HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO
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1. SIDE VIEW FRONT VIEW Where the cabinet dimensions are H 30 cm W 19 cm and D 16 the rotation point called Point of Reference POR in EASE position relative to the edge of the case as in figure are yrp 8 cm and Zrp 15 cm Assuming that the 0 0 0 is the position of the POR the loudspeaker case design is straightforward j View 2 View c EASE 4 1 2Way Loudspeaker 01 12 2005 1 04 32 Proel P A ing Ponteggia The model is complete and can be saved to be used into the simulation program In figure an example of the loudspeaker model used into a room for acoustical coverage prediction is illustrated Once a loudspeaker model is created the model is saved as unauthorized model to authorize the model is it necessary to contact directly ADA and ask for the Authorization software that mark your 10 model as authorized This guarantees that a loudspeaker model is approved by the manufacturer More information on the EASE Loudspeaker base module can be found on EASE manual and documentation another good source of information is the website www auralisation de Conclusions This work is a first attempt to simplify the measurement model simulate process with CLIOwin and EASE It currently allows only the use of horizontal and vertical polar data sets to create magnitude only models We are currently carrying on experimentation with full sp2. Good y Value 0 00 m 1600 H2 600 Hz Good 2000 Hz Good z Value 0 00 m 2500 H2 Good 3150 H2 Good Authorized Mo 4000 Hz Good l 5000 Hz Good ate and Version 5300 Ha Good Checked 8000 Hz Good Yes 10000 H2 Good Check Speaker Ok Check the Symmetric box and follow the instructions then click on the button Check Speaker In EASE 3 0 it is possible to have symmetrical loudspeaker along the y z plane placed only in symmetrical rooms In EASE 4 1 this constraint is relaxed and it is allowed to use asymmetrical loudspeaker models in symmetrical rooms When creating a loudspeaker model with the manual entry or with ASCII import mode is it possible to manage the symmetry into the EASE Speaker Base module discarding an half polar or using the mean value of the two half polars The model must be completed by the calculation of the coverage cone directivity and efficiency Edit gt Speaker Data or just press lt F4 gt Click on Compute Cone Compute Directivity and Compute Efficiency in this order then click X Data Good Sensitivity dB Impedance ohm Efficiency 4 Compute 1250 Hz ee 1600 Hz Directivity dB lo 2000 Hz a 2500 H2 Q 1 _Compute_ 3150 Hz 4000 Hz Max Power W 400 5000 Hz 6300 Hz 8000 Hz t RMS Program C Peak 10000 Hz Data Origin EASE 4 1 ASCI Import Compute Cone Apply Cancel on Apply At this point i
3. seen for the horizontal polar Data analysis with CLIOwin 7 Once horizontal and vertical data are collected is it possible to look at the dispersion patterns thanks to the new possibilities of CLIOwin 7 Waterfall amp Directivity module Please refer to the CLIOwin user manual for detailed explanation of this module Some examples of polar plots and attenuation maps are reported in figures 12 and 13 Remember that the angles of the data collected are those indicated in figure 14 since they refer to the apparent microphone rotation around the loudspeaker Bg m 2 r cited i Ll eco AH ROTH We ET SEE Figure 12 CLIOwin 7 polar plots Proel Directivity 09 10 2005 18 17 27 180 00 0 dB 10 120 00 20 90 00 30 60 00 40 30 00 50 2k 10k 20k22k339 Hz Ref0 1 3 Octave CLIO Figure 13 CLIOwin 7 directivity color map ji y yn A position Figure 14 Horizontal and vertical angle reference as measured with autosave HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO Conversion to the EASE format with CLIOZEASE The conversion from horizontal and vertical sets of CLIO mls impulse responses to EASE data tables is accomplished by the conversion software CLIOZEASE The conversion software remaps the measured polars into the EASE coordinate system calculates the frequency response and the third octave smoothing and perform the interpolation of the missing p
4. chamber if the space dimensions are quite large and the reverberation time is sufficiently short polar measurements sets can performed with success If a non anechoic space is used to perform polar measurements it must be noted that the room reverberation time must be short enough to avoid time aliasing between successive measurements if using an automated process the operation must be trigged to let the acoustic energy in the room to decay A detailed and elegant explanation of the reflection free environment can be found on 5 where an ceiling reflection 2 source wall H receiver wall R direct path reflection e reflection h floor reflection A te MN eee oi d eee da eee idee ot d A a ai Si So Me Figure 3 Shoe box model HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO ellipsoid of free reflections is defined Here are reported only few practical considerations if the room is a shoe box with the loudspeaker and the microphone placed as in figure 3 given the room and measurement setup dimensions is it possible to calculate the threshold frequency Is it also possible given the height of the loudspeaker position h the measurement distance d and the threshold frequency to calculate the minimum room dimensions Once a suitable space anechoic or quasi anechoic for making measurements with the correct band
5. 4 1 can contain or not phase information With EASE is supplied an Excel xls spreadsheet that can be filled with the same data as the EASE attenuation data table with a minimum of possible automation thanks to Excel At the end of the data entry the spreadsheet create an xhn ASCII file that can be imported by EASE In EASE 4 1 is it also possible to import directly a collection of impulse responses in different formats wav tim frq The file naming convention is not compatible with the CLIO one so this approach is not working O x Loudspeaker Info Manufacturer Rogers Speaker Name 2 way Loudspeaker Power Handling 75 Wo Impedance E ohm Clo Data File Set Horizontal CAD aniele MisureSPolan Aogers A oger _0 E Vertical BE antelekisurekPolar Rogers A oger Y Ed Measuring Environemen Distance fi m 6 Speed WF Sound 344 mes dE shift jo dB Horizontal lironin Vertical Mirrorin f Jane f kane E Mean Mean Right 80 f Top 0 180 Left 0180 f Bottom 0 180 Model created with ClioTokase FileType Speaker Types Pormat 3 0 LengthUnit m Measurement Time wWindowin Start l m Stop m Interpolation Function f EASE elliptical balloon Linear Smoothin Ta E ictaves Data Crunch and Expor Export impulses a way Save shn Create ASCII T Include Phase Data Figure 15 CLIOZEASE converter screenshot HOW TO CREATE EASE LOUDSPEAKER MODELS
6. HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO Daniele Ponteggia lt dp audiomatica com gt A procedure to measure loudspeaker polar patterns using CLIOwin 7 software and thus create a model for EASE 3 0 and EASE 4 1 for Windows software is described Magnitude models only are considered since we rely on the measurement of the horizontal and vertical polars The measurements shall be made in a Suitable anechoic space using a software controlled turntable A simple data processing software is presented to manage the large amount of polar data and to convert the data into the EASE xhn ASCII file format Introduction Electro acoustics simulation softwares require the knowledge of the polar pattern of a source In EASE 3 0 and EASE 4 1 the source is modeled as a point with a given attenuation pattern which is function of the angle of radiation The sphere around the source is sampled in 5 angles giving a total number of 2522 points Here is described a simplified procedure that requires the knowledge of the horizontal and vertical polar measurements only This procedure is valid under certain assumptions the loudspeaker must present a mild asymmetry between horizontal and vertical polar patterns An interpolation of the missing spherical polar data must be made the procedure is valid as long as the interpolation algorithm is valid the model must be based on magnitude only data and not on complex data In EASE 4 1 the p
7. LOUDSPEAKER MODELS USING CLIO CLIO ELECTRICAL amp ACOUSTICAL TESTS MLS Frequency Response j ol x R Ele Analysis Controls Window Help 18 x S Bela Z WRENLA Ts WE lea O Infi N 0dBY a vw koni dBis A OUdBV a w enf amp fe a Out 00dBu a 2 t t fa 273 C Unsmoothed a TACT Sara Ji Aubspte a na n TOA CALL LA UTNE LL zan Turntable rntable Contra LUA ann Filename A dBV Unsmoothed 48kHz 16K Rectangular Start0 00ms Stop 341 3ims FreqlO 2 93Hz Length 341 3ims Figure 6 CLIlOwin autosave and turntable control Binary Format AutoSave Sethr lt a X BUT ka Angular Filename amp Settings Folder Star Increment l Total K umbek Ok Cancel Figure 7 Autosave settings CE onn Indirizzo la C Daniele Misure Polari Rogers v Vai Centrale_OO mls Centrale O Centrale O Centrale O amp me Centrale_O Centrale_O Centrale_O 500 mis 1000 mis 1500 mls 2000 mis 3000 mis 3500 mis 2500 mis SB A SB AE 665 A n K Centrale O Centrale O Centrale O Centrale O Centrale O Centrale O Centrale O Centrale O 4000 mis 4500 mis 5000 mis 5500 mis 6000 mis 6500 mis 7000 mis 1 AA BE A AE A 6 4 Centrale O Centrale O Centrale O Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O 8000 mis 8500 mis 9000 mis 9500 mis 10000 mis 10500 mis 11000 mis 11500 mis A A RA A A amp B A A BR Centr
8. USING CLIO Needles to say the easiest way is then to create the xhn ASCII file with the CLIOZEASE conversion software and then to import it into EASE Here is reported a brief examples of the operation that must be carried out in EASE to complete a model Open EASE and import the ASCII xhn file from the EASE Loudspeaker Base module File gt Import ASCII Choose a folder to store the model ID xi r Current File 2 WAY LOUDSPEAKER 2 WAY LOUDSPEAKER Rogers File 2 way loudspeaker Path C Daniele Misure modelii rogers Save Waste Change Destination Path For All Files Save Al Cancel At this point only attenuation data are loaded into the EASE loudspeaker model If the speaker is supposed to be symmetric on the horizontal plane Edit gt Speaker Model File Exists r Existing Files C Skip Existing Files Silently Prompt If File Already Exists C Overwrite All Existing Files lf Speaker Model 2 Way Loudspeaker EASE 4 1 15 x Speaker Model Band _ Cov Line Atten _ Phase a 100 Hz Good 2 Way Loudspeaker 125 He Good Manufacturer 160 Hz Good Symm Bossers tttst S S 200 H2 Good 250 H2 Good Symm pieds taste 5 315 Hz Good i Details gt gt I Symmetric _Details gt gt 400 Ha Good l Use Phase Data ___500 Hz Bel Good 630 Hz Good m Point Of Reference 800H2 M Good 1000 H2 Good x Value 0 00 m 1250 Hz
9. ale_O Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O 12000 mis 12500 mis 13000 mis 13500 mis 14000 mis 14500 mis 15000 mis 1 A A R Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O Centrale_O T 17500 mls 18000 mls 500 mls 1000 mls 1500 mls A RAO R RA R AO AR N zi Oggetti 294 nascosti 1 75 9 MB 4 Risorse del computer Li Figure 8 Folder with saved mis data fe eeeee FEI Pi EZI L D pa Pi EPI FD 5 HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO Microphone ou on Sa a wa Seeeeme eee ee Turntable rotation Figure 9 Vertical polar setup ROTATION AXIS a MICROPHONE SIDE VIEW ROTATION POIN ai Ze oo POINT OF REFERENCE FRONT VIEW Figure 10 Model dimensions vertical setup convenient root file name the file will be automatically named by CLIO as root file name angle the root file name can be called for example DUT H where H denotes that this is the set of horizontal polar measurements To gather the full horizontal polar the angular settings must be start 180 increment 5 total number 72 At this point the set of polar measurement can be run The process will takes few minutes depending on MLS settings If an automated rotating turntable is not available a manual measure rot
10. ate save procedure must be adopted Figure 8 shows a folder with a series of file saved into the CLIOwin polar auto save format Vertical polar setup The loudspeaker must be placed on the turntable on its side inclined 90 towards right as shown in figure 9 The measure set must start with the speaker giving its back side to the microphone Again the clockwise rotation of the speaker is equivalent to an apparent counterclockwise rotation of the microphone around the speaker Care must be spent in positioning the loudspeaker on the turntable letting the rotation axis to pass through the rotation point as indicated in figure 10 This can be quite tricky since it means to move the relative turntable to microphone height Usually the easiest way is to move the microphone height the assumption that the microphone and source rotation point positions on the room are fixed is no HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO Audiomatica LogChirp Impulse Response 21 11 2005 14 52 00 0 20 0 00 1 1 2 3 3 4 46 5 7 6 9 8 0 9 1 ms 10 11 Figure 11 An example of shorter reflection free response more valid in a non anechoic space a previously windowed response can be no more reflection free The windowing needed by the horizontal and vertical measurement sets can be different the worst case must be used to window all the measurements The measurement process is the same already
11. be windowed to eliminate the sound reflections If needed set the window in CLIO with start t O and stop time as required Horizontal polar setup To measure only the horizontal polar the loudspeaker must be placed on the turntable in upright position In case of small loudspeaker it can be required to use a speaker stand to raise the box from the turntable in order to avoid reflections from the surface of the turntable itself The speaker must be initially placed on the turntable rotated around the z axis by 180 facing the back of the enclosure to the microphone as showed in figure 5 In this way the clockwise rotation of the speaker is equivalent to a complete counterclockwise apparent rotation of the microphone around the speaker itself The measurement process can be automated with CLIOwin auto save and external hardware control features Be sure to open the external hardware control window set the proper LPT port for the turntable and activate link to measurement In order to control the turntable this window must remain open during the measurement procedure Open the MLS amp LogChirp Analysis module check the auto save and measure in a loop icons see figure 6 The auto save settings are shown in figure 7 The auto save settings window is available from the file menu Use binary format choose a folder to store the measurements Set a y Figure 5 Horizontal polar setup HOW TO CREATE EASE
12. here automated measurement In the near future a new version of the software will perform data conversion of full sphere measurement sets to realize complex data magnitude phase models Bibliography 1 Electro Acoustic Testing Company What does it take to measure a loudspeaker http www etcinc us Parameters htm 2 S Feistel W Ahnert The Significance of Phase Data for the Acoustic Prediction of Combinations of Sound Sources AES 119th Convention New York 2005 October 7 10 3 F Seidel H Staffeldt Frequency and Angular Resolution for Measuring Presenting and Predicting Loudspeaker Polar Data JAES Vol 44 No 7 8 1996 July August 4 Audiomatica CLIOwin 7 User s Manual http www cliowin com 5 C Struck S Temme Simulated Free Field Measurements JAES Vol 42 No 6 1994 June
13. his distance between the cabinet reference point and the microphone axis along z The reference point the point of rotation and cabinet dimensions must be annotated in a detailed way in order to create a correct model of the loudspeaker see figure 4 It is suggested to take as a reference point a vertex or the center of an edge of the cabinet The distance d between the rotation axis ad the microphone membrane must be recorded to later refer the measurement to the 1 W 1 m standard It is not necessary to feed the speaker under test with a power that produce the 1 W m sound pressure level at the measuring distance d This can lead to overpowering the speaker pushing towards the non linearity zone of the measurement system and the speaker itself Is it recommendable to use moderate output levels reaching the best trade off between level and measurement signal to noise ratio It is possible to modify the levels to specific on axis values when importing the model in EASE or shift the levels of a given amount of dB into the data processing software lf the power feed to speaker is known using d and the nominal power W applied is it possible to calculate the 1 W 1 m on axis response Since the source is modeled as a point source its 1 W 1 m on axis level is given by L 1W 1m L d 20 log d 10 log W Microphone If the measure is made in an anechoic space no time windowing is needed elsewhere the tail of the response must
14. n and in 21 third octave frequency bands as a 37 x 72 x 21 three dimensional matrix Executing polar measurements Measurement setup must be arranged in an anechoic space In order to minimize apex error and diffraction effects the distance between the microphone and the rotating loudspeaker must be sufficiently large In the literature different values are proposed ranging from not less than 4 m to 6 8 m 1 In fact the distance d between source point of rotation and microphone is dependent on the loudspeaker dimensions and geometry the value of 4m is a trade off between measurement distance and anechoic chamber dimensions It has been recently demonstrated 2 that when measuring loudspeakers as point sources the minimum measuring distance that must be achieved in order to minimize simulation errors is dependent from the distance of the acoustic center from the measurement rotation point and frequency Given the loudspeaker geometry and the measurement distance d either for magnitude only and complex data there is a critical frequency threshold below which the error is bounded A detailed explanation is beyond the scope of this document the reader is strongly encouraged to refer to the original paper If an anechoic room is not available is it possible to use an outdoor space or a large room together with the windowing of the measured impulse responses to get rid of the reflections 3 The window length sets the low frequency thre
15. oint source can be described in a more detailed way using magnitude and phase polar patterns While the interpolation of magnitude data can be accepted the interpolation of phase data is not meaningful Thus the procedure here described is valid for fairly simple loudspeakers as example loudspeaker with polar pattern 90 x60 or 50 x40 and for magnitude only models i e EASE 3 0 or EASE 4 1 without phase EASE loudspeaker models The reference system used in EASE is depicted in figure 2 The P 0 0 point is the on axis point the angle O can vary between 0 and 180 from the front to the back of the source The angle can vary between 0 and 355 rotating counterclockwise from the right side of the source to the top and so on Figure 2 EASE reference system The attenuation respect of the on axis value data must be known for every P 8 Q point with 5 resolution for every one third octave frequency band from 100 Hz to 10 kHz Inside EASE loudspeaker data is stored in 21 tables one for each one third octave frequency band in the range 100 Hz 10 kHz Each table is 37 rows x 72 columns containing the attenuation data in respect of the polar coordinates 8 and The version of EASE 4 1 a second set of tables allows to store also phase data Is it possible to consider the entire attenuation data set of a HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO loudspeaker measured with 5 degree resolutio
16. olar data The measurements must be carried out following the procedure indicated before Please note that the software is in early alpha stage but it is already functional and allows to perform conversions The use of the software is straightforward simply fill the form with the manufacturer and loudspeaker name the nominal impedance and choose two files from the data sets for the horizontal and vertical polar data saved in mis format then click on the Create ASCII button After few seconds the ASCII file will be appearing in the Memo box Select the text and copy it to the notepad then save with the xhn extension or just press the button xhn Save The file xhn is readable by the EASE loudspeaker module BE C2E v 0 1 0 3 Importing the xhn into EASE There are three ways to create an EASE loudspeaker model manual entry ASCII import or impulse responses import only for EASE 4 1 Manual entering even only the horizontal and vertical polar attenuation data can be a tiresome task it means filling 21 x 37 x 4 3108 cells It is practically unmanageable Nevertheless it can be quite instructive to play around with the attenuation data tables to deeply understand EASE loudspeaker models The import ASCII feature is the way to automatize the data entry task a file structure is indicated and can be compiled by an external software such as the converter software described later on ASCII files to be imported by EASE
17. s it possible if desired to draw the loudspeaker case Edit gt Case li Case 2 Way Loudspeaker EASI File Item Edit View Insert Tools Utilities Mouse Share Window Help eS q 88 Nea t MB peet eo Ol KFT FRR RES BAmM PM o e DLAS x fay alon as ole x Ala lale eS o s 0 KF BTA TT E 4 Item None PickedLoc 0 00m 0 00m 0 00m Mouse Mode Pick Item Hor 120 Ver 30 Cursor 4 91m 4 50m 5 00m Checked Vero Is it possible to draw the case with faces or with edges Using faces you will see the case solid rendered into the EASE Eyes Module The reference point the point used by EASE as a reference for all the simulation is 0 0 0 unless it is changed by the user inside the case edit by Tools gt Move Point of Reference Since the position of the Point of Reference POR is relative to the case it is not necessary to move the POR if we correctly draw the case around the POR HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO In the loudspeaker of this example the measurement setup is HORIZONTAL POLAR SETUP 4 PO ki ki dine SO La ROTATION POINT e p a se l we MICROPHONE SIDE VIEW Co FRONT VIEW VERTICAL POLAR SETUP ROTATION AXIS d _ O me gt Wajda POIN CG yo Z lt P rp
18. shold for the measurement In brief early reflections means a short time window hence an high low frequency threshold not allowing for polar measurement in the low end The formula for the low frequency threshold is quite simple 4 1 f LOW t window To allow the desired low frequency threshold the loudspeaker must be placed far away enough from boundary surfaces In practical terms for a threshold of 100 Hz the needed reflection free time window length is 10 ms Taking into account the travel time of the sound from the source to the receiver at a measuring distance of 6m with a speed of sound of 340 m s the minimum distance from the first reflecting surface is 3 62m In outdoor this means that is needed to place the loudspeaker in top of a layer structure or suspending it in indoor means also the use of a really high ceiling at least 7 24 m A solution to the problem can be achieved eliminating the floor reflection using highly absorptive material placed on the ground between the source and the microphone position This leads to a practical height for the loudspeaker allowing measurement down to the 100 Hz range in outdoor and large closed spaces Outdoor measurement are anyhow generally not recommendable due to the high susceptibility to noise vibration and environmental variations as wind and heat Measurement in large indoor spaces with anechoic floor between source and receiver can be a real alternative to the anechoic
19. speaker has a regular shape In case of trapezoidal enclosures some care must be made the use of custom made adapters as simple as wooden wedges can improve the stability and the precision of the measurements Before starting to take measurements we have to define a point of rotation of our loudspeaker This does not necessary coincide with the geometrical center of the cabinet and in principle must be near as possible to the acoustic center of the loudspeaker which is not well defined point in Space since for a multi way loudspeaker it is moving with frequency lt is important to define the relationship between the rotation point and a reference point of the cabinet In this way is it possible to include into the model the geometrical dimensions of the loudspeaker cabinet relative to the position of the point source assumed as the acoustical model of the loudspeaker itself ROTATION AXIS a ka Yi p ROTATION POINT VE ii o rp ay MICROPHONE SIDE VIEW mo TK power 2 lt P POINT OF REFERENCE FRONT VIEW Figure 4 Model dimensions horizontal setup 3 HOW TO CREATE EASE LOUDSPEAKER MODELS USING CLIO We call yp as the distance along the y axis between the reference point and the rotation point Also is of great importance the relative height between microphone and cabinet reference point let s call Z t
20. width is found the next step is to decide how to collect polar measurements In making polar measurements there are different possible approaches rotating the microphone around a fixed loudspeaker rotating the loudspeaker in front a fixed microphone using an array of microphones While in theory all these approaches are valid again some practical considerations must be taken into account The most used technique is to rotate the loudspeaker in front of a fixed microphone this allows for a better precision in the positioning of the microphone loudspeaker group this also guarantee a stable acoustical environment Rotating the microphone around the loudspeaker is more prone to positioning errors Using arrays of microphones can speed up significantly the measurement process but is it expensive and some care must be made on the compensation of microphones and environmental differences The loudspeaker rotation can be realized in a rather simple way using a turntable To accelerate the measurement process a software controlled turntable has to be used in our tests we used the OUTLINE ST 2 turntable which can be automatically controlled by CLIO via the PC parallel port A manual turntable can be also used but the process is quite time consuming Measuring only the horizontal and the vertical polars it can be quite easy to place the loudspeaker upright and rotate it around its y axis by 90 folding it on its side at least if the loud
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