Does anyone have experience with Bohlender Grabener RD 75 ribbon transducers?

I owned an pair for a few hours.  Hope this helps

BG isn't in business anymore and the drivers have failure problems associated with tears in the diaphragm. If you have a set that works people are looking for them to replaced failed units.

@atmasphere -- thanks for the info; they're being sold by someone in Santa Ana, CA, who apparently inherited several (that had never been used) from his uncle.  I listened to them, and they sounded good, but would have to be paired with other speakers to cover the low mids and lows, so I passed. If anyone is interested, they should check craigslist in the greater LA area.