Agnostic1er a écrit:Quote de l'ami Joseph:
« there is much bad folklore on the MTM configuration. People seem to forget that the basic reason for the MTM is to stabilize vertical polar response with respect to frequency. This is accomplished by the geometry alone, regardless of interdriver phase relationships, interdriver time delays due to lack of time alignment or crossover type.
Beyond that, you can examine via simulation, just about any crossover configuration you want. Different crossovers will yield different vertical polar patterns, but all patterns will stay centered on the central axis defined by the central driver, usually a tweeter. In-phase (even-order) crossovers will have off-axis nulls in the vertical direction. The depth of the null and its angular location are a function of the crossover frequency, the interdriver spacing and the crossover order. Laying MTMs on their side for center channels as you see in so many home theater systems can lead to poor horizontal coverage with in-phase crossovers.
One of the popular myths is that one must use an odd-order crossover to get the benefits of MTM. Nothing could be farther from the truth. The off-axis null with in-phase crossovers is of great benefit in reducing floor and ceiling reflections. Odd-order crossovers have a 90 deg inter-driver phase shift at crossover and generally do not produce off-axis nulls with time aligned drivers. They are more sensitive to lack of time alignment, however, and may in this case also produce off-axis nulls. »
And so what ?
si c'est pour parler d'analogique.
en quoi se permettre de dire qu'avec son pote,les événements sont existants bien avant LSPcad,
Thierry,Philippe,Alain...qui ne sont pas concernés.
sinon
(pour la démo,au crayon de papier avec une gomme...)
une démarche mathématique ?
