Aren't passive radiators out of phase?

Great info, Bear! Thanks for sharing.

Thanks for enlightening us on the subject Bear.

BTW, on my website there is a page with my version of subs with PRs, 18" PRs. Two per channel. I call them Quadripole, there are now some graphs and a better discussion than I had up a few months back... I do show the output of the PR and the woofer in separate graphs (iirc). I did not put up the impedance curves. FYI the pair (each channel) comes out now to 8 ohms... I can get some more "snot" if I rewire the drivers so that it ends up as 2 ohms, but I have to put back the Crown Macro Techs to drive that low impedance properly.

The cabinets shown are actually a bit too small - these are the original pairs that I built and they should have an extra cubic foot (a few inches back and one or two here and there gets you an extra cu ft!). IF it did have the extra foot the F3 would be at 20 Hz exactly and the overall response without EQ (I don't usually use any) would be a bit flatter...

_-_-

(Dickason's Loudspeaker Cookbook covers some of this theory, btw...)

Thanks Bear. I think I'm beginning to get it. The PR is tuneable with the volume of the cabinet (due to the compressing nature of air) and the properties of the PR stucture. I wonder, have there been any speakers with pressurized cabinets or maybe gas filled? ........ How about liquid filled (he,he)?

The Dayton-Wright Electrostatic speakers were filled with carbon hexafluoride gas. The gas is commonly used in welding. Nothing would impress audiophile friends like breaking out the tank of carbon hex and filling up the speakers. On the days that they worked anyway.