Virtual ground preamplifier for magnetic phono cartridge

摘要

This application discloses a virtual ground pre-amplifier for application with magnetic phono cartridges such as moving coil, moving magnet, moving iron, or similar types. The preamplifier according to the present invention comprises a forward path (an amplifier), and a reverse path (shunt feedback). By presenting a relatively low load impedance to the phono cartridge, the preamplifier effectively damps mechanical resonances of the stylus-cartridge system, and thus serves as a "stylus stabilizer."PPAlso disclosed are techniques for equalizing the overall response of the stylus-cartridge-preamp system so as to provide a predetermined (e.g., flat) frequency response. This predetermined frequency response can be achieved by utilizing any of several circuit arrangements which serve to compensate for the intrinsic inductance and dc resistance of the magnetic phono cartridge. A detailed description is given of a high-performance complementary-symmetry "operational-type" amplifier which is well-suited for use in the forward path of the preamplifier.