The size and type of magnet and the details of the magnetic circuit vary according to the design objectives. For example, the shape of the magnetic pole piece will affect the magnetic interaction between the voice coil and the magnetic field, which is sometimes used to modify the driver's behavior. The short-circuit ring or Faraday ring can be used as a thin copper cap installed on the tip of the magnetic pole or a heavy ring located in the cavity of the magnetic pole. The advantage of this complexity is that it reduces high-frequency impedance, provides extended treble output, reduces harmonic distortion, and reduces inductance modulation, which is usually accompanied by a large voice coil offset. On the other hand, the copper cover needs a wider voice coil gap to increase the magnetic resistance; This reduces the available magnetic flux and requires a larger magnet to achieve the same performance.

As early as the 1950s, electromagnets were often used in instrument amplifier cabinets; The use of tube amplifiers can save economic costs because the field coil can and usually can play a dual role as a power choke. Few manufacturers still produce electric loudspeakers with electric field coils, which is common in early design. Aluminum nickel-cobalt alloy is an alloy of aluminum, nickel, and cobalt, which became very popular after World War II because it eliminated the problem of magnetic field coil driver.

It was not until around 1980 that alnico was fully used, although the alnico magnet was partially demagnetized due to accidental popping or clicking caused by loose connections, especially when used with high-power amplifiers. After 1980, most drive manufacturers switched from aluminum nickel cobalt to ferrite magnets, which are made of a mixture of ceramic clay and fine particles of barium or strontium ferrite.

Although the energy per kilogram of these ceramic magnets is lower than that of alnico, their cost is greatly reduced, which enables designers to use larger but more economical magnets to achieve a given performance. Due to the increase in transportation costs and the demand for smaller and lighter equipment, there is a trend to use more compact rare earth magnets made of materials such as neodymium and samarium cobalt. This creates more possibilities for manufacturing loud speakers with higher requirements.