Understanding of loudspeaker materials--iron sheet

2022 09/28

The iron sheet of PA loudspeaker is also called iron plate, Weiss or upper plate. In the magnetic circuit, the iron sheet and the iron core play the role of magnetic conductivity. They can concentrate the N pole and S pole of the magnet into the gap through the circuit, so that the gap generates a strong magnetic field. The coil width of the voice coil is right in the middle of the gap, so the inner diameter and thickness of the iron sheet are very important. Generally speaking, the loudspeaker, iron sheet and the iron frame with high power or high impact force during vibration are riveted and fixed at their joints and then reinforced with glue to prevent the loudspeaker from being squeezed out of the gap at the riveted joint during operation, resulting in poor airflow. i.e. air leakage. If the magnetic circuit is heavy, the horn speaker is generally in the form of iron self-tapping screws. Or riveted locking screws that can withstand a lot of impact and can withstand all destructive testing. There are 4~6 floating bumps or screw holes for riveting.

Plastic and cast aluminum frames cannot be riveted. Generally, they are locked with screws, and the joints are also reinforced with glue. After the screw is locked, glue should be applied to the connection between the screw head and the bottom of the frame to prevent the SPK from loosening and falling off due to frequent vibration. Part of the plastic frame is formed in the iron sheet during injection molding, which can reduce the cost. Many small-sized SPK iron sheets are fixed on the iron sheet frame by internal riveting, forming a whole with the frame body, and no riveting is required. Therefore, the inner riveting type should also have an accurate hole diameter. The weakness of the inner riveting type is that it cannot withstand the damage test and too much impact robbery. Only applicable to speakers with magnet outer diameter below 45mm. Advantages: The speaker is convenient and time-saving, and the cost of the speaker can be appropriately reduced. The material of the iron sheet is SPHC (S: steel P: sheet steel H: hot forging C: hardness judgment), and the surface is generally multi-color electroplating or galvanized.

When designing and selecting iron sheets of horn speakers, design or select iron sheets according to the use of SPK and the performance required by customers. The inner diameter of the iron sheet is the periphery of the gap in the magnetic air path of the speaker, and the coil vibrates in the gap, so the thickness and inner diameter of the iron sheet are very important. Usually speakers. Strong speakers have the advantages of fast heating, high temperature, wide magnetic field amplitude, fast heat dissipation, and fast attenuation of frequency characteristics, and can also reduce bass resonance to benefit bass. On the contrary, when the iron sheet is thinner, the gap magnetic beam is sharp and the heat dissipation is slower, which is suitable for the type with smaller treble amplitude. But it must be understood that the iron sheet is a kind of water pipe. When the magnetic force reaches a certain level, the magnetic conductivity of the iron sheet will be saturated. Even if the magnet is enlarged and the magnetic force is strengthened, the magnetic conductivity of the iron sheet will be strengthened.