gbadaut a écrit:androuski a écrit:bonjour gbadaut,
tu sembles sceptique sur l'explication liée au baffle step, pourquoi ?
Le baffle ne modifie pas de la même manière la réponse en fréquence à 0° (dans l'axe), qu'à 15°, 30°, 60°, etc (hors axe). S'il crée un creux uniquement dans l'axe, et pas hors axe, alors en linéarisant la réponse dans l'axe, on crée une vilaine bosse hors axe.
Oui, c'est le probleme de la correction de baffle step. Tu peux corriger la reponse dans l'axe, mais du coup ta reponse hors axe n'est plus bonne (ou tout au moins differente).
Theoriquement, tu n'as plus aucun effet de baffle step a partir de 90° hors axe.
D'apres Linkwitz : http://www.linkwitzlab.com/diffraction.htm
While I try to minimize visible diffraction ripples in the frequency response for good measure, I have no evidence that even strong diffraction effects have significant audible consequences, except for the transition region, the "baffle step", where radiation goes from omni-directional to forward firing. Note that there is no baffle step at 90 degrees off-axis, and boosting low frequencies for a flat on-axis response will add to the downward sloping trend of the frequency response off-axis. This causes a spectral imbalance of the reverberant sound field in the room and is a major reason why I prefer dipole radiators.Diffraction effects are always spatially localized and a slight shift in listening position will change their magnitude. While the "baffle step" cannot be avoided, the additional higher frequency ripples can be easily reduced to a magnitude that is much smaller than the first arriving direct sound, by simply optimizing the proportions of a rectangular baffle. The absolute width of a cabinet is not the critical parameter that many people think it is. Much is hypothesized, little is proven and much is overrated when it comes to diffraction.