speaker
speakers are divided into built-in speakers and external speakers, and external speakers are generally referred to as speakers. The built-in speaker means that the MP4 player has a built-in speaker, so that users can listen to the sound of the MP4 player not only through the earphone jack but also through the built-in speaker. An MP4 player with built-in speakers can eliminate the need for external speakers, and it can also avoid the inconvenience caused by wearing headphones for a long time.
The physical meaning of the commonly used parameters of the loudspeaker:
The parameters of the loudspeaker refer to the specific various performance parameter values of the loudspeaker tested by a dedicated loudspeaker test system. Its commonly used
The parameters mainly include: Z, Fo, η0,
SPL, Qts, Qms, Qes, Vas, Mms, Cms, Sd, BL, Xmax, Gap gauss. The following are the physical meanings of these parameters.
1 Z: refers to the resistance value of the speaker, including: rated impedance and DC impedance. (unit: ohm/ohm), usually refers to the rated impedance.
Rated impedance Z of the speaker: It is the minimum impedance modulus value after the first maximum value of the impedance curve, that is, the impedance value corresponding to point B in Figure 1.
It is the basis for calculating the electrical power of the speaker.
DC impedance DCR: refers to the impedance value measured by passing a DC signal when the voice coil coil is stationary.
What we usually call 4 ohms or 8 ohms refers to the rated impedance.
2 Fo (lowest resonance frequency) refers to the frequency corresponding to the first maximum value of the speaker impedance curve.
Unit: Hertz (Hz).
The impedance curve of the loudspeaker is the loudspeaker impedance modulus measured by the constant current method or the constant voltage method under normal working conditions.
The changing curve.
3 η0 (the efficiency of the speaker): refers to the ratio of the output sound power of the speaker to the input electric power.
4 SPL (Sound Pressure Level): Refers to the horn at a point 1m away from the horn on the reference axis when a voltage with a rated impedance of 1W electric power is applied
Sound pressure generated. Unit: decibel (dB).
5 Qts: The total quality factor value of the speaker.
6 Qms: The mechanical quality factor value of the speaker.
7 Qes: The electrical quality factor value of the speaker.
8 Vas (effective volume of the horn): refers to when the sound of the air enclosed in a rigid container is equal to the sound of the speaker unit
The volume of . Unit: liter (L).
9 Mms (vibration mass): refers to the total mass of the components that participate in the vibration of the speaker during the movement, including the drum paper part, the voice coil, and the elastic wave.
and the air quality involved in vibration, etc. Unit: grams (gram).
10 Cms (Lishun): refers to the flexibility of the supporting parts of the speaker vibration system. The larger the value, the softer the entire vibration system of the speaker.
bit: millimeter/newton (mm/N).
11 Sd (vibration area): refers to the effective vibration area of the drum paper/diaphragm during the vibration of the speaker. Unit: square meter (m2).
12 BL (magnetic force): the product of the gap magnetic induction intensity and the effective voice coil line length. Unit: (T*M).
13 Xmax: The linear travel of the voice coil during vibration. Unit: millimeter (mm).
14 Gap Gauss: Gap magnetic induction intensity value. Unit: Tesla (Tesla).
