Wayne Parham Messages: 18784 Registered: January 2001
Illuminati (33rd Degree)
When you measure with a meter, what you see is DC resistance and that's only part of impedance. The other part is voice coil reactance, and that won't show up on a meter. Typical DC resistance value for an 8 ohm driver is 4-6 ohms, for a 16 ohm driver it's usually 8-12 ohms. Some are a little higher or lower.
Couldn't find the specs for 2440, but according to JBL specs, the 2445J has DC resistance of 8.2 ohms, +/- 10%. A 7.5 reading would be within spec for this 16 ohm driver.