• four π loudspeaker performance data

Over the years, I've made several measurements of all my models, mostly pseudo-anechoic that show me behavior through the crossover region but gated high enough there is no usable curve down to the bass. That kind of data is perfect for designing with, because you don't really need to know what is happening down low when optimizing the crossover.

You can be comfortable about bass performance just with impedance charts. Even so, people want to see actual response measurements, all the way down to cutoff. So as useful as my pseudo-anechoic measurements are for designing with, they aren't any good at all for publishing spec sheets.

To get an accurate measurement of response down to the bass range, you have to make the measurement outdoors. This is what I've done at the Prosound Shootout each year. So I'm planning to begin taking all models of speakers outdoors and doing a similar suite of tests on all of them for spec sheets.

As time permits, I'll do on and off axis charts of amplitude and phase response, harmonic and intermodulation distortion, each at various power levels. This gives a much better picture of what's going on than a single chart does. It's pretty time consuming so it won't happen overnight, but in time I'll have a very good set of measurements available.