Mating Acoustats with Ribbons

[ThomasW]

Originally Posted by coloradosound

Finally found another set of RD75's of which one of those is also bad.
Providing I repair the bad units, I think I can do something like the Polk
Stereo Dimension Arrays (SDA's).
Any thoughts on correct spacing between RD75's (will probably build
a narrow HF ribbon to fit between the RD75's to cover the top.
Also any thoughts on the response shaping for the crossfeed drivers?

Can't seem to find much info on how the Polk SDA's worked though.

B&G will rebuild the RD75's for a fee. I had one rebuilt a while back cost was $220. Not what I'd consider a DIY project..

The Polk SDA is nothing more than the old Dyna-quad (ambient recovery) design with hot leads from the corresponding sides run to the hot in and a common wire run between the two (-) terminals. Personally I can't imagine this being of any benefit with dipoles.

[coloradosound]

Originally Posted by david yost

If I had 4 BG75's, I would be tempted to try a F and R Ambiopole set-up using 2 X electro-music.com's AmbiophonicDSP crosstalk cancellation program. This would be much more flexible than SDA and probably sound a lot better too!

It sounds like I would have to insert a computer into the system and go through a
sound card?

[coloradosound]

Originally Posted by ThomasW

The Polk SDA is nothing more than the old Dyna-quad (ambient recovery) design with hot leads from the corresponding sides run to the hot in and a common wire run between the two (-) terminals.

I think the SDA was different than the Hafler-Dyna quad setup in that the ambient
recovery was just out of phase signal extracted by running rears from the two (+)
terminals and anything different between the two(+) was out of phase ambient info.
The SDA, If I recall, had attenuated, equalized, inverted signal crossfed to other channel.
So, it sounds like there are two distinct stereo signals crossfed and inverted. The
spacing between the normal signal of inner driver and the outer driver of a channel
set up the delay timing to produce the SDA effect?

Originally Posted by ThomasW

Personally I can't imagine this being of any benefit with dipoles.

I was thinking of some more fairly heavy damping in the BG ribbon part of the system
and leaving just the little felt pads on the electrostat panels, so the electrostat
would be more dipolar, and then become more monopolar in the highs