Dayton WT3 User Manual
WT3
is produced by:
Dayton Audio
725 Pleasant Valley Drive
Springboro, Ohio 45066 USA
http://www.daytonaudio.com
Online User’s Guide
Revised: May 11, 2008
Copyright © 2007-2008 by John L. Murphy, Andersonville, TN USA All Rights Reserved.
No part of this publication may be reproduced without prior express written permission.
Minimum Requirements for the PC
The minimum requirements to run WT3 are:
•
A PC with a processor running at no less than 500 MHz with 64 MB RAM
•
One available USB port
•
A display with resolution of at least 800 x 600 pixels
WT3 runs under Microsoft Windows 98, Me, 2000, XP and VISTA operating systems.
*** VERY IMPORTANT SAFETY NOTE ***
Quick Start for the WT3 Woofer Tester
NEVER connect the test leads of the WT3 to a speaker that
is connected to any other equipment or to an equipment
ground! Severe damage could occur to the WT3 unit or to
the other equipment. Only connect the WT3 to an
unconnected loudspeaker.
Naturally, you will want to test your first woofer as soon as you get your WT3. Here are step-by-step
instructions to get you going quickly.
1) Install the WT3 software.
•
Insert the WT3 CD and allow the file named "WT3_setup.exe" to auto-run.
(Alternately you can double-click on the "WT3_setup.exe" file to start the installation
process.)
•
Follow the on-screen instructions to complete the software installation
•
Check for available upgrades at: http://www.daytonaudio.com/wt3updates.html
2) Connect the WT3 hardware unit to any convenient USB port on your computer.
After a few seconds the PC will recognize the new hardware. However, on initial power up the unit
requires a full 90 seconds to stabilize before measurements can be made. After this initial plug-in
delay, impedance measurements take only a few seconds to complete. This settling time is due to the
extremely wide low frequency bandwidth required for high precision measurements down to 1 Hz.
3) Set the Windows Volume Controls to Maximum.
From the task bar, double-click on Volume Control to open the mixer and Raise both the "Master" and
the "Wave" sliders to maximum. Make sure the Wave signal is panned to center. Although drivers can
be tested at lower signal levels, WT3 was designed to normally be used with the Windows Volume
control set at maximum.
4) Launch the WT3 application software.
From the Windows "Start" button select "All Programs" then select "WT3". The WT3 software will
launch.
5) Connect the alligator clips from the WT3 unit to the 1k Ohm calibration resistor.
6) Select “Impedance Calibration” under the “Impedance Analyzer” menu.
The software will sweep the resistor and plot the results. The uncalibrated impedance is
displayed and the calibration is complete. You should also calibrate the test leads at this time
by selecting the appropriate command under the "Impedance Analyzer" menu and following
the on-screen instructions.
7) Connect the alligator clips from the WT3 unit to the terminals of the driver under
test.
The driver MUST NOT BE CONNECTED to an amplifier or other equipment. The connection
polarity does not matter. For the best results the driver should be clamped in place during testing. It
may be necessary to elevate drivers with vented pole pieces in order to make sure the vent is not
blocked during testing.
8) Click on the "Measure Free Air Parameters" button at the left of the WT3 window.
You should hear the sweep and then see the impedance response of the driver appear on the screen
similar to the figure below. Note that the driver's measured parameters are displayed in the Parameters
Bar at the right side of the screen. The Impedance Bar at the left side of the screen is where you can set
the upper impedance limit as well as the high and low frequency limits of the display.
9) Measure the driver's V(as).
Once you have measured the driver's free air parameters the "Measure V(as)" button becomes enabled.
Select one of the three methods to measure the V(as). Then press the “Measure V(as)” button to start
the measurement procedure. The three V(as) measurement methods are:
Test Box Method
Added Mass Method
Specified SPL Method
10) After measuring the driver you can:
•
Save the data to one of 20 project memories.
•
Save your work to a WT3 test project file (file type .wt3) which includes your test setup
and all 20 memories.
•
Export the impedance and phase data in either .txt or .zma formats. Parameters are
included in the text notes.
•
Overlay plots of various measured impedances from the 20 memories for detailed
comparison.
•
Print a report showing the impedance plots and parameters of the displayed memories
(see below).
Windows Vista - Additional Setup Requirements
PLEASE NOTE: STEP 2 IS CRITICAL FOR WINDOWS VISTA USERS!
1. Go to the Windows Control Panel and open the “Sound” control panel. At the "Playback" tab make
sure that "USB Audio Codec" is selected as the default sound system for playback. (the icon should
appear with a green check mark as shown). If not, click on the "USB Audio Codec" and then click the
"Set Default" button below.
2. Change to the "Recording" tab at the top of the Sound control panel. As above, make sure that "USB
Audio Codec" is selected as the default sound system for recording (the icon should appear with a
green check mark as shown). If not, click on the "USB Audio Codec" selection and then click the "Set
Default" button below. The "USB Audio Codec" should now appear as the default selection. While at
the "Recording" tab click on the "Properties" button and switch to the "Advanced" tab (shown below).
If not already selected, then select "2 channel, 16 bit, 44100 Hz (CD Quality)" from the list. Click
OK to set the recording format and close the dialog.
3. Click OK to close the "Sound" control panel.
Note that this setup must be performed once for each USB port with which the WT3 unit will be used.
Also, when starting WT3, always click on the Speaker icon in the task bar and make sure the Windows
Volume Control is set at maximum.
Introducing WT3
No other loudspeaker parameter measurement system is as fast or as easy to use as Dayton Audio’s
WT3. WT3 employs powerful new DSP measurement techniques to provide highly accurate
parameters in seconds. While previous generation woofer testers took around 6 minutes to measure 30
impedance points, the new WT3 measures over 30,000 data points in only a few seconds! Using a new
swept sine technique that is only available in WT3 the system achieves very accurate, high resolution
impedance measurements that allow the extraction of high quality driver parameters suitable for the
most critical loudspeaker design work. WT3 is designed to measure impedances in the range from
about 1 Ohm up to 5k Ohms; it operates over a frequency range from 1 Hz to 20k Hz. Within this
range of operation, and with proper calibration, the accuracy of WT3's impedance measurements is
typically within 1%.
The WT3 software is supplied on a CD. The software runs under Windows and provides an easy to use
interface that allows users to be up and running quickly. When the software is launched it opens with
an Untitled Project file. You can save as many as 20 impedance measurements per project and overlay
any or all of the measurements to create a custom report. Your personal notes are included with each
measurement. Operation of WT3 is very simple. Free air parameters are measured first, then V(as) can
be measured by one of three methods:
•
Test Box Method
•
Added Mass Method
•
Specified SPL Method
While the primary application for WT3 will be testing raw drivers in order to gather the speaker
parameters required for speaker design, loudspeaker designers can also use WT3 as follows:
•
Measure a Woofer's Parameters
•
Measure a Tweeter's Parameters
•
Measure a Resistor
•
Measure an Inductor
•
Evaluate a Closed Box Loudspeaker
•
Evaluate a Vented Box Loudspeaker
•
Evaluate a Complete Speaker System
•
Diagnose Loudspeaker Fault Conditions
•
Design a Zobel Network
The WT3 hardware consists of a compact USB interface unit with attached USB cable and alligator
clip leads. A precision resistor (1k Ohm 1%) is included for calibrating the unit.
The WT3 Toolbar
The WT3 Toolbar provides easy access for many frequently used commands. Memory show and hide
operations are especially convenient with the toolbar. Note that empty memories are grayed out until
data is saved to them. Once they contain data they become enabled to switch between show and hide
modes.
Using the WT3 Memories
The WT3 software features 20 user memories for saving your detailed measurements along with much
other user entered information about the driver. Each memory consists of the impedance and phase
plots, the test setup information (test box volume, added mass etc.) along with the three pages of
parameters, ,specifications and comments that are seen at the Driver Editor. When you save a WT3 file
(type ".wt3") to disc this measurement project file contains all the measurements in the projects 20
memories as well as the data currently on the Workbench.
Note: The most recently measured impedance plot is said to reside on the WT3 “Workbench.” This
measurement is overwritten each time the analyzer is run. The Workbench is also overwritten when a memory is
recalled or when data is imported. Once you have measured data you want to keep (even temporarily) save it to
one of the 20 memories before proceeding with another measurement. All data in the 20 memories is saved with
the WT3 project file. Multiple memories can be overlaid to allow for easy comparison of various measurements.
Use the memory buttons in the Toolbar to show or hide various memories. After a memory has been recalled it
can then be saved to a different memory. After a memory is recalled it is available to be exported to a .txt file.
All the commands related to memory operations can be found under the "View" menu. Here are the
details of the memory commands. Note that each command has a keyboard shortcut that you may find
more convenient than the menu command after you become familiar with the software.
View Menu: Save to Memory
These commands cause the plot on the Workbench to be saved to the selected Memory along with all
the driver parameters.
From the keyboard, use Alt+1, Alt+2 etc. through Alt+0 to save to memories 1 through 10. Use
Alt+Shift+1, 2 etc. through 0 to save to memories 10 through 20. For example, to save the current
response to Memory 5 you would press and hold the Alt key and then press the 5 key.
View Menu: Show/Hide Memory
These commands alternately show and hide the selected memory.
•
From the keyboard, use Ctrl+1, Ctrl+2 etc. through Ctrl+0 to show or hide memories
1 through 10
•
Use Ctrl+Shift+1, 2 etc. through Ctrl+Shift+0 to show or hide memories 10 through
20
For example, to toggle the display of the response in Memory 5 you would press and hold the Ctrl key
and then press the 5 key. Use Ctrl+W to toggle the display of the Workbench response. In addition to
the menu and keyboard commands, you can also toggle each memory on or off at the Memory
Toolbar.
View Menu: Clear Memory
These commands erase the contents of the specified memory.
•
From the keyboard, use Ctrl+Alt+1, Ctrl+Alt+2 etc. through Ctrl+Alt+0 to clear the
contents of memories 1 through 10
•
Use Ctrl+Alt+Shift+1, 2 etc. through Ctrl+Alt+Shift+0 to clear the contents of
memories 10 through 20
For example, to erase the response in Memory 5 you would press and hold the Ctrl and Alt keys and
then press the 5 key. Should you need to clear all of the memories it is usually easier to just create a
new project file by selecting "New" under the "File" menu.
View Menu: Hide All Memories (Ctrl+E)
This command turns off the display of all memories without affecting the contents of the memories.
Below are sample screen shots of the three Driver Editor pages. While the WT3 system measures
many of the parameters detailed on the second page the remainder of the data, such as the driver's
manufacturer and model number, may be entered by the user to create a more complete record on the
driver under test. You can add any notes you wish at the Comments field and your notes will be saved
when you save the Workbench to a memory. When you recall a memory to the Workbench your notes
will be displayed at both the driver editor General Information page and in the Notes field below the
plot window. Entering a line or two of descriptive information before saving data to one of the 20
memories makes it easy to keep track of the multiple measurements that make up each WT3 project
file.
Frequently Asked Questions about WT3
Q: Why do I have to wait 90 seconds for the WT3 hardware to warm up?
A: The initial 90 second waiting period delay is required in order for the hardware power supplies to
ramp up and stabilize. To perform precision measurements down to 1 Hz very wide low frequency
bandwidth is required.
Q: My WT3 was working fine but it seems to have stopped working correctly. What might have
happened?
A: The Windows Volume control settings may have been changed (reduced) when the hardware unit
was connected or disconnected. Open the Windows audio mixer by double-clicking on the speaker
icon in the task bar. Make sure that both the "Master" volume and the "Wave" signal are set to
maximum. The "Wave" signal must be panned to center and the audio must not be muted.
Note that it is possible to upset the DC balance of the unit momentarily should a test lead be
accidentally grounded or come in contact with any stray electrical charge. This may result in erratic
measurements until the system stabilizes again (this can take up to 90 seconds). Remember, never
connect the WT3 to a speaker that is connected to any other equipment or damage to the WT3 unit
could result.
Q: The title block is empty on my printed reports. How do I enter my info?
A: Go to Help > User Information to open the User Information dialog. The information you enter here
will appear in the title block of your printed reports.
Q: How accurate is WT3?
A: Because the speaker parameters are extracted from the impedance data they can only be as accurate
as the impedance measurement itself. When calibrated WT3 provides measurements below 1000 Ohms
and above 1 Ohm that are typically accurate to better than ± 1 %.
Removing WT3 from your Computer
You can easily remove WT3 from your computer’s hard drive if needed.
•
Go to the control panel and double click on the “Add/Remove Programs” icon
•
When the Add/Remove dialog appears, locate WT3 in the list
•
Select WT3 and then click on the Add/Remove button
•
When you are asked “Are you sure you want to completely remove the selected application and
all of its components?” select “Yes”
WT3 will be removed from your computer.
File Menu
The commands under the File menu are as follows:
ew (Ctrl+)
Clears all current data to create a new empty WT3 project file. Each project file holds up to 20
measurements in individual memories. The memories can be displayed or hidden by clicking the
corresponding memory buttons on the toolbar.
Open… (Ctrl+O)
Opens a WT3 project file (.wt3) which you have previously saved to disc. Note that WT3 can be
launched and a project .wt3 file opened from the desktop by double-clicking on the file icon. Project
files can also be opened by dragging and dropping them onto the open application window.
Save (Ctrl+S)
Saves a WT3 project file to disc with the .wt3 filename extension. A single .wt3 file can contain up to
20 memories of data and notes in addition to the immediate data and notes on the Workbench. Project
files also contain complete test setup information so that opening a saved project file restores the test
setup that was in place when the project file was saved. This includes such settings as the Impedance
and Frequency plot limits. In addition, a large number of measurement setup variables are saved within
each project file.
Save As…
Brings up a save as file dialog which allows you to save the current project file under a different name
or to a different location on your system.