Taming/Damping Electrostat Backwave


In my understanding of the physics of the situation, the signal coming off the back of an electrostat panel is the same signal that comes off the front though in opposite phase. If there are reflections off a back wall, they cannot be a better signal than the one off the front of the panel. It strikes me that in a strict sense, if one could COMPLETELY eliminate the backwave on electrostatic speakers (a giant silent sound vacuum, sucking in the sound off the back of the dipole), this would be, in the words of the once famous and now infamous [:)] Martha Stewart, 'a good thing'. Am I missing something? Is there any argument to support not trying to eliminate the backwave through all means possible?

My Martin Logan SL3s sound reasonably intolerable when too close to the back wall, great when a certain distance away, and in my limited, ad hoc, distinctly non-scientific (not to mention bad WAF) experiments, even better when I put a variety of dampening material between the panel and the back wall (even when the wall is 6ft back).

Does anyone have a view or experience on the "complete backwave elimination" strategy? Do you try to eliminate it entirely? Do you leave some backwave in for 'flavor'? How do you deal with it? Put shag carpeting on the wall? Hire tall sheepdogs to sit on stools calmly for hours on end a la Fay Ray? I would love to know how other people deal with the backwave issue...
t_bone

Showing 1 response by maxgain

Jamesswei's and Sidssp's sugestions are good ones from my experience with the old CLS's and the old Monoliths. I have owned 3 pair of Maggies as well and they benifit from the same thing. They all like space behind them. The fact that they don't have a cabinet is part of why they sound the way they do,no cabinet resonences to deal with. I have a friend who has Sound Labs and the sound is difficult when things get loud. His room is too hard and reflective. When you put on an acoustic jazz trio the potential is revealed. I have used the tube traps with sucess myself and they alow for some tuning where the results with permenent difusers are harder to predict. If you don't like the sound with the trap just rotate it or move it around until you do.

Sean, you might remember Harold Beveridge did exactly what you are proposing, and also went as far as using a bizare JBL style lens in front of the stat panel to control dispersion. I remember that they could sound quite nice but never heard them in a controlled situation. It always seemed to me like it was an approach that added some of the problems associated with box speakers.

I remember the old Dayton Wrights, the Koss electro stats, I had a boss with double KLH 9's, I also sold Quads and Acoustats at different times, they all have an aluring quality, you just need to acomodate their needs with some space around them and some room treatment. I had to go back to dynamic speakers from a stand point of practicality. Good luck and don't give up, you will be rewarded when you get 'em set up well.

Here is a horror story for Quad fans. I ran across some people while working in a HiFi shop who had inherited some speakers the knew nothing about. After talking with them I determined that they were Quad 57's. They told me about how they liked to watch the light show of sparks inside the speakers when the turned them up REAL loud. It about made me cry!