Alignment (continuation)
For this purpose, the known forth order filter responses are used to identify the terms of a theoretical response of the speaker under the terms of the response of the filter. Thus, we can determine the "typical responces" of a vented enclosure to quickly determine a geometry of an enclosure depending on the speaker parameters.
It is usually considered that the quality factor of the speaker is
. For this case, some classical alignments are given below (additional values are available in Beranek [1])
Remarque : Remark
Some values that are used for the dimensioning of vented enclosures.
is the resonance frequency of the loudspeaker,
is the 3 dB cutoff frequency of the loudspeaker, Vb is a volume of a loudspeaker, Vas is loudspeaker parameter associated with its mechanical flexibility , Qts is total quality factor of a loudspeaker, fb is resonance frequency of a Helmholtz resonator.
Alignement |
|
|
|
|
Sub-Butterworth | 1.7748 | 0.4028 | 0.3010 | 1 |
Butterworth | 1 | 0.9422 | 0.405 | 1 |
Chebyshev (0.01 dB ripple) | 0.8143 | 1.5511 | 0.4572 | 0.8838 |
Chebyshev (0.25 dB ripple) | 0.6374 | 2.9747 | 0.5553 | 0.7259 |
