The speaker resonant frequency (Fs) refers to the frequency corresponding to the first main peak in its impedance curve where the impedance modulus rises with frequency. This frequency point is represented as the maximum impedance on the speaker's impedance curve, usually recorded as Fo or Fs.
Factors affecting speaker resonant frequency
The speaker's resonant frequency is determined by the mass and force compliance of its vibration system. Specifically, the speaker's resonant frequency Fs is determined by the mass Mms and force compliance Cms of its vibration system, and the calculation formula is:
Fs=2π1MK
Where K is the stiffness of the system and M is the mass of the system.
Method for measuring speaker resonant frequency
The speaker's resonant frequency can be obtained by measuring its impedance curve. The impedance curve changes with the frequency, and usually an impedance maximum value appears in the low frequency band. The frequency corresponding to this maximum value is the speaker's resonant frequency Fs.
The impact of speaker resonant frequency on performance
The speaker's resonant frequency is not the lower the better, nor the higher the better, but needs to be selected according to the specific application scenario. For example, in a closed box system, if the resonant frequency is too low, it may cause the speaker's ability to withstand power to decrease, distortion to increase, and require a larger box volume. For home speaker systems, a slightly lower sensitivity is not a major problem. Speakers of different calibers also have different resonant frequency ranges. For example, a 131mm (5in) speaker has a resonant frequency of about 35-40Hz, while a speaker over 200mm (8in) has a resonant frequency of about 20-30Hz.