D'oh !!

That's why I keep coming back here. Where else can I learn so much so quickly ?

OK, a slightly different Google search got me past the 1,135,205 different center speakers on the Internet and found a picture of Dr. Joseph D'Appolito :



http://www.visaton-bausaetze.de/hifi/index_en.htm?/hifi/referenz_en.htm

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8