| # Speaker Project # Prototyping

> > > We're done with the woofer testing. We have an impedance and a frequency response for prototyping a crossover and we've verified the enclosure and port sizes. Now it's time to work on the tweeter.

> > > Next we start working with the tweeter. For the tweeter we really just need to measure the impedance and the frequency response - both done while in the enclosure. The enclosure front will affect both measurements slightly (due to diffraction effects, more than anything).

> > > Here's the tweeter "Free Air" measurement (done in the enclosure) and the tweeter On Axis response.

> > > Before we start prototyping the crossover note that the tweeter dropoff is substantial at the high end (above 15KHz). I haven't decided for sure if I'm going to use this tweeter. It's a large mid-tweeter made by LPG (the 38T) a 1 1/2" midrange dome made from titanium.

> > > The purpose of these speakers is primarily as home theater speakers and as I get older I hear fewer high frequencies so I'm strongly considering this because it should be able to generate more volume at lower distortion than a standard 1" or 3/4" tweeter. Also the crossover should be simpler because it goes farther down in frequency. Finally, the driver is much lower in distortion in that important midrange area (700-2000Hz) than a standard tweeter.

> > > The next step is to prototype a crossover and listen to the speaker to see whether that top 1/2 octave matters to me or not. The crossover prototyping is a good exercise, either way.

> > > On to the next page.

> > > last updated March 12, 2001