miniDSP DDRC-22A, DDRC-22D User Manual

DIRAC SERIES

HIGH-RESOLUTION AUDIO PROCESSORS

WITH DIRAC LIVE® TECHNOLOGY

User Manual

DDRC-22A

DDRC-22D

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Revision

Description

Date

0.9

Initial public release

26 Mar 2014

1.0

First production version

4 April 2014

Revision history

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TABLE OF CONTENTS

Important Information ......................................................................................................................................... 5

System Requirements ...................................................................................................................................... 5

Disclaimer/Warning ......................................................................................................................................... 5

Warranty Terms ............................................................................................................................................... 5

Package Contents ............................................................................................................................................ 6

A Note on this Manual ..................................................................................................................................... 6

1 Product Overview .......................................................................................................................................... 7

1.1 Typical system configurations ............................................................................................................... 7

1.2 How Dirac Live® works ......................................................................................................................... 8

1.3 The Dirac Series / Dirac Live® design process ...................................................................................... 10

2 Installation and Setup .................................................................................................................................. 11

2.1 Hardware connectivity ....................................................................................................................... 11

2.1.1 Digital audio connections (DDRC-22D) ........................................................................................ 11

2.1.2 Analog audio connections (DDRC-22A) ........................................................................................ 11

2.1.3 DC Power .................................................................................................................................... 12

2.1.4 USB ............................................................................................................................................. 12

2.2 Software installation and license activation ........................................................................................ 13

2.2.1 Framework installation ............................................................................................................... 13

2.2.2 Software installation ................................................................................................................... 13

2.2.3 License activation ....................................................................................................................... 13

2.2.4 License validation ....................................................................................................................... 14

3 Acoustic Measurement ................................................................................................................................ 15

3.1 Loudspeaker and microphone positioning .......................................................................................... 15

3.2 Connections for acoustic measurement .............................................................................................. 16

3.3 Configuring for measurement ............................................................................................................. 17

3.3.1 Sound System tab ....................................................................................................................... 18

3.3.2 Mic Config tab ............................................................................................................................ 18

3.3.3 Output & Levels tab .................................................................................................................... 19

3.4 Running the measurements ................................................................................................................ 20

3.4.1 Listening environment ................................................................................................................ 20

3.4.2 Executing measurements ............................................................................................................ 21

3.4.3 Viewing and redoing measurements ........................................................................................... 22

3.4.4 Completing the measurements ................................................................................................... 22

3.5 Saving and loading projects ................................................................................................................ 22

4 Filter Design ................................................................................................................................................ 23

4.1 Working with graphs .......................................................................................................................... 23

4.2 Designing your target curve ................................................................................................................ 25

4.2.1 The Auto Target .......................................................................................................................... 25

4.2.2 Editing the target curve .............................................................................................................. 26

4.2.3 Guidelines for target curve design .............................................................................................. 27

4.2.4 Saving and loading target curves ................................................................................................. 28

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4.3 Generating correction filters............................................................................................................... 28

4.4 Downloading and managing filter sets ................................................................................................ 29

5 Using the Dirac Series audio processor ........................................................................................................ 31

5.1 Status indicators ................................................................................................................................. 31

5.2 Front panel controls ........................................................................................................................... 31

5.3 Infrared remote control ...................................................................................................................... 32

6 Additional Information ................................................................................................................................ 33

6.1 Specifications ..................................................................................................................................... 33

6.2 Troubleshooting ................................................................................................................................. 34

6.3 MCU Firmware upgrade ..................................................................................................................... 35

6.4 Obtaining Support .............................................................................................................................. 36

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IMPORTANT INFORMATION

Please read the following information before use. In case of any questions, please contact miniDSP at
[e-mail].

SYSTEM REQUIREMENTS

To configure your Dirac Series audio processor, you will require a Windows PC with the following minimum
specification:

 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
 Microsoft• ® .NET framework v3.5 or later
 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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PACKAGE CONTENTS

Your Dirac Series package includes:

 One Dirac Series high-resolution audio processor
 One universal 5 VDC power supply with interchangeable power pins
 One USB cable for computer connectivity
 One UMIK-1 calibrated measurement microphone with USB cable
 One tripod microphone stand
 One license for Dirac Live Calibration Tool Stereo for miniDSP
 One printed Quick-start Guide

A NOTE 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.

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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1

1 PRODUCT OVERVIEW

Thank you for purchasing a Dirac Series 24/961 high-resolution 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.

Deploying a miniDSP Dirac Series 24/96 audio processor with Dirac Live® Technology will

 Improve the imaging of your sound system
 Improve the clarity of the music
 Produce a tighter bass
 Reduce listening fatigue
 Improve the timbre
 Remove resonances and room modes
 Reduce early reflections

Dirac Series processors are available in different versions. The DDRC-22A has analog inputs and outputs, while
the DDRC-22D has digital inputs and outputs. Each is inserted into the signal chain in the appropriate location
(see below for examples).

1.1 TYPICAL SYSTEM CONFIGURATIONS

The DDRC-22A (analog input/output) is typically inserted into the analog signal chain just before power
amplification, such as between a preamp or mixing/mastering console and power amp. Since it has on-board
volume control, it can also be used in systems where there is no other volume control, such as between a CD
player and a power amplifier.

All Dirac Series processors operate with 24-bit 96 kHz resolution.

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The DDRC-22D (digital input/output) is typically inserted into the digital signal chain just before D/A conversion;
for example, between one or more digital sources and a DAC. From there, a regular power amplifier or an
integrated amplifier complete the system. Variants on this theme include the use of an integrated amplifier with
a digital input or the use of a digital input of an A/V receiver, in which case a separate DAC is not required.

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 Dirac Series 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

Each model in the miniDSP Dirac Series of audio processors includes Dirac Live®, a premium mixed-phase room
correction technology. This technology is used not only in home stereo 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.

Differences between the impulse responses of the two loudspeakers at the listening position will also affect
soundstage and imaging. The more similar the impulse responses, the more easy it is to “trick” the brain into
thinking that the loudspeakers are not really there, and that the sound emanates from a virtual stage spanned
by the physical speakers.

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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® magnitude response correction

Illustration of Dirac Live® impulse response correction

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1.3 THE DIRAC SERIES / DIRAC LIVE® DESIGN PROCESS

The design process for optimizing your system with the Dirac Series audio processor and Dirac Live® is
summarized as follows:

1. Connect the Dirac Series 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 Stereo 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 Dirac Series 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, as computer
connectivity is not required for normal listening. See Section 5,

Using the Dirac Series audio processor.

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2 INSTALLATION AND SETUP

2.1 HARDWARE CONNECTIVITY

All connections to the Dirac Series audio processors are made on the rear panel.

2.1.1 Digital audio connections (DDRC-22D)

Connect up to three digital sources to the DDRC-22D inputs: AES-EBU on XLR, S/PDIF on RCA, or optical
(TOSLINK). Connect one of the digital outputs to your DAC or other device with a digital input. All digital outputs
are simultaneously active, so multiple output connections can be made if necessary.

The digital outputs of the DDRC-22D operate at 96 kHz sample rate. Any connected DAC must support
this sample rate. (The digital inputs of the DDRC-22D accept any sample rate up to 216 kHz.)

2.1.2 Analog audio connections (DDRC-22A)

Connect the analog inputs to your preamp or other analog source. Connect the analog outputs to your
amplification. All analog connections are via balanced XLR connectors, so in the event that your other
equipment has only single-ended (RCA) connections, use suitable RCA-XLR adapters or adapter cables.

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