MC step-up transformers and MC cartridges containing an iron core are magnetized due to long years of use and various causes. When magnetized, a magnetic bias is applied and the operating point gets off position causing distortion in the music signal that is being played and deterioration of the sound quality. In order to restore the original sound quality of a product, the magnetized magnetism must be removed.
By using our knowledge of producing MC step-up transformers and iron core MC cartridges, Phasemation will release the DG-100 which is the best for degaussing.
Magnetism of MC cartridges Containing an Iron Core
If iron core MC cartridges are used for a long period of time, the spool of magnetic material winded with coil in the magnetic circuit formed by 2 yokes and a magnet will become magnetized.
Magnetism on the MC Step-Up Transformer
Fig3 is a diagram of an MC step-up transformer. An MC cartridge is connected to the primary coil and the MM input of the amplifier is connected to the secondary coil. When a vinyl record is played with an MC cartridge, a current of I1 flows in the primary coil due to the generating voltage E1 and this magnetizes the core. As a result, magnetic flux (φ) flows out. This magnetic flux (φ) also flows to the secondary coil and the ratio of the primary coil N1 to the secondary coil N2 creates a voltage to the secondary side. Generally, permalloy is used on the core material. If the signal is set to «0», theoretically the permalloy will have a Coercive force of «0», but in reality it will not be «0». Therefore, it is slightly magnetized and this is maintained.
The Principle of Degaussing
A sine wave of 440Hz is applied to the MC step-up transformer or to the iron core MC cartridge and the signal is exponentially decreased for 20 seconds as shown in Figure 4. In other words, the spool frame and the core of the magnetic material degausses by making the magnetic field gradually smaller and getting closer to «0».
By short-circuiting the MC cartridge while the vinyl record is being played, the MC cartridge can be degaussed. For example, a cartridge with impedance of 4Ω and an output voltage of 0.3mV has a degaussing current of 0.075mA. Similarly, a cartridge with an impedance of 40Ω and an output voltage of 0.3mV has a degaussing current of 0.0075mA. Since the degausser, DG-100, flows out about 50 times more degaussing current, the degaussing effect is doubled.
This effect will increase the resolution at a micro level and produce a clearer sound. The MC step-up transformer can also be degaussed.