Methods and Measures to Reduce the Interference of Transformer to Amplifier(Part 1)

The power transformer can interfere with the amplifier through the magnetic field, electromagnetic induction, and circuits, and is the biggest source of interference in audio equipment. Therefore, it is necessary to deal with its working state and application environment, in order to effectively avoid the interference generated by the power transformer, so that the amplifier can get excellent sound effects. The following power transformer suppliers will discuss this with you.

1. In addition to supplying power to the amplifier, the power transformer can also couple the amplifier and the power supply to allow interference sources in the power grid to enter the amplifier, and at the same time reflect the voltage and current changes generated by the amplifier to the power grid. In order to cut off the electrostatic field and capacitive coupling between the windings, isolation and common mode suppression of the resulting interference, avoid coupling the common-mode voltage in the power grid or circuit to the secondary or primary, add the windings of the audio power transformer Faraday electrostatic shielding is critical. This kind of shielding can be copper foil with alternating layers or a complete combined structure. In short, the more the winding (especially the primary winding) is surrounded, the better the common-mode suppression.

2. The magnetic field interference generated by the power transformer has always been a problem that plagues the quality of the amplifier. Even with a pure power supply, the magnetic field induction from it can cause serious degradation of the amplifier quality. Due to the high price of magnetic shielding isolation cover (even higher than the transformer itself, which is the reason for the high price of some imported transformers), general domestic machines rarely use magnetic shielding isolation cover to cut off the magnetic interference of the transformer, and many just use simple iron sheets. Cover isolation, or even barely install the transformer, so effective magnetic shielding cannot be performed. Foreign high-quality transformers often adopt the structure of multi-layer manganese alloy and blister copper layer to surround the transformer. On the one hand, the high resistance and high permeability of manganese alloy are used for magnetic short-circuit, and on the other hand, it is caused by the copper layer. The eddy current produces a magnetic field opposite to the interference magnetic field to cancel the magnetic interference, thus greatly reducing the magnetic field leakage of the transformer. It is difficult to obtain a manganese alloy cover under amateur conditions, but a 1.5 mm soft iron plate and copper plate can also be used to make a multilayer structure magnetic shield.