RTR electrstatic speakers

Sean, thanks for replying and good luck moving. Jes45 you may be right about the early Wilsons, I'll do some checking. Rwd yes if I can sort out some fairly large issues, I'll build a pair of Line Source speakers using the RTR's. If you have questions, I'd be happy to answer the ones that I can. Brain

Hi Sean, The e-stat panels used in the Crown ES 212 are about 5.625" x 5.625". There 12 of these panels (4 wide x 3 high) used with 2 - 10" woofers. Years ago Don at Crown told me that he thought they were crossed at around 350hz and had a sensitivity about 85 db. He wasn't there when they came out, so he said to take the info with a grain of salt. The 350hz sounds about right, but they are a lot easier to drive than the Maggies or Acoustats that I have owned, so I think the 85 db is of a bit. I am trying to use them in a Nearfield Line Array configuration similar to the Linus Array. They will be used along side 9 vertical 6½" midbass drivers. The two major concerns are the sensitivity and horizonal dispertion. The sensitivity can be designed around, but with stacking 12 RTR panels vertically, the desired horizonal dispertion has to be inherit of the design of the speakers. Sean, thanks again for your time and if anyone else has any specs for the RTR panels, it would be nice to hear from you. Thank, Brian

Sean, although I remember seeing the Crowns on the sales floor in the late 70's, it seems that they came out in 73 or 74 and were produced for 2 years. Albert Porter could answer that question. As far as cross over points, I plan to cross at about 1000hz between the panels and the 6½" drivers. This should help the panels quite a bit. A subwoofer will be used mainly to lighten the load on the 6½'s allowing them to keep up with the speed of the panels. The highs produced by the RTR's sound very nice to me, but it has been suggested that the surface area of my panels is a little big to get the placement right at the highest frequencies. I'm not quite sure if this is a problem, but would hate to push forward if additional tweeter panels should be used. Thanks for your time, Brian

Sean, thank you for all the research work on the RTR e-stat panels. That was the most info I’ve seen so far, the verification of 375hz crossover point was an import piece of the puzzle. I had been swapping speakers in and out of my system with known specifications trying to get a handle on where the RTR’s were in comparison.
Keeping the crossover point between the panels and the dynamic drivers lower has raised some very good questions. Hopefully some of it can be sorted out before they are fired up, but as you suggested the rest can be dialed in with the crossover.
As far as the over all design, I didn’t start out building line array speakers, talking with Albert Porter started all that. He also suggested talking with Danny at GR Research (gr-research.com), who provided some very useful information.
I had drawn up speaker plans before talking to Albert and Danny, but decided to learn more about line array speakers before going any farther. It was becoming apparent that the RTR panels would excel in this configuration if certain obstacles could be overcome.
Someone had suggested James Griffin’s paper, which is a “must read” if you are going to build anything close to a Near Field Line Array speaker. Finding out that by placing drivers within the sound radiation pattern of another driver increases the overall sound pressure level (SPL) is where I decided to take Albert’s suggestion and post on Audiogon. The efficiency of the RTR panel became a major issue when it was learned that the SPL of the dynamic drivers would rise from the mid 80’s to the mid 90’s.
As for the speaker box, the dynamic drivers will go in a sealed box. The drivers could have gone lower in a ported box, but a sub will be used below 120hz. It would have been fun to figure out a good way to “free air” the drivers to match RTR’s dispersion, but for now it looks like a sealed box for the drivers and free air for the RTR panels. Building another box later to experiment with is a possibility.
Sean the info you provided answered a lot of important questions. It was funny to see that you suggested Griffin’s publishing’s on the Linus Array; it’s kind of the foundation that this project is now based on. Thanks for the help, Brian