Fick det här från AE inatt...
Har vara läst det snabbt en gång o känner att jag inte riktigt är med på allt i början. Är så dålig på engelska.
Menar, det är ju svårt som det är på svenska!
Måste iväg nu så jag klipper in det så ni kan begrunda hans svar.
Tar nya tag i kväll...
john@aespeakers.com wrote:
After looking more in depth at the "ripole" concept, there are some issues with this that I was not aware of 2 years ago. The design fires the woofer into a slot. This slot provides additional acoustic loading on the driver. It increases the apparent Qts of the driver. It lowers the upper end efficiency. This is the type of design used when trying to force a non-ideal, low Qts driver to work in an open baffle application. The decrease in upper end efficiency and increase in Qts give an apparent lower F3 point. It requires a lot of power though. It also causes additional resonances due to the slots.
The rolloff at 40hz is a function of three things. One is the "loading" effect on the woofer in the ripole. Two is the position in the room. Three is the baffle size. The Dipole12 itself has an F3 at about 30hz and is only 8dB down at 20hz. This requires a VERY large open baffle to get this though. The baffle also has to be placed appropriately in the room to avoid cancellation from the back wave reflecting off the wall behind and coming back out of phase with the front wave.
If you were to use the Dipole12 in a standard flat open baffle you will likely get better results. A U-baffle you would give even more distance between front and back wave, increasing the efficiency.
Kyron Audio achieves 32hz in the Kronos:
http://aespeakers.com/kronos-kyron-audi ... e-woofers/The Lotus Group Granada achieves 25Hz:
http://aespeakers.com/the-lotus-group-g ... dipole12s/Both use 2x Dipole12, but have some processing to do this.
Additionally, open baffles, u-baffles, etc, typically all benefit from some EQ to correct the low end response.
The best option is to model the U baffle with something like ABC Dipole to know what to expect.
http://www.musicanddesign.com/A_B_C_Dipole.htmlPost Link:
http://aespeakers.com/forums/topic/ae-d ... post-37900