RTR electrstatic speakers

I believe the WAMMs use them, or used to.

Spfury1965: The RTR's are strictly tweeters, nothing more. Even if you ran a bunch of these, i wouldn't expect any type of bass output out of them. Sean
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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

Working from memory, the RTR panels that i have are 3" x 5.75" or so. The panels that you have are obviously different than what i've got and almost twice the size, hence the greater amount of low frequency displacement. Even with the greater size, i would cross them measurably higher than what you mentioned. This will lower distortion through reduced excursion, increase power handling, improve transient response, improve "transparency", etc...

As to the efficiency level, that sounds much too low for that quantity of panels. While bandwidth limited and actively crossed, i was seeing figures that were WAY, WAY above that. Most of these that i have came from Mike who posts as Magnetar over at AA. He had used several of these stacked in parallel as supertweeters and was seeing VERY high SPL's out of them. The fact that he was using them with 109 dB horns should tell you something. If i can recall correctly, i think he mentioned a figure of appr 111 dB's @ 1 watt when used above 10 KHz. I don't know how many of these smaller panels he had wired up though, so i'm not much help there. The fact that you want them to go MUCH lower in frequency is going to drastically reduce their average sensitivity, so keep that in mind.

To get around the displacement and excursion limitations on these little panels, i've got two different sets of midrange panels that i was tinkering with. One set is 1' x 6' tall and the other set is 2' x 6' tall. Each panel is actually 3' tall with one stacked on top of the other. Each panel was driven by it's own channel of amplification, keeping the load on the amp very reasonable. Since i was mono-blocking this set-up, that meant 6 stereo amps with all 12 channels being used.

Depending on how things go once i move, i've been thinking about using both sets and moving up to active quad-amping rather than active tri-amping. This would mean two more stereo amps for a total of 16 channels driven, but it could give me even more dynamic range with improved transient response ; )

As far as the Crown's go, if you can find me the appr years of production, i might be able to find more specific info for you on them. Sean
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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