- What is the double voice coil
Double voice coil. It uses two unconnected wires wrapped around the same circle of the skeleton, and their endpoints are independent of each other. In general, these two wires have the same number of turns and lengths, therefore they have the same characteristics.
The specific winding method is to wind one coil on the bobbin first and then wind the second voice coil on the first one. Use two lead-out wires respectively (four lead-out wires in total), and the two sets of lead-out wires are usually distributed at 180°. The schematic diagram and cross-sectional view of the dual voice coil are shown in the following figures.
The advantages of dual voice coils. The most basic benefit of the dual voice coil is the flexibility of the use of the voice coil impedance value. This dual voice coil speaker can be connected in series, parallel, and directly. For example, a 4Ω dual voice coil speaker will be 8Ω when connected in series, and 2Ω when connected in parallel.
You can also connect the dual voice coils to the left and right channels of the amplifier, which is useful. If there are stereo amplifiers that cannot or are inconvenient to connect to mono, this method is very efficient. Four-channel amplifiers can also be connected as two channels for a subwoofer to use. If the low-frequency box in the home theater uses a dual voice coil, good results can be obtained.
Another dual voice coil. This voice coil uses a folded ring to connect each part, as shown in the picture above. For low-frequency input signals, the voice coil vibrates. For high-frequency input signals, the voice coil of the heavier part with more turns does not move, while the voice coil of the lighter part with fewer turns vibrates. The high-frequency impedance is reduced so that the two parts get a uniform response.
This method can be further developed. As shown in Figure (a) above, using two voice coils and diaphragms, and a folding ring is connected between the two voice coils, which is equivalent to a single voice coil and a single diaphragm at low frequencies. . At high frequencies, the small diaphragm is driven by the small voice coil. This system is equivalent to two separate speakers, so the frequency band is wider, as shown in (b) above.