I just acquired a pair of Advanced Acoustics 440 Bi-Phonic Coupler Speakers from the late 50's - early 60's. My son says they're in great shape as he picked them up for me in Toronto. 22"X19"X4". Apparently the entire wooden face/board is made to resonate from behind via some sort of conventional dynamic motor for bass with a tweeter inset at the top corner. Weird.
Oldest piece of gear you own
I will start - Pass Aleph Ono, vintage about 1997 or so, followed closely by an LP12, ca 1998. Speakers and tuner both are from 2000. Newest gear is a cd spinner, Simaudio, ca 2011.