Wheezing accompanying the operation of the audio system is a very common occurrence. It can occur both in the speakers themselves, and at any intermediate stage of signal processing. You can successfully fight it only by localizing the place of its origin.
Most often, the speakers wheeze not at all due to their own fault, but due to the fault of the amplifier. This is due to the fact that any amplifying elements - lamps, bipolar and field-effect transistors, including those included in microcircuits - operate in a linear mode only in a certain range of control voltages (for a bipolar transistor, control currents). To bring the amplifying element into linear mode, a technique called displacement is used - it is slightly opened. If the offset is too small, the amplifier is more economical, but with insufficient linearity. It is nonlinear distortions that are perceived by ear as wheezing. If it is too large, the amplifying element wastes energy, and the linearity still does not increase beyond a certain limit. Therefore, all amplifier pre-stages typically operate in so-called class A, that is, with an offset that provides maximum linearity, and the output stage in class AB, in which linearity is slightly reduced, which has a beneficial effect on economy. However, there are exceptions to this rule.
But if you apply too strong a signal to the input of the amplifier, then at least part of its stages will work in overload mode. This means that the control voltage at the inputs of the stages, even taking into account the offset, will go beyond the linear section. So, wheezing is inevitable. In general, the rule must be observed: in the entire chain of cascades, none should be overloaded. Sometimes, in order for this to be so, it is enough to reduce the gain of one of the stages and proportionally increase the gain of the next one.
In theory this sounds complicated, but in practice it is simple. You have connected a receiver or player to the amplifier. The volume on the amplifier was low, and not on the signal source - high. Thus, you have created all the conditions for the appearance of distortion in the output stage of the player or receiver. Decrease the volume on the player or receiver, and increase proportionally on the amplifier so that it becomes the same by ear. Distortion will be significantly reduced. But do not make the resulting sound level too high, otherwise this time the amplifier stages, and even the speakers, will be overloaded, and this is harmful for the hearing.
With an increased signal level at the amplifier output, distortion can occur directly in the speaker systems. Oscillating with too much amplitude, the diffuser will hit adjacent parts, hitting them. Restricting the diffuser travel is also perceived as wheezing. If the speaker does not have a so-called dust cap, dust particles trapped in the moving system can also cause wheezing. Then it must be blown out, and then, so that the situation does not repeat itself, the entire head must be wrapped in a cloth. This operation should be carried out when the amplifier is not working.
