WT3 Conclusion
Odds & Ends
The Dayton Audio’s WT3 is product designed to measure impedance only. It will not make dB spl measurements of the driver/system under test. For that you’ll need to rely on some other measurement software/system. You’ll also need to look elsewhere to model system simulations based on the raw data/T/S parameters generated by WT3. Fortunately, the WT3 application includes an export utility that makes it easy to do all your post-processing/simulation work outside the program. (There’s an import utility as well). For the job it is designed to do, the WT3 does very well indeed.
The few quirks found in the review sample mainly relate to the user interface. For example, the Ctrl-V (Paste) keystroke sequence wouldn’t paste text data into text boxes ordinarily used for data entry. Also, the text box used in the Impedance Calibration screen is masked in such a way that you can’t enter a value such as “.9967”; rather it needs to see “0.9967”.
Additionally, there is no mouse (or other) cursor function
attached to the measurement plots; you can’t use a cursor to scroll across the
plots to look at individual datapoint values. To view individual datapoint
values, you’d need to export the raw data as a text file and read the
information from the resultant file.
The WT3 allows you to save up to 20 impedance plots in memory, though it provides no direct way to name them. This isn’t an issue if you’re working with only 2 plots. But if you’re working with 20 plots, how long before you forget just exactly what plot # 7 is? (WT3 does allow collections of saved impedance plots to be saved as a Project file). To be fair, it should be mentioned you can save 3 tabbed pages worth of text data per driver measured (the Workbench Measured parameters are filled in automatically as measurements are taken), using the handy Driver Editor utility, shown at right.
Conclusion
Dayton Audio’s WT3 Woofer Tester is a budget-priced measurement tool for working up impedance plots of raw drivers and various electrical components, such as resistors, caps and inductors. It can also provide the all-important Thiele/Small parameters, essential to the loudspeaker design process.
The product is easy to install and easy to use. Though purposely limited in its capabilities, what it does do it does very well, in a number of important ways comparing favorably to a system costing better than 10 times as much. Not bad!
Dayton Audio WT3 Woofer
Tester
MSRP: $99.88US/unit
http://www.daytonaudio.com
The Score Card
The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:
Performance × Price Factor/Value = Rating
Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.
Audioholics Rating Scale
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Recent Forum Posts:
The writer of the article implies that WT3 cannot provide SPL. While it's true that it cannot measure the driver's SPL it can calculate it.
In order to determine V(as) in WT3 for the driver being tested there are 3 methods:
1. input the driver SPL @1w/m as provided by the manufacturer (assuming you have a spec, and redundant in the context of this discussion)
2. mount the driver in a known (volume) closed enclosure and resweep
3. add a known mass (coins, plasticine etc) to the driver cone and resweep
When using either of the latter 2 methods, WT3 will automatically calculate the driver sensitivity and display the SPL @1w/m
*I have found both the closed box and added mass methods in WT3 to be very accurate as compared to micrphone SPL measurments
In fact, PE is now bundling a low cost (but sutably precise) digital scale to permit easy mass addition. This is the easiest method I have found.
I tried using coins as suggested by the WT3 docs (eg a Nickel is 5g) but found they jumped around too much.I now use a small "cookie" of automotive sealer (aka dum dum) that I roll into a ball, weigh, then flatten and place centered on the dome. It seems to have just enough tackiness to prevent "decoupling" when the sweep occurs. (after entering the mass of the added weight into the WT3 sotware)
after completing thee steps you will now have the driver V(as) AND SPL
Works for me!
WopOnTour
All of the volume levels for both audio out and record in should be at the max and the balance be set to the middle. If your settings are not these you will possibly see anomalies (i.e. strange spikes or dips, jagged plots, etc...) in the plot graphs.
Also in Vista on some systems the USB ports can be individually adjusted, so if you set it up on one port for testing and then the next day use a different port you may see anomalies in the measurements.
And as stated in the article there is a 90 second stabilization time for the unit, it is necessary to wait otherwise there will be anomalies in the test graphs.
And if you have it set up properly and calibrated and are getting strange graphs there could be two other causes:
1) Other noise in the testing area (i.e. kids, dogs barking, etc...) these things will affect the plot (testing should be done in a semi-quite room.
2) The .ini file became corrupted, just delete it and restart the WT3
Hope this helps.
