12/05/2020-13:58:21
RE: UREI 813
Le principe du filtrage Time Align appliqué à l'UREI 813 est décrit dans l'article Fink, Dennis G.,"Time Offset and Crossover Design", 64th AES Convention, November 1979
http://www.aes.org/e-lib/online/download...df?ID=2802
"This paper examines some aspects of crossover design to correct for the time offset due to acoustic center displacement in coaxial transducers. The effect of this time delay on the magnitude response of first, second, and third order crossover networks is isolated from the entire crossover/transducer system. This is accomplished by examining the steady-state vector sum of outputs of a transfer function model of the low pass filter, high pass filter, and time delay portions of the entire system. Secondly, Bessell low pass and all pass networks are analyzed as approximations to the spatially related time delay. The magnitude and group delay characteristics of second and fourth order networks of these types are examined. Finally, the magnitude of response of crossovers employing time delay approximation networks are considered. The model used to evaluate the effect of time offset on crossovers is modified to include the compensation effects of the Bessell low pass and all pass networks."
![[Image: 20051203000223417416792975.jpg]](https://nsm09.casimages.com/img/2020/05/12//20051203000223417416792975.jpg)
![[Image: 20051202562823417416792971.jpg]](https://nsm09.casimages.com/img/2020/05/12//20051202562823417416792971.jpg)
On y explique l'utilisation d'une approximation de délai par filtre passe-tout approximé par filtre de Bessel complémentaire au filtre LP.
Cela correspond à l'utilisation d'un filtre d'ordre supérieur pour le grave par rapport au médium aiguë pour en compenser le retard.
http://www.aes.org/e-lib/online/download...df?ID=2802
"This paper examines some aspects of crossover design to correct for the time offset due to acoustic center displacement in coaxial transducers. The effect of this time delay on the magnitude response of first, second, and third order crossover networks is isolated from the entire crossover/transducer system. This is accomplished by examining the steady-state vector sum of outputs of a transfer function model of the low pass filter, high pass filter, and time delay portions of the entire system. Secondly, Bessell low pass and all pass networks are analyzed as approximations to the spatially related time delay. The magnitude and group delay characteristics of second and fourth order networks of these types are examined. Finally, the magnitude of response of crossovers employing time delay approximation networks are considered. The model used to evaluate the effect of time offset on crossovers is modified to include the compensation effects of the Bessell low pass and all pass networks."
On y explique l'utilisation d'une approximation de délai par filtre passe-tout approximé par filtre de Bessel complémentaire au filtre LP.
Cela correspond à l'utilisation d'un filtre d'ordre supérieur pour le grave par rapport au médium aiguë pour en compenser le retard.