The newer CLS driver that replaced the original full range F and A drivers back in the 80's are now in their 4th generation of revision.
Original OHM Fs and As were unique in that they used a single physical Walsh omni driver with no electronic crossover to cover full range to 16-17kz or so. The achilles heel of this design was that they were easily over-driven and damaged as a result, so reliability was not the greatest.
The CLS design effectively solved this problem by offloading the very top end from the Walsh driver to a separate tweeter mounted in a manner so as to preserve the "phase coherency" and sound of the original Walsh design as much as possible. Output levels are also physically damped or attenuated in wall facing directions to make placement easier compared to the original full omni WALSH drivers.
mk II and series 3 revisions of the CLS driver use the same Walsh driver but the series 3 a more refined soft dome tweeter as I understand it.
OHM recently announced newer version of some of their larger drivers, including the 5000, which supposedly uses new Walsh driver components for the first time in quite a while, stronger magnets, greater efficiency supposedly, described as evolutionary and not revolutionary in terms of the resulting sound.
New incarnations of the original OHM F and A with updated and supposedly improved full range Walsh drivers can be had here:
http://www.hhr-exoticspeakers.com/HHRabout.htm
..but the in-home trial/guarantee comparable to OHMs may not be available. My understanding is that these new designs by Dale Harder are advertised as somewhat more resistant to over-driving than the originals.
I've never seen nor heard Dale Harder's new creations, but he seems to be most knowledgeable and also seems to be a true lover of the Walsh driver technology.
Original OHM Fs and As were unique in that they used a single physical Walsh omni driver with no electronic crossover to cover full range to 16-17kz or so. The achilles heel of this design was that they were easily over-driven and damaged as a result, so reliability was not the greatest.
The CLS design effectively solved this problem by offloading the very top end from the Walsh driver to a separate tweeter mounted in a manner so as to preserve the "phase coherency" and sound of the original Walsh design as much as possible. Output levels are also physically damped or attenuated in wall facing directions to make placement easier compared to the original full omni WALSH drivers.
mk II and series 3 revisions of the CLS driver use the same Walsh driver but the series 3 a more refined soft dome tweeter as I understand it.
OHM recently announced newer version of some of their larger drivers, including the 5000, which supposedly uses new Walsh driver components for the first time in quite a while, stronger magnets, greater efficiency supposedly, described as evolutionary and not revolutionary in terms of the resulting sound.
New incarnations of the original OHM F and A with updated and supposedly improved full range Walsh drivers can be had here:
http://www.hhr-exoticspeakers.com/HHRabout.htm
..but the in-home trial/guarantee comparable to OHMs may not be available. My understanding is that these new designs by Dale Harder are advertised as somewhat more resistant to over-driving than the originals.
I've never seen nor heard Dale Harder's new creations, but he seems to be most knowledgeable and also seems to be a true lover of the Walsh driver technology.