miniDSP DDRC-88A User manual

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DDRC-88A
8-CHANNEL AUDIO PROCESSOR
WITH DIRAC LIVE®TECHNOLOGY
User Manual

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Revision history
Revision
Description
Date
0.1
First draft
25 November 2014
0.2
Preliminary pre-release version
5 December 2014
0.3
Draft pre-release for comment
20 January 2015
0.4
Second draft pre-release for comment
28 January 2015
1.0
First public release
2 February 2015
1.1
Updated firmware update procedure
20 May 2015
1.2
Update for Mac software
11 July 2015
1.3
Updated Output & Levels tab
16 July 2015

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TABLE OF CONTENTS
Important Information .........................................................................................................................................................5
System Requirements ......................................................................................................................................................5
Disclaimer/Warning .........................................................................................................................................................5
Warranty Terms...............................................................................................................................................................5
FCC Class B Statement......................................................................................................................................................6
CE Mark Statement ..........................................................................................................................................................6
Package Contents.............................................................................................................................................................6
A Note on this Manual .....................................................................................................................................................6
1Product Overview..........................................................................................................................................................9
1.1 Typical system configurations ..............................................................................................................................9
1.2 How Dirac Live® works.......................................................................................................................................10
1.3 DDRC-88A / Dirac Live® configuration steps .......................................................................................................12
2Installation and Setup.................................................................................................................................................. 13
2.1 Hardware connectivity.......................................................................................................................................13
2.1.1 Analog input and output ...........................................................................................................................13
2.1.2 DC Power.................................................................................................................................................. 14
2.1.3 USB........................................................................................................................................................... 14
2.2 Software installation and license activation .......................................................................................................15
2.2.1 Installation ― Windows ............................................................................................................................15
2.2.2 Installation ― Mac OS X ............................................................................................................................16
2.2.3 License activation......................................................................................................................................17
2.2.4 License validation......................................................................................................................................18
3Acoustic Measurement................................................................................................................................................19
3.1 Loudspeaker and microphone positioning..........................................................................................................19
3.2 Preparing for acoustic measurement .................................................................................................................20
3.2.1 Connections and microphone placement................................................................................................... 20
3.2.2 Subwoofer settings ...................................................................................................................................20
3.3 Configuring for measurement............................................................................................................................21
3.3.1 Sound System tab .....................................................................................................................................22
3.3.2 Mic Config tab........................................................................................................................................... 23
3.3.3 Output & Levels tab ..................................................................................................................................24
3.3.4 Custom System configuration....................................................................................................................25
3.4 Running the measurements...............................................................................................................................26
3.4.1 Listening environment...............................................................................................................................27
3.4.2 Executing measurements .......................................................................................................................... 28
3.4.3 Completing the measurements ................................................................................................................. 29
3.4.4 Viewing and redoing measurements..........................................................................................................29
3.5 Saving and loading projects ...............................................................................................................................29
4Filter Design ................................................................................................................................................................30
4.1 Working with graphs .........................................................................................................................................31
4.2 Designing your target curve ...............................................................................................................................33
4.2.1 The Auto Target ........................................................................................................................................33
4.2.2 Editing the target curve............................................................................................................................. 33
4.2.3 Guidelines for target curve design .............................................................................................................34
4.2.4 Saving and loading target curves ...............................................................................................................35

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4.3 Generating correction filters..............................................................................................................................36
4.4 Downloading and managing filter sets ...............................................................................................................37
5Using the DDRC-88A audio processor ..........................................................................................................................38
5.1 Configuring source equipment...........................................................................................................................38
5.1.1 Level trims ................................................................................................................................................38
5.1.2 Subwoofer channel gain............................................................................................................................ 38
5.1.3 Bass management.....................................................................................................................................38
5.1.4 Delays/speaker distance............................................................................................................................38
5.1.5 Room correction and EQ ...........................................................................................................................38
5.1.6 Other processing.......................................................................................................................................39
5.2 Front panel........................................................................................................................................................ 39
5.2.1 Status indicators ....................................................................................................................................... 39
5.2.2 Front panel controls.................................................................................................................................. 39
5.3 Infrared remote control.....................................................................................................................................40
6Gain structure .............................................................................................................................................................41
6.1 Gain structure overview .................................................................................................................................... 41
6.2 Choosing gain structure settings ........................................................................................................................42
6.2.1 To change input sensitivity ........................................................................................................................44
6.2.2 To change output gain............................................................................................................................... 44
6.3 Optimizing gain structure ..................................................................................................................................45
6.3.1 Procedure for optimizing output gain ........................................................................................................45
6.3.2 To increase output gain.............................................................................................................................46
6.3.3 To reduce output gain ............................................................................................................................... 46
6.4 LFE alignment gain.............................................................................................................................................47
6.4.1 The LFE channel and the DDRC-88A........................................................................................................... 47
6.4.2 LFE effect on gain structure .......................................................................................................................48
6.4.3 LFE gain structure problems ...................................................................................................................... 49
6.4.4 Bass management and LFE alignment gain................................................................................................. 49
7Additional Information ................................................................................................................................................50
7.1 The DDRC-88 Utility program.............................................................................................................................50
7.2 Balanced wiring tips...........................................................................................................................................51
7.2.1 Phoenix terminal blocks ............................................................................................................................51
7.2.2 XLR adapters .............................................................................................................................................51
7.2.3 RCA adapters ............................................................................................................................................51
7.3 Specifications .................................................................................................................................................... 52
7.4 Troubleshooting ................................................................................................................................................53
7.5 MCU Firmware update ......................................................................................................................................54
7.5.1 Windows...................................................................................................................................................54
7.5.2 Mac OS X................................................................................................................................................... 55
7.6 Obtaining support .............................................................................................................................................56

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IMPORTANT INFORMATION
Please read the following information before use. In case of any questions, please contact miniDSP via the
support portal at minidsp.desk.com.
SYSTEM REQUIREMENTS
To configure your DDRC-88A audio processor, you will require a Windows or Apple Mac computer with the
following minimum specification:
Windows
Intel Pentium III or later, AMD Athlon XP or later
2 Gigabytes (GB) of RAM or higher
Keyboard and mouse or compatible pointing device
Microsoft• ® Windows® Vista® SP1/Win7/Win8
Two free USB 2.0 ports
Mac OS X
Intel-based Mac with 1 GHz or higher processor clock speed
2 Gigabytes (GB) of RAM or higher
Keyboard and mouse or compatible pointing device
Mac OS X 10.6 or higher
Two free USB 2.0 ports
DISCLAIMER/WARNING
miniDSP cannot be held responsible for any damage that may result from the improper use or incorrect
configuration of this product. Please read this manual carefully to ensure that you fully understand how to
operate and use this product, as incorrect use or use beyond the parameters and ways recommended in this
manual have the potential to cause damage to your audio system.
Please also note that many of the questions we receive at the technical support department are already
answered in this User Manual and in the online application notes on the miniDSP.com website. So please take
the time to carefully read this user manual and the online technical documentation. And if an issue arises with
your unit, please read through the Troubleshooting section first. Thank you for your understanding!
WARRANTY TERMS
miniDSP Ltd warrants this product to be free from defects in materials and workmanship for a period of one
year from the invoice date. Our warranty does not cover failure of the product due to incorrect connection or
installation, improper or undocumented use, unauthorized servicing, modification or alteration of the unit in any
way, or any usage outside of that recommended in this manual. If in doubt, contact miniDSP prior to use.

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FCC CLASS BSTATEMENT
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
This device may not cause harmful interference.
This device must accept any interference received, including interference that may cause undesired
operation.
Warning: This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection. This
equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance
with the instructions, may cause interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful interference to radio
or television reception, which can be determined by turning the equipment off and on, the user is encouraged to
try to correct the interference by one or more of the following measures:
Reorient or relocate the receiving antenna.
Increase the separation between the equipment and receiver.
Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
Consult the dealer or an experienced radio/TV technician for help.
Notice: Shielded interface cable must be used in order to comply with emission limits.
Notice: Changes or modification not expressly approved by the party responsible for compliance could void the
user’s authority to operate the equipment.
CE MARK STATEMENT
The DDRC-88A has passed the test performed according to European Standard EN 55022 Class B.
PACKAGE CONTENTS
Your DDRC-88A package includes:
One DDRC-88A audio processor
One universal 12 VDC power supply
One USB cable for computer connectivity (1.5m)
One UMIK-1 calibrated measurement microphone with USB cable
One tripod microphone stand
One full license for Dirac Live Calibration Tool for miniDSP
ANOTE ON THIS MANUAL
This User Manual is designed for reading in both print and on the computer. If printing the manual, please print
double-sided. The embedded page size is 8 ½” x 11”. Printing on A4 paper will result in a slightly reduced size.

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For reading on the computer, we have included hyperlinked cross-references throughout the manual. In
addition, a table of contents is embedded in the PDF file. Displaying this table of contents will make navigation
much easier:
In Adobe Reader on Windows, click on the “bookmarks” icon at the left. The table of contents will appear on
the left and can be unfolded at each level by clicking on the “+” icons.
In Preview on the Mac, click on the View menu and select Table of Contents. The table of contents will
appear on the left and can be unfolded at each level by clicking on the triangle icons.

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1PRODUCT OVERVIEW
Thank you for purchasing a miniDSP DDRC-88A audio processor powered by Dirac Live®, the world’s premier
room correction solution. We are delighted to offer you this software and hardware combination, the fruit of
extensive research and development and years of experience in sound system tuning.
The DDRC-88A is an 8-channel digital audio signal processor (DSP) running the Dirac Live® room correction
algorithm. The onboard floating-point SHARC processor provides time and frequency correction of a 7.1
monitoring, home theater or multichannel audio system. Inputs and outputs are analog, available as both single-
ended signals connected via RCA jacks, and as balanced signals via Phoenix terminal blocks.
The DDRC-88A is a member of the miniDSP Dirac Series of audio processors. Deploying a DDRC-88A will:
Improve imaging and immersion
Improve clarity of music and dialog
Produce a tighter bass
Reduce listening fatigue
Remove resonances and room modes
The DDRC-88A can be used anywhere an 8-channel room correction processor is required, such as in home
theaters, recording and mastering studios, performance venues, places of worship, and so on.
1.1 TYPICAL SYSTEM CONFIGURATIONS
The DDRC-88A is inserted between line-level analog sources and power amplification. In home theater
applications, signal to the DDRC-88A typically comes from an A/V receiver or A/V processor with one or more
source devices, and the amplification is typically a multichannel power amplifier. A source such as a Blu-ray
player with multichannel analog outputs can also be connected directly to the DDRC-88A.

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In studio or sound reinforcement applications, the DDRC-88A is typically connected between a mixing console
and power amplification, as shown below. Individual channels can be set for either full-range or subwoofer
operation.
Computer connectivity is used to perform acoustic measurements and generate digital room correction filters.
Up to four sets of correction filters can be stored on the DDRC-88A processor and recalled from the front panel
or via an infrared remote. Once the processor is fully configured, the computer is no longer needed.
1.2 HOW DIRAC LIVE®WORKS
The miniDSP DDRC-88A audio processor includes Dirac Live®, a premium mixed-phase room correction
technology. This technology is used not only in home stereo and home theater systems but also in cinemas,
recording studios, and luxury cars.
As with any room correction system, Dirac Live® corrects the system’s magnitude response (often referred to
imprecisely as “frequency response”). In contrast to fully automated systems, Dirac Live® corrects the
magnitude response towards a user-adjustable target response. The target response takes account of the
natural frequency range of the loudspeaker system and the normal effects of loudspeaker dispersion on the
measured in-room magnitude response.
In addition, Dirac Live® corrects the system’s impulse response, which reflects how the system responds to a
sharp transient such as a drumbeat. Reflections, diffraction, resonances, misaligned drivers, and so on, all
combine to smear out the transient. An ideal loudspeaker has none of these, so correcting the impulse response
makes the speaker in the room behave much more like that ideal loudspeaker. The impulse response is a critical
factor for accurate sound-staging, clarity and bass reproduction. Dirac Live® employs a sophisticated analysis
algorithm to make the optimal correction across the whole listening area, not just at a single point.

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Illustration of Dirac Live® magnitude response correction
Dirac Live® accomplishes this using mixed-phase filters –filters that match a desired magnitude response and
generate a customized impulse response. This contrasts with the minimum-phase and linear-phase filters that
are commonly used in audio applications. While minimum-phase and linear-phase filters are relatively easy to
design, they are tightly constrained in their impulse response characteristics –neither can make a desired
change to the magnitude response independently of controlling the impulse response. In some cases, they may
even make things worse.
Mixed-phase filters are more difficult to design, but the audible performance of Dirac Live® is due to its success
in using mixed-phase filters to make the system response across the whole listening area more closely resemble
that of an ideal speaker. The energy from the direct wave and from early reflections is optimally combined to
arrive as a single wavefront to the listener. Late reflections are left largely untouched, being corrected only for
their spectral coloration, as they contribute to a larger, more enveloping soundstage.
Illustration of Dirac Live® impulse response correction

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1.3 DDRC-88A /DIRAC LIVE®CONFIGURATION STEPS
The steps for configuring the DDRC-88A audio processor with Dirac Live® are summarized as follows:
1. Connect the DDRC-88A audio processor into your system and
install software. See Section 2, Installation and Setup.
2. Run a series of acoustic measurements using the Dirac Live
Calibration Tool For miniDSP program, to capture the acoustic
behavior of your speakers and room. See Section 3, Acoustic
Measurement.
3. Generate digital room correction filters that will be executed by the
DDRC-88A processor. Up to four filter sets can be downloaded into
the processor for easy real-time recall and auditioning. See Section
4, Filter Design.
4. Once the digital room correction filters are designed and
downloaded, the computer can be disconnected for normal
listening. See Section 5, Using the DDRC-88A audio processor.

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2INSTALLATION AND SETUP
2.1 HARDWARE CONNECTIVITY
All connections to the DDRC-88A are made on the rear panel.
2.1.1 Analog input and output
Up to eight channels can be connected to the DDRC-88A. Be sure to take careful note of the channel numbering:
On the input side, it is very strongly recommended that all connections be of the same type –i.e. balanced or
unbalanced. The Dirac Live algorithm equalizes levels on all channels, and a mixture of balanced and unbalanced
connections on the input side will require special gain adjustment steps after Dirac Live calibration.
On the output side, a mixture of balanced and unbalanced connections can be used if desired. Doing so may
necessitate additional work to check and adjust system gain structure. For more information on gain structure,
see Gain structure starting on page 41.
Unbalanced connections are made directly
to the RCA jacks.
Balanced connections are made by
connecting bare wire ends to the push-in
Phoenix terminal blocks. For advice on
using these, see Balanced wiring tips on
page 51.

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2.1.2 DC Power
Fit the supplied IEC cable to the 12 VDC power supply. Plug the AC mains plug into the power outlet, and then
plus the DC connector into the +12VDC socket on the rear panel of the DDRC-88A.
Apply power to the DDRC-88A only after all analog input and output connections have been made. The
DDRC-88A uses little power and can be left powered on.
If powered on and off, the following turn-on/turn-off sequence is recommended:
On: Power on line-level equipment, including the DDRC-88A, then turn on power amplification.
Off: Turn power amplification off, then power off line-level equipment, including the DDRC-88A.
2.1.3 USB
To configure the DDRC-88A using Dirac Live Calibration Tool for miniDSP:
Connect the USB port of the DDRC-88A to a USB 2.0 port on your computer using the supplied cable.
Connect a miniDSP UMIK-1 to a second USB port on your computer.
Note: the miniDSP UMIK-1 is the only measurement microphone that can be used with the DDRC-88A and Dirac
Live Calibration Tool for miniDSP.

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2.2 SOFTWARE INSTALLATION AND LICENSE ACTIVATION
When your order ships, your software will be available from the User Downloads section of the miniDSP
website. You will need to be logged into the website with the account you created when purchasing. The User
Downloads link is visible from the dropdown menu at the top right of the website page:
Navigate to the Dirac Series section and then to DDRC-88A software. There you will find the following zip files
available for download:
DDRC-88 configuration tool
This will install the DDRC-88 Utility program, used to configure remote control codes and
perform various other maintenance operations on the DDRC-88A, including obtaining the serial
number necessary for software license activation. Download this file for both Windows and Mac.
Dirac Live Calibration Tools for DDRC-88A
This will install Dirac Live Calibration Tool for miniDSP (DLCT), which is used to perform
measurements, generate correction filters, and load them into the processor. Download this file
for both Windows and Mac.
2.2.1 Installation ― Windows
Prior to installing the software, download and install the following frameworks. You will need to accept the
license agreements in order to successfully complete the installation. If you haven’t updated these recently,
check that you have the latest versions prior to running the miniDSP install programs.
Microsoft .NET framework (version 3.5 or later)
Latest version of Adobe Flash
Latest version of Adobe Air
Microsoft Visual C++ 2010 Redistributable Package: for x86 (32-bit operating system) or x64 (64-bit operating
system).
DDRC-88 Utility installation
Unzip the downloaded file. Navigate to the Windows sub-folder and double-click on the
DDRC_88.exe installer program to run it.

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Dirac Live Calibration Tools (DLCT) installation
Unzip the downloaded file. Navigate to the Windows sub-folder and double-click on the
DLCT_nanoAVR_DDRC-88A-v1.1.0.6607_Setup.exe installer program to run it. (The version
number starting with v1.1... may be different.)
We recommend that you accept the default installation settings.
2.2.2 Installation ― Mac OS X
On versions of OS X from 10.7 (Lion) and later, you will need to inform the GateKeeper program that it is OK to
install and run this software. Go to System Preferences, then click on Security & Privacy and select the General
tab:
1. Click on the padlock icon in the lower left corner and enter your password, in order that you can make
changes to the settings.
2. Under the text “Allow Applications downloaded from:”, click on “Anywhere.”
Then, download and install the following programs. You will need to accept the license agreements in order to
successfully complete the installation:
Latest version of Adobe Flash
Latest version of Adobe Air
DDRC-88 Utility installation
Unzip the downloaded file. Navigate to the Mac sub-folder and double-click on the
DDRC_88.dmg disk image file to open it in a new window. Then double-click on the Install
DDRC-88.app installer program to run it. Once installation is complete, the DDRC-88 Utility will
automatically start.
Dirac Live Calibration Tools (DLCT) installation
Unzip the downloaded file. Navigate to the Mac sub-folder and double-click on the .dmg disk
image file to open it in a new window. Then double-click on the Dirac Live Calibration Tool for
nanoAVR 1.1.0.6931.mpkg installer program to run it. (The version number starting with v1.1...
may be different.)
We recommend that you accept the default installation settings.

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2.2.3 License activation
1. If you are running the Dirac Live Calibration Tool already, quit from that program. (You cannot run this
program and the DDRC-88 Utility program at the same time.)
2. Start the DDRC-88 Utility program. It will appear as shown on the left below.
3. Connect your DDRC-88A processor to your computer via USB, then click on the Connect button. It will
change to a green tick.
4. Click on Get Activation Serial Number. The program will get your unique serial number from the connected
DDRC-88A and display it, as shown on the right below.
5. Using this serial number, activate your license on the miniDSP Dirac Live activation page:
http://www.minidsp.com/dirac-series/activate/#activate
If you have not activated a Dirac Live license before, use the New User screen on the left. If you have
previously activated one or more Dirac Live licenses, use the screen on the right.

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Notes:
1. The serial number that must be entered in the activation screen is not the serial number printed on the
hardware unit. A unique activation serial number for Dirac Live is programmed into the firmware of each
unit and can only be accessed with the DDRC-88 Utility program (step 4 above).
2. The email address used during license activation is not related to your user account on miniDSP.com. To
activate and validate a Dirac Live license, you must create a separate account on the Dirac server using the
form shown at left in step 5 above.
3. If you purchase more than one DDRC-88A or Dirac Series processor, each will need to be activated with its
unique serial number. Use the form shown on the right in step 5 above and enter the activation serial
number of each additional processor, and they will in turn be added to your license.
2.2.4 License validation
Start the Dirac Live Calibration Tool For miniDSP program. It will ask you to validate your software license. Enter
the email address and password that you used when activating your license, and then click on Validate:
You will need to be connected to the Internet to validate your license. Any active firewalls will need to have
HTTP (normal web traffic) enabled.
The Username that you enter in the validation screen must be the email address that you used in the
activation screen in step 5 on page 17. It is not your miniDSP website username.

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3ACOUSTIC MEASUREMENT
The Dirac Live Calibration Tool For miniDSP uses a set of measurements made in your listening room to gather
all the acoustical information about your room and speakers that it needs to calculate the correction filters. The
measurements are made using the DDRC-88A processor and a miniDSP UMIK-1 measurement microphone (must
be purchased separately).
3.1 LOUDSPEAKER AND MICROPHONE POSITIONING
Prior to performing acoustic measurements, loudspeaker and subwoofer positioning should be optimized. In a
home theater setting, the location of the subwoofer within the room will have a large impact on the smoothness
of bass response. With Dirac Live®, you have more freedom with loudspeaker and subwoofer placement, but the
best result will still be achieved if optimal placement is used together with Dirac Live®.
Typical home theater measurement setup
A total of nine measurements are needed, with the microphone located in different positions in the room and
pointed vertically (that is, at the floor or ceiling). The first measurement must be taken at the central location of
the listening area, as this location sets the levels and delays of each speaker. Eight more measurements are then
taken at locations spread around the listening area and at different heights from the floor.

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3.2 PREPARING FOR ACOUSTIC MEASUREMENT
3.2.1 Connections and microphone placement
The figure below shows a typical connection diagram for performing acoustic measurement. No changes to the
audio connections are needed. Simply:
1. Connect the supplied USB (type A to type B) cable from the DDRC-88A to a USB port on the computer.
2. Connect a USB cable (type A to mini type B) from the UMIK-1 to a USB port on the computer.
Place the UMIK-1 microphone into a microphone stand and position the computer and cabling so that there is
enough freedom of movement to move the microphone into the needed locations. A small tripod stand is
supplied with the UMIK-1, but a larger stand with boom arm can be used if desired. If necessary a USB extension
(up to a total USB cable length of 5 meters) can be used. In larger spaces, an active USB repeater may be
needed. We recommend that the microphone be oriented vertically (pointed at the floor or ceiling) and the “90
degree” calibration file used (see Mic Config tab below).
3.2.2 Subwoofer settings
We recommend that the low pass filter of the subwoofer be disabled if possible, or set to its highest frequency if
it cannot be disabled. Any EQ on the subwoofer should be disabled or set “flat.” High pass filters used to protect
the driver from over-excursion should be left in place.
If the subwoofer’s low pass filter is an important part of the overall bass management in the system, it can be
re-enabled after completing Dirac Live calibration and loading correction filters into the DDRC-88A.