M-Audio USB Audio Duo User manual

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
What’s in the Box? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Quick Start Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Duo Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Minimum System equirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Front Panel: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Back Panel: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Bottom of Unit: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Basic Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Hardware & Software Installation on the PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Windows XP Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Windows 2000 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Windows ME Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Hardware & Software Installation on the Mac . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Hooking up your USB Audio Duo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Using the Input and Output Level Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Using the Mic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Setting the Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Phantom Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Using the Pad Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Standalone Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Duo Operation on the PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
The USB Audio Configuration Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
The Duo and the Windows Sound System . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
The Duo, MME, and Your Music Program . . . . . . . . . . . . . . . . . . . . . . . . . . .16
ASIO/EASI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
ASIO/EASI Control Panel and Operating Modes on the PC . . . . . . . . . . . . . .17
Advanced Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Duo Operation on the Macintosh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
The Macintosh Sound Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
ASIO Operation on the Macintosh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
ASIO Control Panel and Operating Modes on the Mac . . . . . . . . . . . . . . . . . .21
Optimizing Your System for USB Audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Troubleshooting: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Before You Call Midiman/M-Audio Technical Support . . . . . . . . . . . . . . . . . .25
Limited Lifetime Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
AUDIO
TM
DUOTM
Users Manuual

Introduction
Congratulations on your purchase of the Duo, designed and manufactured by
M-Audio. The Duo is a complete USB audio solution for your PC or Macintosh
computer. With two inputs and two outputs of 24-bit audio and up to 96kHz
sampling frequencies, coupled with two high quality mic preamps, the Duo utilizes
the power and convenience of USB audio in a convenient half-rack size unit.
The Duo lets you operate its analog inputs and outputs at either +4 or -10 line
levels, gives you a S/PDIF output, plus a headphone output for personal
monitoring. Additionally, the Duo has a “Standalone” mode that lets you operate
it as a mic preamp or A/D converter independent of your computer.
Please take the time to read this manual. It contains important information that
will help you get the most out of your Duo.
What’s in the Box?
Your Duo box contains:
• This Manual.
• The Duo.
• One (1) Standard USB cable.
•9V AC 1 Amp “Wall Wart” power supply.
Quick Start Guide
The USB Audio Duo is a powerful little device that you will find easy to use once
you familiarize yourself with its many features. The many aspects of the Duo are
detailed in this manual, and for that reason we suggest giving it a good read through.
Here is a basic outline of the steps you will need to take to get your Duo up and running:
1. Install the drivers, follo ing the instructions for your particular platform and
operating system (see “Hard are and Soft are Installation” sections).
2. Hook up your microphone and/or other audio gear to the Duo inputs, and
connect the output(s) to your sound system, mix deck, or headphones (see
section, “Hooking Up Your USB Audio Duo”).
3. Configure your music soft are to utilize the Duo as its audio interface.
4. Make music.
Whether your music program uses ASIO drivers, EASI drivers, Windows MME
or Macintosh Sound Manager, will determine how you configure the Duo in your
music program. There are entire sections devoted to using your Duo either on the
PC or on the Mac.
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Other aspects of the Duo, including use of the +4/-10 line level switches,
phantom power, etc., are also covered in depth. Also, be sure and check out the
section, “Optimizing Your Sytem for USB Audio,“ later in the manual. So, please
read on, and enjoy your Duo.
Duo Features
• 2 critically acclaimed DMP2 mic preamps ith individual gain controls.
• Balanced/unbalanced line outputs on 1/4” TRS, unbalanced line
inputs on 1/4” TS.
• Preamps have maximum gain of 60dB ith signal and clip indicator
LEDs per channel.
• S/PDIF digital output on gold-plated RCA jack.
• Headphone output ith level control.
• 48V global phantom po er ith s itch and indicator LED.
• 20dB pad available for each microphone input.
• Multitrack recording and mixing using the convenience of your USB port.
• PC drivers include Windo s XP, 2000, ME and 98SE, ASIO, EASI
and WDM.
• Mac drivers include OS 9.1 and higher, Sound Manager, and ASIO.
Performance Specs:
• Dynamic Range (Direct Line In to Line Out): 105dB
• THD+N (Direct Line In to Line Out): <0.002%
• Dynamic Range (Mic In to Line Out): 107dB
• THD+N (Mic In to Line Out): <0.002%
Minimum System Requirements
Macintosh
• USB (native) equipped Mac G3.
• Mac OS 9.1 minimum.
• 64M available RAM for 44.1 or 48k operation, 128 recommended.
128M available RAM for 96k operation, 256M recommended.
Windows
• USB equipped Pentium.
• Windo s 98SE or higher.
• 64M available RAM for 44.1k or 48k operation, 128 recommended.
Pentium 266 MHz MMX.
• 128M available RAM for 96k operation, 256M recommended.
Pentium II, 333 MHz.
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Front Panel:
1. Line Level Input S itch: This s itch ill set the input line level for the Duo.
With the s itch in the out position, the Duo ill operate at a +4dBu line level.
Pressing and locking this s itch to the in position ill set the operating line
level to -10dBV.
2. Pad S itch: One pad s itch has been provided for each mic input on the Duo.
Pressing in and engaging the Pad s itch ill apply a 20dB pad, or “cut,” to
the microphone input prior to the microphone preamp.
3. Gain: This potentiometer controls the amount of gain applied to the
microphone preamp. One Gain pot is provided for each mic input.
4. Clip LED: This LED responds to the signal present at the Duo’s respective Mic
input, and ill begin to light hen the signal reaches clipping.
5. Sig. (Signal) LED: This LED responds to the signal present at the Duo’s
respective Mic input, and ill begin to light hen a nominal signal is present
at the input.
6. Standalone: Pressing in and engaging the Standalone s itch ill connect the
Mic and Line inputs directly to the analog Line Outs, S/PDIF output, and the
Headphone output. Standalone mode allo s for use of the Duo as a mic
preamp and/or analog to digital converter independent of the computer. This
feature of the Duo also allo s you to directly monitor the inputs hen
connected to a computer.
7. Headphone Out Jack: This output jack is designed to connect to a 1/4” TRS
plug, typically for use ith a set of stereo headphones. The source for the
signal at the Headphone Out is identical to the Line Outs.
8. Headphone Level: This knob controls the amount of monitoring level sent to
the Duo’s Headphone Out jack.
9. Phantom Po er S itch & corresponding LED: Pressing in and engaging the
Phantom Po er s itch ill send 48V of phantom po er to the Duo’s Mic
inputs. When phantom po er is s itched on, the corresponding Phantom
Po er LED ill light and remain lit.
10. Po er S itch & corresponding LED: Pressing in and engaging the Po er
s itch ill po er up the Duo, provided that the proper po er supply is
connected to the 9V AC Po er jack. When po er is s itched on, the
corresponding Po er LED ill light and remain lit.
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Back Panel:
1. 9V AC Po er Jack: This po er jack accepts a 9v AC 1 Amp 2.5mm po er
supply. This po er supply is included ith your Duo, and ONLY the proper
supply should be used.
2. USB Connector: This jack accepts the device-end of a standard USB cable.
3. S/PDIF Out: This coaxial RCA digital audio output connector receives audio
from one of t o sources. With the “Standalone” s itch in the Out position,
the S/PDIF Out receives audio from the computer’s soft are outputs. With
the “Standalone” s itch in the In position, S/PDIF Out receives audio from
the Mic or Line inputs of the Duo.
4. Line Outputs: These 1/4” TRS jacks, labeled “Outputs,” are the main outputs
for the Duo. Using a TRS (tip-ring-sleeve) 1/4” plug, the Duo ill provide a
balanced line-level output. Using a TS (tip-sleeve) 1/4” plug, the outputs ill
be unbalanced. The Line Outs receive audio from one of t o sources. With the
“Standalone” s itch in the Out position, the Line Outs receive audio from the
computer’s soft are outputs. With the “Standalone” s itch in the In position,
the Line Outs receive audio from the Mic or Line inputs of the Duo.
5. Line Level Output S itch: This s itch sets the operating line level for the Duo
Line Outs. In the ‘out’ position, the Duo Outputs 1 & 2 are set to +4dBu line
level operation. Pressing and locking this s itch to the in position sets these
outputs to a -10dBV line level.
6. Line Inputs: These 1/4” jacks accept TS 1/4” plugs. These are line level
inputs, and generally ill be connected to the outputs of a line level
instrument or preamp.
7. Mic Inputs: These are the balanced, lo impedance microphone inputs to the
pre-amp channels. NOTE: When phantom po er is engaged, po er is sent to
BOTH of these channels. An XLR jack is disabled hen an instrument is
plugged into the corresponding 1/4” jack.
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Bottom of Unit:
At the bottom of the unit are two DIP switches that will set the sampling rate
while the Duo is used in standalone mode. The Duo can be used as an A/D
converter independent of the computer, using either the line inputs or the mic
preamp inputs. The relative positions of these DIP switches will determine the
sample rate at the S/PDIF output when used in standalone mode.
You will see the rather tiny numbers 1 and 2 at the bottom of the set of two DIP
switches. Using a miniature screwdriver or similar instrument, you can change
the position of each switch. The default setting is both switches “down,” which
is the position closest to the numbers 1 and 2, representing a sample rate of
44.1kHz. The full list of settings is as follows:
1. 44.1kHz: Both s itches in the do n position (do n being in the direction of
the numbers).
2. 48kHz: S itch #1 do n, s itch #2 up.
3. 88kHz: S itch #1 up, s itch #2 do n.
4. 96kHz: Both s itches in the up position.
Basic Theory of Operation
The Duo attaches easily to your computer’s USB port--no tools or computer
disassembly is necessary. Following the installation of the included driver software,
the Duo can be attached or unattached to your computer according to your needs.
The Duo is a 2x2 audio interface, providing two channels of audio TO the
computer and two channels of audio FROM the computer. The Duo gives you
two high quality, low impedance Mic Inputs on XL connectors, plus two
unbalanced Line Inputs on 1/4” TS jacks that can be used alternately. When a
Line Input is in use, the corresponding Mic Input is disabled.
The Duo can be configured for +4 or -10 line level operation simply by pressing
the “Line Level” buttons on the front and/or back panels. This allows for
seamless integration into the studio, giving you compatibility with professional
balanced (balanced T S, +4dBu) or semi-pro (unbalanced TS, -10dBV) audio
devices (see section, “Using the Input and Output Level Switches”).
Audio from your computer is sent simultaneously to the Duo’s two
balanced/unbalanced Line Outputs on 1/4” T S jacks, the coaxial S/PDIF
Output, and the Headphone Out. The Duo can also be used in a Standalone mode,
which connects the Mic/Line inputs directly to the Line Out, S/PDIF Out, and
Headphone Out. Pressing the “Standalone” switch turns the Duo into a mic
preamp and A/D converter that can be used independent of the computer.
Standalone mode can also give you a direct monitoring option when using the
Duo as an audio interface with your computer.
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The Duo can be used with the Sound Manager on the Macintosh, or with the
Windows Sound System in Windows, and therefore can operate as your system
sound card. If your software is ASIO or EASI compliant, such as Steinberg’s
Cubase or Emagic’s Logic, we suggest using the ASIO or EASI drivers. These
drivers will allow you to monitor audio through your music program with greatly
reduced latency. The WDM drivers that are used in Windows ME, 2000, and XP
will give you similar monitoring capability when using a music program that
takes advantage of them, such as Cakewalks’s Sonar.
Hardware & Software Installation on the PC
Here is a simple, step-by-step procedure for attaching and powering up the Duo.
See the section, “ASIO/EASI Operation” for information on configuring ASIO
or EASI drivers.
1. Plug the Duo all- art into your all receptacle and to the Duo 9vAC po er
jack. Use only the included po er supply, or a similar po er supply ith the
exact same specifications.
2. Connect the USB cable to your computer and the Duo (one end of the cable is
for the computer, and the other is the device end). Find an appropriate spot on
your desktop or ork area for the Duo.
Windows XP Installation
1. Boot Windo s XP ith your M-Audio USB Duo po ered OFF. After
Windo s XP has been booted, po er up the Duo.
2. Windo s XP ill then detect and automatically install the drivers for the USB
Composite Device and USB Audio Devices.
3. Insert the included Driver CD into your computer’s CD drive. Assuming that
your CD drive is the “D” drive, locate the Duo driver at
D:\USB_AUDIO\DUO\WINXP.
4. Run the program “Duo XP PostInstaller” program by double clicking on it.
This ill install the Duo’s Windo s MME drivers, plus the ASIO and EASI
drivers.
Windo s ill sho the "Digital Signature Not Found" Dialog. Press
"Continue Any ay."
5. Restart the computer after the installation is finished.
Windows 2000 Installation
1. Boot Windo s 2000 ith your M-Audio USB Duo po ered OFF.
2. Insert the included Driver CD into your computer’s CD drive. Assuming that
your CD drive is the “D” drive, locate the Duo driver at
D:\USB_AUDIO\DUO\WIN2000.
3. Run the "Duo W2k Installer" program by double clicking on it.
4. Windo s ill sho the "Digital Signature Not Found" Dialog. Press "Yes."
5. Connect and po er ON your M Audio USB Duo.
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6. You ill then see Windo s 2000 detect and automatically install the driver for
the USB Composite Device.
7. Windo s ill detect and automatically install a number of drivers. As it does
this, it ill sho the "Digital Signature Not Found" Dialog a fe times. Press
"Yes" for each dialog.
8. Restart the computer after the installation is finished.
Windows ME Installation
1. Boot Windo s ME ith your M-Audio USB Duo po ered OFF. After
Windo s ME has been booted, po er up the Duo.
2. Windo s ill proceed ith the installation of the "USB Composite Device"
driver. Note: If the "USB Composite Device" has already been installed then
Windo s ill skip this step. This ill occur if another USB audio device had
been installed on your system at any time.
3. Windo s ill report that “USB Duo Ne Hard are” as found. When the
Add Ne Hard are Wizard reports that it ants to search for a driver for a
USB Composite Device, click "Next".
4. On the next screen, select the "Specify the location of the driver" item, and
then click "Next".
5. Windo s ill ask you here you ant it to search for the drivers. Remove the
check marks from all of the optional search locations except "Specify a location."
Insert the included Driver CD, click “Bro se,” then, on your computer’s CD
drive, locate the folder “USB_AUDIO\DUO\WINME.” Click "Next".
6. On the next screen, Windo s ill indicate it has found an updated driver for
this device. Keep the updated driver selected and click "Next".
7. Windo s ill report that is it ready to install the driver. Click "Next" to continue.
8. Windo s ill process the files and then indicate it has finished installing the
soft are that your ne hard are device requires. Click the "Finish" button.
You ill need to repeat these steps as many times as Windo s finds a ne
hard are device. By the time everything is finished you ill have installed
the Duo’s Windo s MME drivers, plus the ASIO and EASI drivers.
9. Windo s might indicate it cannot find a file it is attempting to copy from the
Windo s ME CD. If so, insert your Windo s ME CD, then use the Bro se
button to point to this CD and continue.
10. Windo s ill process the files and then indicate it has finished installing the
soft are that your ne hard are device requires. Click the "Finish" button.
Note: At this point you might need to wait for several minutes while
Windows configures the hardware. Please be patient.
11. Restart the computer after the installation is finished.
Windows 98 Second Edition Installation
1. Boot Windo s 98 SE ith your M-Audio USB Duo po ered OFF. After
Windo s 98 SE has been booted, po er up the Duo.
2. Windo s ill proceed ith the installation of the "USB Composite Device"
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driver. Note: If the "USB Composite Device" has already been installed then
Windo s ill skip this step. This ill occur if a USB audio device had
previously been installed in your system.
3. Windo s ill report that “USB Duo Ne Hard are” as found. When the
Add Ne Hard are Wizard reports that it ants to search for a driver for a
USB Composite Device, click "Next".
4. On the next screen select the "Search for the best driver for your device." item,
and then click "Next".
5. On the next screen, remove the check marks from all of the optional search
locations except "Specify a location." Insert the included Driver CD, click
“Bro se,” then, on your computer’s CD drive, locate the folder
“USB_AUDIO\DUO\WIN98SE.” Click "Next".
6. On the next screen, Windo s ill indicate it has found an updated driver for
this device. Keep the updated driver selected and click "Next".
7. Windo s ill report that is it ready to install the driver. Click "Next" to
continue.
8. Windo s ill process the files and then indicate it has finished installing the
soft are that your ne hard are device requires. Click the "Finish" button.
You ill need to repeat this step as many times as Windo s finds a ne
hard are device. By the time everything is finished you ill have installed
the Duo’s Windo s MME drivers, plus the ASIO and EASI drivers.
9. Windo s might indicate it cannot find a file it is attempting to copy from the
Windo s 98 CD. If so, insert your Windo s 98 Second Edition CD, then use
the Bro se button to point to this CD and continue.
10. Windo s ill process the files and then indicate it has finished installing the
soft are that your ne hard are device requires. Click the "Finish" button.
Note: At this point you might need to wait for several minutes while
Windows configures the hardware. Please be patient.
11. Restart the computer after the installation is finished.
Hardware & Software Installation on the Mac
Here is a simple, step-by-step procedure for attaching and powering up the Duo
on the Macintosh Computer. The Duo comes with an installer program that will
place all driver components in their proper folders.
The installer program will give you a list of ASIO compliant programs that it
will recognize and subsequently install the appropriate ASIO driver if the
program exists on your system (that being said, it is a good idea to first install
your music program before installing the Duo drivers, though Duo drivers can be
installed again if necessary). Otherwise, the Duo ASIO drivers (and the
remaining ASIO drivers that have not been used) will be placed in a folder on
your desktop called “Duo ASIO,” and must be inserted into your music
program’s ASIO folder manually, provided that your music program uses ASIO.
1. On the Driver Disk that came ith your Duo, locate the folder
“USB_Audio_Duo” that contains the USB Duo Installer for the Macintosh.
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Double click on the Installer program. The Installer program installs all Duo
extensions, and installs the ASIO driver in a folder named “Duo ASIO”on
your desktop.
2. locate the program’s ASIO folder (it ill be found ithin the program’s folder
on your Macintosh HD). Drag the ASIO driver (located in the “DUO ASIO”
folder created by the Installer) to that folder.
3. Properly shut do n the computer.
4. Plug the Duo all- art into your all receptacle and to the Duo 9vAC po er
jack.
5. Connect the USB cable to your computer and the Duo. Po er up the Duo,
then po er up the computer.
For information on how to enable the Sound Manager to use the Duo, see the section
“The Duo and the Macintosh Sound Manager.” For further information on using
and configuring ASIO drivers, see the section “ASIO Operation on the Macintosh.”
Hooking up your USB Audio Duo
The Duo provides two line inputs and two line outputs. The Duo also provides a
S/PDIF digital output on a coaxial CA connector, plus a Headphone Out on a
1/4” stereo T S jack for monitoring with headphones.
Each 1/4” T S Line Out jack will accept a +4dB balanced signal on 1/4” T S
plugs (tip-ring-sleeve), or a -10dB unbalanced signal on 1/4” TS plugs
(tip-sleeve). Each of the Duo’s 1/4” TS “Direct In” jacks are unbalanced, and
will accept an unbalanced +4dBu or -10dBV signal on 1/4” TS plugs.
The Duo provides two microphone inputs on balanced XL connectors. Either a
mic or a line input can be used on any one of the Duo’s input channels. When a
line input is in use, the corresponding mic input is disabled.
You may connect the output of a line level instrument such as an electronic keyboard,
instrument preamp, or the output of a CD player or similar line-level device to the Duo’s
Line Inputs, Channel 1 and Channel 2. Check your device’s documentation for information
on its operating line level (+4dBu balanced or -10dBV unbalanced), and see the section,
“Using the Input and Output Level Switches” in this manual for more information.
The Duo’s Mic Inputs, Channel 1 and Channel 2, accept balanced, low
impedance microphones. If your microphone is a condenser type that requires
phantom power, you may apply phantom power by engaging the phantom power
switch (see section, “Phantom Power”). An impedance transformer, such as an
active (i.e., powered) direct box or passive transformer with 1/4” female TS to
male XL jacks can be used to connect electric or acoustic guitars or a high
impedance mic to the Duo’s microphone inputs.
You may connect the Duo’s two line level outputs to the stereo inputs of a
monitoring system (power amp and speakers, or a home stereo), powered
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