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Holm DSPre 1, User Manual

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Holm DSPre 1 User Manual Download Page 66

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

HOLM Acoustics

HOLMFIR User Guide v0.4.4

Summary of Contents for DSPre 1

Page 1: ...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...

Page 2: ...y 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...

Page 3: ...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 Custo...

Page 4: ...ing 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...

Page 5: ...1 of 65 Part I HOLMFIR in Basic Mode HOLM Acoustics HOLMFIR User Guide v0 4 4...

Page 6: ...he 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 w...

Page 7: ...rt 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 HO...

Page 8: ...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...

Page 9: ...s 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...

Page 10: ...e 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 c...

Page 11: ...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 Upl...

Page 12: ...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 compute...

Page 13: ...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...

Page 14: ...plifers 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...

Page 15: ...e 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 cabl...

Page 16: ...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...

Page 17: ...plifers 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...

Page 18: ...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 Acoust...

Page 19: ...re 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 frequencie...

Page 20: ...ne 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 frequencie...

Page 21: ...th 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 swi...

Page 22: ...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 th...

Page 23: ...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...

Page 24: ...ploaded 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...

Page 25: ...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 HOLM Acoustics HOLMFI...

Page 26: ...y 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 fil...

Page 27: ...com 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...

Page 28: ...e 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 v...

Page 29: ...st 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 P...

Page 30: ...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 HOLM Acoustics HOLMFIR User Guide v0 4 4...

Page 31: ...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 ful...

Page 32: ...yer 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 7 V 5 V Technical Note If you...

Page 33: ...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...

Page 34: ...e 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 exp...

Page 35: ...31 of 65 Part II HOLMFIR in Advanced Mode HOLM Acoustics HOLMFIR User Guide v0 4 4...

Page 36: ...idden 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 Ampli...

Page 37: ...y 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 Acoustic...

Page 38: ...micolon tabular Ignores lines not starting with a number Accepts and or as decimal point An example of such a file could be HOLM Acoustics Mic 1 Calibrated Frequency Gain dB Phase degrees 0 8 29504 0...

Page 39: ...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 ple...

Page 40: ...f 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 differen...

Page 41: ...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 a...

Page 42: ...ce 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...

Page 43: ...t 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 clic...

Page 44: ...se 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 Dis...

Page 45: ...hich 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 maki...

Page 46: ...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 t...

Page 47: ...ithout 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 meas...

Page 48: ...ou 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 effec...

Page 49: ...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...

Page 50: ...iver 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...

Page 51: ...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 HOLM Acou...

Page 52: ...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 e...

Page 53: ...er 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 cl...

Page 54: ...e 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...

Page 55: ...Driver Correction Customization and Presentation Options 51 of 65 12 2 Customization and Presentation Options Explain the 3x10 measurement slots HOLM Acoustics HOLMFIR User Guide v0 4 4...

Page 56: ...en 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 Meas...

Page 57: ...3 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...

Page 58: ...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 ca...

Page 59: ...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 maxim...

Page 60: ...ting 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 S...

Page 61: ...57 of 65 Part III Appendices HOLM Acoustics HOLMFIR User Guide v0 4 4...

Page 62: ...ics 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...

Page 63: ...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...

Page 64: ...ently 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 upgrading...

Page 65: ...SPre volume and source 1 Disconnect the USB cable to the DSPre 2 Close the HOLMFIR application 3 Connect the USB cable to the DSPre 4 Start HOLMFIR There was a powerfailure when I was uploading filter...

Page 66: ...y 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 distor...

Page 67: ...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 HOLM Acoustics HOLMFIR Use...

Page 68: ...Equalization files 20 Equalization Mode 17 Export Graphs 30 Extended Range 48 Filter Banks 22 FIR 14 Forum at www holmacoustics com 58 Fourier Transforms 63 Frequency Response 62 Frequency Rolloff 15...

Page 69: ...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...

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