Ultimate Equalizer V8.0 Supplemental User Manual
Contents
1. A A TEN P m e n 2 m MM ORS I m Front Left Figure 1 Experimental FIR filter with four notches The above filter is rather difficult proposition to manage by a DSP device It has been specifically designed to stress the FIR filter and unmask any potential low frequency deficiencies It is quite unlikely that you will ever need this type of DSP filter as loudspeakers typically do not exhibit such high Q peaks in the bass response We can now implement the filter from Figure 1 using a FIR filter with various low frequency resolutions and examine the results First a FIR filter with bass resolution of 11 72Hz was used and the result is shown on Figure 2 below 2 SPL Phase Mike Preamp Post Processing 12 180 120 160 105 100 85 20 80 0 78 20 65 0 80 80 59 42 40 460 dB deg 10 20 30 40 60 80 100 200 300 400 500 1k 2k 3k 4k Bk 8k 10k 20k 30k 40k Hz Figure 2 Experimental FIR filter with four2. E sasansnsnanacsnsnsnsnsesosnanavevansnansnananandiansnansenesnsnaginsseneennn sveseusnanananensnsnsnsensafossnseansnsensssnananenonens O LETTERE Mii fen ti Se i Sn Sires OOA E Sere PR E D e 0 TT EE E ttn X tien M e X A
3. 53 4 1 1111 1 1 11 C 34 1 141111 552 Figure 23 Example of MP stop band attenuation difference with smoother window 16 The effect of the window s shape is even more pronounced in linear phase mode Here is the impulse response of the linear phase version of the same filter Impulse Response Window sponse Window Impulse Re Reduced artifacts Reduced artifacts _ dues 10 smoother window s slope window s slope dow ing smoother win 24 Apply Figure By applying smoother window Wide Window OFF we can observe reduced artifacts towards both ends of the symmetrical impulse response This reduction will result in by 1S CaSe in th I 1 3 r Sea i as can be seen on the picture on the right 1 iid i 4 1 Rd 10 1 d stop band attenuat as much as 40dB improve E ETAEREREHSES 4 8 E ES 6 TII 4 b below 140dB as well ise t reduced no 1 pass filter will exhi 20Hz Low E 4 _ 4 __ 4_ 4 SS GEN CE CEEP 1 I 1 1 oS 1 LT L d d4 CECEH
4. 4 4 3 3 T l f t EE gt 1024 buffer 1 T 2 8 oe 2048 buffer 4 ert ee saa s e gt gt gt 4 4 rte eR 4 4 4096 buffer 4096 buffer SPL Window r Figure 26 Example of LP stop band attenuation difference with smoother window 18 Method 1 and Method 2 Explained Method 1 rotates impulse response by fixed amount 128 bins Method 2 rotates impulse response by UE partition size 4 Location of IR Method 1 2 667ms IR latency at 48kHz sampling Impulse Response Window ku Figure 27 Method 1 vs Method 2 explained graphically Latency figures given in UE7 Manual on page 5 are given for Method 1 Method 2 will add additional 19ms latency There are some simple but obvious rules when you deal with a set of impulse responses 1 You can not mix minimum phase and linear phase impulse responses in one project file this 1s obvious as the latencies would be quite different for ea
5. 25 i dB um 08 0 7080 0 20 30 40 5060 80 10 20 30 40 60 80 100 200 300 400 600 2k 3k 4k Bk 8k 10k 20k 30k 40k 50k 60k 80k 100k 200k Hz Figure 8 Measured E and e fully extended and perfectly cleaned by HBT In summary extended MLS frequency range extended frequency range of the HBT operation resulted in quality data points to match the requirements of high performance FIR filter In addition please note that the phase response can be made as close to true minimum phase as they come Design and optimization of FIR impulse response Note Before you select Optimize Export Impulse response please select Position IR Windows FIRST to position and re size the two display windows associated with the process see menu option highlighted below Import IMP SPL 2 Ref 0d6 Import LMS SPL Z TS ReF 5SPLdEB Import CLIO SPL Z TS Import MLS54 SPL Z Export SPL Phase AE 0 008 TRG TT Optimize Export Impulse Response Position IR Windows FIR impulse response can not be obtained by simply performing inverse FFT on the desired amplitude phase response of your filter Such raw impulse response would have to be shifted truncated and windowed in this order The final outcome the ability of the impulse response to deliver the required amplitude and phase responses will depend on how the raw impulse response is processed Design and optimization of the impulse response can be perform
6. 0885591927 236 08 5 1 5670545963e 06 bz024 4 60371635420e 06 b 2 2018602976e 06 0 25 88452134596 08 7 3 1433348795e 06 l b2026 5 84044 8835 8 08 8 3 989849932 366 08 b2027 4 8 58 25333 6 08 9 5 1637171055e 06 2028 83 48 11092 2 08 Figure 33 Start of the miniDSP ASCII file 6 4077 748902e 06 f 7561289800e 06 9 57236231 742e 06 1 0815708223e 05 1 3195950720343e 05 1 4830262444e 05 1 749934592 7e 05 1 907 7506295e 05 2 249994 0314e 05 2 378372060476 05 2 79530183721e 05 3 0313878597e 05 3 333949804 82e 05 3 8228758058e 05 3 858096017 7 05 4 6902352943 05 4 5740631681e 05 5 435009 3446 05 4 5478802096e 05 6 01090541 75e 05 S HI 23 7 0345348104 8e 0 6 24265224150e8 08 2804087203e 05 l1 0438008236e8 05 13550165958 08 819382 9416 08 1 81 48054956 08 4 51914239116 09 6 656781 7925e 10 1 2 766 04982e 08 1 1088148177e 06 1 231382 27850e 06 4 9530949872326 09 4 0582119887e 09 7 198097673526 09 3 3021558821e 09 1 615749645272 e 09 1 6410042769e 10 1167635353e 11 end of the miniDSP ASCII file The number of impulse response coefficients in the exported file depends on the size of UE buffer mode of operation and UE version 8 partitions or 16 partitions Currently the 8 par
7. h a EENE EREE EE DES uM DEA MEEA SEED GEED uM SERD WERS gt to smoot Figure 25 Example of LP stop band attenuation difference with smoother window 17 EEHEEHE als j t es i 4 i anno nen en EA EA E t E D 1 t GERNS GEM 1 1 t t teste gt gt gt gt gt gt gt 4 4 4 pete Liu Lr 4 T f e lt e 4 4e lt e4 t Ee t 4 4 B N Wide Window OFF SPL Window LL AHHH H AHAHHH HHAH H HAH When should you apply wide window Typically for short filters like 512 1024 buffer in partition mode see comparison below with 121117 24dB oct LR 4T Blackman dow win 512 buffer T 1 31 1 ff tt S 512 buffer Wide Window ON 1024 buffer Q tt El A A A UNES VINE
8. 9 473623174219e8 06 1 0819 70822270e 05 1 31997270342538 05 1 483026244387e8 05 1 7200345502731e 05 1 907750629471e8 05 2 2490954031445e 05 2 3 837 26646808 05 2 7 05018372126e 05 3 031387859664e 05 3 2538 949804 0 05 3 822875805781e 05 3 8380960177165e 05 4 6903529437268 05 4 574963168125e 05 File Edit Format wiew Help 2 680280705097 28 08 2 08855015225028 08 4 63 16354204 38 08 2 88452713586068 08 5 84044 883567 08 08 4 85B8725333175e8 08 6 48 11050373148 08 634548104818e 00 6 24 62 418995e 08 280408 202334 05 4 0438008 355 09 152 50168595 9 08 2 819382594055e 08 1 6174805494 9 e 08 4 6160143911562e 09 6 6567817 92458e 10 1 27662049082038 08 1 108814817741e 08 1 23138228502 8 08 4 950949872295e 09 4 0582115886078e 00 1980976 73466e 09 3 3027155882 068e 09 1 615749645190e 09 1 6410042769058 10 2 116763535287 8 11 Figure 32 Start of the ASCII file end of the ASCII file miniDSP ASCII Files example shown below BjLR i1000Hz Min Phase 24dB HP mir File Edit Format View Help loj x 1 1 x File Edit Format View Help 0 0000000000e8 r00 5 8888158350e8 08 3 80403030468 08 1 906543589 7e 09 2 2 4612918997ea 0 7 b2021 7 053953 8816 08 3 5 4127400517e 07 bz 022 2 68020 05108 08 4 9 79846390698 07 2023
9. data below 10Hz Figure 5 Measurement system showing results in 10Hz 50000Hz bandwidth One issue immediately observable from the Figure 5 15 that there is no visible frequency data below 10Hz and this may present a problem Second issue is with the break up region above 3kHz The break up region is about 35dB below driver s operating level and should be avoided and filtered out in the final design but for now it s not contributing anything to the design just making the graphs less readable As discussed in previous chapters good low frequency resolution is important in any serious subwoofer and room equalization work Recall that high performance FIR filters begin to use frequency bins well below 10Hz see table below showing several initial frequency steps of FFT in two example FIR filters 0 00 0 00 Hz 1 46 0 73 Hz 2 03 1 46 4 30 2 20 5 86 2 93 32 3 66 8 79 4 30 10 25 5 13 11 72 5 86 13 18 6 59 14 65 7 32 15 11 8 08 17 58 8 790 19 04 95 52 20 531 10 25 21 97 10 99 23 44 11 72 24 90 12 45 26 37 13 18 27 83 13 92 So what are the options for improving the measured data quality 6 1 Provide SPL Phase measurements extending well below 10Hz and into the frequency range required by FIR low frequency resolution Starting with V8 UE software release all internal data processing is conducted from 0 51Hz to 272 000Hz This extended frequency range is available in t
10. notches implemented in low bass resolution FIR Our FIR filter employs a sequence of frequency bins starting like in the table below 0 00 41 72 23 44 35 16 46 88 38 50 0 51 82 03 03 75 105 47 It 15 observable that none of the notch frequencies are close to the frequencies used by the FIR filter therefore the filter has great difficulties executing the requested filter curve Next an FIR filter with bass resolution of 2 93Hz was used and the result 1s shown on Figure 3 below SPL Phase Mike Preamp Post Processing 15 180 o IUS el 115 140 110 120 105 100 100 80 35 amp 3 40 85 20 80 0 78 20 70 40 55 100 50 142 45 140 35 1180 i i 4 j i i i 3d 1 1d i 1 E i 323 b de 4 1 4 E B dB deg 10 20 30 40 60 80 100 200 300 400 600 2k 3k 4k Bk 8k 10k 20k 30k 40k Hz Figure 3 Experimental FIR filter with four notches implemented in high bass resolution FIR The second FIR filter employs a sequence of frequency bins starting like in the table below 0 00 79 10 161 13 2 03 87 03 164 06 55 84 95 188 38 11 72 87 89 172 85 60 2 14 65 175 78 17 58 93 73 178 71 20 51 59 98 181 64 23 44 99 61 184 57 26 37 102 54 onus 29 30 105 47 32 23 108 40 133 35 35 16 111 33 195 29 s 199 22 41 02 114 76 262 5 43 95 117 19 205 08 46 88 170 127 208 01 49 80 123 05 210 94 It is ob
11. Phase Wike Preamp Post Processing SPL Phase Nike Preamp Past Pracessing 35dB extra attenuation Figure 4 Examples of natural stop band attenuation of loudspeaker drivers However we certainly hope that our FIR filter will run with better figures than those discussed above Once again Steven W Smith in his book Digital Signal Processing A Practical Guide for Engineers and Scientists page 296 concludes 1 you really need more than 100dB of stop band attenuation you should use double precision Single precision round off noise on signals in the passband can erratically appear in the stopband with amplitudes in the 100dB to 120dB range Realistically if the single precision FIR filter can achieve 110 to 120dB stop band attenuation it will be doing quite well For more information please see Design and optimization of FIR impulse response chapter Performance Improvements in HBT and MLS Typical DIY audio PC based measurement system will measure and present the resulting frequency response as some SPL phase curves between 20Hz and 20000Hz Some systems will go beyond these limits and offer frequency range 10Hz 50000Hz An example of such system is shown below 3I MLS Frequency Domain Ampl 147 00 dB Phase 0 00 deg Freq 42706 0 Hz m ol x SPL Phase Mike Preamp Post Processing 125 180 120 160 111698 lt _ 105 100 100 80 Missing
12. Ultimate Equalizer V8 0 Supplemental User Manual June 2015 New Features Implemented in Ultimate Equalizer 8 0 Digital 1 Implemented importing Impulse Response in ASCII files into MLS system 2 New function for design and optimization of FIR impulse response 3 Colour Cycling in MLS plots 4 Export of Impulse Response in ASCII format and miniDSP format 5 Performance improvements in HBT and MLS 6 Imports UE V7 files This User Manual is intended to provide information about new features in version 9 and should be read in conjunction with the full User Manual for version 5 6 and 7 and available from Bodzio Software Pty Ltd website 1 Low frequency accuracy Low frequency resolution Low frequency resolution considered in this manual is defined as LF Res Sampling frequency FFT length In DSP systems incorporating frequency domain convolution the IR length relates to the size of the FFT used in DSP process Therefore the above formula could also use IR length in the denominator Why is low frequency resolution important Let s assume that we have designed a FIR filter having four notches at low frequencies just like the one below where the first notch is located at 15Hz second notch 15 located at 50117 third notch 15 located at 100Hz and the last notch 15 located at 200Hz All Q factors are equal to 20 3 Ultimate Equalizer Frequency Domain 16 Outputs X
13. ch option 2 Youcan not mix Wide Window ON and OFF options in one project This is a global project wide setting If you wish to change this setting you must exit Optimize Export Impulse Response dialogue box then change this setting in System Response dialogue box and then re deploy the Optimize Export Impulse Response dialogue box it will have now the correct settings 3 You can not mix IR Optimizations Method 1 and Method 2 this is obvious as the latencies would be quite different for each option 4 Youcan choose and mix FFT Windows in one project This is whole purpose of optimizations 5 Youcan choose and mix IR Opt optimization parameter in one project This 15 whole purpose of optimizations 19 6 Mixing Project Files between 8P and 16P versions of Ultimate Equalizer is allowed but you may wish to re optimize impulse responses to always get optimum stop band attenuations 7 Every time you change the UE buffer size you must re plot all frequency responses in the System Design screen before you re optimize impulse responses An example of fully edited and optimized set of 16 impulse minimum phase impulse responses large 7 2 HT system is shown below All data is saved to the project file so when the project is opened again you should firstly re plot all port outputs on System Response screen then go to the Optimize Export Impulse Response dialogue box to see exactly what optimization options have been saved Now
14. d the measured data into the new wide frequency range of V8 MLS measurement system in V8 will import impulse response files res files generated by SoundEasy so you can use driver measurements performed by SoundEasy Recommended Reading Digital Signal Processing A Practical Guide for Engineers and Scientists by Steven K Smith Newnes an imprint of Elsevier Science ISBN 0 75067444 X 26
15. e eee ee ee a eee 4 4 b 4 4 4 4 O 4 4 gt gt gt Figure 17 Examples of L R band pass filter 500 2000Hz cut off and 4096 coefficients You will need to perform the tree step process of optimization outlined before but the optimizer will throw the final answer right away The only parameters that may have visible effect on the stop band performance is the selection of Wide Window ON OFF in the System Design dialogue v Use HBT Data SPL Only EQ Wade Window 13 Optimizing Equalizing filters So far we have been reviewing the design and optimization of impulse responses associated with crossover filters As it happens there is no difference in the sequence of this process when you design a filter intended to equalize your loudspeaker driver in both linear phase or minimum phase Impulse Response SPL Window Figure 18 Minimum phase equalizing filter Impulse Response SPL Window Figure 19 Linear phase equalizing filter As shown on the figures above minimum phase version after optimization and linear phase version have very similar stop band attenuation better than 130dB Please observe phase response differences in both type of filters 14 Monitoring Impulse Response Impulse response can be viewed on a separate window titled Impulse response Window Impulse Res
16. e 05 1 483026244387e 05 1 729934592731e 05 O x 3 031387859664e 05 3 335949804750e 05 3 822875805781e 05 3 838096017716e 05 4 690352943726e 05 4 574963168125e 05 When the program detects the ASCII file import it will display small information box confirming the number of data point Warning Importing Impulse Response TAT File X File Size 41979 bytes Data 2048 points In this case it is the same file as shown in the exporting example with 2048 data points And here is the content of this file MLS Impulse Response Ref 32000 00 In 0 00 Bin 50 Scroll O 2000 Figure 34 Impulse response imported into MLS system 2 MLS Frequency Domain mfe x SPL Phase Mike Preamp Post Processing 125 180 120 160 105 100 100 80 35 90 85 80 mc 70 65 60 50 40 35 i H i i i i H i H i H H i H i i H i i H i i oi i i H dB deg 10 20 30 40 60 80 100 200 300 400 600 1k 2k 3k 4k Bk 8k 10k 20k 30k 40k Hz Figure 35 Corresponding frequency response 23 File Compatibility Driver files and project files generated with Version 8 are not compatible with Ultimate Equalizer s older files However SPL phase can be imported from V7 driver files so measured frequency response can still be extracted from older files If you intend to use older files it is recommended to import those files into V8 and run Hilbert Bode Transform in File Editor to exten
17. ed in both UE main operating modes linear phase and minimum phase The mode of operation is selected from a checkbox in the System Design dialogue box W Use HET Data M Use HET Data SPL Only EQ ar SPL Only EQ mar Wide Window M Wide Window Figure 9 Linear Phase Mode Minimum Phase Mode The design optimization and exporting of the impulse response 15 available for all 16 DSP channels and can be performed using single dialogue box shown below Optimize Export Impulse Response l X 1 Select Transfer Function to 3 IE Optimization 4 IR Windows summary Output Port 2 Output Port 3 Output Port 4 Output Port 5 2 select FFT Window 7 term Blackman Hatris Cosine Hide Phase Above Show Reference SPL Use Longer FFT Clear SPL Response Impulse Response Window 5 Select File Format a Raw Impulse Response UE format IE Mag Gain 3 miriDSP ASCII Format C3V m E 1 IR Time Scale 2060 nave Impulse Response Figure 10 Controls for design optimization of impulse responses for all 16 channels 1 Select Transfer Function to This list box allows you to choose which transfer function will be converted to impulse response It is essential to use this selection in accordance with the main system diagram This selection determines which impulse response will be exported 2 Select FFT Window This list box contains a selection of many popular FFT windows You may need to t
18. figures obtained with simple algorithm are quite encouraging The average optimization improvements of 30dB will push the stop band attenuation level into 120 to 130dB level and this somewhat better than the expected level for single precision arithmetic If you prefer you can couple this figure with natural driver attenuation in the stop band of 30dB conservative figure would result in acoustical performance of stop band attenuation in the vicinity of 150dB Optimization results of low pass filters particularly with short IRs looks differently and yields somewhat different results Figure 14 Optimization of short low pass impulse response 11 This is particularly visible as in the figure above when original IR of the filter is quite short In this example the impulse response has 2048 coefficients and the filter is asked to perform Butterworth 24dB oct cut off 100Hz The zoom in figure below shows that the default filter has developed some irregularities below 70dB level which translates into phase fluctuations The optimized version is actually performing very well right down to 130dB level with the noise floor at 155dB level n TIT M ei R 100 200 300 400 500 7 1k 2k 3k 4k Bk Bk 10k 20k 30k 40k Figure 15 SPL and phase fluctuations disappear after optimization of short filter Optimization and export of the impulse response is the final stage in your project development Optimization can only be
19. he File Editor screen as shown below i undetectable air movement Figure 6 Measurement system showing results in 0 51Hz 272 000Hz bandwidth But another problem is immediately visible what is going on below 10Hz This measurement was taken outdoor and utmost care was taken to prevent even faint background noises from contaminating the measurement However an imperceptible air movement still managed to creep in and resulted in erratic amplitude and phase fluctuations below 10Hz and particularly below 1Hz The same measurement taken short time later had nearly identical frequency response above 10Hz but was quite different below 10Hz again FFT windowing 15 not the solution but fortunately there 15 a simple processing tool designed to alleviate such problems the HBT The algorithm once properly applied between 12Hz and 2700Hz will maintain the originally measured SPL and phase but it will also clean up all wind noise below 10117 and remove the obnoxious break up fluctuations below 30dB see Figure 7 below Figure 7 Using HBT to eliminate unwanted noise creeping into the measurements 7 We can now supply the improved measurement results to the DSP engine This new data contains mathematically valid frequency data points down to 0 51Hz and a simple parser can extract this data into the FFT frequency bins below 10Hz 3 HBT Editor Window
20. he export Q3 Je L Computer Local bisk C gt Abbey30_IR 823 search 50 0 Organize New folder Favorites amp bbeySO_ir txt Libraries Abbey30 new 1 Documents DB250 IR Ext a Music 06250 30 txt E Pictures Frequencies_Buffer_512 txt H Videos Frequencies Buffer 512 HBT ExE Computer H Frequencies Buffer HBT 3000 5 Frequencies Buffer HBT 3050 5 Frequencies Buffer HBT 3100 5 2g Local Disk ti Network File name Hide Folders Figure 31 Saving impulse response 22 20 03 2015 2 25 PM 20 03 2015 1 07 PM 27 03 2015 2 51 PM 25 03 2013 11 46 AM 10 06 2015 4 37 PM 18 05 2015 1 58 PM 11 06 2015 1 40 PM 16 05 2015 2 09 PM 16 05 2015 2 11 PM nave as type Export SPL Phase TXT Name Date modified Type 4 Text Document Text Document Text Document Text Document Text Document Text Document Text Document Text Document Text Document w E ts Standard ASCII files example shown below BEjLR 1000Hz Min Phase 24dB HP Exi inl x BjLR 1000Hz Min Phase 24dB HP Ex File Edit Format View Help 0 000000000000e amp ec r00 5 88815834965e 08 461291899181e 0 7 5 4127400517258 07 58 70H463006018e 07 1 5657054596308e8 06 2 201860297646e 06 4 1433534879496e 06 3 998499373643 e 06 4 16371 7105461e 06 6 4077 74890749e 06 756128979963 e 06
21. lowest stop band level or somewhat higher level say 120dB but better defined phase response if you prefer Impulse Response SPL Window Figure 12 Selection Opt 928 has resulted in 35085 improvement in stop band attenuation If performed correctly the above process can improve the stop band attenuation of high pass and band pass filters as much as 40 50dB in some instances Average improvement figure would be in order of 30 35dB A couple of examples a low pass and a band pass filter with UE buffer of 512 bins and sampling frequency of 48kHz are shown below These filters would be exported as 2048 long impulse responses and would comfortably fit into many commercially available DSP boards 10 Figure 13 Example of optimization improvements Generally performance level of impulse responses will depend on their length or in UE terms buffer size cut off frequency steepness of slopes configuration and optimization choices The optimization algorithm is actually quite simple and gives you the final say It is quite feasible to employ more advanced optimization scheme one that would involve variable shift of the raw impulse response and perform optimization for every new position However it seems not necessary as the
22. n method However a 4096 point FFT is one thousand times faster For small values of N say 32 to 12 amp the FFT is important For large values of N 1024 and above the FFT is absolutely critical 4 Secondly the DSP engine uses Radix 8 FFTs which offer speed improvement over standard FFT 3 Single precision DSP maths Single precision maths is known as 32 bit floating point arithmetic in computer language The need for the program to run fast on 32 bit CPUs dictated the single precision arithmetic But what are the consequences Single precision arithmetic may affect stop band performance of the filter Before we look at this issue in more details let s first consider what level of performance we desire from our FIR filter The filter can be assessed in pass band transition band and stop band Firstly from the acoustical perspective the stop band of one driver 15 the band pass of the complimenting driver Acoustic summation of signals differing in level by 40085 15 unlikely to cause the softer driver affecting the performance of louder driver If the level difference 1s 60dB the interference from the softer driver 1s 1naudible Secondly all drivers have a natural roll off in the stop band which adds as much as 35 A5dB of extra band stop attenuation see tweeter and woofer examples below MS Frequency Domain Angl 147 80 di Phase 0 00 Freq 47S0G L Hz 0x DiS Frequency Domain 101 SPL
23. performed using finalized SPL phase plots so please make sure that you plot and review transfer functions of all channels and you are happy with the results before taking the final step of optimizing and exporting impulse responses Every time the UE buffer size is changed from Preferences screen the SPL phase needs to be re plotted to obtain the most recent SPL phase curves Optimization information is saved to Project File so every time you load new project new optimization information will be used Linear Phase filters This process is actually very simple Because optimization is not really needed but you may choose to check the impulse response performance with Wide Window option turned ON and OFF Shown below is an example of the same filter as it was used above without any optimization Please note the linear phase shown in grey colour 12 Figure 16 Linear Phase impulse response is performing optimally The second example shows an L R band pass filter with 500 2000Hz cut off frequencies and 4096 coefficients used for it s impulse response It had it s minimum phase version optimized but linear phase version performed with 140dB stop band attenuation right away 4 a OS S E S O s e gt gt ff Qh A gt gt gt SS ee ee ee ee
24. ponse Window bibana Seaga Figure 20 Impulse response monitoring window The impulse can be magnified in amplitude and stretched in time domain using the controls provided on the control dialogue box see below Optimize Export Impulse Response 1 Select Transfer Function to 3 Optimization 4 IR Windows summary Output Port 2 Output Port 3 Output Port 4 Output Part 5 A Delect FET Window 7 term Blackman H artis Cosine Hide Phase Above W Show Reference SPL gt Use Longer FFT Clear SPL Response Impulse Response Window 111 Mag Gain Ia ATE Time Scale 2060 Figure 21 Controls for impulse response window It must be stressed that the impulse response shown in this window is NOT the final impulse response of the audio channel assigned as Portl Port2 Portl6 The complete audio channel must obviously include the loudspeaker Therefore the final audio channel impulse response would be obtained by convolving the impulse presented in the monitoring window with the impulse response of the loudspeaker Interestingly when designing impulse response for the purpose of equalizing the loudspeaker the final audio channel impulse response EQ filter convolved with loudspeaker will be that of a perfect textbook electrical filter Well this is the purpose of equalizing drivers with Ultimate Equalizer 15 Window shape may improve stop band attenua
25. ry a couple of different windows to see which one results in better stop band performance 3 IR Optimization This button as step 3 activates calculation algorithm The algorithm will provide 49 resulting options for your evaluation All curves will be displayed in the Impulse Response SPL Window and colour coded You may need to pay some attention to the display as the process runs uninterrupted till completion The vertical scale in the SPL window is 10dB per division J Impulse Response SPL Window ioi xt Bon tae Serre E M 5 5 Tet Home EUN OPI t nt NI Priest IP o0 UH US RE E A E X XX O 160 180 BE 4 H Po i dB deg 0 0 8 880 20 3 0 405 05 0 8 01 20 30 40 50 80100 20k 30k 405060k SOKI 00k 200kHz Figure 11 Colour coded selection of SPL phase curves resulting from IR optimization 9 200 300400 600 1k 2k 3k 4k 6k 8k 10k Once the algorithm has completed you can display individual results by double click on the items in the list box below the IR Optimization button Your selection will be instantly transferred to 4 IR Summary Window and will be used by the DSP engine from now on see below 3 IR Optimization 4 IR Windows summary Visual inspection gives you the opportunity of selecting the
26. servable that 15Hz notch will be approximated by 14 65Hz 50Hz will be approximated by 49 80Hz 100Hz will be approximated by 99 61Hz and 200Hz will be approximated by 199 22Hz Now all notch frequencies are close to the frequencies used by the FIR filter therefore the FIR filter has no difficulties executing the requested filter curve Generally high performance DSP filters would require 2 93Hz resolution or better The next step up in resolution would be 1 47Hz and 0 735Hz However quite reasonable results in everyday loudspeaker work can be achieved with 5 86Hz and 11 72Hz can be used for crossovers upwards of 200Hzz and very basic loudspeaker equalization Speed and Performance Ultimate Equalizer has been designed to run with equal performance level on 32 bit and 64 bit Windows7 computers This has been mostly accomplished by using the following software approach 1 Multi threaded coding The DSP engine within the UE opens several threads and spreads the maths intensive calculations over parallel CPU cores The threads are synchronized and the results collated when the slowest thread finishes This approach can almost half the calculation time for each doubling the number of threads 2 Frequency domain convolution Steven W Smith in his landmark book Digital Signal Processing A Practical Guide for Engineers and Scientists page 237 concludes For example a 32 point FFT is about fen times faster than the correlatio
27. ssover performance with 2048 long impulse response with 500Hz and 5000Hz Butterworth 24dB oct Sampling is 488117 Minimum Phase first SPL Phase Mike Preamp Post Processing 125 180 120 160 E 105 100 IS LL 25 30 85 80 75 70 55 60 50 35 dB deg 10 20 30 40 60 80 100 200 300 400 600 2k 3k 4k Bk 8k 10k 20k 30k 40k Hz SPL Phase Mike Preamp Post Processing 125 180 120 160 115 140 110 120 105 100 100 80 35 80 30 40 85 0 80 0 75 0 70 40 65 0 60 80 55 100 50 120 45 440 40 160 An now the linear phase version SPL Phase Mike Preamp Post Processing 125 180 120 160 115 140 110 120 105 100 100 80 35 80 30 40 85 20 80 0 ia lt All 70 40 65 60 60 80 55 100 50 120 45 440 40 160 35 480 i i ee ORES ene a ee 3 i i Poo Po Po Po P P P H H PO PON IO POP E i dB deg 10 20 30 40 60 80 100 200 300 400 600 1k 2k 3k kk 6k 10k 20k SPL Phase Mike Preamp Post Processing 125 180 120 160 115 140 110 120 105 100 100 80 35 80 30 40 85 20 80 0 0 70 40 65 60 60 80 55 100 50 120 45 140 40 160 35 180 dB deg 10 Figure 29 crossover performance with 2048 long impulse response with 500Hz and 5000Hz Butterworth 24dB oct 21 Exporting Impulse Response After the optimization process there is the final step in dealing with impulse response the e
28. tion In the next example we have impulse response of an 48dB oct 20Hz Butterworth HP filter Apart from the initial peak there is nothing much that can be observed on this picture Figure 22 Full view of impulse response When the impulse response gain 15 set for 50000 magnification we are able to see what happens at the far end of the impulse response Minimum Phase example is presented first Figure 23 Applying smoother window By applying smoother window Wide Window OFF we can observe reduced noise on the left end of the impulse response This reduction will result in improved stop band attenuation as can be seen on the picture on the right alx b bb 4 dt dt a S Baa ee 111 1 ee eS ee oe oe oo oe oe ee S a eS d el2d 2 381115 I 1 14 p lj m mes EM ERG Ge ERN ER ERN RR RERO RR ER UNI SSS 1 ERIS See 1 11111 1111101 8 11 r 1 T9rH8HTHE 31 19 0999 rr3 8 81r t1 1xe222p2422 es
29. tition version is available as follows 1 Minimum Phase Mode UE buffer size Standards ASCII miniDSP 512 2048 coefficients 1024 4096 coefficients 2048 8192 coefficients 4096 16384 coefficients 2 Liear Phase Mode UE buffer size Standards ASCII miniDSP 512 4096 coefficients 1024 8192 coefficients 2048 16384 coefficients 4096 32 768 coefficients You should be able to use miniSHARC DSP board with minimum phase 2048 coefficients impulse responses and openDRC with minimum phase 2048 coefficients 4096 coefficients and linear phase with 4096 coefficients All sampled at 48kHz Other DSP products available on the market may be able to use standard ASCII files exported by program Sample files of IKHz LR high pass and low pass filters are available on Bodzio Software website Importing Impulse Response in ASCII files into MLS system In addition to importing it s owne impulse response files RES files the MLS system has now the ability to import ASCII impulse response files The file has to be in the following format just a sequence of floating point numbers ljiR 1000Hz Min Phase 24dB HP tx File Edit Format View Help 0 000000000000e400 5 888815834965e 08 2 461291899181e 07 5 412740051725e 07 9 798463906918e 07 1 567054596308e 06 2 201860297646e 06 3 143334879496e 06 3 998499323643e 06 5 163717105461e 06 6 407774890249e 06 7 756128979963e 06 9 573623174219e 06 1 081970822270e 05 1 319972034253
30. xporting process There are two types of files available for exporting standard ASCII files and miniDSP formatted files Data in both files is identical the only difference is presentation of the data in the files In order to export the impulse response file please proceed to step 5 Select File Format from the provided list box Optimize Export Impulse Response E X 3 IK Optimization 4 IE Windows summary 1 Wide Window L P Mode 1 Select Transfer Function to Output Port 2 Cutz Wide Window L P Mode Output Port 3 Outs Wide Window L P Mode Output Port 4 uta Wide Window L P Mode Output Port 5 Outs Wide Window L P Mode Cute Wide Window L P Mode Wide Window L P Mode ute Wide Window L P Mode ute Wide Window L P Mode Cratitd Wide Window L P Mode Cratl 1 Wide Window L P Mode Cratl Z Wide Window L P Mode Chat 3 Wide Window L P Mode Cati 4 Wide Window L P Mode Cratl 5 Wide Window L P Mode 16 Wide Window L P Mode Select FFT Window 7T term Blackman H arris Cosine Hide Phase Above W Show Reference Use Longer FFT Clear SPL Response Impulse Response Window n Jel IR Mag Gain 3 m omm 1 IE Time Scale 4110 Figure 30 Controls for exporting impulse response And then press Save Impulse Response button This will open standard Windows file saving dialogue box where you can enter file name and finalise t
31. you can double click on any of the listing in the 4 11 Windows Summary box and you will se all saved options impulse response optimizations re plotted on the Impulse Response SPL Window Optimize Export Impulse Response X 1 Select Transfer Function to 3 IER Optimization 4 IE Windows summary Output Port 12 Method 1 Qutl Wlet2 1556 Cosme Output Port 15 Method 2 Cute Meti 512 Cosine Output Port 14 Ont 1664 Outs Metz 1696 Hanning Output Port 15 c 1506 Cata Wet2 1920 3 term Blackman Cuts Wlet2 1088 4 term Blackman Harris ut Wlet2 512 T term Blackman Harris A elect FFT Window c oe Out Met2 2048 Hanning noli Out Met2 1632 Cosine niit ie Cnat9 Met2 2016 Nuttall nes ia Outl0 Metz 2048 Hanning an Ta Outl L Metz 1856 7 term Blackman Harris Hide Phase Above p 1 Wlet2 512 term Blackman Harris Modifie S oda cr Out13 Metz 2048 Hanni v Show Reference SFL Ont 1924 utls Wets 4561001116 p Outl4 Met2 2048 Cosine Use Longer FFT Opt 2016 ique Chatl5 Mets 2048 Cosme Clear SPL Response Doo Outl Metz 1728 Hanning Impulse Response Window 5 Select File Format 5105 cl Raw Impulse Response UE format IR Mag Gain 6 miniDSP ASCII Format CSV m m IF Time Scale 4110 Save Impulse Response Figure 28 fully edited and optimized set of 16 impulse minimum phase impulse responses Typical cro
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