An unexpected response 😉 I wasn't really thinking about measurements when you asked...
I was alluding to the various interactions between the front and back panel which are likely to affect what you hear. (but not talking about the out of phase rear radiation into the room)
It seems that it was more important to eliminate the standing waves than the resonances ...
I was about to use Sonotube for my DIY subwoofers but I didn't get them here, how much work it would have saved me !
I was about to use Sonotube for my DIY subwoofers but I didn't get them here, how much work it would have saved me !
I have an anecdote here regarding the Andromeda of Phase Linear . We sold that speaker system to a client who had a huge room, but totally empty, there was only one grand piano inside, and the side wall was completely glazed. I estimate about 20 meters x 8 meters (65 "x 26" approx). His amplifier of choice was a 125 Rms / channel Marantz receiver. We told him that it was low power for those speakers but for budget reasons he did not accept the advice.
At Audio 2001 we had a 6 x 4 meter audio room. fitted out with carpet and cork panels on the walls. There the sound was very good and the common opinion was that in a large room the sound would be wonderful.
Big fiasco! Reverberations from lack of acoustic treatment and distortion from lack of "headroom" was a fatal combination ! 😡
The story ended with threats of trial, which did not materialize, but this good man found the solution by consulting with the Phase Linear importer, who recommended that he carpet the entire floor and put thick curtains, and sold him a PL 700 model. .....
At the time I found out that he was very happy with the sound, but you know who were the bad guys in the movie.
Sorry OT
At Audio 2001 we had a 6 x 4 meter audio room. fitted out with carpet and cork panels on the walls. There the sound was very good and the common opinion was that in a large room the sound would be wonderful.
Big fiasco! Reverberations from lack of acoustic treatment and distortion from lack of "headroom" was a fatal combination ! 😡
The story ended with threats of trial, which did not materialize, but this good man found the solution by consulting with the Phase Linear importer, who recommended that he carpet the entire floor and put thick curtains, and sold him a PL 700 model. .....
At the time I found out that he was very happy with the sound, but you know who were the bad guys in the movie.
Sorry OT
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My conclusion is the increase in efficiency coupled with the full damping is responsible. Likely why the top end has better resolution. It appears to be a lucky outcome. Resonance was a paramount issue when I contemplated stacking the panels. I expected output to be a wash with the additional amps since the cavity between the panels is completely filled with med density felt similar to that glued to the backs of the originals which I did remove completely btw. However, output is noticeably higher. Bolserst commented on another thread that there would not be any noticeable change in output if they were tightly sealed as proper isobarics just because of the nature of the large panels. Radiating surface area into the room is the same. So I suppose output is naturally boosted as if there was more stator area with the added benefit of virtually no resonance. Tapping on the speaker anywhere results in no lingering resonance, just a dead thud.
Isobarik.. do you mean they're out of phase? Otherwise they're pressuring the small space between them.
If they are in phase there will be a difference at the edges.
If they are in phase there will be a difference at the edges.
No, in phase. They are moving in unison, so why would there be compression?
Initially I thought out of phase would be the way to run them but discovered the contrary. That caused them to cancel each other with a huge reduction in output.
Initially I thought out of phase would be the way to run them but discovered the contrary. That caused them to cancel each other with a huge reduction in output.
Oh, so you don't have the back panel turned around to face the back, they both move in the same direction at the same time, which is like what happens when you have only one panel....