Detailed analysis of the composition of dynamic speakers
The loudspeaker is a transducer device that converts electrical signals into acoustic signals, and the performance of the loudspeaker has a great influence on the sound quality. The loudspeaker is the weakest part in the audio equipment, but it is the most important part for the sound effect. There are many types of loudspeakers, and their prices vary widely. Audio electrical energy, through electromagnetic, piezoelectric or electrostatic effects, causes its cone or diaphragm to vibrate and resonate (resonate) with the surrounding air to produce sound.
Low-grade plastic loudspeakers have no sound quality because of their thin cabinets and cannot overcome resonance (there are also some well-designed plastic loudspeakers that are far better than inferior wooden loudspeakers); wooden loudspeakers reduce the sound dyeing caused by cabinet resonance. Sound quality is generally better than plastic loudspeakers.
Usually multimedia loudspeakers are dual-unit two-way design, a smaller loudspeaker is responsible for the output of the mid-high, while the other larger loudspeaker is responsible for the output of the mid-bass.
The material of these two loudspeakers should be considered when selecting a loudspeaker: the tweeter of a multimedia active loudspeaker is now dominated by a soft dome (in addition to a titanium film dome for an analog sound source, etc.), which can reduce high-frequency noise when combined with a digital sound source. The bluntness of the signal gives people an ethereal and delicate feeling. Multimedia loudspeakers are mostly made of soft domes such as better quality silk film and lower cost PV film.
The woofer determines the sound characteristics of the loudspeaker, and it is relatively important to choose. The most common types are the following: paper cones, glued paper cones, paper-based wool cones, and pressed cones.
The composition of the loudspeaker
T iron (YOKE), also known as iron core, plays the role of magnetic conduction together with Washer, and the two form a uniform magnetic circuit and magnetic air gap. Currently in production there are one body and two bodies. The difference between these two:
1) The integrated T iron has high magnetic permeability and small magnetic field distortion. The disadvantage is that the cost is high
2) The two-body T iron often has a large magnetic resistance on the riveted contact surface between the pole center and the lower splint, which affects the magnetic induction density of the loudspeaker to some extent. The magnetic conduction effect is not as good as the integrated one, and the magnetic field distortion is also large. is lower cost. In actual use, the two-body T iron has both T-type and U-type. T iron is used on external magnetic loudspeakers, and U iron is used on internal magnetic loudspeakers.
1) The magnet is a ring sintered with hard magnetic materials. Its function is to generate a constant magnetic field with a certain magnetic induction density in the magnetic air gap of the loudspeaker. At present, most loudspeakers use strontium or barium ferrite magnets. Ferrite has the characteristics of high coercivity, oxidation resistance, corrosion resistance, and light weight. But the disadvantage is that the remanence is low, the temperature coefficient is large, and it is fragile. Now the new type of loudspeaker starts from reducing the volume and improving the technical indicators of the loudspeaker. It often uses AlNiCo or NdFeB with better performance. The probability of using AlNiCo is the lowest, because cobalt is a rare metal. It is difficult to obtain, but NdFeB is used a lot, and most speakers are now using it. Its disadvantages are low temperature resistance, low coercive force, and high cost, so speakers with high power are generally not selected.
2) Classification of ferrite: Y20, Y25, Y30, Y35, Y35H, Y40
NdFeB grade classification: N32, N35, N38, N38H, N40
Normally used magnet grades are as follows:
Y25/Y30, N35/N38, auxiliary magnetic use Y20/Y25
3) Evaluate several performance parameters of the magnet
#Br (remanence), unit is Gauss (GUASS)
#Hcj (coercive force) in kiloamperes/square meter (KA/m2)
#(BH)m (maximum magnetic energy product), the unit is kilojoules/meter (KJ/m)
Huasi is usually called the upper splint or iron sheet. In the magnetic circuit, both Washer and T iron play the role of magnetic conduction. It can concentrate the N pole and S pole of the magnet to the gap through the ring, so that the gap generates a strong magnetic field, and the volume of the voice coil is located in the middle of the gap, so the inner diameter and thickness of the washer are very important. The riveting between the basin frame and the washer is usually fixed with rivets first and then reinforced with special washer glue. On the one hand, it is to prevent the speaker structure from loosening and the screws to fall off under the vibration of the high-power speaker, and at the same time to ensure the speaker When working, there is no airflow flowing out from the gap between the washer and the magnet, which affects the working accuracy of the speaker. Large speakers also use locking screws. When developing the washers, the thickness of the washers is also particular depending on the application.
In a large loudspeaker, the washer must be thick enough, which makes the magnetic circuit strong and powerful. The loudspeaker with strong vibration heats up quickly, has a high temperature, a wide magnetic field width, fast heat dissipation, and fast decay of frequency number characteristics. The advantage can also reduce F0. Good for bass. On the contrary, the washer is thin, the gap magnetic flux is sharp, and the heat dissipation is slow, so it is used with the type with small treble amplitude.