Top-Of-The-Range Preamplifier-3

EE 30 January 1987 TOP-OF-THE-RANGE PREAMPLIFIER-3 This concluding part of the article deals with the construction of the preamplifier. Additionally, it gives a detailed discussion of the various types of capacitor, both myths and realities. The preamplifier contains three printed-circuit boards: mother board, bus board, and supply board. The dimensions of the boards have been chosen to allow the unit fitting in a stan- dard 19 inch cabinet with a height of 2 units (88 mm). The mains transformer is fitted in a separate aluminium enclosure, the dimensions of which are not critical. In addition to the PCBs, two foils are available through our READERS SERVICES: one for the front panel and one for the rear panel. High-quality components It is important to use only high- quality components to ensure optimum performance. All re- sistors should be metal film types with a tolerance of 1%, although that of R7 and R8 should preferably be 0.1%. If these prove unobtainable, sel- ect a pair of...