Discussion on active frequency division and passive frequency division speakers

Discussion on active frequency division and passive frequency division speakers

There are many ways to classify speakers. Today we will discuss active crossover and passive crossover speakers.

Passive frequency division, also known as power frequency division, uses the LC filter in the speaker to divide the frequency of the audio signal. The frequency divider network is set between the power amplifier and the speaker. The power audio signal output by the power amplifier passes through the ratio filter, divides the frequency of the signal and distributes it to each speaker according to different frequency bands. The passive frequency division method is simple, low cost, and easy to use. The disadvantage is that the frequency division network needs to flow a large current, so a larger volume of inductor is used, and because its parameters are directly related to the impedance of the speaker, and the impedance of the speaker is also It is a function of frequency, and it deviates greatly from the nominal value, so the error is large and the adjustment is difficult.

Just imagine: the energy of the power amplifier is sent to the voice coil of the midrange/bass unit through the thin and long inductance coil, the energy loss is very large, especially for the bass, a considerable part of the energy of the power amplifier is converted into heat through the inductor and consumed . We usually say that the speaker is difficult to push and the dynamics are not good. In addition to the sensitivity of the speaker unit itself, the energy loss of the passive crossover is the main reason.

Due to the use of inductance and capacitor devices, it not only affects the efficiency of the system, but also produces phase distortion while completing the frequency division, which is very unfavorable for high-fidelity audio restoration. Phase distortion directly affects the transient state, sound field and positioning of the restored sound , as long as it is a passive crossover system, these situations cannot be avoided.

In order to solve the problems mentioned above, the active frequency division system came into being. The so-called active frequency division (also called external frequency division) means that there is no frequency divider between the internal units of the speaker, but an electronic frequency division outside the speaker. The device divides the electrical signal of the full audio frequency into two high and low frequency bands or three frequency bands of high, medium and low, and then sends the electrical signals of the divided frequency bands to their own independent amplifiers, and then the independent amplifiers drive the corresponding speaker units. Compared with passive frequency crossover, active frequency crossover can achieve lower distortion and less loss.