timc skrev:
men 15" spiller i motfase ikke sant (push-pull)?
Eller er det push-push, altså bipolar?
Siterer fra Audio Circle:
Dipole bass also seemed to cause some challenges, both because this only allows for effective in room performance with a very limited extension of the bass region, and because it does give any considerable output power at the lowest frequencies. The solution to this was simply to combine closed cabinet and dipole. This is done by putting two woofers at the back of the enclosure and two woofers at the front of the enclosure. The two groups (rear and front) are then measured in room both in phase, out of phase and at a variety of different phase angles between 0 and 180 degrees in order to get a picture of the phase relations that gives the best 3D dispersion effect in the bass region at each different tiny frequency point. By adjusting the phase response relation between the two groups one can pull out the best compromise between closed cabinet, dipole, desired SPL and so on. The concept gets even more complicated as the adjustment can be done both in phase and delay, and it can be done to both the front and rear pair of woofers. The sum of the four woofers in the end is then corrected to get the best possible impulse and frequency response in room.
These two systems seemed to work really fine by them self, but combined there must be some kind of cross over point. This is the point where the system crosses over from limited dispersion monopole, to either dipole, bipolar or something in between. To solve this, the front firing subwoofers are placed inside the midbass dispersion lenses, and the rear woofers are added smoothly in where the room dimension allows them to without giving an unwanted contribution to the sound image.