Power transformer by the magnetic field, electromagnetic induction, and interfere with the amplifier circuit is a sound machine largest source of interference. So, it's working condition and properly handle the application environment, in order to effectively avoid the interference generated by the Transformer company, the amplifier has been an excellent sound. Here I will discuss this with you to make a, please let us know.

1, except for the power transformer power amplifiers, but also to the amplifier and power supply coupling, so that the power of the interference into the amplifier, but also the amplifier voltage and current changes in reflection to the grid. To cut off the electrostatic field between the windings and capacitive coupling, isolation, and the resulting common-mode rejection of interference, avoid power or circuit coupled to the common-mode voltage in the secondary or junior to, the sound increases with the power transformer windings Faraday electrostatic shield is critical. This shield can be alternating layers of copper foil, it can be a full co-like structure, in short, to the winding (especially for the primary winding) surrounded by the more common mode rejection better.

2, the magnetic field generated by the power transformer interference improve the quality of the amplifier has been troubled by the problem, even with pure power, from its magnetic field sensor can also cause a serious decline in the quality of the amplifier. As the magnetic shielding cover the high cost (or even higher than the transformer itself, which is the high price of some imported transformers reasons), generally made little use of the machine cut off the transformer magnetic shielding enclosures magnetic interference, many just a simple metal cover isolation, or even just the bare transformer installation, so it can not be effective magnetic shielding. Foreign high-quality multi-layer transformer often travel manganese alloy and white blister layer structure, surrounded by the transformer, on the one hand the use of high-resistance alloy manganese tour, the characteristics of high permeability magnetic circuit, the other caused by the copper layer The eddy current produces a magnetic field with opposite magnetic interference offset magnetic interference, thereby significantly reducing the leakage of the transformer's magnetic field. Amateur conditions is very difficult to get travel manganese alloy cover, but can also be soft 1.5 mm multi-layer structure made of iron and copper magnetic shield.
  
3, when the transformer primary impedance is equal to source resistance with the load resistor in parallel reflection value, low-frequency cut-off will occur, increasing the noise from the transformer, it must also have sufficient power transformer inductance. But this can not be blind to increase the output power transformer reason. Because the transformer primary inductance is the flux density varies with the core, the secondary load power hour, core flux density will decrease, so that the inductor down. General, the power transformer power supply in the secondary power to choose between 1.4-2 times, be more appropriate.
  
4, high-quality transformer core permeability is high, magnetostrictive effect is also high on the external magnetic field, pressure, vibration-sensitive, can therefore generate additional voltage, causing interference. To this end, the assembly or installation of transformers, the
To take the following measures:
- Before assembly to be core or shield demagnetization process.
- Avoid short circuit core, eddy current, reducing the magnetic flux, the inductance down.
- The transformer should be vacuum impregnation, lamination can not make another move.
- The transformer to be installed in the shock absorber base, but also mounting, any magnetic source.
- If installation space allows, for the acoustic Frequency Transformer should be.

5, in the form of the transformer is also important to reduce interference. General, ring or O-type transformers, high efficiency, magnetic flux leakage is small, but the flux easily filled, but the grid is not conducive to resist interference. EI-type on the contrary, and because there is a certain gap, make the core of the permeability and stability. R is between this type between the two. As China's power grid more polluting, so many "fans" more EI transformer is selected as the audio power.