Reality Check! Are like make / model loudspeakers consistent?

By Pat Brown

Are like make / model loudspeakers consistent? Pat Brown measured twelve like make / model loudspeakers. The results may surprise you.

From Dick Campbell’s Loudspeaker Park Part 3 article, this issue:

It is difficult to control the nature of a spring made of “soft goods,” like the spider and surround.

This insightful statement caught my eye, as the issue of loudspeaker response consistency is of interest to system designers, since what happens at the drawing board is expected to be realized in the finished system.

From time-to-time I measure and publish loudspeaker data of like make/model loudspeakers as opportunities arise. The motive is to develop a feel for the unit-to-unit consistency of loudspeakers, something for which relatively little information has been published. It is logical to assume that all loudspeakers in a given run are identical, and that any sample is representative of all units.

Shown at right are the overlaid responses of 12 loudspeakers of the same make and model. The data was smoothed at 1/6-oct. The impedance data is especially relevant to Dick Campbell’s Loudspeaker Park series. He describes an impedance measurement as “an electrical probe into the mechano-acoustic environment and is responsive to the different conditions found there.”

The magnitude differences can be compensated for in the final system tuning, but individual equalizer channels would be required if the same response was expected from each loudspeaker.

The lesson here is one that is well-understood in other industries – “Your mileage may vary.” pb