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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
8 responses Add your response
sniffles OP
7 posts
 
Playing the rtr's and walking back and forth showed no real beaming since 8 of the 15 "stats" were angled off axis. I also did this sitting down at the listening height. The center stud of the e-stat panel is the diaphram connection so I STRONGLY" recommend using the above described screwdriver slot on the back side of this stud to prevent and rotation of the threaded stud when removing or tightning the nuts/connections.

I finally finished re-voice coiling all the maggie ID panels. The 4 mid/bass pnls and the tweeters. This was quite a job especially to do right and proceeded cautiously.
sniffles OP
7 posts
 
I didn't cross my line sourced RTR's to the 1D's but augmented them. I run the 1d's full range bi-amped. the id tweeters are used from 1K up since the recommended audio reasearch x-over is used before the tweeter amp. I'm trying to figure out if R2,L2 and C1 are the x-over components in the schematic (of the rtr 6-15's) and if so Which can I change to up the x-over point from 1200 to about 3000 Hz? The esr 6's crossed at 1.5K the esr 15's at 1.2K. I y'd out of the audio research x-over and go to a st 70 to run Just the rtr15's and to a mosfet 120 (60+60) to drive the maggie tweeters.

I also run a Janis W2 subwoofer w/it's supplied crossover amp combo. I use the Janis and the rtr's very sparingly mainly to kind of fill in the freq range. A bit more "air and gut punch". i don't turn up the volume (high voltage) past the "0" midpoint mark on the rtr's. never an arc or strain especially using the modified st-70 tubed amp.

I settled on placing the maggie tweeters on the inside and the rtr's on the outside of the maggies. The "air" is spread and not beamed at you and the maggie tweeters handle the center field. As always the 1d's need a lot of placement experimentation to get the tweeter field and the whole speaker sounding right to the individual listener.
barrysandy
192 posts
 
Wow! A tidal wave of nostalgia sweeps over me. I own a pair of Infinity 2000As, one of my favorite speakers of all times, owned RTR-ESR6s and also own a pair of T IDs. Yes, maybe 30 years ago I did the RTR line source with the Tymps. There's a bit of a challenge with this as I recall. The xo of the T-1Ds is 6dB @1.1k. The Infinity/RTR tweeters crossed over at 1.8k in the 2000As and 1.5k in the stand alone add- on RTR units. The stats can't reasonably be crossed over to the T1D bass panels at the lower frequency that would mate well with them Especially at such a shallow slope.
ampup
12 posts
 
Years ago, I combined the Acoustat 1+1 with 16 RTR elements in a line source, which were absolutely superb. I ditched the Acoustat HF transformer, as it muddied the sound and reduced the efficiency of the panel to force the extended HF response of the wide panels. They were crossed over at 1500 cycles using the RTR power supply and crossover, with upgraded components.

No problems with beaming, and the result was one of the most accurate, open window to the music I have ever heard.

One of these days I will have build them again, as the Acoustat components are on hand.

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.
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.
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.
salectric
747 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?
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