VIBOX - Measure Impedance at Any Power Level

Applications

Using the VI Box, impedance as well as SPL can be measured simultaneously without the need of changes to the test setup or wiring. This is ideal for production line QC. Passive crossover components can be measured under actual load conditions as well. Many other valuable measurements are also possible including electrical distortion, temperature rise, TC, etc. If reliable and accurate loudspeaker parameters are the problem-
VI Box is the answer

Measure
• Speaker impedance at any power level.
• Crossover components at any power level.
• Average power consumption and effective impedance over any range of frequency.
• Impedance, SPL, and Power simultaneously.

Determine
• Speaker parameters at any power level.
• Speaker temperature coefficient, temperature rise, and power handling limits.
• Nonlinear impedance characteristics.

Loudspeaker Impedance at difference power levels

The example shown here is a typical 15In woofer mounted in a 4cuFt box with 4In diameter port.

The impedance at four different power levels was measured: 0.1W, 1W, 10W and 100W.

The lower impedance peak shows dramatic changes with drive level. This is a result of the relatively small port saturating with the increasing velocity through the port.

A larger port would produce less nonlinear behaviour.