Wayne Parham Messages: 18789 Registered: January 2001
Illuminati (33rd Degree)
Back-EMF is the voltage produced when the mass of motor causes it to act as a generator after the drive voltage has shut off or reversed. It is a real concern in some cases, but not in high-efficiency speakers like these. The electro-mechanical properties that make it efficient also tend to reduce those kinds of side effects.
What you should watch for - an indirect measure of this - is the maximum impedance. You don't want a tube amplifier to have a wide fluctuation in impedance. But all models of π Speakers have very benign impedance curves. I've called them "tube friendly" speakers in the past, because they truly are. They offer high efficiency and gentle impedance curves.