| # Speaker Project # Testing the Woofer (2)

> > > So, we've done a Free Air impedance test and estimated the woofer parameters. Now, we can do two things to look at and evaluate our results.

> > > First, open the driver window and bring up the properties dialog. Go to the Parameters tab. Mine now looks like:

> > > Everything below the Calculated line has been calculated by this first Estimate parameters pass. Compliance is also set because I've cheated and done an added mass test, as well. If you had not done the added mass (or sealed box) test yet the Compliance value will not be set.

> > > Of particular note are the total Q (.415) and the Free Air Resonance (43.67). They matter because they affect the box size selection significantly (as well as the F3, 3 dB down point). Also, they are not at spec - which is why you should use a product like Speaker Workshop.

> > > The Vifa is spec'ed at 39Hz and a Q of .35. We are measuring a higher Fs and a higher Qts but well within factory specs (also note that increasing both means that our box design will be very similar to a factory spec box design).

> > > To check the results, you can compare the Free Air impedance chart to the .Estimate chart. I don't have that picture here, but take a look at the subwoofer test for an example of doing that. As expected the correlation was excellent.

> > > Next, we'll do an added mass test to calculate the compliance (VAS) of the driver..

> > > Click here for the next page

> > > last updated March 12, 2001