The Process

For my first speaker measurement I used a Yamaha SM15 IV. After making some successful measurements I decided to measure the response off axis, to both the left and the right. The graphs are zoomed into the frequency range from 132Hz to 16kHz to emphasize the most important effects.


Yamaha SM15IV, centered

This curve represents the response of the wedge measured from a position roughly centered in front of it.


Yamaha SM15IV, right

When the measurement is taken from a position equivalent to a couple steps to the right it becomes quite apparent that the woofer and tweeter are strongly interacting, creating phase cancellation in the crossover range.


Yamaha SM15IV, left

The surprise when the position was moved to the left was that the curve was actually smoother than the one from center. The lack of cancelation in the crossover range suggests that the sound from the two drivers is in phase measured from this angle.

Next: Testing an Experimental Stage Monitor