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SLOU                           TI Information – Selective Disclosure 

14

 

PurePath™ Smart Amp User Manual (TAS5766M/68M) 

3 

Loudspeaker Characterization 

The main objective of the loudspeaker characterization is to obtain the 

electro-mechanical

 and 

thermal

 parameters and establish the safe operating area (SOA) of the loudspeaker system. The 

electro-mechanical and thermal parameters are obtained using the 

Learning Board

. 

The 

Learning Board App

 has a step-by-step wizard that guides the user through the entire 

loudspeaker characterization process. 

3.1 

Characterization Process 

To perform a loudspeaker characterization: 

1.  Connect the 

Learning Board

 to your PC using the USB cable. 

a.  Provide a power supply. 

b.  Do not connect the speakers yet. 

2.  In PurePath™ Console 3, open the 

Learning Board

 App and select 

New

. 

 

 

 

 

3.  If the Learning Board is shown as offline, 

click 

Connect

.  

 

4.  Click 

Characterization

. 

 

 

 

5.  Follow the step-by-step 

wizard

 until the 

characterization is 
complete. 

6.  Once complete, the 

Characterization Summary

 page will be shown. 

Содержание PurePath TAS5766M

Страница 1: ...ctly or indirectly any product or technical data as defined by the U S EU and other Export Administration Regulations including software or any controlled product restricted by other applicable nation...

Страница 2: ...ation 17 4 2 Smart Bass Tuning 18 4 2 1 Bass Enhancement Low Volume Tuning 19 4 2 2 Morphing Control Mid to High Volume Tuning 21 4 2 3 Harmonic Bass Alignment Mid to High Volume Tuning 22 4 2 4 Excur...

Страница 3: ...e Ratio Source 27 Figure 9 Audio Clip B 9dB Peak to Average Ratio Source 27 Figure 10 Effects of Decoupling for Audio Frequencies 29 Figure 11 Power Supply Current Measurement 30 Figure 12 Smart Amp S...

Страница 4: ...With that knowledge the designer can adapt conventional power systems to peak output power needs of Smart Amp designs Chapter 6 explains how to transfer the Smart Amp code into a microcontroller so t...

Страница 5: ...nts that define the Safe Operating Area SOA which establishes the boundaries of maximum speaker diaphragm excursion and voice coil temperature during operation If the SOA is set correctly the audio en...

Страница 6: ...it is difficult to obtain accurate low frequency acoustical measurements without an expensive anechoic chamber Smart SPL automatically merges electrical and acoustical measurements to create a full p...

Страница 7: ...maximize output and quality See Section 1 7 for tips on development 3 Obtain Speaker Parameters The next step is to understand the characteristics of the speaker to be tested This is covered in Chapt...

Страница 8: ...in the end system Table 1 Equipment and Software 2 Channel Mid Power Smart Amp 2 1 Channel Mid Power Smart Amp 4 Channel Mid Power Smart Amp Hardware Tools 1 6 1 PurePath Smart Amp Learning Board x x...

Страница 9: ...re can be downloaded from the PUREPATHCONSOLE Software Product page in mySecureSoftware as shown below There is no need to download separate plugins Smart Amp Apps will automatically be available with...

Страница 10: ...aphragm area Sd Also used to measure port area Sp Plastic is preferred to prevent the magnet from pulling the ruler Not required if Sd and Sp parameters are known 24V Power Supply A lab power supply c...

Страница 11: ...Smart Amp code will be downloaded during start up and how much time is needed to boot Smart Amp Set clear performance targets Use characterization and tuning results to work with speaker vendor to im...

Страница 12: ...tion for installation details 2 2 MATLAB Runtime Installation The Smart Amp software requires the MATLAB Compiler Runtime MCR 7 16 engine in addition to the PurePath Console 3 installation to run The...

Страница 13: ...the PUREPATHCONSOLE Software Product in mySecureSoftware Refer to the PurePath Console 3 documentation for installation details 2 Once PurePath Console 3 is installed click the Sign in button as show...

Страница 14: ...ning Board App has a step by step wizard that guides the user through the entire loudspeaker characterization process 3 1 Characterization Process To perform a loudspeaker characterization 1 Connect t...

Страница 15: ...shown as well as the established safe operating area SOA If desired click the button to redo the characterization The button will bring back the Characterization Summary page 3 3 Saving a Characteriz...

Страница 16: ...ocess also referred to as voicing are Improve bass performance using Smart Bass controls Section 0 by adjusting Bass Enhancement Section 4 2 1 Morphing Control Section 4 2 2 Harmonic Bass Alignment Se...

Страница 17: ...final system b Connect the loudspeaker 2 In PurePath Console 3 open the App that corresponds to the board that was connected Learning Board or Target EVM 3 If the board is shown as offline click Conn...

Страница 18: ...the audio engineer to focus on choosing the desired sound with just a few clicks When tuning Smart Bass for the first time it is best to first disable the Equalizer in the page To start tuning Smart B...

Страница 19: ...he Corner Frequency indicates the 3dB point of a flat response target indicated by the green curve Selecting a proper Corner Frequency is important for the overall performance of the speaker system If...

Страница 20: ...shaped in amplitude frequency and Q Bass EQ works well in concert with the Morphing feature that dynamically cuts Bass as excursion and thermal headroom drops with increase in loudness It is recommen...

Страница 21: ...m creating a psychoacoustic bass enhancement effect Audible artifacts indicate too high Morphing setting Little but clean bass could indicate that the Morphing setting is too low NOTE This is an itera...

Страница 22: ...g on the type and quality of the speaker as characterized in the measurement phase the Peak Excursion SOA setting sometimes needs a post audio tuning adjustment for best sound quality As a typical spe...

Страница 23: ...the page and click the Expand symbol next to the Equalizer section as shown below 1 Set Smart EQ to On to enable it The compensation curve is calculated based on the SPL measurement obtained during th...

Страница 24: ...w acoustic response The Dip Suppression feature controls how many dBs can the response dip A 0dB setting means that dips are completely suppressed as shown to the right A 1dB setting means that the re...

Страница 25: ...e Smart SPL response which would otherwise require a large amount of positive compensation that may not be audible and cause distortion The example to the right shows a 20dB per octave rolloff at 10kH...

Страница 26: ...algorithm i e pre processing If it is discovered that the optimal Digital Gain level is below 6dB then it may be a better option to adjust the post processing gain levels instead requires re calibrat...

Страница 27: ...provided as an input This is due to the fact that a square wave has 6dB higher average power than a sinusoid of the same peak amplitude as well as having the presence of higher frequency components C...

Страница 28: ...is the rated speaker impedance Note that the actual voltage observed at the load depends on factors such as RDS on of a Class D amplifier among others As described in the previous section Smart Amp sy...

Страница 29: ...r against thermal failure associated with high currents for prolonged periods of time This means that a large signal will be reduced in amplitude and settle into a steady level corresponding to a safe...

Страница 30: ...the output levels in more detail 2 The table below lists several peak supply current examples Note that these calculations assume a resistive load Speakers are inductive in nature and may cause highe...

Страница 31: ...PWM signal must have good integrity in order to provide a good fidelity output signal As mentioned previously the power supply and PCB layout may not be capable of delivering the initial switching cur...

Страница 32: ...the device 14dB 20dB The peak full scale output voltage can be calculated as follows 2 2 10 20 For example if 0 0 and 20 then 28 28 differential Note that this level is slightly above the maximum supp...

Страница 33: ...oaded into the TAS5766M EVM in order to generate the required header files This is explained in detail in Section 6 1 The second step is to determine the system gain in the end system This is importan...

Страница 34: ...EVM App e g TAS5766M App 1 Connect the Target EVM to your PC using the USB cable a Provide a power supply matching the one to be used in the final system b Connect the loudspeaker 2 In the PurePath C...

Страница 35: ...wn below 2 10 For example if a 2Vrms signal is observed at the output this means that the System Gain is approximately 28 Similarly a 1Vrms measured signal will yield a System Gain of approximately 14...

Страница 36: ...a System Calibration This process ensures that the Smart Amp algorithm is properly scaled based on the amplifier output gain Having the loudspeaker connected provides more accurate results 8 Save a pp...

Страница 37: ...into the end system device through I2 C commands The typical way of achieving this is to compile a header file into the system code This header file can be generated by using the Dump feature found in...

Страница 38: ...38 PurePath Smart Amp User Manual TAS5766M 68M 2 Select the desired Snapshot 3 In the End System Integration page select Dump Current State into a Header File 4 Click the Dump to File button as shown...

Страница 39: ...ient Memory C RAM_D Buffer A Dump Page 44 0x2C Dump 0x00 0x2c CFG_META_BURST 121 0x08 0x40 0x26 0xe7 Wake Select Page 0 0x00 0x00 Wake from Standby 0x02 0x00 Figure 15 Example Header File Output Snipp...

Страница 40: ...Register 127 Definition of the cfg_reg type typedef union struct cfg_u8 offset cfg_u8 value struct cfg_u8 command cfg_u8 param cfg_reg Figure 16 Example Header File Output Snippet The microcontroller...

Страница 41: ...aring protection equipment 3 Connect the positive and negative terminals of the loudspeaker to a multi meter volts AC setting 4 Set the volume of the host processor to a low level e g 20dB to 40dB 5 P...

Страница 42: ...low shows the differences between the two files Two things can be determined by observing these differences the page register location and the value In the left column a value of 0x400000 or 0dB is wr...

Страница 43: ...art Amp User Manual TAS5766M 68M 43 7 Support Smart Amp is supported through the Audio Amplifiers Support Forum Please include the words Smart Amp and the part number in the subject line Contact your...

Страница 44: ...Methods of measuring and specifying the performance of loudspeakers for professional applications Drive units Audio Engineering Society New York NY US 3 Class D LC Filter Design application report SL...

Страница 45: ...center point to center point of the surround as shown below Diaphragm area for other speaker shapes such as racetrack speakers can be calculated by either approximating the speaker as a square or by...

Страница 46: ...speaker when prompted Sd Enter the diaphragm area as measured Sp if applicable Enter the total port or passive radiator area as measured In box SPL for Passive Radiator Follow the steps in the wizard...

Страница 47: ...ter the area of that element divided by 2 In other words 2 o Dual Port or Passive Radiator If both elements have the same area then enter the area of only one of the elements In other words Otherwise...

Страница 48: ...river Sd Enter the sum of the diaphragm area of both speakers in the same cabinet 1 2 Sp if applicable Enter the total port or passive radiator area as measured In box SPL for Passive Radiator Follow...

Страница 49: ...uld be used However the tweeter may not be protected for sinusoidal signals which would require stress reliability tests by the customer Electro mechanical Characterization Connections Remove the cros...

Страница 50: ...tegrate the Smart Amp header file into end system Section 6 4 Perform Basic and System Gain Verification in the end system Section 6 5 Perform stress and reliability tests of the loudspeaker system NO...

Страница 51: ...require un hiding files in the Windows system settings 4 Open PurePath Console 3 load the Smart Amp App 5 If issues persist refer to Chapter 7 for support contact information Some antivirus software m...

Страница 52: ...sion Date Author s Additions Modifications Deletions SLOU 20150820 J Arbona Added additional details to the Smart SPL section SLOU 20150715 J Arbona H Rajagopala C Neesgaard S Kandadai M Spence M Kuci...

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