Jim Griffin had an array using twelve of the FR125SR version of this driver with an array of eight Aurum Cantus tweeters at the 2006 Lone Star Audio Fest. It was bi amplified using a DEQX preamp/crossover. I had no need for another line array at the time or it would have gone home with me. He also had a pair of bipole speakers using the eight ohm full range version of this driver, and I was impressed enough with the its sound to build a pair of those.

• 60" Ribbon w/TL Loaded Extremis Hybrid

But I prefer a different tweeter technology if you want an
extreme ultimate system. I don't even like the system design goals,
ie operating the driver down to a few hundred hertz. While this
is a great DIY project, be open to it's limitations.

Some of the specs that interest me are average, ie 1/2 Tesla gap
plus "According to Linesource's effeciency formula, they will be
right at 98 dB/W with 8 micron foil". This is boring specs.

You can find affordable commercial ribbons with 1T gap and higher
sensitivity right now. Plus, if you do parallel elements and can
live with a line array vs. line source, as low as 1.5khz - 2khz
crossover point, it would beat out this project pretty badly.

Last, I would never use low powered amplifiers to drive an ultimate
sound system.

A 3" wide x 90" long 8u Al midrange riggon with 0.6T could reach 103 db/watt

Custom DIY bridge topology amps would be necessary to direct drive the 0.1-0.2 ohm midrange ribbon. 32 watts Class-A would seem adequate, and a high current delivery challenge

Five 15" woofers in parallel could match the 103 db/watt of the ribbons. A high 0.94 Qts like the Lambda Dipole woofers would save some baffle boost power. Should reach below 30Hz in most rooms.

Since this is Ultimate...an array of sealed bipole woofer stacked pairs would pressurize the room for 16Hz-30Hz.

ULTIMATE requires a 40K Hz tweeter ribbon.
ULTIMATE requires a full vocal range midrange ribbon.