Oh, the F's had multiple problems, but the ringing wasn't common to all of the drivers. At any rate, the design was so problematic that they dropped it, and Ohm moved on to another technology.
There is a guy in Ohio, Dale Harder, who actually has refined the Walsh driver and builds them in his custom shop.
http://www.hhr-exoticspeakers.com/
The German brand was probably German Physiks, who also modified the original Walsh design.
Still, when the F was in good shape and amped adequately, it was pure magic.