Loudspeaker Impedance Variance

by Pat Brown

A recent project required the measurement of the electrical impedance of a family of loudspeakers – nine units total. These are all “16 ohm” rated devices (Figure 1).

It serves as a reminder as to why we drive loudspeakers from “nearly zero” output impedance amplifiers. This buffers the amplifier and loudspeaker response from variances in the impedance curve.

A modern amplifier would have the same frequency response into any of these loads.

All of these devices have a relatively flat axial frequency response magnitude.

The curves were measured by the constant voltage method using Monkey Forest.  pb

Figure 1 – Nine overlaid loudspeaker impedance curves.