miniDSP 2X4 HD User manual

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2X4HD
COMPACT 2-IN 4-OUT
HIGH-RESOLUTION AUDIO
PROCESSOR
2X4HD KIT
2-IN 4-OUT HIGH-
RESOLUTION AUDIO
PROCESSOR CIRCUIT BOARD
User Manual

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Revision history
Revision
Description
Date
V1.0
First preliminary release version
15 January 2016
V1.1
Added kit board, installers
31 January 2016
V1.2
Updated installation procedure
22 February 2016
V1.3
Updated installation procedure, added USB Audio
21 March 2016
V1.4
Updated installation procedure
31 January 2017

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CONTENTS
Important Information ...............................................................................................................................................5
System Requirements.............................................................................................................................................5
Disclaimer/Warning................................................................................................................................................5
Warranty Terms......................................................................................................................................................6
FCC Class B Statement............................................................................................................................................6
CE Mark Statement.................................................................................................................................................6
A note on this manual ............................................................................................................................................6
1 Product Overview ................................................................................................................................................7
1.1 Typical Applications....................................................................................................................................7
2 The miniDSP workflow.........................................................................................................................................9
3 Software installation......................................................................................................................................... 11
3.1 Windows.................................................................................................................................................. 11
3.1.1 Possible Windows installation issues .............................................................................................. 11
3.1.2 2x4 HD plugin installation................................................................................................................ 12
3.1.3 USB Driver installation..................................................................................................................... 12
3.2 Mac.......................................................................................................................................................... 13
3.2.1 Possible Mac installation issues....................................................................................................... 13
3.2.2 2x4 HD plugin installation................................................................................................................ 13
4 Hardware connectivity...................................................................................................................................... 14
4.1 Digital input ............................................................................................................................................. 14
4.2 Analog inputs and outputs ...................................................................................................................... 14
4.3 USB .......................................................................................................................................................... 15
4.4 DC power................................................................................................................................................. 15
5 The 2x4 HD Kit board ........................................................................................................................................ 16
6 Configuring the 2x4 HD..................................................................................................................................... 17
6.1 Synchronizing with the processor ........................................................................................................... 18
6.2 Inputs & Routing tab ............................................................................................................................... 19
6.2.1 Input selection................................................................................................................................. 19
6.2.2 Input channel strips......................................................................................................................... 20
6.2.3 Routing ............................................................................................................................................ 21
6.3 Output tab ............................................................................................................................................... 22
6.3.1 Channel strip layout......................................................................................................................... 22
6.3.2 Channel label ................................................................................................................................... 22
6.3.3 Level meter and gain control........................................................................................................... 22
6.3.4 Parametric EQ.................................................................................................................................. 23
6.3.5 Crossover......................................................................................................................................... 25
6.3.6 Compressor...................................................................................................................................... 27
6.3.7 FIR .................................................................................................................................................... 28
6.3.8 Invert and mute............................................................................................................................... 28
6.3.9 Time delay ....................................................................................................................................... 28
6.4 Custom biquad programming.................................................................................................................. 29

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6.4.1 What’s a “biquad? ........................................................................................................................... 29
6.4.2 Using custom biquad programming ................................................................................................ 29
6.4.3 Biquad design software ................................................................................................................... 31
6.5 FIR filtering and design............................................................................................................................ 32
6.5.1 FIR filtering overview....................................................................................................................... 33
6.5.2 FIR filter design software................................................................................................................. 33
6.5.3 Filter file format............................................................................................................................... 33
6.5.4 Loading filter coefficients ................................................................................................................ 34
6.6 Working with configurations................................................................................................................... 35
6.6.1 Online and offline mode.................................................................................................................. 35
6.6.2 Selecting a configuration................................................................................................................. 35
6.6.3 Saving and loading configurations................................................................................................... 36
6.6.4 Restoring to defaults ....................................................................................................................... 36
6.7 Keyboard shortcuts ................................................................................................................................. 37
7 USB Audio ......................................................................................................................................................... 38
7.1 Mac OS X.................................................................................................................................................. 38
7.2 Windows.................................................................................................................................................. 39
7.2.1 Status............................................................................................................................................... 39
7.2.2 Format ............................................................................................................................................. 39
7.2.3 Buffer settings ................................................................................................................................. 40
7.2.4 Volume............................................................................................................................................. 40
7.2.5 Info................................................................................................................................................... 41
8 Infrared remote control.................................................................................................................................... 42
9 Additional information...................................................................................................................................... 43
9.1 Specifications........................................................................................................................................... 43
9.2 Firmware upgrade ................................................................................................................................... 44
9.2.1 Windows.......................................................................................................................................... 44
9.2.2 Mac OS X.......................................................................................................................................... 46
9.3 Troubleshooting ...................................................................................................................................... 47
9.4 Obtaining support.................................................................................................................................... 48

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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 the miniDSP audio processor, you will require a Windows PC or Apple Mac OS X computer with the
following minimum specification:
Windows
PC with 1GHz or higher processor clock speed. Intel® Pentium®/Celeron® family, or AMD K6®/AMD
Athlon®/AMD Duron® family, or compatible processor recommended.
512 megabytes (MB) of RAM or higher
Keyboard and mouse or compatible pointing device
USB 2.0 port
Microsoft• ® Windows® Vista® SP1/ XP pro SP2/Win7/Win8.1/Win10
Microsoft• ® .NET framework v3.5 or later
Adobe AIR environment (latest version)
Adobe Flash player (latest version)
Mac OS X
Intel-based Mac with 1 GHz or higher processor clock speed
512 megabytes (MB) of RAM or higher
Keyboard and mouse or compatible pointing device
USB 2.0 port
Mac OS X 10.8 or higher
Adobe AIR environment (latest version)
Adobe Flash player (latest version)
DISCLAIMER/WARNING
miniDSP cannot be held responsible for any damage that may result from the improper use of this product or
incorrect configuration of its settings. As with any other product, we recommend that you carefully read this
manual and other technical notes to ensure that you fully understand how to operate this product. The miniDSP
audio processor is a powerful tool, and misuse or misconfiguration, such as incorrectly set gains or excessive
boost, can produce signals that may damage your audio system.
As a general guideline, you should perform the initial configuration of the miniDSP audio processor before
enabling audio through any connected output device or amplification. Doing so will help ensure that the
software is correctly configured.

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Finally, note that the miniDSP audio processor is a very flexible device, and many of the questions we receive at
the tech 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
support. Thanks 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.
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 2x4 HD has passed the test performed according to European Standard EN 55022 Class B.
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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1PRODUCT OVERVIEW
Thank you for choosing the miniDSP 2x4 HD or 2x4 HD Kit audio processor. The miniDSP 2x4 HD is an extremely
compact yet powerful and flexible digital audio processor for active crossover and other audio processing
applications. It features:
Asynchronous XMOS USB input for streaming audio (up to 192 kHz)
Stereo digital optical TOSLINK input
Two analog input channels and four analog output channels
Parametric EQ on all input and output channels, Butterworth and Linkwitz-Riley crossovers up to 48
dB/octave, and advanced biquad programming for an unlimited range of filters and crossover types
FIR filtering on every output channel (total 4096 taps)
Matrix mixer for flexible channel assignment and configuration
Real-time configuration of all processing parameters
Volume control by infrared remote
Four on-board presets, selectable by infrared remote
1.1 TYPICAL APPLICATIONS
The miniDSP 2x4 HD has a wide range of applications in home and professional audio. In this example, the 2x4
HD acts as both preamp and two-way crossover:
Figure 1 - 2x4 HD as preamp and 2-way crossover

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The miniDSP 2x4 HD is a perfect solution for subwoofer integration, providing accurate and flexible integration
between the subwoofers and the main speakers, as well as comprehensive EQ and tuning options. In this role,
the 2x4 HD is added after the preamp, as shown here:
The miniDSP 2x4 HD is a perfect solution for multi-subwoofer management for home theater. Driven from the
A/V receiver’s subwoofer output, the 2x4 HD can be used to adjust gain and delays individually for each
subwoofer, and provide parametric EQ both singly and for all subwoofers:
The 2x4 HD Kit allows construction of the 2x4 HD circuit board into more sophisticated builds that combine
other components such as power amplifier boards.
Figure 2 - 2x4 HD for subwoofer integration (2.1-way)
Figure 3 - 2x4 HD for multisub management

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2THE MINIDSP WORKFLOW
We strongly recommend taking a methodical approach to your new miniDSP audio processor. Remember that
the audio processor is a powerful tool and incorrect settings can potentially cause damage to your system.
Please follow the steps below carefully.
1. Download and install the software
When your order ships, your ordered plugin (or plugins) will be available from the User
Downloads section of the miniDSP website. Download and install the plugin and USB driver (for
Windows), as described in Software installation on page 11.
2. Familiarize yourself with the plugin
Before connecting your computer to the processor, start the plugin and familiarize yourself with
its user interface. Click on and explore each of the tabs (Input&Routing, Output). For more
information, see Configuring the 2x4 HD starting on page 17.
At this time, the plugin is still in offline mode, so any changes you make will not be downloaded
into the miniDSP hardware. Since all of the processing parameters will be reset in the next step,
you can feel free to experiment at this point.
3. Reset all parameters
From the Restore menu, select the Factory Default option. This will reset all processing
parameters back to the defaults and ensure that you have a "clean slate" for the next step.
4. Perform initial configuration
Use the plugin to set up an initial audio processing configuration as intended for your
application. For example, typical things that can be done at this point are to:
Set the labels of input and output channels
Mute unused input and output channels
Set crossover frequencies and slopes
Set up any essential equalization
5. Save configuration
Save your initial configuration to a file. A configuration is the set of all audio processing
parameters. You should save your configuration to a file on a regular basis, to ensure that you do
not lose your work if you inadvertently restore the processor to default settings. For more
information on configurations, see Working with configurations on page 35.
6. Make audio connections
With the initial configuration done and now that you are familiar with the various controls, it’s
time to connect the miniDSP 2x4 HD into your system. Ensure that all power is turned off when
making audio connections. See Hardware connectivity on page 14.

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7. Go into online mode
Apply power to the processor. (See DC power on page 15 for more information. Leave other
equipment turned off at this stage.) Connect the USB cable to your computer, click on the
Connect&Synchronize button, and select the Synchronize option. If all goes well, you are now in
online mode, and any changes that you now make in the plugin user interface will be
immediately sent to the processor.
Before proceeding, click on each Configuration preset button (Config 1, 2, etc.) to ensure that all
presets have been synchronized and/or set to defaults.
For more information, see Synchronizing with the processor on page 18.
8. Initial audio check
Power on your connected equipment, first on the input side (e.g. source or preamp), then on the
output side (e.g. power amps). Set a low volume (turn the volume on your source down low, or
program the infrared remote and reduce the master volume to -50 dB) and start playing music
or a pink noise test signal. Gradually increase the volume until your hear audio quietly coming
from the speakers. Verify that the plugin is performing the intended function. (For example, if
implementing a two-way crossover, confirm that the tweeter is playing high frequencies, and
that the woofer is playing low frequencies.)
9. Fine-tune your configuration
With your initial setup running, you can now proceed to fine-tune and optimize your system.
You will need to perform acoustic measurements and use the configuration screens to adjust
processing parameters.
Be sure to save your configuration on a regular basis while working on fine-tuning it.
Configurations can be saved to different files, in order to archive different versions, or to enable
auditioning of alternative configurations.
10. Continue to operate offline
With your miniDSP processor configured, you can continue to operate in offline mode—that is,
without the plugin software running. The processor “remembers” the configuration last set, and
will continue to operate without the computer.
Note: while in offline mode, the configuration can still be modified in the plugin interface. These
changes will not be downloaded to the processor until it is synchronized again. See Working with
configurations on page 35.