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					              HOLMFIR User Guide




Document version              0.4.4 (November 1, 2008)
Compatible HOLMFIR versions   1.0.8.x
Compatible DSPre version      DSPre 1
Compatible Microphone         Mic 1
CONTENTS                                                                                                 i




    Contents

    Contents                                                                                         i


    I   HOLMFIR in Basic Mode                                                                       1

    1 Introduction                                                                                  2
        1.1   How to use this User Guide . . . . . . . . . . . . . . . . . . . . . . . . . . .      2

    2 Quick Start                                                                                   3
        2.1   The DSPre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     3
        2.2   Installing HOLMFIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .      4
              2.2.1   Computer Requirements . . . . . . . . . . . . . . . . . . . . . . . . .       5
        2.3   DSPre-1-way Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     6
        2.4   DSPre-2-way Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     8
              2.4.1   Adjusting Gain Levels . . . . . . . . . . . . . . . . . . . . . . . . . . 10
        2.5   DSPre-3-way Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
              2.5.1   Adjusting Gain Levels . . . . . . . . . . . . . . . . . . . . . . . . . . 13

    3 Crossover & Target                                                                           14
        3.1   Crossovers (Only for DSPre-2,3-way) . . . . . . . . . . . . . . . . . . . . . . 14
        3.2   Low Frequency Rolloff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
        3.3   High Frequency Rolloff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

    4 Equalization - Tonal Balance                                                                 17
        4.1   Zoom with the Pointing Device (e.g. a mouse) . . . . . . . . . . . . . . . . . 18
        4.2   Graphical Equalizer Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
        4.3   Enable/Disable Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
        4.4   Open and Save Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
        4.5   Presets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

    5 Filter Bank                                                                                  22
        5.1   Save and Open Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . 23
        5.2   Copy Filter Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23




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CONTENTS                                                                                                 ii


    6 Control the DSPre                                                                            24
         6.1   Source Text in the Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
         6.2   DSPre Mixer (Windows XP)         . . . . . . . . . . . . . . . . . . . . . . . . . . 25
         6.3   DSPre Mixer (Windows Vista) . . . . . . . . . . . . . . . . . . . . . . . . . 26
         6.4   Playing Music via USB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
         6.5   Analog Input Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

    7 Customization (Look and Feel)                                                                29
         7.1   Linewidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
         7.2   Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30


    II    HOLMFIR in Advanced Mode                                                                31

    8 Introduction to Advanced Mode                                                                32
         8.1   Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
         8.2   Configuring the DSPre with Full Correction . . . . . . . . . . . . . . . . . . 32

    9 Get Ready to Measure                                                                         33
         9.1   Microphone Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
         9.2   Microphone Calibration File . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
         9.3   The Measurement Chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
         9.4   Protect Your Ears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
         9.5   DSPre Volume and Surroundings . . . . . . . . . . . . . . . . . . . . . . . . 35
         9.6   What is Measured - and How? . . . . . . . . . . . . . . . . . . . . . . . . . . 36

    10 Control Measurements                                                                        37
         10.1 Target Frequency & Impulse Response . . . . . . . . . . . . . . . . . . . . . 37
         10.2 Making a measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
         10.3 Customization and Presentation Options . . . . . . . . . . . . . . . . . . . . 40
               10.3.1 Impulse Response Axis . . . . . . . . . . . . . . . . . . . . . . . . . . 40
         10.4 Measurement Quality       . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
         10.5 Errors and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
         10.6 Compare Different Measurement Conditions . . . . . . . . . . . . . . . . . . 42

    11 Automatic Driver Alignment                                                                  43
         11.1 Time Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
         11.2 DSPre-2-way Automatic Alignment . . . . . . . . . . . . . . . . . . . . . . . 45
         11.3 DSPre-3-way Automatic Alignment . . . . . . . . . . . . . . . . . . . . . . . 46

    12 Driver Correction                                                                           48
         12.1 Extended Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
               12.1.1 DSPre-1-way Extended Range . . . . . . . . . . . . . . . . . . . . . . 49
               12.1.2 DSPre-2-way Extended Range . . . . . . . . . . . . . . . . . . . . . . 49
               12.1.3 DSPre-3-way Extended Range . . . . . . . . . . . . . . . . . . . . . . 50

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               12.1.4 Uploading the Extended Range Filters . . . . . . . . . . . . . . . . . 50
          12.2 Customization and Presentation Options . . . . . . . . . . . . . . . . . . . . 51
          12.3 Correcting a Bass/Subwoofer (DSPre-2,3-way) . . . . . . . . . . . . . . . . . 52
               12.3.1 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
               12.3.2 Limit the Maximum Gain . . . . . . . . . . . . . . . . . . . . . . . . 54
          12.4 Correcting a Midtone Driver (DSPre-2,3-way) . . . . . . . . . . . . . . . . . 56
          12.5 Correcting a Tweeter (DSPre-2,3-way) . . . . . . . . . . . . . . . . . . . . . 56
          12.6 Correcting a Bookshelf Speaker (DSPre-1-way) . . . . . . . . . . . . . . . . 56


    III     Appendices                                                                            57

    A Support                                                                                     58
          A.1 The Forum at www.holmacoustics.com . . . . . . . . . . . . . . . . . . . . . 58
          A.2 Emails to support@holmacoustics.com . . . . . . . . . . . . . . . . . . . . . 58
          A.3 Remote Assistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

    B Frequently Asked Questions                                                                  60

    C Troubleshooting                                                                             61

    D Technical Note - Measuring Response                                                         62
          D.1 Frequency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
          D.2 Nonlinearities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

    E Technical Note - Fourier Transforms                                                         63
          E.1 The Time Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

    Index                                                                                         64




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                     Part I

             HOLMFIR in Basic Mode




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Introduction                                                                                 2 of 65




     Chapter 1

     Introduction

     The HOLMFIR application allows you to configure the DSPre using bleeding edge algo-
     rithmens, but to begin with you just want to get the DSPre playing.
     HOLMFIR in ’Basic Mode’ lets you configure the DSPre as a digital active crossover (2,3-
     way) with equalization option.
     The ’Basic Mode’ makes it easy to configure the DSPre as the cornerstone of your personal
     setup with amplifiers and speakers. The Quick Start (Chapter 2) guides you through the
     initial setup of the DSPre, which can be done in just a few minutes.


     1.1       How to use this User Guide
     Please note that throughout the text the following nomenclature is used:


       HOLMFIR        The application HOLMFIR developed by HOLM Acoustics. Version 1.0.8.x
       DSPre          The DSPre 1 manufactured by HOLM Acoustics
       DSPre-1-way    A set of fullrange speakers
       DSPre-2-way    A set of bi-wired speakers with or without analog crossover
       DSPre-3-way    A set tri-wired speakers with or without analog crossover

     HOLMFIR can be used to setup 1,2,3-way systems, so skip the pages not relevant for you
     - hence do you have a DSPre-2-way system then skip the DSPre-1-way and DSPre-3-way
     chapters/sections.
     Typical usage of this user guide in ’Basic Mode ’is:

         • Chapter 2 Quick Start: Get the DSPre playing within a few minutes

         • Chapter 3 Crossover & Target: Tune the Crossovers and/or target for your system

         • Chapter 4 Equalizing: Experience some of the cababilities in a DSPre

         • Chapter 5,6,7: Use these chapters when needed

     When you are familiar with HOLMFIR in ’Basic Mode’ and would like to take the DSPre a
     step further regarding perfection of sound, then continue to Part II: HOLMFIR in Advanced
     Mode.


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Quick Start                                                                                  3 of 65




     Chapter 2

     Quick Start

     The purpose of this chapter is to get the DSPre playing in your setup, i.e. get sound out
     of your speakers within a few minutes.


     2.1      The DSPre
     The DSPre interface with display fields is very simple:




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Quick Start - Installing HOLMFIR                                                           4 of 65


     All connections are kept on the back panel of the DSPre:




     2.2    Installing HOLMFIR
     HOLMFIR is installed using a Microsoft installer package. It is recommended to
     download the latest version found at www.holmacoustics.com/holmfir.php

      HOLMFIR-1.0.8.x-wxp.msi        Installer package for Windows XP (32 bit)
      HOLMFIR-1.0.8.x-wvista.msi     Installer package for Windows Vista (32 bit)
     When executing the installer package you can safely answer ’Run’ to below security
     question




     Note when upgrading HOLMFIR then just execute the new installer package - it is not
     necessary to uninstall the previous version.




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Quick Start - Installing HOLMFIR                                                          5 of 65


     2.2.1   Computer Requirements
     HOLMFIR is a lightweight application, but does require some computer power. HOLMFIR
     will work if your computer is from an older date, but updating the graphs might take a
     while.
     Hardware requirements:

        • Minimum 1 GHz CPU

        • Minimum 512 MB RAM

        • Minimum 50 MB free disk space

        • USB port

     Software requirements:

        • Windows XP or Windows Vista

        • .Net 2.0 platform (Standard free library for Windows XP and Vista )

     Note, that when the DSPre once has been configured you can use ANY computer to play
     sound via USB without having to install HOLMFIR - that is any computer supporting
     the USB 1.1 audio standard. The most commonly used operative systems support this as
     Plug’n’Play without installing any special drivers: Windows 2000, Windows ME, Windows
     XP, Windows Vista, Mac OS X, Linux (Ubuntu, fedora, RedHat, ...) .
     See Section 6.4 ’Playing Music via USB’ for further details.




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Quick Start - DSPre-1-way Setup                                                              6 of 65


     2.3    DSPre-1-way Setup
     In a DSPre-1-way setup the DSPre basically acts as a pre-amplifier with digital correction
     and equalization options.
     To use the DSPre-1-way setup you need:

       1. A DSPre 1
       2. A stereo amplifier (or two mono amplifiers)
       3. Two full range speakers
       4. Signal and speaker cables
       5. A computer running Windows XP or Vista (only needed to configure the DSPre)

     Connect the Cables
     Connect the cables as shown in the diagram below.
     Input sources available: 1 USB, 2 analog and 5 digital




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Quick Start - DSPre-1-way Setup                                                             7 of 65


     Configure the DSPre using HOLMFIR
     Turn on the DSPre and start the HOLMFIR application. The DSPre can easily be config-
     ured using the setup wizard found in the menu: ’Help’ → ’Setup Wizard’




     Click ’Done’ and answer ’Ok’ to overwrite the current configuration




     Upload these settings to the DSPre by clicking ’Upload Filters to DSPre’ in the
     ’Crossover & Target’ tab




     After uploading, the DSPre is ready to play!




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Quick Start - DSPre-2-way Setup                                                            8 of 65


     2.4    DSPre-2-way Setup
     In a DSPre-2-way setup the DSPre basically acts as a pre-amplifier and active crossover
     with digital correction and equalization options.
     To use the DSPre-2-way setup you need:

       1. A DSPre 1 with 2 output modules
       2. Two stereo amplifiers (Can be of different kind)
       3. Two speakers with two inputs (Bi-wire - with or without analog crossovers)
       4. Signal and speaker cables
       5. A computer running Windows XP or Vista (only needed to configure the DSPre)

     Connecting the cables
     Connect the cables as shown in the diagram below.
     Input sources available: 1 USB, 2 analog and 5 digital




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Quick Start - DSPre-2-way Setup                                                             9 of 65


     Configure the DSPre using HOLMFIR
     Turn on the DSPre and start the HOLMFIR application. The DSPre can easily be config-
     ured using the setup wizard found in the menu: ’Help’ → ’Setup Wizard’




     Click ’Done’ and answer ’Ok’ to overwrite the current configuration




     Upload these settings to the DSPre by clicking ’Upload Filters to DSPre’ in the
     ’Crossover & Target’ tab.




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Quick Start - DSPre-2-way Setup                                                                  10 of 65




     After uploading, the DSPre is ready to play!

     2.4.1    Adjusting Gain Levels
     If the sensitivity of the amplifers or drivers are not the same - the gain levels can easily be
     aligned in the ’DSPre Settings’ tab.




     You can now align the levels of the outputs while playing music.

     If you want to align levels using a microphone, please refer to ’Advanced Mode’ Chapter
     11 Section 11.2 ’DSPre-2-way Automatic Alignment’




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Quick Start - DSPre-3-way Setup                                                           11 of 65


     2.5    DSPre-3-way Setup
     In a DSPre-3-way setup the DSPre basically acts as a pre-amplifier and active crossover
     with digital correction and equalization options.
     To use the DSPre-3-way setup you need:

       1. A DSPre 1 with 3 output modules
       2. Three stereo amplifiers (Or two HOLM Acoustics AMP 1 with three outputs)
       3. Two speakers with three inputs (Tri-wire - with or without analog crossovers)
       4. Signal and speaker cables
       5. A computer running Windows XP or Vista (only needed to configure the DSPre)

     Connecting the cables
     Connect the cables as shown in the diagram below.
     Input sources available: 1 USB, 2 analog and 5 digital




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Quick Start - DSPre-3-way Setup                                                            12 of 65


     Configure the DSPre using HOLMFIR
     Turn on the DSPre and start the HOLMFIR application. The DSPre can easily be config-
     ured using the setup wizard found in the menu: ’Help’ → ’Setup Wizard’




     Click ’Done’ and answer ’Ok’ to overwrite the current configuration




     Upload these settings to the DSPre by clicking ’Upload Filters to DSPre’ in the
     ’Crossover & Target’ tab.



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Quick Start - DSPre-3-way Setup                                                                  13 of 65




     After uploading, the DSPre is ready to play!

     2.5.1    Adjusting Gain Levels
     If the sensitivity of the amplifers or drivers are not the same - the gain levels can easily be
     aligned in the ’DSPre Settings’ tab.




     You can now align the levels of the outputs while playing music.

     If you want to align levels using a microphone, please refer to ’Advanced Mode’ Chapter
     11 Section 11.3 ’DSPre-3-way Automatic Alignment’




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Crossover & Target                                                                           14 of 65




     Chapter 3

     Crossover & Target

     Before the digital era one had to solder a new analog crossover with new components to
     try out a new configuration. With the DSPre you can change the frequency and steepness
     with a huge degree of freedom via a simple interface.


     3.1    Crossovers (Only for DSPre-2,3-way)
     A HOLMFIR digital crossover is defined by a crossover frequency and a transition band.
     The HOLMFIR digital crossover is a FIR (Finite Impulse Response) filter customized
     especially for HighEnd audio by HOLM Acoustics.




     This digital filter can not be directly comparred with a classical analog filter due to the
     completely separated frequency domains. When playing tones away from the transition
     band the tone is only represented in one driver - this corresponds to an analog filter with
     an infinite order.




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Crossover & Target - Low Frequency Rolloff                                                  15 of 65


     3.2    Low Frequency Rolloff
     The low frequency rolloff can be used to limit how low tones that are sent to your bass
     driver. Often bass drivers do not play tones below 30 Hz and small bookshelf speakers
     useally do not play tones below 40 Hz. When music consists of tones below this natural
     limit of the speaker you get heareable distortion. When the lower frequencies are damped
     this will not happen.
     The amplifier will often also distort when playing low-frequencies at a high volume which
     also validates the need to damp low frequencies.




     In the above example frequencies above 40 Hz are not affected and frequencies below 25
     Hz are simply not played.

     Motivations for Low Frequency Rolloff
        • Less distortion from the driver/speaker

        • Less excursion of driver/speaker - hence can prevent no blown drivers

        • Less power consumption from the amplifier - hence less distortion

        • Less low frequency room-modes

        • Less wide range deep sound presure for your nabo




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Crossover & Target - High Frequency Rolloff                                                    16 of 65


     3.3    High Frequency Rolloff
     The high frequency rolloff can be used if the tweeter of your system is poor - some fulltone
     drivers do not have a pleasant sound in high frequencies, or if you have tinnitus, which is
     triggered by high frequencies.




     In the above example frequencies below 10 kHz are not affected and frequencies above 15
     kHz are simply not played.

     Motivations for High Frequency Rolloff
        • Damp sharp and unpleasant high frequency sound




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Equalization - Tonal Balance                                                                17 of 65




     Chapter 4

     Equalization - Tonal Balance

     Do you want more or less bass? Is the treble to sharp? By equalization you can modify
     the frequency response of your system with a huge degree of freedom, or try out some of
     the presets to obtain your preffered tonal balance.


     Switching to Equalization Mode
     The ’Equalization Mode’ helps you focus on the equalization, so please switch HOLMFIR
     into ’Equalization Mode’ from the menu: ’Options’ → ’Equalization Mode’.
     The starting point is a flat frequency response - hence no equalization is applied




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Equalization - Tonal Balance - Zoom with the Pointing Device (e.g. a mouse)               18 of 65


     4.1    Zoom with the Pointing Device (e.g. a mouse)
     When equalizing it is appropriate to view a smaller range so that you can fine-tune your
     preference




     To zoom back right-click or click the ’Zoom Back’ button.




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Equalization - Tonal Balance - Graphical Equalizer Tool                                    19 of 65


     4.2    Graphical Equalizer Tool
     The equalization curve is defined with points, that can be placed at any freedom.

     How to add new equalizer points

      Left - Click                 Add a point

      Right - Click                Add a point at 0 dB - Hence bound the curve to be neutral

     How to modify existing equalizer points

      Left - Drag’n’Drop point     Move a point

      Right - Click point          Delete a point

      Left - Double click point    Modify point by entering extact values in the Equalization box




     The low- and high-frequency end-levels are edited the same way as normal equalizer
     points, except that they have a static frequency and cannot be deleted.




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Equalization - Tonal Balance - Enable/Disable Equalization                                    20 of 65


     4.3    Enable/Disable Equalization




     The equalization can be enabled or disabled by changing the checkbox status, but the new
     equalization is not present on the DSPre before filters are uploaded.
     A basic test is to listen to a piece of music without equalization and thereafter upload the
     equalization and hear the difference.


     4.4    Open and Save Equalization
     From the ’Equalization’ menu you can also save and open equalization files. This feature is
     convenient if you want to save your favorite equalization or interchange this with another
     user.

                                  ’Equalization’ → ’Open Custom’


                                  ’Equalization’ → ’Save Custom’




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Equalization - Tonal Balance - Presets                                                     21 of 65


     4.5    Presets
     HOLM Acoustics has designed a collection of presets available from the menu. The collec-
     tion might inspire you how to adjust the tonal balance.




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Filter Bank                                                                                22 of 65




     Chapter 5

     Filter Bank

     When you want to try out a new configuration or use the DSPre for an entirely different
     system you can utilize the filter bank consisting of filters marked F0-F9.
     Enter a note to identify the configuration in the note field.




     The current filter present on the DSPre can be identified on the display as F0-F9 in the
     upper right corner.




     Note that after a new filter has been selected the filters has to be uploaded to the DSPre
     for the change to take effect. The filter number in the DSPre changes when the upload is
     finished - that is when the DSPre is playing with the new filter.



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Filter Bank - Save and Open Configurations                                                     23 of 65


     5.1    Save and Open Configurations
     As an alternative to the filter bank you can save and open configurations as files from the
     menu:

                              ’File’ → ’Save current configuration as...’
                        ’File’ → ’Open saved configuration to current bank’

     Note that the configuration file is a human readable XML-file but it is strongly recom-
     mended not to edit saved configuration files by hand.

     Autosave of the current configuration
     The configuration is autosaved when HOLMFIR is closed, so when HOLMFIR is restarted
     you will see the same configuration and have the same filterbank as when you closed the
     application.


     5.2    Copy Filter Configuration
     You can copy a filter-configuration (or parts) from one filter to another. This is convenient
     if you want to modify an already existing configuration, but would like to use another filter
     in the bank.




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Control the DSPre                                                                            24 of 65




     Chapter 6

     Control the DSPre

     You can to some extend customize and control the DSPre from HOLMFIR. These settings
     can of course only be controlled from HOLMFIR when the DSPre is turned on and con-
     nected via the USB-cable to the computer. Volume and source can be selected via the
     DSPre remote-control, the DSPre frontpanel or HOLMFIR:




     Note that when the DSPre has been turned off, the current source is remembered, but the
     volume is reset to the moderate value 15.


     6.1    Source Text in the Display
     The source text can be specified with 13 characters. The source text is static - hence will
     be remembered when the DSPre is turned off.




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Control the DSPre - DSPre Mixer (Windows XP)                                             25 of 65


     6.2    DSPre Mixer (Windows XP)
     You can adjust the Microsoft Windows volume settings via the ’DSPre Mixer’ tab. The
     HOLMFIR and Windows XP sliders corresponds as follows:




     The optimal quality sound (from a digital point of view) is achieved when USB Play and
     USB Wave Volume are both set to maximum.




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Control the DSPre - DSPre Mixer (Windows Vista)                         26 of 65


     6.3    DSPre Mixer (Windows Vista)




     Write how to control the sound in Windows Vista




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Control the DSPre - Playing Music via USB                                                    27 of 65


     6.4    Playing Music via USB
     When the DSPre once has been configured you can use ANY computer to play sound via
     USB without having to install HOLMFIR - that is any computer supporting the USB 1.1
     audio standard.
     The most commonly used operative systems support this standard as Plug’n’Play without
     having to install any special drivers:

        • Windows 2000, Windows ME, Windows XP, Windows Vista

        • Mac OS X

        • Linux (Ubuntu, Fedora, RedHat, SUSE, ...)

     Best sound quality
     It is possible to achieve an extremely high digital signal quality (the same as from a CD-
     player), if some software requirements are fullfilled:

        • The software USB - ’Speaker volume’ should be 100 % (maximum)

        • The samplerate should be 44.100 kHz
          - hence ’44.100kHz LOCK’ in the DSPre display

        • No other applications than your music player should stream audio to the DSPre

     Recording via USB
     Any source can be recorded via the DSPre, but recording is of course most relevant when
     using an analog source such as a turntable or a FM-tuner.




HOLM Acoustics                                                             HOLMFIR User Guide v0.4.4
Control the DSPre - Analog Input Gain                                                         28 of 65


     6.5    Analog Input Gain
     The DSPre has two analog inputs with variable sensitivity (gain). When using an analog
     source such as a record player or a FM-tuner the rule of thumb is that the listening volume
     should be the same as when listing to a digital source such as a CD-player or your computer.




     Below table can be used if you know the output voltage of your analog source:

                   Input Gain                 0 dB    3dB    6 dB   9 dB    12 dB
                   Voltage (Peak-to-Peak)     20 V   14 V    10 V    7V      5V

     Technical Note
     If you record the analog source from the DSPre via a computer while playing, you are able
     to analyze the level simply by identifying clipping or a to low level.
     Audacity is free software for recording and editing sounds. Audacity can be downloaded
     here: http://audacity.sourceforge.net




HOLM Acoustics                                                               HOLMFIR User Guide v0.4.4
Customization (Look and Feel)                                                              29 of 65




     Chapter 7

     Customization (Look and Feel)

     This chapter inspire you how to customize the appearance of the information the way you
     like it.
     Note that the filters and configuration of the DSPre are NOT affected when changing
     settings in the ’Options’ menu - hence just try out some options with no risk.


     Tooltip Popups
     The tooltip popups can be enabled or disabled by two menu entries:
     ’Options’ → ’Show tooltips’ or ’Help’ → ’Show tooltips’


     7.1    Linewidth
     The linewidth can be adjusted from the menu: ’Options’ → ’Set General Linewidth’.
     This option is relevant when HOLMFIR is maximized using high screen resolution:




HOLM Acoustics                                                            HOLMFIR User Guide v0.4.4
Customization (Look and Feel) - Colors                                                    30 of 65


     7.2    Colors
     The colors of the components in the graphs can all be customized:




     The ’Text & Grid Color’ and ’Background Color’ are reached from the ’Options’ menu
     where as the other colors changed by clicking the Color box




     Export Graphs as Bitmap Images
     The graphs can be exported as bitmap graphics from the menu:
     ’File’ → ’Crossover & Target Image’




HOLM Acoustics                                                           HOLMFIR User Guide v0.4.4
                                               31 of 65




                   Part II

          HOLMFIR in Advanced Mode




HOLM Acoustics                HOLMFIR User Guide v0.4.4
Introduction to Advanced Mode                                                               32 of 65




     Chapter 8

     Introduction to Advanced Mode

     In ’Advanced Mode ’you have an outstanding opportunity to implement corrections and
     fine tune your speakers.
     The response of your system is measured with a calibrated microphone, and with a known
     response you can to a far extend correct for the imperfectness in your system.


     Switch to Advanced Mode
     Switch to ’Advanced Mode ’from the options menu: ’Options’ → ’Advanced Mode’.
     The changes/configurations made in ’Advanced Mode ’are still in effect (but hidden) when
     switching back to ’Basic Mode ’.


     8.1    Functionality
     The functionality achieved in ’Advanced Mode ’is:

        • Automatic gain-level adjustment

        • Automatic time-align adjustment

        • Linear frequency response (Amplitude vs. frequency)

        • Correction of Q-Damping factor for the bass-driver

        • Linear phase response


     8.2    Configuring the DSPre with Full Correction
     The chapters 10, 11 and 12 are increasing in complexity and concepts, but if you want the
     fastest way of configuring the DSPre with full correction you should:

       1. Correct each driver in the system (Chapter 12 ’Driver Correction’)

       2. Align the drivers (Chapter 11 ’Automatic Driver Alignment’)

       3. Verify the full setup (Chapter 10 ’Control Measurements’)




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Get Ready to Measure                                                                       33 of 65




     Chapter 9

     Get Ready to Measure

     Perhaps you are familier with the concepts when measuring the response of an audio
     system, then you will find this chapter obvious, but relevant.
     If you are not familier with audio-measurements you should definitely pay extra attention
     to this chapter.


     9.1    Microphone Connection
     Any microphone can in principle be connected to the DSPre, but for simplicity it will be
     assumed, that ’The Microphone’ is the HOLM Acoustics microphone Mic 1.
     Connect the microphone to the DSPre analog 1 Left input on the DSPre and adjust the
     analog input gain (12 dB for the Mic 1)




                  Microphone Input Gain     0 dB    3dB   6 dB    9 dB   12 dB
                  Voltage (Peak-to-Peak)    20 V   14 V   10 V    7V      5V



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Get Ready to Measure - Microphone Calibration File                                           34 of 65


     9.2      Microphone Calibration File
     Microphone calibration is enabled from the menu:
     ’Measurements’ → ’Open microphone calibration’




     The file format of the calibration file is pure ASCII-text, which is parsed according to the
     following rules:

         • Expects data in columns:
           Frequency <separator> dB <separator> phase in degrees <eol>

         • Accepts the following characters as <separator>: space, semicolon, tabular

         • Ignores lines not starting with a number

         • Accepts ’,’ and/or ’.’ as decimal point

     An example of such a file could be:

     # HOLM A c o u s t i c s Mic 1 C a l i b r a t e d
     Frequency ; Gain [ dB ] ; Phase [ d e g r e e s ]
     0 ; −8 . 2 9504;0
     9.42078; −8.29504;0
     1 5 1 0 . 0 2 ; −8.2746; −0.0360637
     1 5 4 7 . 7 ; −8.25409; −0.0359415
     1 5 8 6 . 7 3 ; −8.23392; −0.0348953
     1 6 2 7 . 1 ; −8.21392; −0.0332587
     1 6 6 8 . 8 2 ; −8.19389; −0.0310393
     1 7 1 1 . 8 9 ; −8.17369; −0.027908
     1 7 5 6 . 3 ; −8.15318; −0.0232595
     1 8 0 0 . 7 1 ; −8.13287; −0.0164973
     1 8 4 5 . 1 3 ; −8.11274; −0.00696385
     1890.88; −8.09221;0.00625865
     1936.64; −8.07198;0.0230672
     1983.75; −8.05157;0.0437466
     2 0 3 2 . 2 ; −8.03114;0.0676501
     2081.99; −8.01077;0.0935485
     .
     .
     .




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Get Ready to Measure - The Measurement Chain                                                   35 of 65


     9.3    The Measurement Chain
     Before a measurement, please make sure that the full measurement chain is in place:

       1. A PC/Laptop running HOLMFIR is connected to the DSPre via a USB cable

       2. The DSPre is powered on

       3. The amplifier(s) are connected to the DSPre and powered on

       4. The speakers are connected to the amplifiers

       5. The microphone is connected to the DSPre and powered on


     9.4    Protect Your Ears
     When measuring, HOLMFIR uses a frequency-sweep, which goes from 10 to 22050 Hz at
     full amplitude from the computer. It is therefore important that you protect your ears
     while measuring, since the high tones from 4000 to 22050 Hz might not sound loud, but
     can damage your hearing, so please remember to protect your ears - hence the warning
     pop-up when measuring:




     9.5    DSPre Volume and Surroundings
     Start with a DSPre volume at 15, then increase if record level is to low.
     Some guidelines:

        • Near field (less than 10cm) use low volume to avoid clipping

        • Far field (further than 1m) use higher volume to get a better signal to noise ratio

        • Close windows and doors to the outside

        • Do not hesitate to make a new measurement, eg. if a large truck drove by or if your
          neighbor slammed the door




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Get Ready to Measure - What is Measured - and How?                                            36 of 65


     9.6    What is Measured - and How?
     HOLMFIR measure the impulse response and thereby also the frequency response. If the
     speaker/drivers where ideal they would play the electrical signal received, but this is not
     the case.
     Often only the amplitude is represented in plots of the frequency response, but HOLMFIR
     goes further by measuring the phase. The phase response reflects the meachanical prop-
     erties of the speaker. If the phase response is zero, then all tones at different frequencies
     arrive to the ear at the same time. An uncorrected driver/speaker will typical have that
     lower tones arrive later than the higher.
     Below diagram illustrates this by the blue curve not being identically with the green curve
     (for technical details refer to Appendix D).




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Control Measurements                                                                        37 of 65




     Chapter 10

     Control Measurements

     A cornerstone in the HOLM Acoustics filosofy is that you must have the oppertunity
     to verify your setup. In the ’Control measurements’ tab you can verify your setup and
     compare settings.


     10.1     Target Frequency & Impulse Response
     Without making a measurement HOLMFIR shows the target response as a frequency
     response and impulse response:




     If the amplifier, speaker, room and microphone was perfect you would measure this response
     - hence the name ’target’.




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Control Measurements - Making a measurement                                                   38 of 65


     10.2     Making a measurement
     Place the microphone 150 cm away from the left speaker on the axis of the listening position




     Note the 150 cm is just meant to be a guide - try out other distances for your personal
     reference.
     Now click the measure button to start the measurement:




HOLM Acoustics                                                               HOLMFIR User Guide v0.4.4
Control Measurements - Making a measurement                                               39 of 65


     Thereafter the result is shown:




     Now zoom in the impulse response window by defining a rectangle with the left mouse
     button as described in Section 4.1. It is most convenient to zoom when adjusting the
     window, and after zoom it is often appropriate to rescale the vertical axis by clicking
     ’Rescale’
     Adjust the time window by dragging the right edge or click ’Auto Detect’ to let HOLMFIR
     try and figure out where the echoes starts.
     Note that per default the time-window is adjusted by HOLMFIR just after the measure-
     ment.




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Control Measurements - Customization and Presentation Options                                40 of 65


     10.3     Customization and Presentation Options
     The general rule is that colors are changed by clicking the colorboxes and components are
     plotted when the corresponding checkbox is marked.




     You have 30 measurement slots (0-29) where measurements are stored.

     10.3.1    Impulse Response Axis
     The horizontal axis for the impulse response has different representations

        • Time in milliseconds
          The unit on the axis for the impulse response is per default set to milliseconds, that
          is the amplitude of the speaker as time goes by

        • Distance in cm.
          Instead of time you can consider the distance which the sound has moved in a certain
          period of time. This is convenient when considering the reflections of your room or
          speaker

        • Number of samples at 44100 Hz
          The CD format and the DSPre native samplerate is 44100 Hz, so you can also consider
          how many samples that goes by in time




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Control Measurements - Measurement Quality                                                  41 of 65


     This is configured from the ’Options’ menu:




     10.4     Measurement Quality
     If the sound level is to low you will obtain a lower quality of the measurement, but with
     a to high sound level you might reach the clipping level for the recording, which is NOT
     acceptable. A reasonable peak record level is from -30 to 0 dB




     The default signal length is approximately 6 seconds, which is what gives the best result
     for an average system. If your are making many measurements then try to set the signal
     length to 17 which is 3 seconds to save time. If you want to eliminate noise from the
     surroundings or measure at a low level you can try to increase to a signal length of 19
     which is 12 seconds.




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Control Measurements - Errors and Warnings                                                  42 of 65


     10.5     Errors and Warnings




     - Explain Polarity Warning
     - Record level to low error


     10.6     Compare Different Measurement Conditions
     With a microphone connected to the DSPre you can easily produce and reproduce a lot
     of measurements within a few minutes. So whenever you are in doubt about something
     then do not hesitate to make another measurement - either to ensure reproducibility or to
     inspect the difference of two measurement conditions




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Automatic Driver Alignment                                                                    43 of 65




     Chapter 11

     Automatic Driver Alignment

     If the sensitivity of the amplifers or drivers are not the same - the gain levels must be
     aligned. In ’Basic Mode ’without a microphone connected one has to adjust the levels by
     hand while listening to music - eg. for a DSPre-2-way system:




     This process is automated with a precision within 0,1 dB in HOLMFIR using a measure-
     ment signal.
     In classical analog filters the process of gain alignment would be to adjust resistors/poten-
     tiometers in the analog crossovers.




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Automatic Driver Alignment - Time Alignment                                                    44 of 65


     11.1     Time Alignment
     Time alignment of drivers is a feature only available in ’Advanced Mode ’, it gives you the
     ability to align the drivers to be at the same phase plane. Below sketch illustartes this
     using assuming ideal drivers:




     Typical the bass is delayed and the tweeter is a little to early. This effect can be corrected
     in the ’DSPre Settings’ tab.




     Note that classical analog filters cannot correct for these delays.




HOLM Acoustics                                                                HOLMFIR User Guide v0.4.4
Automatic Driver Alignment - DSPre-2-way Automatic Alignment                    45 of 65


     11.2    DSPre-2-way Automatic Alignment




     Screenshots etc as in DSPre-3-way automatic Alignment




HOLM Acoustics                                                 HOLMFIR User Guide v0.4.4
Automatic Driver Alignment - DSPre-3-way Automatic Alignment                              46 of 65


     11.3    DSPre-3-way Automatic Alignment
     As a guideline it is suggested that the driver alignment is done 2 m away from the left
     speaker to the axis of the listening position:




     Ensure that the measurement chain (9.3) is in place and click ’Align Drivers’ under the
     ’Driver-Measurements’ tab




     Now the DSPre has aligned the delays and amplitude, so the drivers are matched in the
     crossover frequencies.



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Automatic Driver Alignment - DSPre-3-way Automatic Alignment                           47 of 65


     Verification by Control Measurements
     By making a full-range measurement in the ’Control-Measurements’ tab you can verify
     that the drivers are indeed aligned




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Driver Correction                                                                          48 of 65




     Chapter 12

     Driver Correction

     The DSPre is able to correct the frequency response in terms of amplitude and phase.
     The HOLM Acoustics approch is to measure each driver section in an extended frequency
     range. This characterization of the components creates the basis for a correction. The
     driver correction is optionally and can be switched on/off for each component.


     12.1     Extended Range
     When characterizing the drivers it is necessary to have an extended range without equal-
     ization. The extended range let you measure a datasheet for each driver. Guideline for
     frequency intervals:

                        Type          Working Range      Extended Range

                        Sub-Woofer    −→ 100 Hz          −→ 150 Hz
                        Woofer        −→ 300 Hz          −→ 500 Hz
                        Mid/Woofer    −→ 2000 Hz         −→ 3000 Hz
                        Mid           300 −→ 2500 Hz     100 −→ 4000 Hz
                        Tweeter       2000 Hz −→         1500 Hz −→
                        Full Range    All                All




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Driver Correction - Extended Range                                                          49 of 65


     12.1.1    DSPre-1-way Extended Range
     Select the ’Extended Range’ mode in the ’Driver Measurements’ tab. The 1-way extended
     range is simply the fullrange frequency interval from 0 Hz −→




     12.1.2    DSPre-2-way Extended Range
     Select the ’Extended Range’ mode in the ’Driver Measurements’ tab and click ’Futher Options’,
     then enter the extended range for the two outputs (drivers)




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Driver Correction - Extended Range                                                          50 of 65


     12.1.3    DSPre-3-way Extended Range
     Select the ’Extended Range’ mode in the ’Driver Measurements’ tab and click ’Futher Options’,
     then enter the extended range for the three outputs (drivers)




     12.1.4    Uploading the Extended Range Filters
     Before characterizing the drivers by extended range measurements you will have to upload
     the extended range filters




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Driver Correction - Customization and Presentation Options                    51 of 65


     12.2     Customization and Presentation Options




     Explain the 3x10 measurement slots




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Driver Correction - Correcting a Bass/Subwoofer (DSPre-2,3-way)                            52 of 65


     12.3     Correcting a Bass/Subwoofer (DSPre-2,3-way)
     A bass/subwoofer typically has a frequency range from 30 Hz to 300 Hz, which corresponds
     to wave lengths from 1m to 10m, which means that the echoes from the room will have a
     huge effect. So when measuring these low frequencies you will do a near field measurement
     - that is 5cm or closer:




     Measurement Checklist
        • The microphone is placed close to the left driver as shown in above picture

        • The Measurement Chain (Section 9.3) is in place

        • The extended filters are uploaded and adjusted (Section 12.1)

        • The ’Active Output’ under ’Driver-Measurements’ is is set to 1st.

        • The DSPre Volume is set to for a near-field measurement (Typical 10-20)

     When ready click the ’Measure’ button:




HOLM Acoustics                                                            HOLMFIR User Guide v0.4.4
Driver Correction - Correcting a Bass/Subwoofer (DSPre-2,3-way)                             53 of 65


     When the measurement is finished you will have an extended characterization of the driver:




     If the measurement went well, then adjust the time window and use this extended mea-
     surement as a basis for the correction:




HOLM Acoustics                                                            HOLMFIR User Guide v0.4.4
Driver Correction - Correcting a Bass/Subwoofer (DSPre-2,3-way)                               54 of 65


     Important Note
     You can correct other drivers in your system, but alignment of the drivers (Chapter 11
     Automatic Driver Alignment) is necessary after uploading corrected filters.

     12.3.1    Verification
     After uploading the filter with corrections you will have a DSPre, which corrects your driver
     to have a perfect impulse response, which can be verified simply by making a measurement
     without moving the microphone:




     12.3.2    Limit the Maximum Gain
     Under ’Futher Options’ the maximum gain can be adjusted




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Driver Correction - Correcting a Bass/Subwoofer (DSPre-2,3-way)                            55 of 65


     This is usefull if you want to have full control over just how much extra gain the DSPre
     will put into your system. The compromise is:

                             The more gain, the less dynamic range
                                The less gain, the less linearity

     Several measurements on different systems have shown that a maximum gain of 6dB is a
     good compromise, but your system can of course change the determining factors




HOLM Acoustics                                                            HOLMFIR User Guide v0.4.4
Driver Correction - Correcting a Midtone Driver (DSPre-2,3-way)                    56 of 65


     12.4     Correcting a Midtone Driver (DSPre-2,3-way)




     Step By Step Correcting a Midtone Driver



     12.5     Correcting a Tweeter (DSPre-2,3-way)




     Step By Step Correcting a tweeter



     12.6     Correcting a Bookshelf Speaker (DSPre-1-way)




     Step By Step Correcting a small speaker




HOLM Acoustics                                                    HOLMFIR User Guide v0.4.4
                                               57 of 65




                   Part III

                 Appendices




HOLM Acoustics                HOLMFIR User Guide v0.4.4
Support                                                                                     58 of 65




     Appendix A

     Support

     HOLM Acoustics is aware that the huge degree of freedom within DSPre and HOLMFIR
     can be a challenge. HOLM Acoustics will advise you how to configure the DSPre to satisfy
     your preference.


     A.1     The Forum at www.holmacoustics.com
     Using the forum at www.holmacoustics.com is a great way to interchange knowledge and
     experiences. NB! Please help HOLM Acoustics and use this forum for communication
     whenever possible.


     A.2     Emails to support@holmacoustics.com
     HOLM Acoustics welcome emails send to support@holmacoustics.com with a specific ques-
     tion or request, but please remember to include relevant information.
     It is an advantage to initiate the email from HOLMFIR while the DSPre is connected and
     powered on. This is done from the menu:

                          ’Help’ → ’Email Support at HOLM Acoustics’

     Windows will start the default email client with some prefilled data. Here an example with
     Microsoft Outlook 2003 as email client:




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Support - Remote Assistance                                                             59 of 65


     A.3     Remote Assistance
     Windows Remote assistance will allow a supporter at HOLM Acoustics to control HOLM-
     FIR on your computer while you see what is going on. Remote assistance can be started
     from HOLMFIR:

                              ’Help’ → ’Request Remote Assistance’

     Please arrange a time with support at HOLM Acoustics before sending the request




HOLM Acoustics                                                         HOLMFIR User Guide v0.4.4
Frequently Asked Questions                                                          60 of 65




     Appendix B

     Frequently Asked Questions


      Question                                            Answer

      Can the DSPre play without a computer connected?    Yes

      Can I connect the DSPre after HOLMFIR is started?   Yes
      Do I loose my current filter-configuration when
                                                          No
      upgrading HOLMFIR?




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Troubleshooting                                                                           61 of 65




     Appendix C

     Troubleshooting


      Problem                              Solution

                                           1. Make sure that a USB cable is connected between
      The status field in HOLMFIR says:     the DSPre and the computer
      No compatible DSPre found            2. Turn on the DSPre
                                           3. Restart HOLMFIR
                                           1.   Disconnect the USB cable to the DSPre
      HOLMFIR cannot control the           2.   Close the HOLMFIR application
      DSPre volume and source              3.   Connect the USB cable to the DSPre
                                           4.   Start HOLMFIR
      There was a powerfailure when I
      was uploading filters to the DSPre,   1. Perform the upload again
      which is not responding now.
      The DSPre is powered on, but         1a. Turn off the DSPre and turn the DSPre on again
      there is no text in the display      1b. Find the remote control and adjust the dimming




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Technical Note - Measuring Response                                                       62 of 65




     Appendix D

     Technical Note - Measuring Response

     Motivations for using log-sweep as measuring signal

        • Extremely good signal to noise ratio
        • Filter all non-linearities away
        • Same energy per octave - hence reflects the ear.
        • Extreme reproducibility


     D.1     Frequency Response




     Write that HOLMFIR does not correct for distortion and other stuff


     D.2     Nonlinearities




     Write that HOLMFIR does not correct for distortion and other stuff


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Technical Note - Fourier Transforms                               63 of 65




     Appendix E

     Technical Note - Fourier Transforms




     Write a short intro to Fourier Transforms


     E.1     The Time Window




     Write a short intro to the time window




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INDEX                                                                                   64 of 65




    Index

    Analog input, 28                          Fourier Transforms, 63
    Analog source, 28                         Frequency Response, 62
    Audacity, 28                              Frequency Rolloff, 15, 16
                                              Full-range measurement, 47
    Bitmap Images, 30
                                              Graphical Equalizer, 19
    Clipping, 28                              Graphical Equalizer Tool, 19
    Colors, 30
    Computer Requirements, 5                  High Frequency Rolloff, 16
    Control Measurements, 37                  HOLMFIR, 2
    Control the DSPre, 24                     HOLMFIR digital crossover, 14
    Crossover & Target, 14
    Crossovers, 14                            Impulse Response Axis, 40
                                              Installing HOLMFIR, 4
    Display, 24
    Driver Alignment, 43                      Linewidth, 29
    Driver Correction, 48                     Linux, 27
    DSPre, 2                                  Look and Feel, 29
    DSPre Mixer, 25                           Low Frequency Rolloff, 15
    DSPre volume, 35
    DSPre-1-way, 2                            Mac OS X, 27
    DSPre-1-way Extended Range, 49            Measurement Chain, 35
    DSPre-1-way Setup, 6                      Measurement Conditions, 42
    DSPre-2-way, 2                            Measurement Quality, 41
    DSPre-2-way Automatic Alignment, 45       Measuring Response, 62
    DSPre-2-way Extended Range, 49            Microphone Calibration, 34
    DSPre-2-way Setup, 8                      Microphone Connection, 33
    DSPre-3-way, 2                            Nonlinearities, 62
    DSPre-3-way Automatic Alignment, 46
    DSPre-3-way Extended Range, 50            Output voltage, 28
    DSPre-3-way Setup, 11
                                               Plug’n’Play, 27
    Emails to support at holmacoustics.com, 58 Presets, 21
    End-Levels, 19                             Protect Your Ears, 35
    Equalization, 17, 20
    Equalization box, 19                       Record level, 41
    Equalization files, 20                      Remote Assistance, 59
    Equalization Mode, 17                      reproducibility, 42
    Export Graphs, 30
    Extended Range, 48                         Sensitivity, 43
                                               Signal length, 41
    Filter Banks, 22                           Source Text, 24
    FIR, 14
    Forum at www.holmacoustics.com, 58         Time Alignment, 44

HOLM Acoustics                                                         HOLMFIR User Guide v0.4.4
INDEX - INDEX                                                  65 of 65


    Time Window, 63
    Time window, 39
    Tonal Balance, 17, 21
    Tooltip, 29
    Tooltip Popups, 29

    USB 1.1 audio standard, 27

    Verification by Control Measurements, 47

    Zoom, 18
    Zoom Back, 18




HOLM Acoustics                                HOLMFIR User Guide v0.4.4

				
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