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RTR esr 15 info

I'm new to this forum and others after getting my eqpt. out of storage. After researching the RTR esr 15's I wanted to refurb. I have some needed? info on these. I have a schematic of the esr 6/15's and some reprints? I've cleaned and brought up the esr 15's on a variac, tested and updated MY version of the schematic I have.I then made my esr 15's a line source speaker to "go with" my Maggie 1d's. I have great pics of the final speakers,don't know how/if I can post these here? I saw a old pic of someone who did this "line source arrangement" but it wasn't pretty. Some hints for the blue elements (panels)...Hold the bottom (jam nut) nut while tightening/loosening the top nuts. You don't want the threaded post to rotate. The center post is slotted on the side opposite from the nuts side so you can use a small screwdriver to keep this post from rotating (on my panels at least).My elements are date coded 1974 as I recall. I used a super soft artist "fan" brush w/a fan blowing across me while dusting both sides of the "grids". I used those magnifier goggles you see the watchmakers/hobbiest use. This was time consuming for 30 esr panels, but the safest/most thorough way I felt. I could examine the grids and even straighten any "bent" grid/stator? wires I found.
sniffles
salectric
748 posts
 
I am curious about your line array and whether you ran into problems with beaming. Back in the 1970s when I had a RTR ESR-6 with my Fulton FMI-80s, I tried making a new mounting panel so that all 6 electrostat panels were in the same plane. The resulting sound was much too beamy and bright. It turned out the RTR knew what they were doing when they angled each of the panels to get a broad dispersion pattern with tolerable beaming on each one. Your line array wouldn't have quite the same issues as mine since the panels are spread out vertically. You probably don't have as much concentrated HF energy on axis as I did, but what about horizontal dispersion? Does the treble balance fall off considerably if you listen off-axis?
sniffles OP
7 posts
 
Hard to explain w/o pics but 8 of the 15 elements are angled outward by about 15 degrees or so. have not measured them yet. I only tried them out by themselves as I have to rewire my Maggie 1D's and get the whole system up. I'll know more then. I intend to try to put the maggie tweeters on the outside configuration and put the rtr's on the inside of the inside panel first. This is not the "normal" way to set up the tympani 1D's.I'll have to give an update near the end of the summer when I hope to have it all up. The rtr's are arranged 1 horiz and the next 2 under vertically w/4 of the 5 groups angled out. All vertical elements and the 2 mid height horiz elements face on axis. the line array matches the 1D's as the element array is about 4 feet high about 2 feet off the ground which mimics the tympany's tweeter config. I can sen some pics if your interested w/your email address if not I'll understand.
josh358
286 posts
 
Interesting project. The 1-D's are close to my heart since I owned a pair for many years. And I remember the RTR's well.

Here's an interesting illustration of the radiation pattern of straight and curved lines:

http://www.xlrtechs.com/dbkeele.com/images/Card%20Back%20Large.png

The RTR, with its facets, approximated a curved line. At high frequencies, a curved panel will radiate like a pie slice -- the angle of the arc made by the curve being the angle of the pie slice. As frequency gets lower and wavelength starts to approach the wavelength of the arc, directionality starts to fall off, and eventually the arc will start acting like a point source (or dipole in the case of the RTR's). The facets do the same thing as the continuous arc, but since they're an approximation you'll generally get some lobing at the higher part of the frequency range.
dopogue
1,773 posts
 
Interesting thread. I had two pairs of Infinity 2000A speakers (stacked) and was unaware until I sold them of just how many RTR tweeters had quietly died. There were 4 of the blue RTR panels in each speaker, arrayed in a vertical line with the top one tilted, as I recall. I ended up selling them for next to nothing because nobody I queried at the time could tell me how to bring them back to life. I doubt that there were more than 3 tweeters (out of 16) still working at that time. No, I didn't play the speakers especially loud.
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