Bohlender Graebener RD75 Planar Transducer

I was so impressed with these drivers at the demo I took the plunge and swapped out all of my DJ and Sound reinforcement setups to them. No regrets, totally awesome. I agree with the other reviews that they should be crossed over higher than the suggested limits. I crossed them at about 300 hz. These speakers have the best vocal clarity of any driver I have ever heard. As a singer with these as the monitors vocals cut through clearly even in previously unmanageable environments. And I don't have to have them as loud as I did my previous monitors. Which of course is less feedback. Matched with a pair of 18" woofers crossed at 500 hz they are incredible for PA useage the people in the rear can hear just as well as the people in the front with far lower overall volumes, they carry just that much better.

I have long been a fan of electrostatic loudspeakers and when I heard that the RD 75 B&Gs are even better than electrostatics I was eager to give them a try. I have found it very difficult to get these to perform at the level I have come to expect. First, there is the 5K anomaly that requires a notch filter to tame. Instead I cross over to a RAAL 70-10B at 4K via a Pass Labs XVR1 electronic crossover to avoid this and to get extension up past 20K. Next, there is the dipole issue. I like the dipole nature of electrostatics, but on the Bohlender...mmm not so much. Soon I will try them in an enclosure to see if this helps. Finally, there is the usable range. As others have noted, you really should cross these over at a much higher frequency that the 150Hz stated. I have tried many and settled with 220HZ with a 4th order 24/db octave slope mated to an array of 6 Usher 8955A in sealed enclosures with 1cuft of space per driver. All in all many dollars spent for sound that doesn't necessarily sound better than my electrostatics. Don't get me wrong, these are phenomenal drivers; however, they are just plain difficult to implement sucessfully.

I used these in DEQX based system which can correct resonance and droop in high frequencues as well as provide stee/phase perfect XO. These are terrific transducers; apart from peculiar imaging with female vocalists which make them appear larger than real life,superp in all respects IMO. And much, much better than many well regarded high end speakers such as Thiel, Dunlavy, Infinity Prelude I have owned before. I also like effortless dynamics and ability to deliver high SPL's at distances of 12'. I used with two Scan Speak 7" per side, and gargantuan pair of 18" Audire Avalanche subwoofers that could throw 17Liters/stroke (in infinite baffle). I would agree tho if cost no object, begs for line array of high quality, low distortion midwoofs. (As did other reviewer, I ran down to 300Hz just to avoid stress, even though I could have used 300dB/octave XO and lower point probably).