The parameters of loudspeaker refer to the specific performance parameters of loudspeaker measured by the loudspeaker test system. The commonly used parameters include: Z, Fo, 0, SPL, Qts, Qms, Qes, Vas, Mms, Cms, Sd, BL, Xmax, Gapgauss. The following are the physical meanings of these parameters.
Z:
It refers to the impedance of loudspeaker, including: rated inductance and dc resistance. (unit: ohm /ohm), usually referred to as rated impedance.
Rated impedance Z of loudspeaker: the minimum impedance modulus following the first maximum value of the impedance curve, namely the impedance value corresponding to point B in FIG. 1.
Speaker It is the reference for calculating the electric power of the loudspeaker.
Dc resistance DCR: the measured impedance of a dc signal when the voice coil is at rest. What we usually call 4 or 8 ohms is rated impedance. (ACR ac impedance: resistance measured under dynamic conditions of the voice coil) Fo(lowest resonant frequency) : refers to the frequency corresponding to the first maximum value of the speaker impedance curve. Unit: the impedance curve of Hertz (Hz) loudspeaker is the curve of speaker impedance modulus measured by constant current or constant pressure under normal working conditions.
Power 0(loudspeaker efficiency) : refers to the ratio of loudspeaker output power to input power.
SPL(sound pressure level) : refers to the voltage when the horn is connected to the electric power of rated impedance of 1W. At a point 1m from the horn on the reference axis. Unit: decibel (dB) produced sound pressure.
Qts: total quality factor of the speaker.
Qms: mechanical quality factor of loudspeaker.
Qes: the electrical quality of the speaker.
Vas(effective volume of loudspeaker) : the volume of sound of air enclosed in a rigid container equal to that of the speaker unit.
Mms(vibration mass) : it refers to the mass sum of all parts involved in vibration during the moving process of loudspeaker, including the paper parts, sound coil and elastic wave. Unit: gram. And air quality involved in vibration, etc.
Cms(force compliance) : refers to the flexibility of the supporting parts of the speaker vibration system. The larger the value, the softer the whole vibration system of the speaker. Unit: mm/ Newton (mm/N) Sd(vibration area) : refers to the vibration area of the paper/diaphragm during the vibration of the speaker. Unit: square meter (m2).
BL(magnetic force) : the product of gap magnetic induction intensity and voice coil length. Unit :(T*M).
Xmax: linear motion of the voice coil during vibration. Unit: mm (mm).
GapGauss: clearance magnetic induction intensity value. Setting: Tesla (tsla).
Troubleshooting Open fault: the resistance between the two pins is large, which is silent in the circuit and silent in the speaker.
Paper cone rupture fault: direct inspection can find this fault, this fault of the speaker should be replaced.
Poor sound quality fault: this is the soft fault of the speaker, usually can not find what fault features, but the sound is not pleasant, this fault speaker to replace the processing.
In the case of amateur condition, only audiometry and table test can be used to detect the loudspeaker.
Audiometry is to connect the loudspeaker to the output end of the power amplifier.
Using tables to detect speakers is also rough.
Dc resistance measurement: the dc resistance between the two pins of the speaker is measured with R*1, which should be slightly smaller than the impedance of the speaker under normal conditions. For example, 8 ohms of the speaker measured a normal resistance of about 7 ohms.
Listen to the click: when measuring dc resistance, unpin a watch bar intermittently. You should be able to hear the click of the speaker. The bigger the click, the better.
Visual inspection: check whether the speaker is cracked or not.
Check the magnetism: try the magnetism of the magnet with a screwdriver. The stronger the magnetism, the better.