The front panel has a POWER button and 3 INPUT SELECT buttons. We can choose:
- MC - Support for Moving Magnet inserts
- MC-HI-Z - Moving Coil ≥50Ω support
- MC-LOW-Z - Supports Moving Coil <50Ω
The rear panel has a network socket and 2 pairs of RCA inputs for connecting a turntable player with a MM or MC cartridge.
Types of phono cartridges
Gramophone cartridges are divided into two main groups:
- MM - Moving Magnet
- MC - Moving Coil
The signal level from the MM cartridge ranges from a few to several mV. The MM cartridges are between 0.2 and 0.9 mV.
That is why in the Yaqin MS-33B amplifier we have separate RCA signal inputs for MM and MC cartridges.
In the audio world, it is believed that MC cartridges are better because the moving element is a coil and not a magnet, as is the case with MM cartridges. Because the mass of the coil is many times smaller than the magnet, and thus the reaction of the needle-coil mechanical system is faster.
Description of the RIAA characteristics
Acoustic recording on gramophone records is carried out by means of a stylus which cuts the mother disc.
The stylus speed is proportional to the amplitude. To maintain a constant signal level independent of frequency, stylus swings must be greater at a lower signal frequency. With this recording, the groove amplitude would be very large. This would reduce the writing time on the disc because the distance between the grooves would be increased. Reading would also be difficult because the turntable needle would have to track a groove with a larger amplitude. In turn, with high frequencies there is a problem of noise level, because as the frequency of the signal increases, the amplitude of the deflections decreases, and thus the distance from noise decreases. The frequency response correction made before cutting the mother board comes in handy. On the other hand, in the phono preamplifiers there is a correction system with inverse characteristics. In 1955, the American association of the phonographic industry RIAA developed a correction curve that became a widely used standard