Understanding of Speaker Material -- Iron Sheet

2022 11/28

Iron sheet is also called iron plate, washer or T-yoke. In the magnetic circuit, the iron sheet and iron core play the role of magnetic conductivity. They can concentrate the N and S poles of the magnet into the gap through the circuit, so that the gap can generate a strong magnetic field. The coil width of the voice coil is just in the middle of the gap, so the inner diameter and thickness of the iron sheet are very important. Generally speaking, horn speakers, iron sheets and iron frames with large power or impact force during vibration shall be riveted and fixed at their joints and then reinforced with glue to prevent speakers from extruding from the gap at the riveting joint during operation, which will cause poor air flow sound, i.e. air leakage. If the magnetic circuit is heavy, the form of iron sheet tapping screw is generally adopted. Or the riveted locking screws can withstand great impact force and all destructive tests. There are 4-6 floating bumps or screw holes for riveting.

Plastic frame and cast aluminum frame cannot be riveted. Generally, they are locked with screws, and the joints are also reinforced with glue. After the screw is locked, the connection between the screw head and the bottom of the frame shall be coated with glue to prevent SPK from loosening and falling off due to frequent vibration. Some plastic frames are molded in iron sheets during injection molding, which can reduce the cost. Many small size SPK iron sheets are fixed on the iron frame by internal riveting, forming an integral part with the frame body. There is no need for riveting. The joints need to be reinforced around to prevent falling off due to poor riveting. Therefore, the inner riveting type should also have an accurate middle hole diameter. The weakness of the internal riveting type is that it can not withstand damage tests and too much impact. It is only applicable to loudspeakers with magnet outside diameter less than 45mm. Advantages: The PA loudspeaker is convenient and time-saving, and the cost of the loudspeaker can be appropriately reduced. The iron sheet is made of SPHC (S: steel P: plate steel H: holding hot forging C: hardness judgment), and the surface is generally multicolor electroplating or zinc plating.

When designing and selecting iron sheet, the iron sheet shall be designed or selected according to the use of SPK and the performance required by customers. The inner diameter of the iron sheet is the periphery of the magnetic air path gap of the horn speaker. The coil vibrates in the gap, so the thickness and inner diameter of the iron sheet are very important. Generally speaking, it is a horn loudspeaker. Strong speakers have the advantages of fast temperature rise, high temperature, wide magnetic field amplitude, fast heat dissipation, fast attenuation of frequency characteristics, and can also reduce bass resonance in favor of bass. On the contrary, when the iron sheet is thin, the gap magnetic beam is sharp and the heat dissipation is slow, which is suitable for the type with small high sound amplitude. However, it must be understood that the iron sheet is a kind of water pipe. When the magnetic force reaches the degree, the magnetic energy of the iron sheet will be saturated. Even if the magnet is increased and the magnetic force is strengthened, the magnetic energy of the iron sheet will also be strengthened.