ELECTRICAL & ACOUSTICAL TESTS CLIO Software Release 10 Version Standard User's Manual AUDIOMATICA
© Copyright 1991–2010 by AUDIOMATICA SRL All Rights Reserved Edition 10.10, 2010/12 IBM is a registered trademark of International Business Machines Corporation. Windows is a registered trademark of Microsoft Corporation.
CONTENTS 1 INTRODUCTION............................................................11 1.1 ABOUT THIS MANUAL.........................................................................11 1.1.1 WHAT THIS USER MANUAL DOES COVER .......................................11 1.2 GENERAL CONDITIONS AND WARRANTY...............................................11 2 THE CLIO SYSTEM.........................................................15 2.1 THE FW-01 FIREWIRE AUDIO INTERFACE..............................................
.6 QCBOX & LPT CONTROLS....................................................................40 4.6.1 CONTROLLING THE QCBOX 5 POWER AMPLIFIER, SWITCHING AND MEASURING BOX..................................................................................41 4.7 CONTROLLING TURNTABLES................................................................42 4.7.1 TURNTABLES OPTIONS DIALOG.....................................................43 4.8 MAIN MENU AND SHORTCUTS...................................................
7.6 MLS.................................................................................................82 7.7 CHIRPS............................................................................................83 7.8 PINK NOISE......................................................................................85 7.9 ALL TONES........................................................................................87 7.10 SIGNAL FILES............................................................................
10.6 PROCESSING TOOLS BY EXAMPLE ...................................................131 10.7 MLS Vs. LOG CHIRP........................................................................134 10.8 RELATED MENUS............................................................................136 11 SINUSOIDAL.............................................................137 11.1 INTRODUCTION ............................................................................137 11.2 SINUSOIDAL CONTROL PANEL......................
13 MEASURING IMPEDANCE AND T&S PARAMETERS......181 13.1 INTRODUCTION.............................................................................181 13.2 GENERALS.....................................................................................181 13.3 INTERNAL MODE............................................................................181 13.3.1 MEASURING IMPEDANCE OF LOUDSPEAKERS..............................183 13.3.2 SETTING THE RIGHT LEVEL.......................................................
18 WAVELET ANALYSIS.................................................219 18.1 INTRODUCTION.............................................................................219 18.2 WAVELET ANALYSIS CONTROL PANEL................................................220 18.2.1 COMMON TOOLBAR BUTTONS AND DROP DOWN LISTS.................220 18.3 WAVELET ANALYSIS SETTINGS.........................................................221 18.4 WAVELET ANALYSIS OPERATION.......................................................222 18.
1 INTRODUCTION 1.1 ABOUT THIS MANUAL This User's Manual explains the CLIO system hardware and CLIO 10 software. All software versions are covered, please note that CLIO 10 software is designed to operate in conjunction with the supplied PC hardware. If the hardware is absent or the serial numbers do not correspond then CLIO 10 will operate in demo mode only. 1.1.1 WHAT THIS USER MANUAL DOES COVER The CLIO System is a complete electro-acoustic analyzer.
AUDIOMATICA’S WARRANTY Audiomatica warrants the CLIO system against physical defects for a period of one year following the original retail purchase of this product. In the first instance, please contact your local dealer in case of service needs. You can also contact us directly as outlined above, or refer to other qualified personnel. WARNINGS AND LIMITATIONS OF LIABILITY Audiomatica will not assume liability for damage or injury due to user servicing or misuse of our product.
REGISTRATION CARD AUDIOMATICA REGISTRATION CARD (EMAIL OR FAX TO US) CLIO SERIAL NUMBER: ______________________________ SOFTWARE VERSION: _______________________________ PURCHASE DATE: ___________________________________ NAME: ___________________________________________ JOB TITLE: ________________________________________ COMPANY: ________________________________________ ADDRESS: ________________________________________ ZIP OR POST CODE: ________________________________ PHONE NUMBER: ______________________
2 THE CLIO SYSTEM Depending on the hardware options that have been purchased, the CLIO system consists of the following components: – The FW-01 firewire audio interface – The MIC-01 or MIC-02 or MIC-03 (also Lite) microphones – The PRE-01 microphone preamplifier – The QCBox Model 5 power amplifier, switching and testing box In the next few pages we will describe each component and give its respective technical specifications.
2.1 THE FW-01 FIREWIRE AUDIO INTERFACE The FW-01 Firewire Audio Interface sets new hardware precision standards for the CLIO System. The FW-01 unit has been designed to be a complete two channels professional A/D D/A audio front-end for your PC; it is connected to the computer by an IEEE-1394 link giving you maximum performances; it can be powered by the same link giving you maximum portability.
2.2 THE MIC-01 MICROPHONE The MIC-01 microphone is an electret measuring microphone that is particularly well suited to being used in conjunction with the other components of the CLIO system. It is furnished with its own stand adapter and a calibration chart reporting the individually measured sensitivity, all fitted in an elegant case. Its long and thin shape renders it ideal for anechoic measurements.
2.2.3 TECHNICAL SPECIFICATIONS MIC-01 Type: Accuracy: Maximum level: Dimensions: Accessories: MIC-02: MIC-03: Polar Response: Condenser electret ±1 dB, 20 Hz to 10 kHz ±2 dB, 10 kHz to 20 kHz (direct field) 130 dB SPL 8 mm diameter, 25 cm long wooden case, 2.7 m cable, stand adapter Same as MIC-01, but 12 cm long. Same as MIC-01, but 7 cm long. MIC-01-MIC-02-MIC-03 2.2.
2.3 THE PRE-01 MICROPHONE PREAMPLIFIER The microphone preamplifier PRE-01 has been designed to match Audiomatica’s microphones MIC-01, MIC-02 and MIC-03. It is particularly useful when the microphone has to be operated far from the analyzer or when weighted measurements are needed. PRE-01 powers the microphone connected to its input with an 8.2V phantom supply and adds a selectable weighting filter (A or B or C); also available there is a 20 dB gain stage.
2.4 THE QCBOX MODEL 5 POWER AMPLIFIER, SWITCHING AND TESTING BOX The QCBOX Model 5 power amplifier, switching and testing box is of invaluable help when configuring an automatic or manual quality control setup, or even in everyday laboratory use. It can be configured, under software control via USB, to assist frequency response and impedance measurements or to perform DC measurements.
19” RACK MOUNT ASSEMBLY Using the Rack QC panel it is possible to assemble the QCBOX Model 5 together the FW-01 Audio Interface so that they can be mounted in a standard 19” rack frame. 2.4.1 TECHNICAL SPECIFICATIONS Inputs: Four line/microphone inputs with selectable phantom power supply (0÷24V variable) One TTL input for external trigger 5 digital lines Outputs: Isense 6 digital lines Functions: USB controlled internal switches for impedance and DC measurements DC measuring: Isense current ±2.
3 CLIO INSTALLATION 3.1 MINIMUM PC CONFIGURATION The CLIO FW-01 firewire audio interface running the CLIO software can be installed in any personal computer with the following minimum system requirements: – Pentium IV processor (suggested minimum 1GHz) – One free IEEE-1394 port – 256 MB RAM – 1024x786 video adapter – Microsoft Windows XP or Vista – Adobe Acrobat Reader DO NOT CONNECT THE FW-01 UNIT TO THE PC UNTIL REQUESTED! If you are installing under: - Windows XP go to section 3.
WHEN PROMPTED CONNECT THE FW-01 UNIT! To connect the FW-01 unit to your PC you need to do the following: 1) Locate an IEEE-1394 port on your PC. You may either use a standard 6-pin port (with or without power supply) or a standard 4-pin (small connector, without power supply) port. 2) If you use a 6-pin port use the supplied 6-pin-to-6-pin cable. If you use a 4-pin port please provide an IEEE 1394 6-pin-to-4-pin cable (often referred as i-Link).
Let's now verify the correct installation of the FW-01 driver. Click with the right mouse button on the 'My Computer' icon on the Windows desktop. Then click 'Properties', select the 'Hardware' tab and press the 'Device Manager' button as in the following figure. Verify the presence of the 'Clio Firewire' driver under the 61883 device class. Your driver installation was successful! 3.
To connect the FW-01 unit to your PC you need to do the following: 1) Locate an IEEE-1394 port on your PC. You may either use a standard 6-pin port (with or without power supply) or a standard 4-pin (small connector, without power supply) port. 2) If you use a 6-pin port use the supplied 6-pin-to-6-pin cable. If you use a 4-pin port please provide an IEEE 1394 6-pin-to-4-pin cable (often referred as i-Link). 3) If you use a 6-pin port verify that it is capable of power supply.
Verify the presence of the 'Clio Firewire' driver under the 61883 device class.
3.4 SOFTWARE INSTALLATION This paragraph deals with software installation. The CLIO software is provided either on its own CD-ROM or, in electronic format, as a single, self-extracting, executable file. Be sure to have administrative rights when installing CLIO. To install the CLIO 10 software in your computer you should follow the instructions presented below: 1) Insert the CLIO 10 CD ROM in the computer. 2) Wait for autorun application or run "Clioinstall.exe".
3.5 THE 'CLIO BOX' A few words about the FW-01 firewire audio interface. Figure 3.26 This unit is needed to correctly interface analog signals to your PC; it is also important as it has an internal reference used to calibrate the system and also stores the system's serial number inside its internal EEPROM; Fig.3.27 shows where is located your CLIO system serial number. Figure 3.
3.6 RUNNING CLIO FOR THE FIRST TIME If you have completed the preceding installation procedure, you are ready to run CLIO! The following steps will guide you through a complete verification of the system performance and operation. From the Start Menu choose Programs, then CLIO 10 and click on the CLIO icon. The program should start smoothly and present the main desktop. If the the system is not calibrated, as the first time you run it, you will receive the following message.
Figure 3.28 If everything is OK you should obtain a reading of circa 1V, variable between a minimum of 0.95V and a maximum of 1.05V, which is the mean output level of a sinusoidal signal when the system is not calibrated. Now press the FFT button (or CTRL-F), then press the Oscilloscope button and finally the GoButton. The result you should obtain is an FFT analysis of the 1kHz sinusoid (one spectral line @ 1kHz at 0dBV) and its time representation given by its oscillogram.
3.7 SYSTEM CALIBRATION This section describes how to perform the system calibration. Be sure that, any time you perform a calibration, the system has warmed up for, at least 15-20 minutes. Select Calibration from the File menu (5.6); Leave the CLIO Box front plugs unconnected. Answer OK to the initial prompt; this will run an automatic procedure that will last several minutes. The calibration procedure is completely automatic and several progress indicators will accompany all the executed measurements.
To verify the calibration first check that the generator output level is set to 0dBV (refer to 4.5.3 for details). Press the channel A In-Out Loop button . Then click on the MLS button to invoke the MLS control panel. Press the Go button to execute an MLS frequency response measurement; after about 1 second you should obtain the desired result, a straight line (black) as in Fig.3.29.
3.8 CLIO SERIAL NUMBER AND DEMO MODE Each CLIO system has its own serial number which plays an important role since the CLIO software is hardware protected and relies on a correct serialization in order to run. Refer to 3.5 to identify your system's serial number.
4 CLIO BASICS 4.1 INTRODUCTION This chapter gives you the basic information about CLIO and the related hardware and how to connect and operate it, while the following chapters explain in more detail the individual measurements available to users of CLIO. Chapter 5 deals with other general functionality of CLIO. Here you will find information about: - Help - Main desktop, toolbars and menu - Shortcuts - Generator, Input and Output, Microphone - Amplifier & SwitchBox, Turntable - Connections 4.
4.3 CLIO DESKTOP The CLIO desktop presents itself as in Fig. 4.2 and gives you access to the main menu, the (upper) main toolbar and the (lower) hardware controls toolbar. Figure 4.2 CLIO Desktop Inside the main toolbar and the hardware controls toolbar you can locate several distinct functional areas as shown in the above figure. There now follows a description of all the controls inside the two toolbars. Refer to Section 4.8 for a detailed view inside the main menu. 4.
4.4.1 MEASUREMENT ANALYSIS By clicking on these toolbar buttons it is possible to interact and display each measurement control panel. Once the toolbar button is clicked the appropriate panel will be opened or reactivated. Any currently active panel will automatically be deactivated on activation of the new one. The same functionality will be obtained with the relative shortcuts or by making a selection inside the Analysis Menu (see 4.6.2); a third way is to select a window through the Windows Menu (see 4.
4.5 HARDWARE CONTROLS TOOLBAR 4.5.1 INPUT CONTROL channel A input peak meter Constantly monitors channel A input signal level vs.full digital input scale. Controls channel A input polarity. channel A input sensitivity display & control buttons Displays the actual input sensitivity (in dBV) of the instrument, i.e. the voltage level beyond which the hardware saturates. It is possible to modify it in 10dB steps by pressing the (F9) and/or (F10) buttons.
It is also possible to input a numeric value directly with the following dialog which pops up when you click on the output level display. In this case (manual input) the output level will be approximated with a 0.01dB precision. If you right-click on the output level display you invoke the out units pop up from which it is possible to select the output level unit among dBu, dBV, V and mV. Checking the Unbalanced option the output level display is referred to the unbalanced outputs of the Clio Box.
4.5.4 MICROPHONE CONTROL Switches Channel A 24V phantom power on and off. This supply is capable of operating any balanced microphone and also to operate Audiomatica's microphones MIC-01, MIC-02 and MIC-03 (see later). Switches Channel B 24V phantom power on and off. To enter the microphone sensitivity please refer to 5.4 Options. 4.5.5 SAMPLING FREQUENCY Indicates the current sampling frequency of the instrument. To change it simply click on it and refer to 5.4 Options. 4.
You can also read and write a PC parallel port: 4.6.1 CONTROLLING THE QCBOX 5 POWER AMPLIFIER, SWITCHING AND MEASURING BOX With this dialog box it is possible to access to the QCBox 5 enhanced features. It is possible to superimpose a DC voltage on the amplifier output, set the microphones phantom voltage and the output current protection threshold. It is also possible to read the Isense DC current and the IN 3 and IN 4 DC voltages.
4.7 CONTROLLING TURNTABLES This control panel allows the control of one or two turntables. The control of two turntables is available only with the QC software. Using two turntables it is possible to measure the loudspeaker response in three dimensions, i.e. the software can send commands to the turntables to aim the loudspeaker under test in a given direction. Fig.4.
Displays turntable current angle (top) and next angle (bottom), while the turntable is rotating the bottom background is highlighted in red. Open the Autosave Settings dialog Reset turntable angles according to Autosave Settings Open the Turntables Option dialog Start an MLS Autosave measurement set Halt an MLS Autosave measurement set Resume an MLS Autosave measurement set 4.7.
LinearX LT360 The LinearX LT360 turntable uses an USB or COM connection, please refer to the manufacturer documentation to the setup of the device. In the option dialog it is needed to input the communication port to be used. Some turntables settings, such as the rotation speed and the velocity profile must be managed using the software supplied with the turntable. For correct operations with CLIO software the “Display Readout Polarity” setting of the LT360 turntable must be set on “Unipolar”.
The control is achieved with Bit 7 of the parallel port output bits, as shown in Fig.4.6.
4.8 MAIN MENU AND SHORTCUTS The user should carefully read this section which gives you a comprehensive list of all the menu and shortcuts available within CLIO. Shortcuts, i.e. keystrokes that you can press to obtain a certain action, will save you time and increase your productivity. Also refer to Chapter 6 to learn the measurement interface and its associated shortcuts. Note that the measurement specific (MLS submenu, FFT submenu etc.
4.8.2 ANALYSIS MENU The Analysis menu gives you a powerful way to access the measurement menu and menu functions, through the keyboard. Here we present you with all the available menus and shortcuts; the shortcuts, when present, are visible from each submenu and are listed on the right of the function; refer to the specific chapters for each measurement for details about it. Fig.4.11 Analysis Menu CTRL+M Enters the MLS&LogChirp Analysis control panel. CTRL+W Enters the Waterfall&Directivity control panel.
Fig.4.12 MLS&LogChirp Submenu - Frequency and Time Fig.4.13 Waterfall and Directivity Submenu Fig.4.14 Wavelet Analysis SubMenu Fig.4.
Fig.4.16 FFT and FFT Live SubMenu Fig. 4.17 Sinusoidal Submenu Fig. 4.18 Multi-meter Submenu Fig. 4.
Fig. 4.20 Wow&Flutter Submenu Fig. 4.21 Leq Submenu Fig. 4.
4.8.3 CONTROLS MENU The Controls Menu is the heart of your CLIO hardware; learn how to access hardware control through the keyboard in detail. Refer also to 4.4.2, 4.4.3, 4.4.4 and 4.5. Fig. 4.23 Controls Menu ESC Immediately kills the generator. Equivalent to releasing F7 Decreases the output level of 1dB. Equivalent to SHIFT+F7 Decreases the output level of 0.1dB. Equivalent to SHIFT+ F8 Increases the output level of 1dB. Equivalent to SHIFT+F8 Increases the output level of 0.1dB.
CTRL+P Swithces channel A microphone power supply on and off. Equivalent to CTRL+ALT+P Swithces channel B microphone power supply on and off. Equivalent to SHIFT+F4 Enters the QCBox and LPT control panel. Equivalent to CTRL+F4 Enters the Turntables Controls panel. Equivalent to F6 Enables autoscale. Equivalent to 4.8.4 WINDOWS MENU The Windows Menu helps you manage all opened windows (i.e. measurement control panels) in a standardized way.
4.9 BASIC CONNECTIONS In order to correctly interface CLIO with the outside world you should always keep in mind the following electrical specifications: MAXIMUM INPUT VOLTAGE: MAXIMUM OUTPUT VOLTAGE: INPUT IMPEDANCE: OUTPUT IMPEDANCE: +40 dBV (283 V peak-to-peak) +18dBu (6.156Vrms) (sine) 128 kOhm 660 Ohm 4.9.1 CONNECTING THE CLIO BOX The CLIO system is stereo and can simultaneously process two balanced analog I/O channels which are named channel A and B.
4.9.2 CONNECTING A MICROPHONE For acoustical measurements, the microphone (optionally followed by a preamplifier or power supply) requires to be connected to CLIO's input channel. When using a MIC-01, MIC-02 or MIC-03 microphone it is possible to connect it directly to CLIO's input; remember, in this case, to switch the phantom voltage on by pressing the phantom button . It is good practice to wait a few seconds before taking measurements as the microphone's output stabilizes.
4.9.3 CONNECTING THE CLIOQC AMPLIFIER & SWITCHBOX Fig.4.29 and Fig. 4.30 show the connections of a CLIOQC Amplifier & SwitchBox to CLIO. The unit has its internal switcher set for response measurements. INPUT A CLIO INPUT B OUTPUT A OUTPUT B LPT (Model 1, 2, 3 and 4) USB (Model 5) CLIO QCBOX I SENSE BLACK GAIN FROM CLIO RED TO CLIO INPUT 1 INPUT 2 GAIN = 10 dB (Model 1, 2 & 3) GAIN = 20 dB (Model 4) GAIN = 26 dB (Model 5) INPUT N Figure 4.
5 SYSTEM OPERATIONS AND SETTINGS 5.1 INTRODUCTION This chapter completes the introduction to CLIO started in Chapter 4. Here you will find information about: - Files extensions - File operations - Exporting data - Exporting graphics - Printing - Software option - Desktop control - Calibration of CLIO - Startup options - Measurements settings 5.2 REGISTERED FILE EXTENSIONS During its installation CLIO registers several file extensions which will let you easily find a file done during your work.
Leq data files. Linearity&Distortion data files. Multitone definitions files. Autosave definitions files. Desktop snapshot files. CLIO setup files. OLD CLIO Signal files; not used but supported. OLD MLS&LogChirp impedance data files; not used but supported. OLD Sinusoidal impedance data files; not used but supported.
5.3.1 LOADING AND SAVING FILES Loads a measurement file relative to the active control panel. It is important to note that it is possible to load more than one data file type from the following menu: - MLS loads frequency response files (*.mls) and impedance response files (*.mlsi) - FFT loads FFT files (*.fft) and CLIO4 RTA files (*.rta) - Sinusoidal loads frequency response files (*.sin), impedance response files (*.sini), CLIO4 sinusoidal frequency response files (*.
There are five settings which serve to define the autosaved file name: Path defines the folder where the file will be saved; it is possible to choose it clicking on the browse for folder button (...). In Fig.5.3a we see path defined as My Documents\Audiomatica Root File Name defines the part of the file name that will not change during autosave; in Fig.5.3a it is 'RogersHalfChirp'. Start defines the initial number appended to the root.
5.3.2 EXPORTING DATA CLIO is able to export the currently active measurement in an ASCII file (*.txt). Fig.5.4 Export dialog Upon performing this choice you will be prompted by the Export dialog. Depending on the measurement menu you are working with, it will be possible to choose different data to export.
5.3.3 EXPORTING GRAPHICS CLIO is able to create enhanced metafiles (*.emf), bitmaps (*.bmp), portable network graphics (*.png), JPEG (*.jpg) or GIF (*.gif) of the currently active measurement. The graph is drawn using the same color of printouts; you can define them with the Options dialog, see 5.3.6. Fig.5.5 Export Graphics dialog Check the Black&White box to discard color information. 5.3.
5.4 OPTIONS Opens the CLIO Options dialog box (Fig.5.7) 5.4.1 GENERAL Opening this tab (Fig. 5.7) you can define the following: - The Company Name which will appear in all printouts. - Some On Exit settings regarding when the program has to prompt and if you want to autosave and reload the measurement session (see 5.5). - The Signal Generator prompts. - The location of the Hardware Controls Toolbar. - Some behavior of the graphic curve display (see Chapter 6). Fig.5.
5.4.2 UNITS CONVERSION Opening this tab you can define the following: - Enter the microphone sensitivity and the microphone response correction. - Enter all other transducers sensitivity and reference levels. MICROPHONE SENSITIVITY When taking acoustical measurements, the readings and the scales will be in Pascals (Pa, dBSPL, dBPa or dBPa/V).
CORRECTING THE MICROPHONE RESPONSE By checking the Microphone Correction check boxes the software will correct the measured curve according to the data stored in two text files named “MICA.CAL” (for input channel A) and “MICB.CAL” (for input channel B). The microphone correction files, if present, must be placed inside the installation folder (usually c:\program files\audiomatica\clio 10\). Note: The maximum number of correcting points allowed is 100.
5.4.3 GRAPHICS Opening this tab you can define the following: - Screen Colors - Print (and graphics export) colors - Screen line width - Print (and graphics export) line width and font size. Fig.5.9a Options Graphics dialog Apart from the Default color scheme, which is not changeable, it is possible to load and customize up to 6 different color schemes: Classic (for CLIO 6 users), User1, User2, User3, User4 and Printing.
5.4.4 HARDWARE Within this tab you can select the sampling frequency of the FW-01 unit (see 4.5.6). It is possible to choose either 48kHz, 96kHz or 192kHz. 5.4.5 QC AND OPERATORS AND PASSWORDS In case of QC software version there are also two other tabs QC and Operators & Passwords. Fig.5.
5.5 DESKTOP MANAGEMENT Desktop management is a powerful feature that lets you save your work at a certain point and reload exactly as it was. It is possible to do this automatically when exiting CLIO; at successive startup the program will automatically reload from where you left; to do this activate the Save measurement session from CLIO General Options. Load a previously saved measurement session (*.sna files). Takes a snapshot of current measurement session and saves it to disk (*.sna files).
5.7 STARTUP OPTIONS AND GLOBAL SETTINGS You can start CLIO directly clicking on the CLIO.exe executable that is saved in the installation directory (usually C:\Program Files\Audiomatica\CLIO 10); you may also access CLIO either from Start Menu>Programs>CLIO 10 or creating a shortcut on your Desktop. A second way to run CLIO is to click on a registered file; in this way you will not only run the program but also load the file into the appropriate measurement menu.
6 COMMON MEASUREMENT INTERFACE 6.1 INTRODUCTION This chapter deals with the graphical user interface which is used to display and manage the measured curves within all CLIO frequency measurement menus. In particular this Common Measurement Interface (CMI) is used by the FFT, MLS and Sinusoidal menu. The understanding of CMI behavior and capabilities is very important to use CLIO at its best. 6.2 UNDERSTANDING THE DISPLAY IN FRONT OF YOU Fig.6.
as in the case of Time Data display in the FFT menu. The frequency (or time) scale may be logarithmic or linear. A particular representation is the MLS time domain which will be discussed later in 6.6. It is possible to have two graphs in the same control panel (see FFT). In this case one is referred as active after you have clicked on it. To change the colors of the screen, main curve and overlays refer to section 5.4. 6.2.1 STEREO MEASUREMENTS DISPLAY Fig.6.
6.2.2 COLLAPSING MARKERS If you hold the SHIFT key pressed while moving the markers with the mouse you will obtain that the two markers collapse into a single one reading the same frequency point. 6.2.3 DIRECT Y SCALES INPUT It is possible to direct input of the Y scales values; to activate the input boxes simply click on the scale extremes.
6.3 BUTTONS AND CHECKBOXES Moves (shifts) the selected curve upward. Moves (shifts) the selected curve downward. Expands (magnifies) the selected curve; it also changes the Y scale respectively. Compresses (reduces) the selected curve; it also changes the Y scale respectively. Zooms the curve in; it is possible to execute multiple zoom in actions. Zooms out the curve completely i.e. returns to the default initial zoom state. Switches the main curve A on and off.
6.4 HOW TO ZOOM 1) Click on the Zoom+ button. 2) Position the mouse and PRESS the left mouse button at the beginning of your selection and keep the mouse button pressed. Don't just click otherwise you get a warning message! 3) With the mouse button pressed move the mouse until the second selection point. 4) Only now release the left mouse button.
6.6 THE MLS TIME DOMAIN DISPLAY When entering the MLS&LOG CHIRP (but also Waterfall or Acoustical Parameters) time domain you will find a different display (Fig. 6.2). Figure 6.2 In this case there is only one overlay. It is also possible to select a portion of the main curve by means of three particular buttons. The selected portion of the main curve is identified by a start and stop point and is drawn in a different color from the unselected portion. Defines the start point of the selection.
7 SIGNAL GENERATOR 7.1 INTRODUCTION This chapter deals with the programmable signal generator of CLIO. Each paragraph explains a type of signal, its settings and gives a time frequency analysis obtained with the FFT narrowband analyzer (see chapter 9). Refer also to 4.5.3 for all hardware and software controls associated with the signal generator. Clicking on the generator button drop down you access the signal generator menu. 7.2 SINUSOID It is possible to generate sinusoids of given frequency.
The following figure shows a 1031.25Hz continuous sinusoid. The following figure shows a 100Hz bursted sinusoid.
7.3 TWO SINUSOIDS It is possible to generate two sinusoids of given frequencies and amplitudes. Select the TwoSin choice in the generator menu. The following figure shows a signal consisting of a 1031.25Hz and 2062.5Hz of same amplitude (50% each).
7.4 MULTITONES It is possible to generate multitones (mutiple sinusoids signals). Select the Multitone choice in the generator menu. The following figure shows a multitone signal consisting of 31 sinusoids each with frequency corresponding to the center frequencies of the standard 1/3rd of octave bands from 20Hz to 20kHz and same amplitude.
7.5 WHITE NOISE It is possible to generate a white noise. Select the White choice in the generator menu. The following figure shows the white noise signal.
7.6 MLS It is possible to generate MLS (maximum length sequences) of given length. Select the MLS choice in the generator menu. These signals are the same used in the MLS analysis menu and should be used to test them. The following figure shows a MLS signal of 32k length.
7.7 CHIRPS It is possible to generate Chirps (sinusoids with frequency continuously variable with time between two extremes) in two different ways. You may generate full spectrum Logarithmic Chirps of given length selecting the LogChirp choice in the generator menu. These signals are the same used in the LogChirp analysis menu and should be used to test them. You may instead define Chirps of given length, frequency extremes and kind (linear or logarithmic) selecting the Chirp choice in the generator menu.
The following figure shows a 20Hz to 20 kHz Lin Chirp.
7.8 PINK NOISE It is possible to generate Pink noises of given length. Select the Pink choice in the generator menu. The following figure shows a Pink Noise signal of 32k length measured with the FFT narrowband analyzer. Pink noise signals are used normally to execute Octave bands analysis with the RTA menu due to the flat reponse they produce when analyzed with fraction of octave filters.
The following figure shows the same Pink Noise signal of above measured with the RTA analyzer.
7.9 ALL TONES It is possible to generate All Tones signals of given length; an All tones contains a sum of sinusoids of frequencies corresponding to each frequency bin with respect to their length and sampling frequency. Select the All choice in the generator menu. The following figure shows an All Tones signal of 32k length measured with the FFT narrowband analyzer. All Tones signals are used with the FFT narrowband analyzer due to the flat reponse they produce.
For comparison with Pink noises the following figure shows the same All Tones signal of above measured with the RTA analyzer.
7.10 SIGNAL FILES As a last possibility it is possible to play signal files saved on disk. Standard ‘.wav’ Windows Wave files are supported (‘.sig’ CLIO Signal files are supported for compatibility with older versions of the software). Choose File within the generator menu. The default extension lets you select a CLIO signal file. The following figure shows the IMPULSE(POSITIVE).WAV signal file. The generator menu also keeps track of the recently generated signal files giving you instant access to them.
7.10.1 SAVING SIGNAL FILES The generator menu allows you also to save the current signal present in memory to file. To do this choose Save Current Signal; the format supported is .wav. Please note that it is possible to generate .wav files from the Leq measurement menu; the data captured during Leq measurements can then be saved to disk and later reproduced with the signal generator.
8 MULTI-METER 8.1 INTRODUCTION The Multi-meter is an interactive, real-time, measuring instrument.
8.2.1 TOOLBAR BUTTONS Starts the measurement. Permits execution with the control panel in a minimized state. Only a small stayon-the-top display remains visible. See 8.3.2. Stops the measurement. If pressed displays all measured parameters. Captures the actual reading of the multi-meter as the global reference level (or microphone sensitivity); refer to 8.3.2 and 8.4.1 for details. Control the scale of the meter bar graph. 8.2.2 TOOLBAR DROP DOWN LISTS parameter Selects the parameter to be measured.
8.3 USING THE MULTI-METER The first application of the Multi-meter has been described in section 3.4.1 when CLIO was started for the first time. This was a simple generation of a 1kHz sinusoid (0dBu output level) and relative level capture with the Multi-meter. You can continue the measurement described to familiarize yourself with the instrument. Pressing the magnifier will let you inspect all the parameters that the Multi-meter measures in parallel (Fig.8.
let us go back to the procedure described in 3.7.1 which aims at validating a calibration. This is substantially the measurement of the frequency response of the CLIO board itself which is, when calibrated, a straight line; as said in the cited procedure the acquired level of such a measurement is -5.2 dBV. Let's see a practical way to acquire this level in order to refer future measurements to it. Keep the instrument connected as in Fig.3.29, with input A and output A short circuited.
8.4 THE SOUND LEVEL METER Selecting Pressure as measured parameter gives your Multi-meter the functionality of a Sound Level Meter. Three units are available: dBSPL, dBA and dBC. dBSPL is a direct reading of the sound level, relative to the reference pressure of 20uPa. Remember that CLIO needs to know your microphone sensitivity to carry out this measurement correctly (see 5.4.2).
With the Multi-meter running, fit the calibrator in place and switch it on. Wait a few seconds for the measurement to stabilize. Then press the button. You will receive the prompt in Fig.8.8. Figure 8.8 Be advised that, by answering yes, you will affect all pressure measurements executed with input channel A. You can inspect the newly acquired sensitivity entering the CLIO Options>Unit Conversion dialog (see 5.4.2).
8.5 THE LCR METER This is a particular operating mode of the Multi-meter that gives you the possibility of measure inductors, capacitors and resistors. This measurement is an impedance measurement and is carried out in the Internal Mode; please use Chapter 13 as a reference concerning impedance, related connections and operations.
8.6 INTERACTION BETWEEN THE MULTI-METER AND FFT The Multi-meter uses the same capture and processing units as the FFT control panel. To perform a measurement it programs the FFT routines (changing FFT settings to match its needs) and then effectively starts an FFT measurement in background. The two panels can be opened and can work together but FFT always acts as the master while Multi-meter as the slave.
9 FFT, RTA AND “LIVE” TRANSFER FUNCTION 9.1 INTRODUCTION By selecting the FFT command from the main menu bar, it is possible to carry out Fourier analysis of the input signal to determine its frequency content using the Fast Fourier Transform (FFT). The ability to process two channels simultaneously, to select the appropriate sampling frequency and the possibility of triggering with respect to the generated signal make this control panel a flexible and valuable instrument.
9.2.1 TOOLBAR BUTTONS, DROP DOWN LISTS AND DISPLAYS gonew.gif Starts an FFT measurement. Right-clicking on it you open the associated drop down menu where it is possible to select the Continue switch. In this mode the measurement is not started from blank but accumulates with the previously stopped one; see Averaging (9.6) for details. Stops the current measurement. Enters the FFT Settings dialog box. Enables the Time Data display.
measurement unless, while in exponential averaging, the target has already been reached; see Averaging (9.6) for details. 9.3 RTA - OCTAVE BANDS ANALYZER Fig. 9.2 The RTA control panel Pressing the RTA button you select the octave bands analyzer. Fig. 9.2 shows the RTA control panel (while analyzing the 1/3 octave response of a HT center channel speaker).
9.4 FFT SETTINGS DIALOG Fig. 9.2 The FFT settings dialog box FFT Size Selects the number of samples acquired and processed by each FFT. It is possible to choose a size between 512 and 131072 points. Delay Permits the input of the desired processing delay (in ms) when in Internal Trigger mode. See 9.7 for details. Internal Trigger Enables the Internal Trigger mode. See 9.4 for details.
9.5 FFT AND RTA OPERATION The FFT and RTA measurements (and also Multi-meter ones, see Chapter 8) differ from MLS and Sinusoidal ones in the fact that they are interactive; the user has control over measurement time and generated stimuli. You may also obtain answers about unknown signals from them, without any need for generating a stimulus; or you may leave this job to others, similar to when you measure an audio chain relying on the test signals contained in a CD-ROM.
A better approach is to center the sinusoid to the nearest spectral line i.e. 999.75Hz as shown in the next figure. Note the use of the multimeter as frequency counter; note also that its precision is of 0.1Hz when FFT size is higher than 32k. If you want to generate a full spectrum signal choose an All-tone of proper length matching FFT size. The following figure shows a 16k All-tone (all16384.sig) analyzed with a 16k FFT.
If you had chosen a wrong size, like an all tone of 8k, you would have obtained the following analysis which clearly shows a lack of energy at alternating bins; the effect is visible only at low frequency due to the logarithmic nature of the graph. CLIO has the possibility of internal trigger (and relative delay) i.e. triggering with respect of the generated signal thus obtaining a synchronous capture. As an example let's see how a measurement presented in section 11.4 was done; please refer to figures 11.
and permits the identification of the device harmonic distortion. To proceed further one could vary the stimulus amplitude and test the distortion of the tweeter at different amplitudes; using bursts also prevents the damage of the unit as the overall power delivered to it rather low and a direct function of the duty cycle of the burst itself.
9.6 AVERAGING Averaging plays a very important role in FFT analysis. It is vital when analyzing signals buried with noise. It is also important when taking spatially averaged measurements. CLIO has flexible averaging capabilities. Averaging basically means adding and dividing for the number of additions made.
Audiomatica Srl FFT - 1/3 OCTAVE 10/07/01 18.07.43 80.0 CLIO dBSPL 70.0 60.0 50.0 40.0 30.0 100 File: 1k Hz 10k 20k CH A dBSPL 51.2kHz 16384 Rectangular Figure 9.6 9.7 TIME DATA DISPLAY (OSCILLOSCOPE) The time data (Fig. 9.7) is an ancillary display to an FFT or RTA executed measurement. Here we see a 100Hz sinusoid captured and analyzed with a 16K FFT. Figure 9.
Figure 9.8 9.8 FFT AND MULTI-METER There is a close interaction between FFT and Multi-meter operations. The two measurements share the same acquisition and processing core. Should they operate together the FFT control panel acts as the master while Multi-meter follows as the slave. In this situation, among other peculiarities, the Go and Stop buttons of the Multi-meter are disabled; if an FFT acquisition is started then the Multi-meter runs as well, the same when you stop the measurement.
9.10 “LIVE” TRANSFER FUNCTION ANALYZER Fig. 9.3 The Live transfer function control panel Pressing the Live transfer function button the instrument behaves as a dual channel FFT analyzer referencing one channel to the other and calculating the transfer function between the two. Fig. 9.3 shows the Live transfer function control panel (while measuring the frequency and phase response of a loudspeaker).
delay display Shows the delay correction, in ms, that is applied while processing the two channels. level threshold display and control Sets the peak level versus input full scale of the reference channel below which the measurement is frozen. It is possible to modify the value using the dedicated spin buttons. Setting this threshold properly lets you measure only when the signal is present at the reference channel and avoid that inaccurate readings accumulates with the measure distorting it.
Another factor of maximum importance in order to obtain the best results is to properly set input sensitivity for both input channels separately; the two peak meters of CLIO desktop should help you in this task; set input sensitivity so that both readings average in their respective green areas.
Beyond the magnitude frequency response it is also possible to measure the phase response and the impulse response. When taking acoustical measurements these functions heavily depend on the interchannel delay i.e. the total amount of delay present between the two channels, normally due to electronic equipment, misalignment of sound sources or flight time from speakers to microphone. When the measurement is just started, if you select the Time data display, you may see the following impulse response.
The last obstacle you may find while measuring phase is that, even if the interchannel delay has been correctly removed, still remains a phase inversion in the chain giving the following response. It is possible to control a phase inversion with the dedicated buttons on CLIOwin desktop; simply invert the phase of either channel A or B, obviously not both! In this way the final measurement of phase response will be as follow.
10 MLS & LOG CHIRP 10.1 INTRODUCTION Within this menu two different technique are available that yields to the final result, the complex transfer function of a generic device. They are MLS and LOG CHIRP Analysis. While the internal processing is quite different the result is the same and this justify keeping them together. Advantages of each approach will be described later in this chapter briefly, leaving to the bibliography for details.
10.2.1 TOOLBAR BUTTONS Starts an MLS & LOG CHIRP measurement. If pressed the measurements will be autosaved. The current autosave definitions apply; see 6.3.1 for details. If pressed the measurements will be autostored in overlays. Selects the Loop mode. When in Loop mode the MLS & LOG CHIRP measurement is automatically repeated until the user presses a keystroke or releases the button. If Autosave is active the loop mode ends after the total files to be autosaved are done.
Y scale unit Selects the measurement Y scale unit. Possible choices are dBV, dBu, dBRel as Voltage, dBSPL, dBPa, dBPa/V as pressure, dBmeter as displacement, dBm/s as velocity, dBm/s2 as acceleration and Ohm as impedance unit. Refer to CLIO Options>Units Conversion dialog for reference sensitivities. smoothing Activates a frequency smoothing of the active curve. This smoothing effect will allow a better appreciation of the general features of the response curve.
measurements refer either to the Internal impedance mode or to QC Box Select (the hardware setting of the QC Box determines directly the Impedance Mode, refer to 4.6). When checking Ohm Right Scale the impedance is referred to the right Y scale 10.2.4 MLS & LOG CHIRP POST-PROCESSING TOOLS Figure 10.3 Loads an MLS & LOG CHIRP process. Saves an MLS & LOG CHIRP process. Adds a data value or compatible file to the current measurement. Subtracts a data value or compatible file to the current measurement.
10.3 IMPULSE RESPONSE CONTROL PANEL Figure 10.4 10.3.1 TOOLBAR BUTTONS The following toolbar buttons differ from frequency domain control panel: Displays Impulse Response. Displays Step Response. Displays Schroeder Decay. Displays Energy Time Curve (ETC). Also the following buttons inside the measurement area are particular to this control panel. See Chapter 6 for other general information. Selects the starting point of the measurement window. Selects the end point of the measurement window.
10.4 MEASURING FREQUENCY RESPONSE In a step by step process we will deal with any single aspect that affects MLS & LOG CHIRP measurement results. At first we deal with electrical measurements, leaving acoustical as the last steps. 10.4.1 MEASUREMENT LEVEL Opening the MLS & LOG CHIRP menu for the first time you will see a graph which has frequency on its X-axis. Our first step will be measuring the response of an "A" weighting filter.
size for the FFT. This is important as the frequency resolution you get is calculated as the sampling frequency divided by the FFT size. Again for the default settings this is 48000/16384=2.929 Hz. This is already a high resolution. However thinking in terms of octave or fractions of an octave, which are the terms of a logarithmic frequency axis, 2.929Hz is around 1/2218 of an octave at 10kHz while is around 1/3 of an octave at 10Hz. Again an example is better than a thousand words.
10.4.3 ACOUSTIC FREQUENCY RESPONSE Up till now we measured using CLIO and simple cables. Now we are going to deal with acoustic measurements. The time domain will be an essential part of our interest. Furthermore we need to add two external devices, a microphone and a power amplifier. Connections are shown in Fig.10.10. INPUT (A OR B) CLIO OUTPUT (A OR B) MIC-01 OR MIC-02 BLACK RED RED BLACK POWER AMPLIFIER Figure 10.
Figure 10.11 Any other reflecting surface is further than the floor. If the microphone is directly connected to the CLIO board remember to switch the microphone power supply on. It is also very important to remember to type in the correct microphone sensitivity in the microphone Dialog Box, this is crucial for setting the correct measurement level. We have already dealt with level before, however here, things are more dangerous.
LS3/5A, year 1978. Fig.10.14 shows our result. Audiomatica Srl MLS - Frequency Response 06/07/2001 18.12.25 110.0 CLIO dBSPL 180.0 Deg 100.0 108.0 90.0 36.0 80.0 -36.0 70.0 -108.0 60.0 20 -180.0 100 File: fig10.mls 1k Hz 10k 20k CH A dBSPL Unsmoothed 51.2kHz 16K Rectangular Figure 10.14 What you see is the speaker plus the room where we took our measurement, which is far from being anechoic. It is time to inspect the time domain. Clicking on the Time Domain button we get Fig.10.
Now things look much better and this is almost the anechoic response of the speaker. However nothing comes for free. The low frequency part of the response seems quite optimistic for such a little speaker. The price we paid in setting the impulse tail to 0 is that we lost information on the lower part of the spectrum. The transition frequency between meaningful and meaningless data is calculated as 1 divided by the selected impulse length. In our case we selected a 6.8ms long impulse. 1/0.
10.4.4 PHASE & GROUP DELAY We used the term "Frequency Response" to refer to graphs of Fig.10.5 and Fig.10.8. Frequency is in the x-axis in both figures. The units that respond to frequency, y-axis, are Volt and Ohm, respectively. Both of them are complex quantities (have real and imaginary parts) and their magnitude is shown. Doing this we obtained a very useful piece of information but we lost the original data (infinite numbers of different real and imaginary part can lead to the same magnitude).
be exactly the same.We will take this opportunity to introduce the use of the Wrapped Phase Button. Figures 10.22 and 10.23 shows the tweeter phase curve, unwrapped and wrapped. Audiomatica Srl MLS - Frequency Response 07/07/2001 10.15.18 110.0 CLIO dBSPL Audiomatica Srl 180.0 Deg MLS - Frequency Response 07/07/2001 10.15.18 110.0 CLIO dBSPL 180.0 Deg 100.0 -3132.0 100.0 108.0 90.0 -6444.0 90.0 36.0 80.0 -9756.0 80.0 -36.0 70.0 -13068.0 70.0 -108.0 -16380.0 60.0 20 60.
response can be obtained from the magnitude response by calculation. Another kind of phase (we promise it is the last one), is Excess Phase. This is the algebraic difference between true phase, as in Fig.10.22, and minimum phase. It is exactly what we need to separate the time of flight from the devices own phase response. We won’t use excess phase directly here but a post process of it, Excess Group Delay. Fig.10.25 is the excess group delay of our tweeter vs. frequency.
Audiomatica Srl MLS - Frequency Response 10/07/2001 18.48.53 110.0 CLIO dBSPL 180.0 Deg 100.0 108.0 90.0 36.0 80.0 -36.0 70.0 -108.0 60.0 20 File: tweeteralone.mls -180.0 100 1k Hz 10k 20k CH A dBSPL Unsmoothed 51.2kHz 16K Rectangular Figure 10.27 To finish this difficult paragraph we will summarize what we did with some comments. Measuring acoustic phase response is often far from a "press a button and get it" procedure.
10.5 OTHER TIME DOMAIN INFORMATION Besides the impulse response we already dealt with, CLIO gives three more time related post processing, which are ETC, Step Response and Schroeder Plots. The last is room acoustic oriented and we will handle it later with a T60 calculation example. ETC and Step Response are shown here, Fig.10.28 and 10.29; they are relative to the system of Fig.10.15. Figure 10.
10.6 PROCESSING TOOLS BY EXAMPLE CLIO has powerful processing tools that can be helpful in several circumstances. We saw the basics at the beginning of this chapter. It was just a brief description of the kind "press this to do that". Here we are going to use some of them in practice. Some general rules apply to a group of them for four basic operations. You can add, subtract, multiply and divide the data in memory either with a single complex value or with a compatible file.
"mpro" extension. This allows you to recall any value or file path later on by loading this file again. Suppose you have a small production of ten speakers that you want to test against a previous produced reference which you know is fine. You just have to define and save a process that divides the current data with the reference. Testing a device against itself should produce a flat line, within the frequency range of the device, and this should be checked before saving the process.
Audiomatica Srl MLS - Frequency Response 11/07/2001 18.22.33 110.0 CLIO dBSPL 180.0 Deg 100.0 108.0 90.0 36.0 80.0 -36.0 70.0 -108.0 60.0 20 -180.0 100 File: splwatt.mls 1k Hz 10k 20k CH A dBSPL Unsmoothed 51.2kHz 16K Rectangular Figure 10.35 Our last example will cover the merge function. When we measured the system of Fig.10.17 we stated that the lower frequency limit that had to be considered reliable was 208Hz.
10.7 MLS Vs. LOG CHIRP As anticipated in the introduction, some advise are given to help choosing between MLS and LOG CHIRP stimuli. Both approach are valid and bring to equivalent results. In both cases the device we want to measure is assumed to be Linear and time Invariant. This assumption while reasonably true in general cases in never met in absolute terms. There is always a certain degree of non linearity and, in less degree, a time variance.
impulse response while with LOG CHIRP concentrate itself in single impulses (one for each harmonic) in the tail of the impulse and can easily be manually removed. Figure 10.40 Finally a brief note on level. Setting the CLIO’s output level to 0dB you’ll have – 5.2dBV with MLS and -2.2dBV with the LOG CHIRP, exactly the same level that you’d have within the Sinusoidal menu. While this is our choice, it is a by-product of the fact that MLS, in real life, has a higher crest factor than a sinusoidal signal.
10.8 RELATED MENUS The dual domain data, Frequency and Time, obtainable within this menu, are the starting point for many kind of post processing. While some can be done within MLS & LOGCHIRP, using the Processing Tools, the Time Domain features (ETC, Schroeder Decay, Step response, window selection, transform start and end points) both complexity and results presentation flexibility suggested to implement other very important post processing in separate menus.
11 SINUSOIDAL 11.1 INTRODUCTION Within Sinusoidal, it is possible to carry out Frequency Response Analysis, Impedance Analysis and Distortion Analysis. As should be obvious the stimuli used is a Sinusoidal signal, stepped or continuously swept within user defined Frequency limits. Although Sinusoidal steady state analysis is among the oldest and more traditional kind of measure, CLIO merges the reliability of this well known technique with the power of advanced DSP.
Displays total harmonic distortion, risen the dB defined in the Settings Dialog. Displays Fast-Track Rub&Buzz, risen the amount of dB defined in the Settings Dialog. Note: Fast-Track Rub&Buzz is available only in QC software version. Set output level equalize mode; after a sinusoidal measurement has been taken it is possible to refer to the acquired frequency response in order to generate a colored output that flattens out the subsequent response.
measures impedance sensing current from a dedicated QCBox ISense output (Internal Mode is not allowed as DUT must be connected to amplifier’s output). Smoothing Allows the user to select a Frequency smoothing of the active curve. The smoothing algorithm averages all the value within the selected fraction of octave band, surrounding each analysis Frequency. It is a non destructive post process that can be applied or removed at any moment after the measurement has been taken.
Gating (Acquisition) Settings Gated Check Box Lets the user enable the gating acquisition mode. Checking it will automatically check Stepped Check Box. That is, Gated Measurements are always carried out in Stepped Mode. Delay Edit Box Lets the user define the delay, in ms, applied between the signal generation and its acquisition. When different than 0, gating is active, even when gating or Stepped check boxes (but not both) are not checked.
11.2.4 SINUSOIDAL POST PROCESSING TOOLS The POST PROCESSING Dialog gives access to very powerful tools that, once defined, can be saved, reloaded and automatically be applied to every executed measurement. Loads a Sinusoidal process. Saves a Sinusoidal process. Adds a data value or compatible file to the current measurement. Subtracts a data value or compatible file to the current measurement. Multiplies the current measurement by a data value or compatible file.
11.3 HOW TO MEASURE A SIMULTANEOUS IMPEDANCE RESPONSE OF A LOUDSPEAKER QCBox In1 In2 In3 In4 D.U.T. ISense FREQUENCY AND CLIO To From CLIO CLIO IN A IN B OUT A OUT B Mic Speaker Using the ISense current sensing output of a QCBox it is possible to simultaneously measure frequency response and impedance of a loudspeaker; this tutorial will guide you through the steps nedeed while setting up this test. 11.3.1 SETTING UP THE FREQUENCY RESPONSE Open the sinusoidal menu.
one important parameter now clear is the sweep time that is shown in the sinusoidal menu status bar: with these settings we have 1.05 seconds sweep time. Consider it fine. Save the result to “response.sin” file. The test should now be tuned up to take into account the acoustic environment and completed with missing settings. Open the sinusoidal settings dialog; proper delay should be set to compensate for microphone distance to loudspeaker, this may be evaluated by the two common ways CLIO gives you i.e.
Save the result to “impedance.sin” file. 11.3.3 INTEGRATING THE TWO-CHANNELS MEASUREMENT Starting from the actual situation, i.e. having just measured impedance relying on settings that accumulated from the previous frequency response measurement, we are now ready to integrate all of our work to realize a single stereo sinusoidal measurement.
The measuremenet can be saved as “response_impedance.sin”. To properly set scales it is useful to directly input values at their extremes; refer to 6.2 and 6.4 for details about this. Read carefully 6.2.1 about the stereo measurement display features.
11.4 A BRIEF DESCRIPTION ON SETTINGS EFFECTS 11.4.1 STEPPED VS. NOT STEPPED Although measuring speed increases, use of a “not stepped” sweep can adversely affect measuring results in several circumstances. As an example that should make this clear, let’s see what happens while measuring the impedance of a woofer in Internal or Constant Current Mode. Please refer to Measuring Impedance for more information on this topic.
11.4.2 FREQUENCY RESOLUTION Here the lower the resolution the faster the measuring time. Impedance measurements are again a powerful way to explore problems. Fig.11.3 shows two impedance measurements taken from the same 16" woofer with 1/24 octave resolution (red) and 1/6 octave resolution (black). Deriving T/S Parameters from the black curve would lead to serious errors. This is an extreme case, a huge woofer with high Qms.
11.4.3 GATING Enabling Gating allows quasi anechoic Frequency Response to be carried out in normal environments, with obvious and less obvious limitations. Regarding the geometrical environment required, Sinusoidal analysis does not differ from what has been said about MLS. Nevertheless the latter gives a much more intuitive approach. It is strongly suggested that you become very familiar with quasi anechoic measurements using MLS before dealing with Gating.
evaluation it should therefore have been stopped before it is processed. The time the system evaluates the signal is usually defined as Meter On time. This is automatically set by CLIO around the value of 6 ms, as long as the Frequency involved is high enough to allow this. Fig.11.6 is a plot of the Meter On Time Vs Frequency CLIO uses. 200 Fast Normal Slow time (ms) 100 10 1 10 100 1k frequency (Hz) 10k 80k Figure 11.
11.5 DISTORTION AND SETTINGS Sinusoidal stimuli allow CLIO to evaluated distortion in its single harmonic form. If not Set in Impedance Mode, CLIO always evaluates harmonics from second to tenth plus THD and allows the display of each one separately via the selection drop-down. While it is simple to obtain meaningful distortion figures of electrical devices, measuring Loudspeaker distortion in normal environments (without anechoic chamber) is not easy.
way is to narrow the Microphone to Loudspeaker distance. The next figures, dealing with Gating Effects, refer to a Microphone at 11.5cm (4.5") in front to a good quality tweeter. FFT size is set to 512 points, the equivalent of about 10ms Meter On at 48000Hz sampling rate. Fig.11.9 shows the effects of a wrong delay in capturing a 2kHz 10ms tone burst. All harmonics are buried below the effects of this wrong setting. Audiomatica Srl FFT 02/07/2001 15.11.42 120.0 CLIO Audiomatica Srl dBSPL Pa 100.
Finally Fig.11.12 shows the distortion analysis carried out with the same microphone distance as in the past examples and the gating delay set to 1.5ms with the auto delay option disabled. Fundamental is red, second harmonic (+30dB) blue and third harmonic (+30dB) green. Audiomatica Srl Sinusoidal 02/07/2001 16.28.03 120.0 CLIO dBSPL 180.0 Deg 110.0 108.0 100.0 36.0 90.0 -36.0 80.0 -108.0 70.0 10 File: thd1.sin -180.0 100 1k CH A dBSPL Unsmoothed Stepped Gated Delay [ms]: 1.
12 WATERFALL , DIRECTIVITY & 3D 12.1 INTRODUCTION The Waterfall, Directivity & 3D post processing routines (3D post-processing is available only with QC version software) give CLIO the possibility of making 3D or Color plots by adding a third dimension (time or degrees) to classical amplitude-frequency graphs and to visualize and export 3D polar response balloons. Waterfalls are used to characterize the anechoic sound decay of a loudspeaker or the sound decay in a room.
The 3D post processing permits the following (QC version software only): - 3-D balloon at standard 1/3rd octave frequencies - Ballon Export to EASE or CLF 154 12 WATERFALL , DIRECTIVITY & 3D
12.2 WATERFALL, DIRECTIVITY & 3D CONTROL PANEL Fig 12.1 and 12.2 show the Waterfall, Directivity & 3D control panel in many of its possible configurations; as you may imagine the post processing capabilities of this menu are very powerful. It is important to understand which is the source of data for the waterfall and directivity analysis. Waterfall A waterfall analysis is a post process applied to a measured impulse response.
12.3 WATERFALL SPECIFIC CONTROLS If pressed the waterfall spectra will be referenced to the rearmost one; the directivity spectra will be referenced to the one identified by the Z-Ref value (see 12.5.1) Displays a color map instead of 3D plot. Interpolates colors in order to obtain smooth level contours. Moves the plot up. Moves the plot down. Expands the plot changing its Y scale. The Y range is reduced. Compresses the plot changing its Y scale. The Y range is increased.
Stop Frequency Selects the stop frequency for the analysis. Number of Spectra Selects the number of data slices to display. Time Shift (ms) Selects the time between two consecutive spectra. Window Rise Time (ms) Selects the rise time of the data selecting window. Valid only for CSD. Energy Time Frequency (ETF) Selects ETF mode waterfalls. 12.3.
12.4 MAKING A CUMULATIVE SPECTRAL DECAY A cumulative spectral decay starts loading an impulse response from disk. Suppose we have taken an anechoic response of a medium sized two ways loudspeaker; the impulse response is shown in Fig.12.3. Let's first select a reflection free part of it.
Figure 12.5 One powerful way to inspect a waterfall is to enable its marker. Press the button. The display should change as in Fig.12.6. It is very easy to locate frequency zones where the decay 'suffers', like the peak around 2200Hz. After placing the cursor on it, it is possible to quickly move back and forth the calculated slices by means of the up and down keyboard arrows. Figure 12.6 Let's now change the CSD aspect. Go to the waterfall settings dialog and input 0.1ms Time Shift.
Figure 12.8 As you can now see the slices are referenced to the first one (the rearmost); thus allowing decays of different frequency regions to be compared more easily. Now change the Windows Rise Time from the default 0.58ms to 0.1ms and recalculate the CSD. The result is given in figure 12.9. Figure 12.
12.5 DIRECTIVITY SPECIFIC CONTROLS If pressed the directivity spectra will be referenced to the one identified by the Z-Ref value (see 12.5.1) Displays a color map instead of 3D plot. Interpolates colors in order to obtain smooth level contours. Moves the plot up. Moves the plot down. Expands the plot changing its Y scale. The Y range is reduced. Compresses the plot changing its Y scale. The Y range is increased. Enters the polar pattern mode. Mirror data Figure 12.
12.5.1 DIRECTIVITY SETTINGS AND OPERATION Start Frequency Selects the start frequency for the analysis. Stop Frequency Selects the stop frequency for the analysis. Root File Name and browse button The name of one file within the set to be displayed. By pressing the associated button it is possible to browse the disk and choose the file. Z-Start Value associated to the first (rearmost) file. Z-Stop Value associated to the last (foremost) file. Z-Ref Value associated to the file to be taken as reference.
NAME is a common file name, UNITS are the common measurement units (to be displayed in the graph as Z axis label) and VALUE is a unique value identifying the single file; these quantities needs to be separated by spaces, it is possible to give negative numbers to VALUE. For example 'mydriver deg -250.mls' is a valid file name: as the name tells it is a measurement named mydriver with units deg taken at -2.5 (250 divided by 100) units value.
12.6 MEASURING LOUDSPEAKER SINGLE POLAR DATA (1D MODE) We will use a PC controlled turntable under CLIO's control, and the automation possible within the MLS control panel using the Autosave and naming rules. Now suppose we want to measure and give a graphical representation of the polar response of the same two ways loudspeaker analyzed in 12.4. We need to measure its anechoic frequency response, at various angles and save the files following the rules given in 12.5.1. 12.6.
12.6.2 PREPARING THE TURNTABLE Open the Turntables Control dialog and select the connected turntable (See 4.7). Outline ET/ST (TTL Pulse) We assume that the Outline ET/ST turntable is properly connected to your PC (refer to 4.7.1 for details). To prepare for this measurement session you need to: 1) Manually set the front selector labeled 'Deg Step' to 5°. 2) Rotate the turntable counterclockwise until you reach the desired start position: as we want to start from -180° position it at 180°.
The last thing to do is to activate Autosave and Loop; to do this we press the corresponding toolbar buttons (Fig.12.13). Figure 12.13 Press Go. After each MLS measurement is taken you will see the turntable rotating and CLIO waiting for a sufficient period of time to allow the turntable to stabilize before automatically taking the next measurement. Should this time be insufficient you have to reset the turntable speed value accordingly.
12.7 REPRESENTING SINGLE POLAR DATA To represent the measured data we need to select the Directivity mode in the Waterfall, Directivity & 3D control panel. Then enter the Directivity Settings dialog and press the browse button. Entering our data directory we find the situation in Fig.12.15: Figure 12.15 The set of files is composed by 73 files; it is sufficient to choose one of them.
The final result for our polar data waterfall is in Fig.12.18; the response at 0 degrees is now flat and our plot perfectly identifies the behavior of the speaker, providing clear evidence of the different behavior of the polar response versus different frequency zones. Figure 12.18 Another way to view the same data are the classical circular polar plots. To achieve this ulterior result simply press the Polar Pattern button.
12.8 3D SPECIFIC CONTROLS Please note that the 3D analysis module is available only in the QC version of the software. Expands the plot changing the balloon radius scale. The balloon radius is reduced. Compresses the plot changing the balloon radius scale. The balloon radius is increased. Balloon Top view. Balloon Bottom view. Balloon Left view. Balloon Right view. Balloon Front view. Balloon Rear view. Balloon Perspective view. If pressed show the reference balloon.
Root File Name and browse button The name of one file within the set to be displayed. By pressing the associated button it is possible to browse the disk and choose the file. Symmetry Select the file set symmetry between: None, Half, Quarter, Axial and H+V. Rotation Rotation of the THETA=0 reference angle. The THETA=0 angle is by CLIO conventions oriented as the positive direction of the x-axis. If the data set is saved with a different THETA angle origin the rotation allow to compensate for this.
The autosaving and naming capabilities of CLIO render the job of measuring and creating a complete 3D directivity data set an easy and automatic task (see later 12.9 and 12.10 for examples). In order to reduce the number of files needed to describe the directivity pattern of a source, it is possible to use the source symmetry if any. There are five different symmetries available: The None, Half, Quarter and Axial symmetry modes are self explanatory.
12.9 MEASURING LOUDSPEAKER SINGLE POLAR DATA (3D MODE) Using a single PC controlled turntable (Outline ET2503D or LinearX LT360) under CLIO’s control and automation it is possible to easily collect a single loudspeaker polar with a naming convention equal to the 1D Mode (refer to 12.6 and 12.7). The 3D autosave mode is available with QC version software only. The advantage of this mode is that the turntable is automatically positioned without any operator intervention. 12.9.
12.9.3 TAKING THE MEASUREMENTS You are now ready to begin the measuring session. We suggest you to take an initial measurement (with the speaker in place over the turntables in position 0 – on-axis - and with the turntables link button not pressed) to verify all the parameters, especially viewing the acquired impulse response and setting the start and stop values of the measurement window.
12.10 MEASURING FULL SPHERE LOUDSPEAKER POLAR DATA (3D MODE) Using one or two PC controlled turntables (Outline ET2503D or LinearX LT360) under CLIO’s control and automation is it possible to easily collect sets of loudspeaker (complete or partial) impulse responses balloons. The 3D autosave mode is available with QC version software only.
12.10.3 TAKING THE MEASUREMENTS You are now ready to begin the measuring session. We suggest you to take an initial measurement (with the speaker in place over the turntables and with the turntables link button not pressed) to verify all the parameters, especially viewing the acquired impulse response and setting the start and stop values of the measurement window.
12.11 REPRESENTING 3D BALLOON DATA To represent and export the measured 3D directivity data we need to select the 3D mode in the Waterfall, Directivity & 3D control panel (The 3D analysis mode is available with QC version software only). Then enter the 3D settings dialog and press the browse button. Entering our data directory we find the situation in Fig.12.26: Figure 12.26 The set of files is composed by a certain number of files; it is sufficient to choose one of them.
It is possible to inspect the 3D directivity of the source selecting a 1/3rd octave band from 20 Hz to 20 kHz and rotating the balloon view. To rotate the balloon it is possible to select one of the predefined views by pressing the view buttons, or click and drag the balloon. Figure 12.29 show the balloon response at 5 kHz. Figure 12.29 Figure 12.30 and 12.31 are showing different views (top and right) of the same balloon response at 3150 Hz. Figure 12.30 Figure 12.
12.12 EXPORT 3D BALLOON DATA The 3D mode feature a powerful tool to export the measured data towards the most common simulation software formats. The supported export format are: EASE .xhn EASE .xhn ASCII format (only module, no complex data). CLF v2 .tab Common Loudspeaker Format CLF v2 .tab ASCII format. Impulse Responses Set of Impulse Responses in ASCII .txt format ready to be imported with EASE SpeakerLab.
12.12.1 EXPORT EASE .XHN AND CLF V2 .TAB FILES In case of EASE .xhn and CLF v2 .tab format is selected in the File And Export Format Group then the General Information, On Axis Response and Impedance & Power groups are active. Output File defines the file name and location where the file will be saved; it is possible to choose it clicking on the browse for Choose Output File button (...). The Loudspeaker Name and Manufacturer Name fields will be used into the exported text file.
12.12.2 EXPORT SET OF IMPULSE RESPONSES If Impulse Response is selected only the last Truncation group is active. The Output Folder define the path where the Impulse Responses in text format will be saved. The file will be saved as Time Data impulse responses with the naming convention requested by the EASE SpeakerLab: IR .txt If the Enable Truncation option is selected the time response is windowed with a rectangular window with Time (ms) duration.
13 MEASURING IMPEDANCE AND T&S PARAMETERS 13.1 INTRODUCTION This chapter deals with impedance measurements generally before going onto the Thiele and Small Parameters Menu description. CLIO performs impedance vs. frequency measurements both from within the MLS and the Sinusoidal Menu. You will find specific information in the relative Chapters. Both are relevant to what we will now explain. Here we explain connections, principles and other topics that apply to both menus.
If you are a novice in using CLIO, or to impedance measurements in general, use this mode; also do not start measuring loudspeaker impedance immediately. Get a 22 to 100 Ohm resistor, possibly 1% tolerance, and gain experience with something which you should already know the expected results of. Here are two examples both with Sinusoidal and MLS. Before you press go, remember to set the Y scale to Ohm. For this example we chose a 47 Ohm resistor.
13.3.1 MEASURING IMPEDANCE OF LOUDSPEAKERS We will start with a 5" woofer using Sinusoidal, our preferred choice, with the following Settings (1/24 of octave resolution). Besides frequency range, which can be changed without side effects, those above are problem free settings for impedance measurements. We will experiment a little, pointing out difficulties that might arise. Let’s start with output level, which is a sensitive topic. 13.3.2 SETTING THE RIGHT LEVEL The five curves of Fig.13.
makes life harder even if more interesting. Deriving the principals T&S Parameters from the five curves yields to Table 13.1 Fs Qms Qes Qts +10dBu 69.244 3.105 0.609 0.5094 +5dBu 71.63 3.6461 0.6643 0.5619 0dBu 72.9912 3.986 0.695 0.5920 -5dBu 73.5429 4.1663 0.7147 .61 -10dBu 73.82 4.227 0.7218 0.6166 Table 13.1 Values from 0dBu to -10dBu are in optimum agreement and this sets the maximum level to be used to 0dBu.
Both were taken at-10dBu, a value that gained our favor before. Results are in Fig.13.6 for MLS and Fig .13.7 for Sinusoidal. Audiomatica Srl MLS - Frequency Response 03/07/2001 16.35.18 25.0 180.0 CLIO Audiomatica Srl Sinusoidal 03/07/2001 16.34.16 25.0 Ohm CLIO 180.0 Deg Ohm Deg 20.0 108.0 20.0 108.0 15.0 36.0 15.0 36.0 10.0 -36.0 10.0 -36.0 5.0 -108.0 0.0 20 File: noise-10.mlsi 5.0 0.0 10 -180.0 100 1k Hz 10k -108.0 -180.0 100 File: noise-10.
13.4 I SENSE This requires Audiomatica CLIOQC Amplifier and Switch Box model 2, 3 4 or 5. It is a simplified Constant Voltage method. Simplification arises as both device gain and sensing resistor (around 0.1 Ohm) is known. Fig.13.9 shows the CLIOQC Software Control Dialog Box. I Sense should be selected. Figure 13.9 Fig.13.10 shows required connections.
displayed multiplying it by the ratio between the known resistor value and the marker reading at 1kHz. For example: assume a known resistor value 10 Ohm, reading at 1kHz 9.3 ohm and an I Sense value of 0.127 Ohm. Multiply 0.127 by 1.075268817 to obtain 0.13655914, input this new value and check everything by performing a new measurement. 13.5 CONSTANT VOLTAGE & CONSTANT CURRENT These were the standard approaches to measuring impedance with a traditional set of instruments.
Audiomatica Srl Sinusoidal 04/07/2001 10.13.34 0.0 180.0 CLIO dBV Deg -10.0 108.0 -20.0 36.0 -30.0 -36.0 -40.0 -108.0 -50.0 10 -180.0 100 File: cvreference.sin 1k CH A dBV Unsmoothed Stepped Delay [ms]: 0.000 Hz 10k 20k Dist Rise [dB]: 30.00 Figure 13.12 Let’s now proceed with measuring the device. Connections need to be changed as in Fig. 13.13. We are now going to measure the voltage across Rs, which is proportional to the current in the device.
Pressing OK we get Fig.13.15 which is our final result. Note that the Y Units have been changed to Ohm. This result is only in memory and should be saved now for further use. Audiomatica Srl Sinusoidal 04/07/2001 10.52.16 50.0 180.0 CLIO Ohm Deg 40.0 108.0 30.0 36.0 20.0 -36.0 10.0 -108.0 0.0 10 File: cvresult.sini -180.0 100 1k CH A dBV Unsmoothed Stepped Delay [ms]: 0.000 Hz 10k 20k Dist Rise [dB]: 30.00 Figure 13.15 13.5.
INPUT A CLIO INPUT B RS OUTPUT A OUTPUT B BLACK RED POWER AMPLIFIER Figure 13.17 The figure shows us we are going to measure the voltage across the device. Therefore the next graph, Fig.13.18, will give us detailed information regarding the measuring level. Audiomatica Srl Sinusoidal 04/07/2001 11.40.10 10.0 CLIO dBV 180.0 Deg 0.0 108.0 -10.0 36.0 -20.0 -36.0 -30.0 -108.0 -40.0 10 File: ci.sin -180.0 100 1k CH A dBV Unsmoothed Stepped Delay [ms]: 0.
Audiomatica Srl Sinusoidal 04/07/2001 11.40.10 50.0 CLIO 180.0 Ohm Deg 40.0 108.0 30.0 36.0 20.0 -36.0 10.0 -108.0 0.0 10 File: ciresult.sini -180.0 100 1k CH A dBV Unsmoothed Stepped Delay [ms]: 0.000 Hz 10k 20k Dist Rise [dB]: 30.00 Figure 13.19 13.6 IMPEDANCE: SINUSOIDAL OR MLS Up to now we have almost always used Sinusoidal to perform Impedance Measurements. When MLS has been used, it was to point out problems. We also stated Sinusoidal is the preferred choice.
13.7 THIELE & SMALL PARAMETERS 13.7.1 INTRODUCTION CLIO handles Thiele and Small Parameters, hereafter referred to as T&S, as a post process of impedance measurements. Three options are available for source data, selected by the Data Origin Drop Down Control: Sinusoidal Impedance Data, MLS Impedance Data, File Data, the last created with either of the previous. There are no conceptual differences between File and the first two options, beside where the data resides.
13.7.
13.7.4 T&S STEP BY STEP Getting T&S requires two impedance measurements. As we will use both methods we need three, the first relative to the driver in free air, the second to the driver with a known mass (Delta Mass) added to the cone, the third to the driver loaded with a known volume (Delta Compliance). Fig.13.20 shows the results of the three measurements, overlaid in one single graphic. Audiomatica Srl Sinusoidal 05/07/2001 10.02.11 50.0 CLIO 180.0 Ohm Deg 40.0 108.0 30.0 36.0 20.0 -36.
After the correct values have been typed in and clicking OK we will be prompted for the file name. The file required here is the free air impedance measurement. Opening the file we get this partially filled T&S parameters screen. Now we can save this result for later use or proceed immediately for the missing parameters. Notice that the two Buttons for Delta Mass and Delta Compliance that were disabled before are now enabled.
We can now save our complete results and proceed with the Delta Compliance. The free air derived data is already in memory and we can finally deal with the last part of the procedure, which is nearly the same as before. We will be prompted for volume instead of weight. Obviously the file we have to choose is relative to the driver loaded with a known volume (15.1 liters in this case). Here we show the results for the Delta Compliance method. The two sets of data do agree pretty well. 13.7.
14 LINEARITY & DISTORTION 14.1 INTRODUCTION Linearity and Distortion analysis are grouped together though they are, apparently, opposite terms. From the analyser point of view however, they are similar as either the fundamental or the harmonics (intermodulation) amplitude is evaluated while sweeping D.U.T. input level.
The graphs refers to a linearity measurement of a Push Pull tube amp. After processing, the Y scale can be expanded, still including the whole span, greatly enhancing detail inspection. 14.2.1 TOOLBAR DROP DOWN LIST Input channel Selects the input channel configuration 14.2.2 LINEARITY & DISTORTION SETTINGS DIALOG X Axis Values Allows setting the X axis extreme left and right values.
fundamental/s. When Linearity is selected dBV or Volts will be used as Y Unit. If the compute linearity button is pressed dB or V/V are used. Sweep Settings These are all settings affecting the next measure to be performed. Must be therefore handled with care. Start and Stop Sets the voltage sweep range supplied to the DUT input. Start should be lower in value than Stop. While these values can be chosen in an iterative way, having a rough idea of the DUT gain is a good practice.
DIN Measures Intermodulation distortion using DIN standard. Two tones are generated in a 4:1 ratio at 250Hz and 8000Hz. Intermodulation components up to the 5th order are considered for distortion. CCIF Measures Intermodulation distortion using two equal level near spaced (1kHz) in Frequency tones. Difference Intermodulation components up to the 2 th order are considered for distortion. To keep results directly comparable with THD analysis both output Voltage or Power are single tone equivalent scaled.
15 ACOUSTICAL PARAMETERS 15.1 INTRODUCTION With the Acoustical Parameters control panel it is possible to evaluate the acoustical behavior of a room and carry out sophisticated post processing of a measured impulse response to calculate the acoustical parameters as defined by the ISO 3382 standard. These quantities describe the behavior of auditoria, concert halls and are applicable to any room intended for speech or music reproduction. 15.2 THE ACOUSTICAL PARAMETERS CONTROL PANEL Fig. 15.
15.2.1 TOOLBAR BUTTONS AND DROP DOWN LISTS Starts an Acoustical Parameters calculation. See below the data source for the calculation. Enters the Acoustical Parameters Settings dialog box. impulse response data source drop down Selects the source of impulse response data among the following: - Memory. The impulse response is already in memory and is reprocessed with current settings. - File. The impulse response is loaded from disk. - MLS.
15.2.2 INTERACTION WITH THE A.P. CONTROL PANEL It is possible to interact with the acoustical parameters control panel simply clicking on the parameters data table. To enter the impulse display mode simply click on the table first row and select the desired octave band of interest; the selected column will change accordingly and the decay (or ETC) will also follow. The Fig.15.1 shows the selection of the 1kHz octave to which corresponds the ETC calculated.
15.3 ACOUSTICAL PARAMETERS SETTINGS Frequency Bands Selects either Octave or Third of Octave calculations. The following figure shows the same data analyzed before in octave bands now presented with 1/3 of octave processing. Noise Correction Applies noise correction to the tail of the impulse response as suggested by ISO 3382. The figure below shows the increase in the linear portion of the calculated decay which is obtainable.
15.4 THE CALCULATED ACOUSTICAL PARAMETERS The acoustical parameters are calculated from a measured decay curve. A decay curve is defined as the decay of sound pressure level as a function of time after the sound source has ceased. The decay curves are calculated from the measured impulse response after octave filtering has been applied; also wideband (linear or A-weighted) decay curves are available.
RTU [s]. Reverberation time evaluated from a user defined dynamic range; refer to 15.3 acoustical parameters settings. See also below the correlation coefficient R associated with RTUser. R(RT). Each reverberation time estimation (RT20, RT30 and RTU) has associated a negative number which is the correlation coefficient R showing how closely the corresponding decay curve fits a straight line. A value of -1 gives a perfect linear fit. When the correlation coefficient is smaller than -0.
15.6 STI CALCULATION The Speech Intelligibility Index are calculated from a single measured MLS response. Some care should be followed while executing the measurement of the impulse response to be used for the STI calculation: - the procedure is valid only for an MLS stimulus as the signal to noise ratio is collected in a single measurement. - the impulse length must be at least 1.6 seconds to correctly calculate the lowest modulation frequency needed for the MTF matrix.
The parameters are calculated together with the acoustical parameters and can be viewed in text format by pressing the STI button. --------------------------------------------------------------------STI index --------------------------------------------------------------------Oct.Band 125 250 500 1k 2k 4k 8k f1=0.63 0.716 0.776 0.726 0.781 0.794 0.842 0.933 f2=0.80 0.669 0.718 0.666 0.727 0.733 0.777 0.865 f3=1.00 0.627 0.665 0.612 0.682 0.677 0.717 0.803 f4=1.25 0.584 0.611 0.561 0.640 0.622 0.658 0.
STIr(male)=0.490 rated Fair ALcons=12.0% STIr(female)=0.487 rated Fair ALcons=12.2% --------------------------------------------------------------------RaSTI index --------------------------------------------------------------------Oct.Band 500 2k 0.7 0.766 1.0 0.612 1.4 0.594 2.0 0.486 2.8 0.402 4.0 0.428 5.6 0.260 8.0 0.446 11.2 0.360 --------------------------------------------------------------------RaSTI=0.484 ALcons=12.
16 Leq LEVEL ANALYSIS 16.1 INTRODUCTION With the Leq Analysis control panel it is possible to execute real-time capture and level measurement of any kind of signal present at CLIO’s input. The behavior of the instrument closely resemble that of a graphical level recorder plus direct-to-disk data capture.
16.2.1 TOOLBAR BUTTONS AND DROP DOWN LISTS Starts a Leq acquisition and analysis. If data capture is active the event is automatically registered on the hard disk. Invokes an FFT measurement together the Leq one. Enters the Leq Analysis Settings dialog box. When pressed, resets peak value. Does not affect any other calculation. Activates real time data display; useful for high resolution time measurements (1/100s and 1/1000s).
16.2.2 INTERACTION WITH THE Leq CONTROL PANEL It is possible to interact with the Leq control panel clicking on the left data display where you can find five three state checkboxes. Each checkbox refers to one calculation and data curve. Its state can be: Deselected. The data value and corresponding curve are NOT displayed. Selected. The data value and corresponding curve are displayed with their color. Active.
16.3 Leq SETTINGS Time resolution Selects the time resolution of the measurement. It is possible to choose a value among 1s, 1/2s, 1/4s, 1/10s, 1/100s and 1/1000s. Normally choose the least resolution possible as this choice directly reflects on the measured data size (.leq binary files). This setting is not influencing the sampling frequency that remains 48000Hz. Frequency weighting Selects the frequency weighting applied; you can choose either No Weight or AWeighting.
17 WOW AND FLUTTER 17.1 INTRODUCTION Within this menu Wow & Flutter measurements are possible, meeting both IEC and NAB standards. Basically, what is measured is the frequency modulation that follows instantaneous speed variations due to mechanical imperfections in analog recording or playback devices.
17.3 FEATURES Figure 17.2 Aside a self explaining graphical part, on the left part several numeric data are present simultaneously. From top to bottom they are: IEC LIN expressed in percentage, express the WOW & FLUTTER value, unweighted, following IEC standard. IEC WEIGHT expressed in percentage, express the WOW & FLUTTER value, weighted, following IEC standard. NAB LIN expressed in percentage, express the WOW & FLUTTER value, unweighted, following NAB standard.
Figure 17.3 In the above figure the weighting filter response is displayed. This apply both to IEC and NAB standards. Aside carrier Frequency the main difference between them is the detector that evaluate the demodulated signal, which is peak detection in IEC and RMS in NAB; IEC Wow & Flutter values are usually greater.
18 WAVELET ANALYSIS 18.1 INTRODUCTION The Wavelet Analysis tool allows to post-process impulse responses and to create color plots of the energy of the signal versus time and frequency. The tool is similar to the ETF analysis described in chapter 12, but since it is based on wavelet transform instead of Fourier Transform, does not suffer from the fixed timefrequency resolution. The ETF analysis is based on Short Time Fourier Transform (STFT).
18.2 WAVELET ANALYSIS CONTROL PANEL Fig 18.1 show the Wavelet Analysis control panel, the behavior of this menu is similar to the Waterfall menu as seen in chapter 18. As already stated the source of data for Wavelet Analysis is an impulse response, please refer to chapter 10 (MLS&LogChirp) to have details on how to measure an impulse response. 18.2.1 COMMON TOOLBAR BUTTONS AND DROP DOWN LISTS Starts a Wavelet Analysis calculation.
18.3 WAVELET ANALYSIS SETTINGS Figure 18.2 - Wavelet Settings Dialog Start Frequency Selects the start frequency for the analysis. Stop Frequency Selects the stop frequency for the analysis. Wavelet Q Selects the frequency resolution for the analysis, see also 18.4.
18.4 WAVELET ANALYSIS OPERATION As already stated the data source for the Wavelet Analysis is a measured impulse response. Once you have loaded an impulse response inside the Waterfall Analysis control panel you may easily inspect it, in the same way you also do with the MLS Impulse control panel (See chapter 10). The limits in time of the Wavelet Analysis plot will be the same of the impulse plot view.
Figure 18.4 Wavelet Analysis of loudspeaker impulse response Q=6 Figure 18.
18.4.2 NORMALIZED SCALOGRAMS The Scalogram is a colormap display of the magnitude square of the matrix of Wavelet coefficients. It is possible to interpret every cell of the Scalogram as proportional to the energy of the signal in a domain located around give time and frequency points. Due to the uncertainty in time, the energy content it is smeared in time and somewhat difficult to interpret. Figure 18.
Figure 18.
BIBLIOGRAPHY [1] Joseph D'Appolito, “Testing Loudspeakers”, Audio Amateur Press, 1998. [2] J.M. Berman and L.R. Fincham, “The Application of Digital Techniques to the Measurement of Loudspeakers”, J. Audio Eng. Soc., Vol. 25, 1977 June. [3] L.R. Fincham, “Refinements in the Impulse Testing of Loudspeakers”, J. Audio Eng. Soc., Vol. 33, 1985 March. [4] S.P. Lipshitz, T.C. Scott and J. Vanderkooy, “Increasing the Audio Measurement Capability of FFT Analyzers by Microcomputer Postprocessing”, J.
[19] M.O. Hawksford, “Digital Signal Processing Tools for Loudspeaker Evaluation and Discrete-Time Crossover Design”, J. Audio Eng. Soc., 1997 January/February. [20] D. Clarke, “Precision Measurement of Loudspeaker Parameters”, J. Audio Eng. Soc., 1997 March. [21] IASCA - International Auto Sound Challenge Association Inc. - “Official Judging Rules”. [22] A.Farina, “Simultaneous measurements of impulse response and distortion with a swept sine technique”, AES Preprint n.
NORMS [1] IEC 61672, Sound Level Meters (replacing former IEC 651, Sound level meters and IEC 804, Integrating-averaging sound level meters). [2] IEC 60268, Sound system equipment. [3] IEC 60386, Methods of measurement of speed fluctuations in sound recording and reproducing equipment. [4] ISO 226, Normal equal-loudness-level contours. [5] ISO 266, Preferred frequencies for measurements. [6] ISO 3382, Measurement of reverberation time of rooms with reference to other acoustical parameters.
