Speaker frequency range and frequency response

Frequency range refers to the range between the lowest effective playback frequency and the highest effective playback frequency that the audio system can play back; frequency response refers to the phenomenon that when an audio signal with a constant voltage output is connected to the system, the sound pressure generated by the speaker increases or attenuates with the change of frequency, and the phase changes with the frequency. This change relationship (change amount) between sound pressure and phase and frequency is called frequency response, and the unit is decibel (dB).

The frequency characteristics of the sound system are often described by a frequency response curve with power represented by the ordinate of the decibel scale and frequency represented by the abscissa of the logarithmic scale. When the sound power is 3dB lower than the normal power, this power point is called the high-frequency cutoff point and low-frequency cutoff point of the frequency response. The frequency between the high-frequency cutoff point and the low-frequency cutoff point is the frequency response of the device; the curves of sound pressure and phase lag changing with frequency are called "amplitude-frequency characteristics" and "phase-frequency characteristics" respectively, collectively known as "frequency characteristics". This is an important indicator for examining the performance of the speaker. It has a direct relationship with the performance and price of the speaker. The smaller the decibel value, the flatter the frequency response curve of the speaker, the smaller the distortion, and the higher the performance. For example: the frequency response of a speaker is 60Hz~18kHz +/- 3dB. These two concepts are sometimes not distinguished, and are called frequency response.

Theoretically, the frequency response of 20 to 20,000 Hz is sufficient. Although the sound below 20 Hz cannot be heard, other sensory organs of the human body can perceive it, that is, the so-called bass strength can be felt. Therefore, in order to perfectly play various musical instruments and language signals, the amplifier must achieve the goal of high fidelity to reproduce all harmonics of the tone. Therefore, the frequency band of the amplifier should be extended, with the lower limit extended to below 20 Hz and the upper limit increased to above 20,000 Hz. The method of expressing the frequency response of the signal source (radio head, recording seat and laser record player, etc.) is different. For example, the frequency response of FM stereo broadcasting stipulated by the European Broadcasting Union is +/-2dB at 40 to 15,000 Hz, and the minimum frequency response index stipulated by the International Electrotechnical Commission for recording seats is +/-2.5 +/-4.5dB (normal band) at 40 to 12,500 Hz. The actual indicators that can be achieved are significantly higher than this value. The upper limit of the frequency response of a CD player is 20,000 Hz, and the low-frequency end can be very low, only a few hertz. This is one of the reasons why the CD player has good playback quality.

However, the harmonic components that make up the sound are very complex. The wider the frequency range, the better the sound. However, this is basically correct for mid- and low-end multimedia speakers. In the frequency response labeling, we usually see the two terms "system frequency response" and "amplifier frequency response". It should be noted that the "system frequency response" is always smaller than the "amplifier frequency response", so it is meaningless to only mark the "amplifier frequency response". This is only used to deceive some uninformed consumers. Today's speaker manufacturers generally mark the system frequency response with too large a range. The difference in the high-frequency part is not much, but the marking at the bass end is extremely unrealistic. Foreign famous HiFi (high-fidelity) speakers are only marked at around 4 or 50Hz, while domestic wooden ordinary speakers worth two or three hundred yuan dare to mark this data. Therefore, I would like to advise everyone to listen to the low-frequency sound with your ears and do not easily believe the values ​​on the leaflets.

The music in the multimedia speakers is mainly MP3 or CD music, songs, game sound effects, background music, and human voice and environmental sound effects in movies. These sounds are mostly mid-high pitch, so when choosing multimedia speakers, you should pay more attention to its performance in the mid-high frequency band rather than the low frequency band. If you really want a cinema effect, then a powerful subwoofer can meet your needs.