Interesting reading: Supertweeters and ultra high frequencies

In the early seventies, I made a version of the HQD speaker system which comprised two Hartley 24” bass drivers, a pair of stacked Quad ESL-57s and a pair of Decca Ribbon speakers (see http://www.marklev.com/systems/). The Decca’s were used as supertweeters here to augment the treble roll-off associated with the ESL-57s. Inevitably, the ribbons got damaged and repairs were routine and I became adept at repairing them. This system sounded awesome and I was a sad chappie when I had to leave all behind in Sydney when I came to the UK in 1978.