Dipole line-array idea

[63781]

The nature of dipoles is that they are totally "dead" at 90 degrees, so they might not "fill the room" at all positions. In my setup one speaker goes almost dead if I move from side to side very close to the speaker, but at larger distance its not a problem. Its quite funny to stand right next to one speaker, and only hear the sound from the other one!

Sweetspot can be described as very large, its not a very fixed point like with some boxed speakers.

I have no audible problem with beaming really, the speakers sound natural at most angles and various positions around the room.

I think its a myth that the RD75 has great problems with beaming.

 

[OllBoll]

Cool, the dipole nulls I have planned to compensate by placing them so the nulls are in areas I don't usually sit or stand in.

I'm not that concerned about high frequency beaming, mostly about high frequency output off-axis. http://web.archive.org/web/20081011063351/http://ldsg.snippets.org/ALSR/offaxis.html

What makes me wary about adding planar ribbons as tweeters is cost, wouldn't that require lots and lots of expensive ribbons, paying enough to buy another RD75 even and still not achieve reasonable vertical dispersion, or atleast as high as the RD75? Or is it ok and enough to add a few high-dispersion dome-tweeters in the middle and cross high, or will these non-line source tweeters mess upp the response since those would be point sources and not line?

And another question and probably the most important... how good sounding is the RD75 really? If you pit it against one of the best cone drivers available in the region of 150-3000 which in my potential design probably would be a set of AE Dipole6 or similar, is the RD75 still way ahead or is the difference fairly small?

 

[63781]

In my opinion you will create a real mess if you try to use dome tweeters with the RD75. But then why the heck would you want to do that? The horizontal dispersion of the RD75 is no worse than most 1" domes anyway.

My cone driver references are mainly Seas Excel's, which are very good up to 1 to 1.5 kHz. But the RD75 blows them away with a very very large margin. There is simply nothing quite like a successful RD75 installation in my opinion.

OllBoll, you are Swedish right? Its not all that far to Norway if you want to hear mine.....

 

[OllBoll]

In my opinion you will create a real mess if you try to use dome tweeters with the RD75. But then why the heck would you want to do that? The horizontal dispersion of the RD75 is no worse than most 1" domes anyway.

My cone driver references are mainly Seas Excel's, which are very good up to 1 to 1.5 kHz. But the RD75 blows them away with a very very large margin. There is simply nothing quite like a successful RD75 installation in my opinion.

OllBoll, you are Swedish right? Its not all that far to Norway if you want to hear mine.....

Cool, if they are that good then trying to design around the issues might be a better idea than using cones =)

And sure they have roughly the same dispersion as a 1'' tweeter, but what if you add more tweeters, maybe also at angles like in my very professional example image (rear firing tweeters also ofc) and then cross 6/12 db at around 10 khz or so. Just too slightly help off-axis so that off-axis dispersion is the same at 10-15 khz as at 2 khz. The question is though if you need to add an array of tweeters not to mess upp impulse response or if it is so high in frequency it doesn't matter?

And Norway might be a bit too far away, though I will probably try to ambush someone here in Stockholm... someone is probably sitting on a pair

 

[OllBoll]

Sat some more and thought about different solutions around the off-axis problem, and thought of one that should be the ultimate of simplicity:

If one planar has a non-ideal off-axis response why not just use two, and mount them at an angle?

And if I use two, I'm considering using two RD50 instead of RD75 and raising them 40cm and placing them ontop of the subwoofer. Would it be a problem to raise them from the ground by that height or is the only "problem" that if I lie on the ground in front of the speaker I might not have perfect output?

 

[OB Fan]

Excuse my ignorance, but..... why vertical response of a driver like the RD75 would be a concern if this unit is a planar one which I believe radiates sound from top to bottom in an uniform way and stands so tall that no matter if you stand or sit, you will be covered by its radiation? Yo probably will not be under it or over it due to its height....
from what I have read and heard about these drivers, the sweet spot is wide so it seems that horizontal dispersion is really good, since it is supposed to be ideally as a semi-cylinder... someone correct me......