What is the skin effect
First of all, we need to know what the skin effect is. The following definition is excerpted from Baidu Encyclopedia.
When calculating the resistance and inductance of a wire, it is assumed that the current is uniformly distributed over its cross-section. Strictly speaking, this assumption only holds when the current rate of change (di/dt) in the conductor is zero. Another way of saying it is that the current density is guaranteed to be uniform when the wire is passed through direct current (dc). Or the current rate of change is small, and the current distribution can still be considered uniform. This statement is still valid for thin wires operating at low frequencies.
But in high-frequency circuits, the current rate of change is very large, and the state of uneven distribution is very serious. The magnetic field generated by the high-frequency current in the wire induces the largest electromotive force in the central area of the wire. Since the induced electromotive force induces an induced current in a closed circuit, the induced current is greatest at the center of the wire. Because the induced current is always decreasing in the direction of the original current, it forces the current to be limited to those close to the outer surface of the wire. The main reason for the effect is that the changing electromagnetic field produces a vortex electric field inside the conductor, which cancels out the original current.
Although the definition is very precise, it is a bit difficult to understand. In short, the
skin effect hardly exists in the DC power supply. We can completely ignore it. Only in the case of alternating current, the skin effect will be more obvious. influences.
The audio signal is a constantly changing alternating current, so it seems that the
skin effect cannot be ignored?
In fact, the lowest frequency at which the skin effect really affects is 1MHz, and the only cases where the skin effect really needs to be paid attention to are high-speed PCB circuit design or ultra-high voltage power transmission.
The frequency range of audio signals is only 20~20KHz, let alone high-speed circuits, even the cheapest single-chip microcomputer runs at a speed higher than this 20KHz, so from the perspective of frequency, the
skin effect does not need to be considered at all.
Moreover, the voltage of the audio output signal is usually less than 1V, and the current is only a few hundred milliamps, which is not even a fraction compared with high-voltage transmission. Such a small voltage and current do not need to consider the 'skin effect' at all.
Therefore, in the selection process of cables, we can ignore the existence of 'skin effect', as long as qualified audio cables can provide excellent electrical performance and obtain excellent sound effects.