The topic seems to be concentraing in maximum low end extension, but how about sealed woofers in a three-way constructions & music use?
I've been playing with 12" ATC woofers in WinISD, and a nice way of applying EQ to extend low end seems to be this:
-Model a closed box with Q of 0,500 (with the ATC woofer this is just below 100 litres)
-Add a parametric boost at the FS, +3dB with Q=0,707
This seems to give an equivalent of the driver in box with Q of 0,707, and the end result is of course an equivalent of the textbook Linkwitz transform, but the parametric circuit would be way more flexible in fine tuning, IMO. Nail the frequency and tune the Q and boost to your liking & the room.
How about the back wave elimination of a sealed box, especially in controlling mirange reflections? Non-parallel walls help, of course, but how about building a small diffuser in the back wall?
http://www.tecnec.com/productImage/75X75/SPACEARRAY.JPG
The wave lenghts are obviously longer here, but a diffuser made out of larger, random surfaces combined with damping material could be cool.
I've been playing with 12" ATC woofers in WinISD, and a nice way of applying EQ to extend low end seems to be this:
-Model a closed box with Q of 0,500 (with the ATC woofer this is just below 100 litres)
-Add a parametric boost at the FS, +3dB with Q=0,707
This seems to give an equivalent of the driver in box with Q of 0,707, and the end result is of course an equivalent of the textbook Linkwitz transform, but the parametric circuit would be way more flexible in fine tuning, IMO. Nail the frequency and tune the Q and boost to your liking & the room.
How about the back wave elimination of a sealed box, especially in controlling mirange reflections? Non-parallel walls help, of course, but how about building a small diffuser in the back wall?
http://www.tecnec.com/productImage/75X75/SPACEARRAY.JPG
The wave lenghts are obviously longer here, but a diffuser made out of larger, random surfaces combined with damping material could be cool.
It's not equivalent to using a Linkwitz Transform at all. The LT transposes the poles and zeros to obtain a true perfect target response both in the amplitude and phase responses.
richie00boy said:
Then I must have done something wrong or I do not understand the LT concept correctly. 😕 As a comparison, I started with the same woofer in 0,707 alignment and simulated a LT for identical frequency response. Not surprisingly, group delay & phase matched perfectly.
I'll re-run this again and see how it went.
In any case, a parametric boost of 3dB seemed nice for my use. If I can get an f3 of around 50Hz and still have room for excursion, I'm happy.
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