Toroidal transformers, one of the biggest interference source in audio amplifiers, can interfere with amplifiers through magnetic fields, electromagnetic induction and circuits.Therefore, only by dealing with its working state and application environment well can the interference caused by the power transformer be effectively avoided and make sure the high quality of the amplifier sound.
Electrostatic shielding
In addition to supplying the power to the amplifiers, toroidal transformers can also couple the amplifier and the power supply, making the interference source from the power grid get into the amplifiers and reflecting the variation of voltage and current generated by the amplifiers in to the power grid.
We can solve this problem through electrostatic shielding.Surrounding the winding with alternating layers of copper or aluminum foil.More layers of foil are surrounded in the winding(especially the primary winding), the higher common-mode rejection is.
Reducing the vibration
During the working process of the power transformer, the vibration of the iron core caused by the alternating magnetic field will produce mechanical noise.The first to avoid this problem is to choose transformers with good quality. Then placing the neoprene washers above and below the transformer and bolting the dished washer down firmly to reduce the vibration.Or using the toroidal transformer with epoxy resin in the center hole.
Epoxy resin coating
The magnetic field interference caused by toroidal transformers is always the obstacle of the quality improvement of amplifiers.Installed externally transformers can be keep away from the magnetic field interference but the magnetic induction can not be eliminated completely.
The most effective way to minimize the magnetic field interference is to use the iron plate as the magnetic shield and encapsulate the toroidal transformer with epoxy resin.
Reducing the interference caused by the additional voltage
The magnetic permeability of high quality transformer is high and so is the magnetic strict effect. It is sensitive to the external magnetic field, pressure and vibration.So the additional voltage will be generated and cause the interference.
Here are some solutions while assembling or installing the transformers as below:
1. Demagnetizing before assembling the core or shield.
2. Avoiding the short circuit of iron core, eddy current producing, magnetic flux reducing and inductance dropping.
3. Transformers should be impregnated in vacuum.
4. Transformer shall be installed on the shock absorbing base and so is any other magnetic field source.
Ecko toroidal transformers has low magnetic leakage and less stray flux. The epoxy we used has strong thermal conductivity which is good for heat conduction and heat dissipation.