The lower limit of the low frequency of the speaker is closely related to two factors, one is the resonant frequency of the speaker unit, and the other is the volume of the cabinet. Without boxing, the low-frequency resonant frequency of the woofer is generally considered to be the lower limit of the effective frequency response of the unit. The larger the aperture of the unit, the lower the resonant frequency, so the use of a large speaker will help restore lower low frequencies.
In addition, a larger diaphragm area can push more air under the premise of the same amplitude, and it is easy to obtain more low-frequency volume. After the horn unit is boxed, its resonance frequency will rise due to the stiffness of the air in the box. The larger the box volume, the smaller the effect of air on the unit, and the smaller the rise in resonance frequency, which is beneficial to obtain a lower Comprehensive low frequency response. Large speakers on the one hand facilitate the use of large-caliber woofers, on the other hand they have a larger cabinet volume, so low frequencies are usually better.