is this called a "passive" woofer?

[eshort]

took apart two old EPI 200 three way loouspeakers

found woofers with no electrical connections!--e just mounted in the enclsoure with no electrical connections! I guess they are meant only to produce bass via vibration??

strange design to me--but wonder if this method was used in 1970s (vintage of this speaker)
to achieve "super" bass???

tx

[glc]

Yes, that's called a passive radiator.

[David M]

I built a speaker cabinet with a passive radiator a long time ago. It pretty much does the same thing as a tuned port. Allows some of the pressure out of the inside of the cabinet at a distance from the primary driver so as not to cause partial phase cancellation...it effectively boosts the sound pressure and lowers the frequency response by making the driver "think" its a larger cabinet than it is.