Eaw SMAART V6 User Manual
v.6v.6
SOUND SYSTEM MEASUREMENT,
OPTIMIZATION AND CONTROL SOFTWARE
FOR MICROSOFT WINDOWS® AND MAC OS® X
USER GUIDE
Manual written and edited by Calvert Dayton and Rob Wenig.
Manual design by Rob Wenig.
Cover design by Martin Lindhe.
©2007 EAW Software Company, Inc. All rights reserved worldwide. No part of this publication
may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any
language in any form by any means without written permission from EAW Software Compa ny, Inc.
EAW Software Company, Inc.
One Main Street
Whitinsville, MA 01588
Phone: (508) 234-9877
Fax: (508) 234-6479
web: http://www.eaw.com
e-mail: info@eaw.com
EAW Smaart 6 Operation Manual
Table of Contents
Chapter 1: Getting Started............................................................................................9
1.1 Hardware Requirements............................................................................9
1.1.1 Computer.....................................................................................9
1.1.2 Measurement Microphone........................................................11
1.1.3 Microphone Preamplifier..........................................................11
1.1.4 Cables and Interconnections.....................................................11
1.1.5 Additional Useful Equipment...................................................11
1.2 Smaart 6 Software Installation ................................................................12
1.2.1 First Time Installation...............................................................12
1.3 Smaart 6 Signal I/O.................................................................................14
1.4 Introduction to the User Interface............................................................16
1.4.1 The Menu Bar...........................................................................17
1.4.2 The Plot Area............................................................................17
1.4.3 Cursor Readout .........................................................................17
1.4.4 Start/Stop Buttons.....................................................................17
1.4.5 Measurement Mode Buttons.....................................................18
1.4.6 Display Controls .......................................................................18
1.4.7 Reference Trace Controls..........................................................18
1.4.8 Signal Generator .......................................................................19
1.4.9 Internal Delay Control ..............................................................20
1.4.10 Signal Level/SPL Display and Input Level Meters ..................20
1.5 How to use this Manual...........................................................................21
Chapter 2: Concepts, Glossary, and Bibliography.......................................23
2.1 Concepts..................................................................................................23
2.1.1 Decibels.....................................................................................23
2.1.2 Fast Fourier Transform.............................................................24
2.1.3 Averaging..................................................................................25
2.1.4 Sampling Rate...........................................................................25
2.1.5 Frequency Resolution ...............................................................26
2.1.6 Pink and White Noise ...............................................................27
2.1.7 Data Window Functions............................................................28
2.1.8 Impulse Response .....................................................................29
2.1.9 The Transfer Function...............................................................29
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2.1.10 Coherence..................................................................................30
2.1.11 Signal Alignment ......................................................................30
2.2 Glossary of Terms ...................................................................................31
2.3 Selected Bibliography .............................................................................34
Chapter 3: Analysis Modes and Display Types...............................................37
3.1 Spectrum Measurements .........................................................................38
3.1.1 RTA ..........................................................................................38
3.1.2 Spectrograph.............................................................................40
3.1.3 Spectrum Measurement Parameters..........................................41
3.2 Frequency Response Measurements........................................................44
3.2.1 Basic Frequency Response Measurement Setup.......................44
3.2.2 Frequency Response Overview.................................................45
3.2.3 The Magnitude Display.............................................................45
3.2.4 The Phase Display ....................................................................46
3.2.5 Time Windowing......................................................................46
3.2.6 Averaging and Smoothing ........................................................47
3.2.7 Coherence and Coherence Blanking.........................................49
3.2.8 Magnitude Thresholding...........................................................51
3.3 Delay and Impulse Response Measurements..........................................52
3.3.1 Impulse Response Measurement Parameters............................52
3.3.2 Working with Impulse Response Data......................................54
3.3.3 Automatic Delay Locator..........................................................55
3.4 SPL Measurements..................................................................................56
3.4.1 The Signal Level/SPL Readout.................................................56
3.4.2 Calibrating to SPL.....................................................................57
3.5 Capturing and Loading Measurement Data.............................................60
3.5.1 Capturing a Reference Trace.....................................................60
3.5.2 Loading a Reference Trace.......................................................61
3.5.3 Working with Reference Traces ...............................................61
3.5.4 Averaging Reference Traces.....................................................62
3.6 Internal Delay..........................................................................................63
3.7 Internal Signal Generator ........................................................................63
3.8 Weighting Curves....................................................................................65
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3.9 External Device Control..........................................................................66
3.9.1 External Device Control Interface............................................66
3.9.2 Configuring External Devices...................................................67
3.10 The Locked Cursor..................................................................................68
3.11 Smaart 6 Screen Capture .........................................................................69
3.11.1 Windows ...................................................................................69
3.11.2 Mac OSX...................................................................................69
Chapter 4: Applications.................................................................................................71
4.1 Real-Time Spectrum Analyzer (RTA) ....................................................72
4.1.1 Connecting the Measurement System.......................................72
4.2 Measuring an Analog Equalizer..............................................................74
4.2.1 Measurement Setup...................................................................75
4.2.2 Adjusting Signal Levels............................................................75
4.3 Measuring a Loudspeaker........................................................................77
4.3.1 Adjust Signal Levels.................................................................78
4.3.2 Impulse Response Measurement...............................................79
4.3.3 Frequency Response Measurement of the Loudspeaker...........80
4.4 Measuring a Loudspeaker and Setting an Equalizer ...............................81
4.5 Measuring and Optimizing a Sound System ..........................................84
Chapter 5: Smaart 6 Commands..............................................................................91
5.1 File Menu.................................................................................................91
5.1.1 Save Impulse.............................................................................91
5.1.2 Exit............................................................................................91
5.2 External Devices Menu ...........................................................................91
5.2.1 Add New Device.......................................................................91
5.2.2 Remove Device.........................................................................93
5.3 Options Menu..........................................................................................93
5.3.1 Spectrum...................................................................................93
5.3.2 Frequency Response .................................................................95
5.3.3 IR Analysis................................................................................97
5.3.4 Audio I/O..................................................................................98
5.3.5 Delay.........................................................................................99
5.3.6 Zoom.......................................................................................101
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EAW Smaart 6 Operation Manual
5.3.7 Instantaneous...........................................................................101
5.3.8 Reseed Averages.....................................................................102
5.3.9 High Contrast View ................................................................102
5.4 Help Menu.............................................................................................102
5.4.1 About.......................................................................................102
5.4.2 Smaart Help.............................................................................102
5.5 Keyboard Shortcuts...............................................................................103
Chapter 6: Troubleshooting......................................................................................105
6.1 Installation Problems.............................................................................105
6.1.1 Problems During Installation..................................................105
6.1.2 Problems After Installation.....................................................105
6.2 Configuring Audio Input/Output Controls............................................106
6.2.1 Windows Wave (Wave-in/Wave-out) Devices Only..............106
6.3 Sound Hardware Problems....................................................................107
6.4 Performance Issues................................................................................108
6.5 Font and Display Problems ...................................................................108
6.6 Restoring the Default Configuration.....................................................109
6.7 Technical Support Information..............................................................110
Index..............................................................................................................111
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List of Figures
1-1 Audio I/O tab of the Options dialog ..................................................................................14
1-2 Input levels: too low (left), correct (middle), and too high (right) ....................................15
1-3 Smaart 6 main window ......................................................................................................16
1-4 Menu bar............................................................................................................................17
1-5 Cursor readout....................................................................................................................17
1-6 Display mode (left) and Measurement mode (right) buttons.............................................18
1-7 Capture and Load buttons..................................................................................................18
1-8 Signal Generator and Delay controls.................................................................................19
1-9 Signal Generation dialog ...................................................................................................19
1-10 Signal level, SPL, and input meters...................................................................................20
2-1 Pink noise graphed on octave band (left) and narrowband logarithmic (right) scales.......27
2-2 White noise graphed on octave band (left) and narrowband logarithmic (right) scales....27
3-1 View and plot display after clicking the Spectrum button.................................................37
3-2 Impulse Response Window ...............................................................................................38
3-3 Spectrograph display..........................................................................................................40
3-4 Spectrograph dB Range .....................................................................................................41
3-5 Frequency Scale list...........................................................................................................41
3-6 Average options (left); Weight options (right) ..................................................................42
3-7 Block Diagram of a Frequency Response Measurement...................................................44
3-8 Coherence Blanking parameters in Frequency Response tab of Options dialog...............50
3-9 Block Diagram of a Delay or Impulse Response Measurement........................................52
3-10 Impulse Response window ................................................................................................53
3-11 Delay auto-locator buttons.................................................................................................56
3-12 Units/Options button at the top of the Signal Level/SPL Readout....................................57
3-13 SPL/Calibrations Options and Amplitude Calibration dialogs..........................................59
3-14 Legend dialog ....................................................................................................................61
3-15 Data Information dialog.....................................................................................................62
3-16 Delay Presets in Impulse Response window .....................................................................63
3-17 Signal Generation dialog ...................................................................................................64
4-1 RTA measurement setup....................................................................................................72
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4-2 Default RTA spectrum display (1/12th-octave).................................................................73
4-3 Spectrum parameters..........................................................................................................73
4-4 Spectrograph and SPL displays .........................................................................................74
4-5 Analog EQ measurement setup..........................................................................................75
4-6 Signal Generation screen control (left) and dialog (right).................................................76
4-7 Sample measurement of an analog parametric EQ filter ...................................................77
4-8 Speaker/amp measurement setup.......................................................................................78
4-9 Impulse response of a small loudspeaker in a room ..........................................................79
4-10 Setup to measure and equalize a loudspeaker....................................................................81
5-1 Selecting from External Devices->Add menu (left) and configuring the device (right)...91
5-2 Selecting (left) and configuring (right) a newly added external device input ...................92
5-3 Spectrum tab in Options dialog .........................................................................................93
5-4 Frequency Response tab in Options dialog........................................................................95
5-5 IR Analysis tab in Options dialog......................................................................................97
5-6 Audio I/O tab in Options dialog ........................................................................................98
5-7 Delay tab in Options dialog ...............................................................................................99
5-8 Zoom tab in Options dialog .............................................................................................101
5-9 About screen ....................................................................................................................102
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EAW Smaart 6 Operation Manual
Chapter 1: Getting Started
Since its initial introduction in 1996, Smaart® has firmly established itself as the most
comprehensive and widely used software product in the pro audio industry for real-time
sound system measurement, optimization, and control. Smaart performs dual-channel,
FFT-based audio measurement in an intuitive, accessible in t e r fa c e th a t in t e g ra t e s m e a surement, analysis, and data logging.
Smaart 6 has been rebuilt from the ground up in a modern, object-oriented architectural
design. This significant architectural upgrade enables increased measurement power,
and cr oss -p lat fo rm ope ra tio n. Smaart 6 now runs native under Mac OSX and Windows
XP from the same unified source code. A decade of user input has been integrated
with EAW’s innovations to enhance and streamline the user interface. Smaart 6 can
also remotely control an extensive, constantly expanding list of professional equalizers
and DSP processors.
1.1 Hardware Requirements
1.1.1 Computer
Laptop computers are most convenient for portable field operation. The computer
running Smaart 6 must meet these minimum specifications:
Windows Configuration
• Operating System: Windows 2000 or XP (or higher).
• CPU: 1 GHz or faster Intel Pentium or compatible.
• RAM: 512 MB to 1 GB
• Video: AGP or PCI Express Graphics card with at least 32 Mb RAM.
• Display: 1024 x 768 pixel display device with 24/32-bit colors.
• Sound Hardware: Windows-compatible (Wave/WDM or ASIO) with stereo line level
input, 16-bit/44.1 kHz to 24-bit/96 kHz sampling with full-duplex (simultaneous play
and record) capability.
Macintosh Configuration
• Operating System: Mac OS X 10.4 (Tiger) or higher.
• CPU: Apple Macintosh family CPU with minimum 1 GHz or faster G4, G5 or Intel
microprocessor.
• RAM: 512 MB to 1 GB
• Video: AGP or PCI Express Graphics card with at least 32 Mb RAM.
• Display: 1024 x 768 pixel display device with 24/32-bit colors.
• Sound Hardware: Apple Core Audio compatible with stereo line level input, 16-bit/
44.1 kHz to 24-bit/96 kHz sampling with full-duplex (simultaneous play and record)
capability.
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EAW Smaart 6 Operation Manual Getting Started
Computer Sound Hardware
Smaart does not address computer sound hardware directly. Since audio data is obtained
through platform-native or third-party audio APIs, Smaart should work with virtually
any audio I/O device compatible with the Windows and Mac operating systems. Since
only the A/D and D/A functions of the computer’s sound hardware ar e a c t u a l l y u s ed ,
Smaart 6 w o r k s w e l l w i t h a w i d e v a riety of c o mp u ter audi o input devices including
off-the-shelf sound cards for desktop machines and the built-in sound hardware in many
notebook computers. External hardware with USB, PCMCIA, and Firewire interfaces,
some combining high-quality A/D and D/A converter s with mic preamps, are convenient
for field use.
Two independent external line-level input channels (sometimes found as one stereo
connector) are required for transfer function and impulse response measurements. The
sound hardware must be capable recording and playing simultaneously to use Smaart’s
internal signal generator as the stimulus signal source for measurements.
We do not recommend using the microphone inputs on computer sound cards for measurement applications. Instead, use an external mixer or microphone preamp to route
the microphone to the computer’s line-level inputs.
Smaart 6 makes no use of the sound hardware’s synthesis capability. The relevant factors
that differentiate sound hardware for Smaart 6’s applications are the maximum sampling
rate, sampling resolution (bits per sample) and signal-to-noise ratio (S/N). If your
computer does not have sound hardware, lacks a line-level input, or its existing hardware
is problematic for any reason, there are many devices available for audio I/O. The
following features and audio characteristics are important:
• Simultaneous play and record (full duplex) capability
• Two independent, external, line-level input channels
• 16- to 24-bit sample resolution
• Digital inputs for use with external A/D converters (optional but recommended)
• User-selectable sampling rates: Smaart 6 supports sampling rates from 5512 Hz
to 96 kHz. Audio input devices used with Smaart 6 must support at least one of
Smaart’s primary sampling rates: 44.1k, 48k, or 96k (samples/second).
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EAW Smaart 6 Operation Manual Getting Started
1.1.2 Measurement Microphone
A measurement microphone is necessary to measure anything other than an electronic device. Since the measurement mic must accurately convert acoustical pressure into voltage,
we recommend an omnidirectional mic with the flattest possible frequency response.
Condenser microphones are most commonly used for measurement applications. These
require phantom power, either from the mic preamp or an internal battery. A microphone
calibrator is also required to perform calibrated sound pressure measurements.
1.1.3 Microphone Preamplifier
A mic preamp may be required to interface with the measurement mic. It should have
a low noise floor with sufficient gain to drive the computer’s line input(s) at a useful
level. The preamp must include phantom power if a condenser mic is used. Those who
prefer a small mixer, routing device, or FOH console instead of a dedicated mic
preamplifier, make sure to disable all processing (EQ, dynamics, etc.) on the channels
used to drive the measurement system inputs.
1.1.4 Cables and Interconnections
Use only professional-quality cables, adapters, and interconnections to interface the
measurement system with the equipment being measured. If your sound card has threeconductor 1/8-in stereo connectors, we recommend using breakout cables to convert to
1/4-in phone or XLR connectors.
Y-cables are useful for tying the measurement system into sound systems. Also, as most
sound cards use unbalanced (2-conductor) inputs, several sets of adapters that allow
balanced to unbalanced connections may be necessary.
1.1.5 Additional Useful Equipment
The following equipment may be required depending on the types of measurements you
wish to make:
Mixer/Level Adjustment Device
Although relative signal levels can be set at the computer in many cases, it is helpful to
adjust signal levels externally. Being able to quickly switch the signals reaching the
sound card’s inputs can greatly expedite the measurement process. A compact mixer
with quiet microphone inputs and built-in phantom power is ideal.
Microphone Calibrator and/or Sound Level Meter
To make accurate Sound Pressure Level (SPL) measurements with Smaart 6, the program
must be calibrated using an external reference. The most accurate way to calibrate to
SPL requires a piston microphone calibrator. Calibrating Smaart 6 to SPL can be done
fairly accurately with an SPL meter as a reference if a microphone calibrator is not
available. A high quality sound pressure level meter with an audio output can also be
an effective measurement microphone.
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EAW Smaart 6 Operation Manual Getting Started
1.2 Smaart 6 Software Installation
Respect the License Agreement
Notice that when you install EAW Smaart 6, the installation requires you indicate your
acceptance of the terms of the End User License Agreement. In doing so, you are agreeing
to be legally bound by the terms of this agreement. We strongly encourage you to read
the End User License Agreement and we want to emphasize the following:
EAW Smaart 6 is licensed on a single-user or, in the case of multi-station site license,
a single-station basis. That means that each single-user copy or single-station installation can be used legally by one person on one machine at any one time.
The Smaart 6 installation and copy protection mechanisms are intended to help enforce
this restriction. They are not intended to create any sort of hardship for licensed users
or prevent any legitimate use of the software. If you need to install Smaart 6 to a second
machine for your own use (e.g., on both your office machine and the notebook you
computer you use in the field), that is perfectly permissible. Simply perform the initial
installation on the second machine as you did on the first and register the installation at
my.eaw.com to obtain a keyfile to permanently unlock it. If you require additional installations for additional users, any Smaart 6 license can be converted to a multi-user
site license that allows adding workstations at a reduced price as needed.
1.2.1 First Time Installation
Installing Smaart 6 on any computer for the first time is a two-stage process. The initial
installation installs a temporary, 30-day copy of Smaart 6 to enable immediate use.
Permanent installation of Smaart 6 requires a keyfile created by EAW specifically for
your machine.
The installation program should start automatically (Mac and PC) upon inserting the
installation CD. If the installer does not start automatically, open the CD and doubleclick the Setup program icon.
NOTE: We strongly recommend closing and/or disabling all programs before installing
Smaart 6, particularly anti-virus and/or system monitor software.
1. When the first dialog appears, click Unlock Now to proceed with registration.
Click Continue to use Smaart during the 30-day trial period. Click Purchase
Smaart to buy a copy if this is a demo version. You will be routed to our
website to purchase the software and then proceed with installation.
To register later, initiate the process from the About dialog. To access the
About dialog on Mac OS X, select About Smaart under Smaart on the shared
system menu bar. In Windows, choose Help->About Smaart.
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EAW Smaart 6 Operation Manual Getting Started
2. If you have Internet access from this computer, click Unlock Online (this
example). Otherwise, click Unlock with Keyfile to obtain the necessary information from another computer that can connect to our website. Be sure
to copy the Machine Number before going to the other computer.
3. Enter your existing EAW account information or create a new account. This
will enable you to log onto my.eaw.com and view your Smaart installation information. This is very useful if you need to reinstall Smaart.
4. Click Unlock Now.
When the installation process has completed, restart your computer if prompted to do
so, otherwise you can begin using Smaart 6.
If you experience problems during or after installation, see Chapter 6: Troubleshooting.
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EAW Smaart 6 Operation Manual Getting Started
1.3 Smaart 6 Signal I/O
This section discusses how to recognize your hardware and adjust signal levels.
1. Make sure your computer recognizes your sound card.
2. Connect any external audio devices.
3. Start Smaart 6.
Do not disconnect an external audio device while Smaart 6 is running.
4. Select the proper audio i nput and output device(s) and channel(s) by choosing
Options->Audio I/O.
The Options dialog appears with the Audio I/O tab selected (Figure 1-1).
Figure 1-1 Audio I/O tab of the Options dialog
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EAW Smaart 6 Operation Manual Getting Started
5. Select input and output devices from the Input Device and Output Device area’s
Device drop-lists, respectively. The drop-lists displays your soundcard’s inputs/
outputs and those of any connected external I/O devices already added.
6. Select the desired input channels for your measurement and reference signals
from the Meas in and Ref In drop-lists. Typical assignment for a stereo input
device is Meas In = Left, Ref In = Right.
7. Select the channel(s) to use for output signals from the Main and Aux lists.
8. Select the desired input and output resolution values from the Input/Output
Device Bits Per Sample menus. Resolution values can be 16, 18, 20, 24.
9. Connect devices to the outputs/inputs of your soundcard or external preamp,
and Smaart 6 correctly handles the signals.
Many soundcards use internal circuitry to mix several audio streams together to the
master output, or to select and/or mix the signals presented to the sound card inputs.
These options may need to be configured for your card to enable line-level input and
wave output. Launch the Windows mixer application by pressing Alt+V on the keyboard.
The signal generator defaults to a low level to prevent equipment damage, overload to
input levels, and hearing discomfort. This level, in conjun ction w ith the ou tput lev els and
mixer settings for your device, determines the sound card output level.
9
Figure 1-2 Input levels: too low (left), correct (middle), and too high (right)
Overall input levels should be between –12 and –6 dB for most measurements. The input
levels must be adjusted to avoid clipping the sound card’s A/D converters while
maintaining a high signal to noise ratio. When Smaart 6 is running, the input level
meters indicate the soundcard’s A/D converters peak input levels. If the levels are two
high, the clipping indicators light and the input level must be reduced to perform accurate
measurements.
88
If your computer has both microphone and line level inputs, be sure to avoid sending a line
level signal to a microphone input. We recommend avoiding using the microphone inputs
on most computer sound hardware because their preamp circuitry typically does not approach the quality of even very modestly priced mixers. Also, a small mixer manages
multiple measurement input signals and offers other advantages, such as phantom power.
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EAW Smaart 6 Operation Manual Getting Started
1.4 Introduction to the User Interface
The Smaart 6 interface is designed to put the most frequently used functions for most
sound system optimization applications within a single mouse-click. Almost everything
in the main program window functions as a control. The readout fields for the primary
measurement and display parameters are drop-lists that display available options when
clicked upon. Clicking on the signal generator or SPL readout opens their setup dialogs,
and the delay control pops up a dialog for entering an exact delay time when clicked.
Clicking and dragging with your mouse on any plot zooms its x- and y-axes on the area
selected. Each graph can be assigned any data type with a single button click. Even the
input level meters perform dual functions, bringing the corresponding signal trace
(measurement or reference) to the top of the RTA display when clicked.
To the right of the plot area in the main real-time program window are two groups of
display controls for the two primary measurement types: Spectrum and Frequency Response. Clicking the Spectrum or Freq. Resp. buttons invoke a split window display
with the associated chart types for each: Spectrograph and RTA (Spectrum), Phase and
Magnitude (Frequency Response). Clicking the small arrowhead buttons on the right of
the Spectrum or Freq. Resp. buttons open their tab of the Options dialog. Main display
options for each are grouped together with their shortcut buttons.
The rest of this section introduces Smaart 6’s user interface. See Chapter 5: Smaart 6
Commands for detailed descriptions of menus and settings.
Figure 1-3 Smaart 6 main window
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EAW Smaart 6 Operation Manual Getting Started
1.4.1 The Menu Bar
Smaart’s most frequently used functions and commands are available as on-screen
controls or keyboard shortcuts. Pull-down menus in the Menu Bar provide an alternate
method of selecting many of these same functions, in addition to providing access to
some less frequently used features.
Figure 1-4 Menu bar
A menu command followed by “...” opens a dialog box. An arrowhead to the right of a
menu item indicates a sub-menu that appears to the right when selected.
1.4.2 The Plot Area
The largest section of the Smaart 6 program window is the Plot Area, used for all of
Smaart 6’s primary data displays. See Chapter 3: Analysis Modes and Display Types for
more information.
1.4.3 Cursor Readout
The cursor readout above the plot area provides numeric values for the location of the
mouse tracking cursor (white cross in Figure 1-5) in amplitude/magnitude, frequency
or time, and phase, depending on the current display. When a Locked Cursor is present,
its coordinates are also shown here, along with the delta between the locked and moveable
cursors (page 68).
Figure 1-5 Cursor readout
1.4.4 Start/Stop Buttons
In all real-time operating modes, clicking the Start button starts the Smaart 6 analyzer
and begins plotting data. The Start button turns to Stop during a measurement. Press
Stop to stop the measurement and view the display.
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EAW Smaart 6 Operation Manual Getting Started
1.4.5 Measurement Mode Buttons
The Measurement mode buttons provide one-click access to Smaart’s three primary
measurement types:
• Spectrum: See Spectrum Measurements on page 38.
• Freq. Resp.: See Frequency Response Measurements on page 44.
• IR Analysis: See Delay and Impulse Response Measurements on page 52.
Figure 1-6 Display mode (left) and Measurement mode (right) buttons
1.4.6 Display Controls
The RTA, Spectrograph, Magnitude, and Phase buttons at the top of the Plot Area
(left of Figure 1-6) display different information based on the same input data. Although
the buttons at the top of the plot remain the same, Capture, Load, and Legend are
disabled in Spectrograph display.
1.4.7 Reference Trace Controls
Figure 1-7 Capture and Load buttons
The Capture and Load buttons store and display RTA, Frequency Response, and
Phase traces, respectively. See Capturing and Loading Measurement Data on page 60.
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EAW Smaart 6 Operation Manual Getting Started
1.4.8 Signal Generator
Figure 1-8 Signal Generator and Delay controls
Click the button to activate the signal generator; the square indicator on the button illuminates green when active. To configure the signal generator:
1. Click the arrow to the right of the Signal Generator button (labeled with the
current signal generator type).
The Signal Generation dialog opens.
Figure 1-9 Signal Generation dialog
2. Select a Signal type and specify the signal level(s).
3. Specify the frequency for a sine wave (Freq1) or two frequencies (Freq1 and
Freq2) for a dual sine wave if applicable.
4. Use the s pinner buttons to the right of the Level1 field (and Level2 if Dual Sine
is selected) to set the signal level, or type a value into the text field.
5. Turn on the Signal Generator by selecting the Generator ON checkbox.
6. Click OK to close the dialog.
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EAW Smaart 6 Operation Manual Getting Started
1.4.9 Internal Delay Control
The Delay control (Figure 1-8) provides access to Smaart 6’s internal signal delay. The
internal delay can provide up to 750 ms of delay (in 0.01 ms increments) for one of the
two input signals, intended primarily to provide signal alignment for Frequency Response
measurements. The delay selected and corresponding distance are displayed on the Delay
control. To alter delay times by the increments specified in the Delay tab, use the up and
down arrow buttons to the right of the readout field. Or, click the Delay readout and enter
the desired delay time directly.
Auto Delay Locator Buttons
The Auto Sm and Auto Lg buttons (Figure 1-8) activate Smaart 6’s Automatic Delay
Locator using the small or large time window preset, respectively. See Automatic Delay
Locator on page 55 for more details.
1.4.10 Signal Level/SPL Display and Input Level Meters
Figure 1-10 Signal level, SPL, and input meters
The Signal Level/SPL Display provides a numeric readout of the overall signal level
for the selected SPL Source channel (see Audio I/O on page 98) and can be calibrated
to provide SPL readings.
The input level meters display the levels of the two input signals relative to the maximum
input voltage (regarded as 0 dB) for the A/D converters on the selected input device.
Each meter includes a clip indicator that lights if the input signal level exceeds the A/D
converter’s maximum input voltage. Click the Mea Sig and Ref Sig to show/hide the
corresponding signal on the RTA display.
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EAW Smaart 6 Operation Manual Getting Started
1.5 How to use this Manual
EAW has dedicated substantial time and resources to the Smaart 6 documentation. We
recognize that our customers comprise a diverse range of experience and have strived
to write and organize this manual to be accessible to everyone. Of course it is more fun
to use Smaart 6 than read about it but we are confident that your time spent reading this
manual will be rewarding.
Manual Structure
Those experienced with Smaart 6 can use the manual as a reference and look up subjects
as needed. However, the manual is structured to be read sequentially and anyone who
wants to get the most out of Smaart would likely benefit from doing so at least once.
The manual contains the following chapters:
• Chapter 1: Getting Started discusses hardware requirements, software installation,
and introduces the user interface.
• Chapter 2: Concepts, Glossary, and Bibliography introduces the concepts and
terminology necessary to understand how to use Smaart 6. It includes a Glossary
(page 31) and Bibliography (page 34).
• Chapter 3: Analysis Modes and Display Types discusses Smaart 6’s measurement
modes and displays in detail.
• Chapter 4: Applications presents examples of Smaart 6’s most essential applications.
• Chapter 5: Smaart 6 Commands discusses all menu commands including all of
the Options dialog parameters.
• Chapter 6: Troubleshooting discusses common problems encountered and proce-
dures to diagnose and fix them.
Keyboard Shortcuts
Ctrl/Cmd means press the Control (Ctrl) key if you are using Windows, or the Command key (sometimes referred to as the “Apple” or “Flower” key) on a Mac. Similarly
Alt/Opt refers to the Alt key on a Windows keyboard or the Option Key on a Mac. LeftClick refers to a Windows style two-button mouse and is equivalent to a regular mouse
click on a Mac.
See Keyboard Shortcuts on page 103 for a complete list.
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EAW Smaart 6 Operation Manual Getting Started
How to Use the PDF
The Portable Document Format (PDF) version of this manual is a valuable learning
tool, providing effective online help while using Smaart 6. We have included some
useful amenities to aid your learning and exploration process.
NOTE: We assume Windows users will use Acrobat Reader and Mac users either
Acrobat or Preview.
• The Bookmarks, displayed to the left of the main document in Acrobat or on
the right in Preview, serve as a continuously visible table of contents.The
Bookmark headings are collapsed when the document is first opened. Click on
a subject heading to jump to that page.
• Click the “+” (W indows) or “X” (on Mac) to expand that heading to show subheadings. To collapse an expanded heading, click the “–” (Windows) or “T”
(on a Mac).
• The manual’s Table of Contents and List of Figures entries are active links to
their p ages. Select the hand cursor, move it over the heading until it turns into
a finger, then click to navigate to that page. Be aware that some headings are
active only over their number not the heading text (i.e., List of Figure entries).
• All cross references are active links. Move the hand cursor over the reference
until it turns into a finger and click to follow the reference.
• Use the left and right Navigation arrow keys to go back and forth between
views. This is a great method to follow a cross reference or check out a Bookmark and return to the page from which you were reading.
• Use the Find function as an index on the fly that is as effective as the real index
on page 111. To search for a keyword, press Ctrl+F (Windows) or Cmd+F
(Mac; Cmd is the Apple key).
• Use the magnifying glass tool or the zoom edit box on the top bar to zoom in/
out. This is helpful when examining a complex graphic or setting the text size
for easier reading.
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EAW Smaart 6 Operation Manual
Chapter 2: Concepts, Glossary, and Bibliography
This chapter defines the concepts and terminology used in Smaart 6. These definitions
are accurate with regard to Smaart 6 but are not intended to be mathematically comprehensive. A bibliography is provided at the end of the chapter for those wishing to pursue
a more rigorous study of these topics.
2.1 Concepts
2.1.1 Decibels
The decibel (dB) is a unit that expresses the logarithmic ratio between two amounts of
power, voltage, or any two values that differ over a wide range. Logarithmic scales are
useful in acoustics and audio because of the wide range of human hearing sensitivity to
sound pressure and frequencies. Most audio measurements based on voltage or sound
pressure are expressed in decibels. The power and voltage ratios in Table 2-1 illustrate
why a logarithmic scale is needed.
Table 2-1 Power and voltage ratios as decibels
Power
Ratio
100 20 100 40
1,000 30 1,000 60
10,000 40 10,000 80
100,000 50 100,000 100
1,000,000 60 1,000,000 120
dB
.1 -10 .1 -20
.5 -3 .5 -6
10 1 1
23 2 6
10 10 10 20
Voltage
Ratio
dB
Note that 60 dB, about half the decibel range of human hearing, represents a Power Ratio
of one million to one. A frequent point of confusion regarding decibels is the meaning
of 0 dB. For SmaartLive’s purposes, 0 dB means:
• In a Frequency Response measurement, dB values represent the difference
between the reference and measurement input signals. When the energy in both
input signals at a given frequency is the same, the magnitude response is 0 dB
at that frequency.
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EAW Smaart 6 Operation Manual Concepts, Glossary, and Bibliography
• At frequencies where the measurement signal has more energy than the reference
signal, the transfer function is a positive dB value; when the measurement signal
has less energy, the value is negative.
• With respect to the input level meters and the default Full-Scale calibration
reference, 0 dB (or 0 dBFS) means the maximum possible output of the A/D
converter on the selected input device. All lesser amplitude/magnitude values
are displayed as n dB down from this maximum.
2.1.2 Fast Fourier Transform
The Fast Fourier Transform (FFT) is a special case of Discrete Fourier Transform
(DFT), a mathematical technique used to calculate the frequency-domain representation
of a fi nite length, time-domain data series. Th e output of a Fourier Transform is a set of
complex numbers representing the frequency and phase of the original time series. An
FFT is referred to as a Fast Fourier Transform because it uses mathematical shortcuts
to greatly reduce the computation time required to calculate a DFT. This technique requires
that the time-domain data series used in the FFT contain a power of two number of sam-
ples (i.e., 2n samples, where n is an integer). All Smaart 6 frequency transformations
are FFTs that require the time record to be 2n samples in length.
Table 2-2 Powers of 2
n
8
9512
10 1024
11 2048
12 4096
NOTE: It is certainly possible to calculate the Fourier Transform of a time record with
an arbitrary number of samples. However, when the number of samples is not
a power of 2, the additional calculations required on a PC can become very
large, sometimes resulting in a very slow Fourier Transform.
2
n
256
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EAW Smaart 6 Operation Manual Concepts, Glossary, and Bibliography
2.1.3 Averaging
When using asynchronous test signals such as music or random noise in FFT measurements, it is often beneficial to average data from a number of FFT frames. Averaging
over a number of FFT frames:
• increases the likelihood of having sufficient energy at all frequencies for a
meaningful measurement (particularly with music);
• makes the overall frequency content of a dynamic signal easier to see;
• helps minimize the influence of possible sources of error that might affect a
single FFT measurement.
Nearly all Smaart averaging is based on RMS averaging, aggregated either linearly (all
frames contribute equally to the averaged result), or exponentially (more weight given to
the most recent, than to older data). Linear averaging is also sometimes referred to as
artithmetic averaging. Smaart offers linear averaging options from 1 (no averaging) to 128
frames. There is also a linear infinite averaging option that keeps a running average while
the analyzer runs (or until you Reseed the averaging buffer). The Fast and Slow averaging options, available for Spectrum and SPL measurements, are exponential averages.
2.1.4 Sampling Rate
The sampling rate is the number of amplitude samples taken per second from an analog
audio signal to create a digital waveform. The most important thing to remember about
sampling rate is that it limits the highest measurable frequency. The highest frequency
that can be accurately represented in a digital waveform is equal to half of the sampling
rate. This limit is often referred to as the Nyquist frequency, after Harry Nyquist who
first proved its existence in the course of his work on improving the speed and carrying
capacity of telegraph and teletype systems in the early 20th century.
If frequencies in excess of the Nyquist frequency are present in a signal when it is digitized,
they become aliased or wrapped around and incorrectly added in at lower frequencies.
For this reason, a high-order low pass filter wi th its corner frequency ne ar the Nyquist
limit is normally applied to audio signals before they pass through an A/D converter.
The practical implication of this anti-aliasing filter is that it further limits the highest
measurable frequency at a given sampling rate, typically to about 90% of the Nyquist
frequency.
Compact discs run at a standard sampling rate of 44.1 kHz. Professional digital audio
recording machines sample in the range 48-96 kHz. Computer sound cards commonly
have several user-selectable sampling rates such as 48, 44.1, 22.05, or 11.025 kHz.
Smaart 6 determines the available sampling rates by polling your computer’s sound
hardware each time it launches. The fastest sampling rate supported by Smaart 6 is
currently 96 kHz.
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EAW Smaart 6 Operation Manual Concepts, Glossary, and Bibliography
2.1.5 Frequency Resolution
The frequency resolution (Q) of an FFT is equal to the sampling rate divided by the FFT
size. The frequency data points in an FFT are distributed linearly along the frequency
axis at intervals of Q Hz, from 0 to the Nyquist Frequency (1/2 the sampling rate). For
example, with a sampling rate of 44.1 kHz, an FFT size of 4096 (4 k) yields a frequency
resolution of 10.77 Hz. The resulting FFT has a data point every 10.77 Hz, 0-22.05 kHz.
Fixed-Point Per Octave (FPPO) Frequency Response Display
One problem associated with the linear distribution of FFT data points arises from the
fact that we hear frequencies logarithmically. Human hearing perceives each doubling
of frequency as an equal interval so each higher octave contains twice as many frequencies
as the one below. Using the example discussed on the previous page, in an FFT with a
frequency resolution of 10.77 Hz, there will be only three data points in the range 31.563 Hz (the center frequencies of the two lowest octaves), providing very poor resolution. In the two highest octaves, the span between the center frequencies (8-16 kHz) is
8 kHz, yielding more than 700 data points. When viewed using a logarithmic frequency
scale, these data points are densely packed, creating a very difficult display to interpret.
Smaart 6 addresses this problem by using multiple FFTs, at different sampling rates and
FFT sizes, then combining the results to provide equal resolution in every octave, except
the two lowest. The resolution of the Real-time mode display is 24 points per octave
above 44 Hz, with 24 points distributed over the two lowest octaves. Note that using
multiple FFTs results in a longer time window at lower frequencies and a shorter time
window at higher frequencies.
Frequency Resolution and Octave/Fractional Octave Band Displays
For Spectrum measurements, the multiple-FFT technique used to measure Frequency
Response is not a n o p t i o n d u e t o a m a t h e m a t i c a l l i m itation and so all RTA d i s p l a y s a r e
created from single FFTs. Since the linear distribution of FFT points in a single FFT
yields lower resolution in the lower than higher octaves, there may be bands at the low end
that contain only 0 or 1 data point, depending on the display and FFT input parameters.
The wider spacing between FFT data points in the lower octaves accounts for the missing
teeth seen at the low end in banded displays on some FFT-based analyzers. Smaart uses
an advanced algorithm to properly distribute energy into bands at low frequencies but
very sparse FFT data limits its effectiveness. Therefore, it is still advisable to select FFT
parameters that provide good frequency resolution at the lowest frequencies required.
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EAW Smaart 6 Operation Manual Concepts, Glossary, and Bibliography
2.1.6 Pink and White Noise
Pink and white noise both contain random (or pseudorandom) broadband energy. They
are commonly used as signal sources in audio measurement applications.
Pink Noise
Pink Noise has equal energy in each octave band when averaged over a period of time.
This means that when pink noise is displayed on an octave band plot, its spectrum appears
flat. When its spectrum is plotted on a narrowband display, however, it appears to rolloff, or decrease in energy at the rate of -3 dB per octave (Figure 2-1).
–20
–30
–40
–50
Decibels
–60
–70
32 63 125 250 500
Octave Scale
1K 2K 4K 8K 16K
Frequency (Hertz)
–20
Logarithmic Scale
–30
–40
–50
Decibels
–60
–70
20 100 1K 10K 22K
(Narrow Band)
Frequency (Hertz)
Figure 2-1 Pink noise graphed on octave band (left) and narrowband logarithmic (right) scales
White Noise
White noise has equal energy for each frequency when averaged over a period of time.
This means that when white noise is displayed in narrowband resolution, its spectrum
appears flat. However, because each successive octave band has twice as many Hz,
white noise plotted on an octave band display appears to increase 3 dB in energy for
each successive octave (Figure 2-2).
–20
–30
–40
–50
Decibels
–60
–70
32 63 125 250 500
Octave Scale
1K 2K 4K 8K 16K
–20
Logarithmic Scale
–30
–40
–50
Decibels
–60
–70
20 100 1K 10K 22K
(Narrow Band)
Figure 2-2 White noise graphed on octave band (left) and narrowband logarithmic (right) scales
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EAW Smaart 6 Operation Manual Concepts, Glossary, and Bibliography
Choosing a Noise Source
The distinction between pink and white noise is not important in Frequency Response
measurements. The transfer function compares the two input signals over a given frequency range point-by-point. This is a concern when looking at a single channel RTA
noise measurement. If it appears flat in narrow band resolution, it is white. If it appears
to be slopping down to the right on narrow band resolution (loss at high frequencies) it
may be pink.
NOTE: White noise is often used to test electronic components but has so much high
frequency energy that it can easily damage loudspeakers if played at high levels. For this reason we DO NOT recommend using white noise as a test signal
for sound system measurement applications.
2.1.7 Data Window Functions
Data window functions are commonly used to reduce truncation errors that arise from
segmenting random signals into FFT-size chunks. The FFT is a circular function that
assumes the signal segment being transformed is infinitely repeating. Therefore, discontinuities between the data near the beginning and end of the time domain data series
can result in an excessively high noise component and leakage of data at all frequencies
into neighboring frequency bins when the FFT of the signal is taken.
Data window functions help alleviate this problem by attenuating the samples nearest
the beginning and end of the time record being transformed before the FFT is performed.
Although this technique can dramatically reduce the impact of discontinuities, there are
several trade-offs involved in determining the precise shape of the attenuation curve. A
number of data window functions, with various strengths and weaknesses, have been
developed over the years. For most audio applications, window functions with Gaussian tap e r s work best. We recommend using the default Hanning window (also called
a Hann window) unless you have a specific reason to use a different type.
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EAW Smaart 6 Operation Manual Concepts, Glossary, and Bibliography
2.1.8 Impulse Response
An impulse response is the response of a system under test (SUT) to an impulsive stimulus.
The SUT could be an electronic device, a sound system and/or an acoustical environment.
In Smaart the impulse response is the time-domain representation of the system’s transfer
function, or system identification. For our purposes, this means a signal that describes
the changes a known test signal undergoes as it passes through the SUT. The impulse
response contains a wealth of information about the SUT including its propagation delay
and frequency response. For an acoustical system, it also contains information about
reflections, reverberation, and decay.
NOTE: It is actually possible to use the impulse response of a room/system as a filter
to convolve a dry signal, such as speech or music, and hear exactly what it
would sound like if played through that same system in that room and heard at
the measurement position.
2.1.9 The Transfer Function
All frequency response (Phase and Magnitude) and impulse response data in Smaart 6
rely on a mathematical calculation called a transfer function. The transfer function
compares a reference signal to a measurement signal, typically the input and output of
a device/system under test (DUT/SUT), such as an equalizer, sound system, or room.
Smaart 6 uses the transfer function calculation in both Frequency Response and Impulse Response measurements. Transfer function calculations are always performed in
the frequency domain using FFT data. The results of the calculation are displayed in
either the frequency or time domain, depending on Smaart 6’s display mode.
The Frequency Response display plots transfer function results in the frequency domain
to show the magnitude and phase of the SUT. In Impulse mode, Smaart 6 calculates the
transfer function using data from very long FFTs, then transforms the result back into
the time domain to show the impulse response of the SUT. These two types of Frequency
Response measurements are complementary.
The reference and measurement signals must be aligned in time to obtain a valid frequency response measurement. The impulse response measurement is used to find the
delay time between the two input signals.
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EAW Smaart 6 Operation Manual Concepts, Glossary, and Bibliography
2.1.10 Coherence
The coherence for any two FFT frames The Smaart 6 Coherence display represents a
complex mathematical function used to determine the coherence between the two signals. Smaart displays coherence values as a percentage from 0-100, rather than as a
number from 0-1 because we have found that many people find it more convenient to
think of it as a score than as a probability. The coherence for any two FFT frames measured using the same input parameters is always 1. It is only when two signals are averaged over some period of time that nonlinear issues appear so the Coherence feature
is disabled when the number of averages is set to 1. Overall coherence tends to decrease
as the number of averages increases.
Additional factors that can adversely affect the coherence of transfer function data include delay between the two signals, insufficient energy in the reference signal at a given
frequency, acoustical influences (i.e., reflections and reverberation), and ambient or
electrical noise. Nonlinear processors such as compressors and limiters in the measurement signal path can also have a negative influence on coherence and should therefore
be bypassed for Frequency Response and Impulse Response measurements.
2.1.11 Signal Alignment
When performing Frequency Response measurements, it is essential that the measurement and reference input signals be aligned in time. To make a meaningful comparison
of two signals, the transfer function calculation must measure the same piece of each
signal at the same time. With most analog audio equipment, this is not an issue and
compensation is not normally required. However, all digital signal processors have
some propagation delay, as does sound travelling through air to a microphone.
Before a meaningful Frequency Response measurement of a DUT/SUT with propagation
delay can be made, the delay must be found and compensated for. This process req uir es
finding the delay in the measurement signal and adding it to the reference signal. Smaart
6’s Delay Locator and Internal Delay functions make this process easy (see page 52).
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