As a key component of the magnetic circuit system, the speaker short circuit ring stretched copper directly affects high-frequency response characteristics, distortion control, and overall sound quality. Speaker short-circuit rings made of stretched copper are the mainstream choice due to their high conductivity, good ductility, and thermal stability. However, achieving efficient compatibility with the magnetic circuit requires a multi-dimensional approach involving material property optimization, structural design improvements, and process control.
The conductivity of the stretched copper is the core factor affecting compatibility. The short-circuit ring's function is to counteract changes in voice coil inductance through eddy current effects. If the copper material is not pure enough or contains impurities, it will lead to increased resistivity, decreased eddy current response speed, and an inability to balance magnetic field fluctuations in a timely manner. Therefore, high-purity oxygen-free copper (OFC) or low-oxygen copper must be selected, and processes such as continuous casting and cold rolling should be used to reduce grain boundary defects, ensuring uniform current flow within the copper material and forming a stable reverse magnetic field. Furthermore, the grain structure of the copper material also needs optimization. Nanocrystalline copper, by refining the grains and reducing eddy current losses, can significantly improve high-frequency response speed, making the magnetic field interaction between the short-circuit ring and the magnetic circuit more precise.
The matching of the short-circuit ring's geometry with the magnetic circuit structure is another crucial factor. Traditional short-circuit rings are mostly simple circular ring structures, but modern loudspeaker magnetic circuits often employ T-shaped symmetrical magnetic circuits or radial magnetic circuit designs, requiring short-circuit rings with more complex contours to conform to the magnetic pole shapes. For example, designing a stepped short-circuit ring on the top of the T-shaped iron can increase the eddy current path length and enhance the magnetic field cancellation effect; or using an irregular cross-section design can ensure a uniform gap between the short-circuit ring and the magnetic poles, avoiding distortion caused by localized magnetic field concentration. Simultaneously, the thickness of the short-circuit ring must be compatible with the skin effect of the copper material. The distribution depth of high-frequency current on the conductor surface decreases with increasing frequency. If the copper ring is too thin, the skin effect will lead to a sharp reduction in the effective conductive area, affecting eddy current generation efficiency; if it is too thick, it may increase the magnetic circuit gap, weakening the magnetic field strength. Generally, an appropriate thickness must be selected based on the operating frequency band to ensure sufficient conductive layer thickness is maintained at high frequencies.
The assembly process of the short-circuit ring and the magnetic circuit directly affects long-term stability. The stretched copper short-circuit ring for speakers is relatively soft. Uneven stress during assembly can easily lead to deformation or excessive gaps between the ring and the magnetic poles, disrupting magnetic field uniformity. Therefore, precision mold positioning is required to ensure concentricity between the short-circuit ring and the magnetic poles, and residual stress should be reduced through heat-shrinking processes or low-temperature assembly. Furthermore, the contact surfaces between the copper and the magnetic poles require surface treatment, such as silver plating or sandblasting, to reduce contact resistance and prevent eddy current path obstruction due to oxidation or contamination. For high-frequency applications, thermally conductive adhesive can be filled between the short-circuit ring and the magnetic poles to enhance mechanical connection, improve heat dissipation efficiency, and prevent copper performance degradation caused by high temperatures.
Magnetic circuit design needs to be optimized in conjunction with the characteristics of the short-circuit ring. For example, a nano-oxide layer on top of the magnetic poles can reduce hysteresis loss and minimize interference from magnetic field fluctuations on the short-circuit ring; alternatively, a gradient copper-aluminum composite structure can be used, with a highly conductive inner layer of copper responsible for eddy current generation and a lightweight outer layer of aluminum reducing overall mass and balancing conductivity and density. Such composite structures require simulation analysis to determine the proportions of each layer to ensure stable magnetic field cancellation at high frequencies. Meanwhile, the magnetic saturation design of the magnetic circuit must also consider the influence of the short-circuit ring. This can be achieved by locally trimming the magnetic poles or adding auxiliary magnets to saturate the magnetic field in the short-circuit ring region, reducing nonlinear distortion.
Thermal management of the short-circuit ring is crucial for ensuring long-term performance. When the speaker is operating, the voice coil heats up and is conducted to the short-circuit ring through the magnetic field. If the copper material has poor heat dissipation, it may lead to increased resistivity and decreased eddy current efficiency. Therefore, a heat dissipation structure needs to be designed inside the short-circuit ring, such as embedding ceramic heat sinks or using microchannel cooling technology to enhance heat conduction. Furthermore, the copper surface can be coated with highly thermally conductive materials such as graphene to further improve heat dissipation efficiency, ensuring that the short-circuit ring maintains stable electromagnetic performance even under continuous high-power operation.
Optimizing the fit between the short-circuit ring and the magnetic circuit requires a comprehensive approach encompassing materials, structure, manufacturing process, magnetic circuit design, and thermal management. By selecting high-purity, fine-grained speaker short circuit ring stretched copper material, designing a short circuit ring structure that adapts to the shape of the magnetic circuit, and employing precision assembly and surface treatment processes, along with synergistic optimization of the magnetic circuit design and heat dissipation scheme, the electromagnetic interaction efficiency between the short circuit ring and the magnetic circuit can be significantly improved, high-frequency distortion can be reduced, the frequency response range can be expanded, and ultimately, a comprehensive improvement in the speaker's sound quality and performance can be achieved.
