Under XP, it can get funky, as XP sometimes won't switch to the WT3 as its default play and record device. This does seem a common problem.
I don't have any more trouble under Win7 Starter (a netbook) than XP, but it's a simple setup. Under Win7 Pro I've had nothing but trouble. Gave up
Interesting that it needs to be the default device. I'm sure that is probably a large part of the problem. Definitely don't have any browsers open when using it if that is the case. Also if you have iTunes on the computer make sure it (and any services related to it) are shut down before using the WT3.
I had a lot of problems with my Audigy II ZS on my win7pro 64 bit machine. Once I changed the default sound device to be the on-board sound and manually told the apps that I wanted to use the Audigy with, to use it rather than the on board sound, most of my problems went away. It does occasionally play up, and the only thing that fixes it is a full power down and restart.
When ever I am doing measurements I make sure to do a clean start up from power off, and close all non-essential programs (including the tray icons) before starting up the test software. I don't have a WT3 but I suspect that the problems I have had with my sound card are similar.
Tony.
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http://www.woofertester.com/wt2_accuracy.pdf
For those of you using the WT3, please lash up this easy circuit and let me know if your WT3 actually measures Fs and Qt correctly. When I performed this test on a WT3 it gave erroneous results.
My impression is that the WT3 can measure a resistor but nobody actually has a precision Fs/Qt device to test how it measures a speaker objectively. The attached is a way to construct a precision Fs/Qt emulator.
For those of you using the WT3, please lash up this easy circuit and let me know if your WT3 actually measures Fs and Qt correctly. When I performed this test on a WT3 it gave erroneous results.
My impression is that the WT3 can measure a resistor but nobody actually has a precision Fs/Qt device to test how it measures a speaker objectively. The attached is a way to construct a precision Fs/Qt emulator.
Inductor resistance in ohms
Inductor inductance in Henries
Capacitor capacitance in Farads
For the PDF example
R = 0.274
L= 0.0064 (6.4 mH converted to Henries)
C=0.00689 (6890 uF converted to Farads)
You can spreadsheet this.
The spreadsheet Column B title is "Inductor Resistance Ohms"
Column C title is "Inductor Inductance Henries"
Column D title is "Capacitor Capacitance Farads"
Column E title is "Fs"
Column F title is "Qts"
formula for Fs
=1/(2*3.14159)*SQRT(1/(C5*D5)-(B5^2/C5^2))
formula for Qt
=2*3.14159*E5*B5*D5
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calc spreadsheet
Here is the formula in Excel spreadsheet format. It should open in other spreadsheet software as well. You'll notice I've changed the input a bit. You can now enter directly in mH and uF for your inductance and capacitance.
Thanks for this. I will check my WT3 and report back. I hope that others will check their own testers and report the results.
Here is the formula in Excel spreadsheet format. It should open in other spreadsheet software as well. You'll notice I've changed the input a bit. You can now enter directly in mH and uF for your inductance and capacitance.
Thanks for this. I will check my WT3 and report back. I hope that others will check their own testers and report the results.
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Great. Thanks. Is the second entry the parts for your personal emulator? I am calling the circuit a speaker emulator. It describes the function and usage.
If so, those are good values. It gives you an emulator that would be a great speaker.
Make sure your measurements of the R, L and C are made with a good accuracy instrument. I have a reasonable decent LCR meter.
Post up your results of 10 trials. It will be instructive to see and discuss.
If so, those are good values. It gives you an emulator that would be a great speaker.
Make sure your measurements of the R, L and C are made with a good accuracy instrument. I have a reasonable decent LCR meter.
Post up your results of 10 trials. It will be instructive to see and discuss.
Will do.
WT3 tests
Here are 3 trials of 10 sweeps on the same driver. Software shut down and restarted between run 2 and 3.
Qts=
0.6457
0.6457
0.6456
0.6459
0.6458
0.6528
0.6459
0.6456
0.6452
0.6456
0.6573
0.6572
0.6569
0.6568
0.6570
0.6566
0.6569
0.6573
0.6570
0.6575
0.6569
0.6566
0.6571
0.6567
0.6571
0.6567
0.6566
0.6565
0.6569
0.6567
I'll build an emulator and try that.
Here are 3 trials of 10 sweeps on the same driver. Software shut down and restarted between run 2 and 3.
Qts=
0.6457
0.6457
0.6456
0.6459
0.6458
0.6528
0.6459
0.6456
0.6452
0.6456
0.6573
0.6572
0.6569
0.6568
0.6570
0.6566
0.6569
0.6573
0.6570
0.6575
0.6569
0.6566
0.6571
0.6567
0.6571
0.6567
0.6566
0.6565
0.6569
0.6567
I'll build an emulator and try that.
Strange, I see that my emulator post from Monday didn't make it thru. A glitch.
Anyhow, with a big inductor of about 11.5mH and a 10000 uF cap I got results that were somewhat near the mark. Trying with a smaller inductor, like 6 mH, I could not get numbers anywhere near what they should be by formula. So maybe the WT3 doesn't work that way?
Anyhow, with a big inductor of about 11.5mH and a 10000 uF cap I got results that were somewhat near the mark. Trying with a smaller inductor, like 6 mH, I could not get numbers anywhere near what they should be by formula. So maybe the WT3 doesn't work that way?
Add 5% to the capacitor and run the calculation. Subtract 5% from the capacitor and run the calculation. That should bracket the measurement.
Report the calculated Fs and Qt bracketed values and what results you obtained for your WT3. That will be a starting point for the discussion. There is an easy experiment once you have this base line reported.
The Smith & Larson WT2 is WAY better than the WT3 (at least for T/S, i don't use it for anything else).
dave
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