In fact, Smith & Larson offers two methods, the one you say, quite slow but said to be precise, and the other (in fact many others), very fast, using Chip, Impulse, MLS... signals.
I have DATS and LMS. One area where they differ is with LMS, two plots are displayed. If the plot with delta mass or compliance looks different from the free air one, the T/S will be off. The two plots must look similar except for the shift in resonant frequency.
Regards
Mike
An externally hosted image should be here but it was not working when we last tested it.
I don't see any point in using that mode except in cases where you need a pretty impedance curve for presentation.
dave
Do you know if the WT2 provides enough current for not being a "low voltage solution" so to speak? If not, what is needed?
It is not a powerful amplifier and works at low levels. I believe, althou not checked it out, that it can be configured to use a higher power amplifier (which i have).I only use it for matching drivers. Except in cases where i have no other T/S i use factory data as a starting point formy designs. Rarely have i had to adjust because these were not sufficient.
dave
You can ask your question at woofertester.com. It's my understanding for higher voltage woofer tests beyond what T/S originally intended, you need the WTPro.
Another feature that the Smith & Larson Woofer Tester provides is the provision for the direct calculation of the components for impedance correction of a speakers Le and Re at a specific frequency i.e.a Boucherot cell and not the misnamed Zobel and the nonsensical formula that has long been associated with its use.
Although there is no guarantee the published data is accurate, I think getting Mms within let's say 10%, along with a consistent set of parameters and no obvious measurement errors, might be a good indication that your driver is just that. A driver with consistent production quality should have a tight value for Mmd (Mms follows...) and this might be a fair "reference" parameter. Looking at Cms can probably explain a lot after that.
Looking at typical Bl(x) and Cms(x) curves, it seems that a low-level measurement should often come up with fairly low Qes/Qts and Fs values as Bl and Cms should be close to peak value, not to mention linear. Rest position (x=0) does not always equate peak position for either Bl or Cms and this is probably what we sometimes see, but it seems the difference between value @ x=0 and peak should not be large in a well-designed driver. Yet it often seems these parameters (Fs and Qts) come up higher than published. I may be overlooking something as I'm not exactly seasoned in the field, but this is my current understanding.
Looking at typical Bl(x) and Cms(x) curves, it seems that a low-level measurement should often come up with fairly low Qes/Qts and Fs values as Bl and Cms should be close to peak value, not to mention linear. Rest position (x=0) does not always equate peak position for either Bl or Cms and this is probably what we sometimes see, but it seems the difference between value @ x=0 and peak should not be large in a well-designed driver. Yet it often seems these parameters (Fs and Qts) come up higher than published. I may be overlooking something as I'm not exactly seasoned in the field, but this is my current understanding.
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