Top-of-the-range preamplifier (2)

EE 54 December 1986 TOP-OF-THE- RANGE PART 2 PRE- AMPLIFIER This monthS instalment of the article deals with the description of the circuits of the phono and line amplifiers. Constructional details will follow in next montI8" issue. Initial considerations In essence, there are only two types of good-quality pick-up cartridge in use nowadays: the moving coil- MC-and the magneto-dynamic- MD. The main difference between these is the level of output voltage they provide. The signal provided by a modern MC cartridge is 100-400 NV, whereas that of a MD type is 2-5 mV. In the design of an IEC (RIAA) equalization circuit that is suitable for use with both types of cartridge, there are two choices: one in which one or more stages of amplification can be switched on or off depending on whether an MC or an MD car- tridge is used; or one with variable (or switch-selected) gain. In the pres- ent preamplifier, the second choice has been adopted. This choice makes heavy demands on the input st...