental need.
This manual explains how to install, set up and operate your MPAII. It also
provides instructions on how to improve room acoustics and resolve minor
technical problems, should any arise.
If you need information on how to install, set up or operate your system, please
contact Gentner Communications Corporation at the location noted below. We
welcome and encourage your comments so we can continue to improve our
products and serve your teleconferencing needs.
Gentner Communications Corporation
1825 Research Way
Salt Lake City, Utah 84119
TEL: Worldwide [phone] In U.S.A. [phone]
FAX: Worldwide [phone] In U.S.A. [phone]
FAX-On-Demand 24-Hour Information line [phone]
Worldwide Web Page @ http:\\www.gentner.com
Please register your MPAII by completing the self-addressed, postage prepaid
warranty registration card and return it to Gentner Communications by mail. You
may also FAX it to the above listed fax number or call Gentner Communications.
When your product is properly registered, Gentner Communications will be able
to serve you better should you require technical assistance or desire to receive
upgrades, new product information, etc.
Ensure that the following equipment (See Figure 1, below.) was received with
your shipment:
SHIPPING NOTE:
Gentner Communications is not responsible for product damage incurred during
shipment. You must make claims directly with the carrier. Inspect your shipment
carefully for obvious signs of damage. If the shipment appears damaged, retain
the original boxes and packing material for inspection by the carrier. Contact
your carrier immediately.
Introduction
Warranty
Registration
Unpacking
Figure 1. Equipmentdiagram

Page 2 MPAII Installation and Operations Manual
Technical orSetup Assistance
Telephone:[phone] (USA) or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com
Eight-channel automatic/non-automatic, gated microphone mixer and two 15W
power amplifiers
AUX IN connector for audio feed (CD/tape)/AUX OUT connector for recording
PC-programmable for easy setup with supplied software
Six factory-preset programs and six user-programmable parameters
RS232 port with supplied software for custom programming
Logic output (DB15) connector for controlling cameras, etc.
Switchable microphone phantom power
Easy to set up and operate
Increased audio intelligibility
Reduced risk of feedback
Tamper-proof after setup
Expandable
The MPAII can be tailored to most any application including audioconferencing
and videoconferencing, courtrooms and public meetings, distance learning, hotels
and government meetings, houses of worship and talk shows.
Audioconferencing and Videoconferencing
The MPAII’s design makes the equipment particularly useful in
audioconferencing and videoconferencing applications where quality audio is
a must. With the logic output, it is possible to connect the MPAII to
cameras, electronic signs, and other equipment that can be controlled
electronically.
Courtrooms and Public Meetings
Courtrooms, city councils and other public meeting rooms also use the
MPAII successfully because of its ability to control up to eight microphones.
With simple setup routines and programming options, you can tailor your
meeting’s PA operation to its best room and acoustic advantage.
Distance Learning
Distance-learning applications, where multiple sites are connected, often
using multiple microphones and speakers — often at each location — can be
managed with the MPAII. These meetings can be managed easily with the
MPAII’s intuitive programs available.
Hotels and Government Meetings
Business meetings, hotels and convention centers find the MPAII a useful
tool when conducting panel discussions where several participants each have
their own microphone.
Features and
Benefits
Applications

MPAII Installation and Operations Manual Page 3
Technical orSetup Assistance
Telephone:[phone] (USA) or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com
The MPAII contains many unique features that make the MPAII simple to
set up and use. Specific user programming capabilities tailor-make MPAII
functionality to suit the environment in which it is used.
Houses of Worship
This application presents some unique challenges in providing sufficient and
balanced audio for the congregation. Choirs, the soloist, organist or pianist,
speakers, and the minister may all require microphone coverage at one time
or another during the session. The MPAII, with its standard and custom
programming options, allow for such variety.
Talk Shows
The same techniques can be applied in talk show formats where single or
multiple microphones are used. Because of the variety of setup routines for
different talk-show formats, microphones can be preset to automatically gate
on during use and gate off when not in use. Feedback and extra noise are
eliminated.
For more detailed explanations of MPAII use in these applications, see Appendix
D (Page 36).
MPAII
Microphone mixers can be classified into three basic types: non-gating,
gating, and automatic. The MPAII is an automatic microphone mixer, the
most advanced type of mixer. For explanations of non-gating and gating
types, see Appendix A (Page 28).
The MPAII is especially well suited to overcoming excessive room noise,
reverberation, and other problems associated with multi-microphone
installations. The gain (mixing level) of each microphone is automatically
adjusted based on audio levels. The MPAII monitors the audio levels at each
microphone and reduces the mixing level for microphones not in use. By
lowering the level of the microphones not in use, ambient room noise,
reverberation level and total system gain are reduced. This improves the
audio quality for the listener and decreases the possibility of feedback.
The MPAII operates on two basic principles. First, the MPAII gates
microphones on/off when the sound within a microphone’s acceptance
pattern reaches a certain level. Second, the MPAII makes decisions for each
microphone individually, based on each microphone’s specific conditions.
Each microphone operates using the same set of global parameters, as
programmed by the user. However, each microphone behaves independently
according to its own surroundings. Each microphone observes its own
ambient surroundings and makes decisions based on the individual
environment. Thus, a microphone located in a highly reverberant area of the
conference room is able to compensate for the changes in its own
environment.
Product
Description

Page 4 MPAII Installation and Operations Manual
Technical orSetup Assistance
Telephone:[phone] (USA) or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com
Front-Panel Controls
The MPAII front-panel control (See Figure 2, below.) perform the following
functions. The controls are numbered for easy indentification.
1. Mic 1–Mic 8 LEDs. These LEDs light green when the corresponding
microphone gates ON. They do not indicate signal level.
GATING LED NOTE:
These indicators, in conjunction with the PA LEVEL indicator [4], will also be
used to indicate whether the current operating program is one of the six factory
preset programs (the PA LEVEL LED will glow green ), or one of six user-defined
programs (the PA LEVEL LED will glow red). See Page 14 for a more detailed
explanation of this feature.
2. Aux In LED. This LED lights green to indicate audio presence on the
auxiliary channel. It does not indicate signal level.
3. Master Mix LED. This LED indicates the level of audio being sent out the
MASTER OUTPUT. The LED lights green with normal audio presence and
lights red to indicate audio peaks.
4. PA Level LED. This LED indicates the level of audio being received from
the PA INPUT. The LED lights green with normal audio presence and lights
red to indicate audio peaks.
5. Power LED. This LED lights green when power is being received by the
MPAII and the POWER switch [6] is ON.
6. Power Switch. This switch turns ON/OFF the MPAII and any equipment
connected to the auxiliary power connector.
7. Program Button. This button, when pressed, scrolls through the 12 MPAII
operation programs. The MIC LEDs [1] and the PA LEVEL LED [4] display
which program the MPAII is currently running. When the PA LEVEL LED
is green, the six factory default programs are shown on MIC 1–MIC 6 LEDs.
When the PA LEVEL LED is red, the six user-programmable programs are
shown. Hold down the PROGRAM button to use the selected program.
8. PA Level Control. This control is used to adjust the audio level to the
power amplifier.
9. Program B Button. This button, when held down, selects a program.
When this button is pressed, MIC LEDs [1] momentarily cycle on, one at a
time, to indicate the MPAII is ready to select a new program. Complete
instructions begin on Page 14.
Product Description
Continued
Figure 2. MPAII front-panel controls

MPAII Installation and Operations Manual Page 5
Technical orSetup Assistance
Telephone:[phone] (USA) or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com
10. Master Mix Control. This control is used to adjust the audio level of the
mixer’s MASTER OUTPUT.
11. Aux Input Control. This control adjusts the audio level into the mixer
received through the AUXILIARY INPUT connector.
12. Mic 1–8 Auto-Mix Switches. These switches enable and disable auto
mixing on each microphone channel.
13. Mic 1–8 Controls. These controls adjust the audio level received by each
microphone.
Back-Panel Connectors
1. Power Connector (AC). Connect a power cord (See Figure 3, below.)
between this connector and the line voltage source.
2. Line Voltage Selector. Select the line voltage input as 100V, 120V, 220V,
240V.
3. Baud Rate Select. The correct baud rate must be set to interface your
MPAII with your PC for programming. Proper selection of the baud rate is
required for correct communication between the MPAII and the PC.
4. COM Port. Connect this RS232 port to your PC or other programming
device.
5. Logic Output Connector. This connects to any electronic equipment you
choose (i.e. cameras, signage, timers). When connected to a camera, for
example, the camera will focus on the area in which the microphone is
placed when the microphone become active.
6. Speakers Jacks. Connect 8ohm speakers here.
7. PA Output Connector. Loop the MPAII input to additional MPAIIs or
other devices.
8. PA Input Connector. Connect to the mixer’s output or external device to
route audio to the power amplifier.
9. Mic Input 1–8 Connectors. Connect microphones here. Each input
corresponds to the microphone-channel indicators and adjustments on the
front panel.
10. Phantom Power Selector. These back-panel dip switches are easily
Figure 3. MPAIIback-panelconnectors

Page 6 MPAII Installation and Operations Manual
Technical orSetup Assistance
Telephone:[phone] (USA) or 801.975.7200 (worldwide) •WorldwideWeb @ http://www.gentner.com
accessible for switching phantom power ON/OFF to accommodate your
microphone requirements.
11. Auxiliary Input Connector. This is an additional non-gated input (See
Figure 3a, below.) to the mixer. Connect this input to the Auxiliary output of
another MPAII for expansion, or to input audio from a tape player or other
audio source. This audio is combined with the audio from the eight
microphones.
12. Auxiliary Output Connector. This is an unbalanced output. Use this
connector to connect to the auxiliary input of another MPAII when adding
additional microphones, or to a tape recorder to record the audio on all
microphones. This audio is combined with the audio from the eight
microphones.
13. Master Output Connector. This is the balanced output of all
microphones and the auxiliary input.
The MPAII is designed to work in almost any acoustic environment. However, to
maximize your audio quality, we recommend that you prepare your site by taking
the following factors into consideration:
Room Planning
Before installing your MPAII, we recommend that you carefully plan your
installation to ensure that you achieve the best possible results. Having a
basic understanding of room acoustics and conference-room design will not
only help you install and operate your MPAII, but will assist you in the
installation and operation of other equipment used in your audioconference.
Acoustics
Just as humans have unique personalities, conference and broadcasting
rooms have unique acoustic environments. Each room has a different
acoustic make up (Figure 4, next page, top). The acoustic make up of the
room determines how sound travels within the room. Wall fabrics, windows
or hard surfaces, room size, people walking or other movements, and the
audio equipment used, are all factors that impact the room’s acoustic
conditions.
Directly related to the room’s acoustic make up are several problems
common to all conferencing and broadcast situations: reverberation, acoustic
echo and ambient noise. The objective is to minimize the impact that these
conditions have on your audioconference.
Reverberation. Reverberation is the persistence of sound due to repeated
Product Description
Continued
Before You
Install
Figure 3a. MPAII back-panelconnectors