The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 04, 1982
Filed:
May. 12, 1980
Stephen Kurtin, Sherman Oaks, CA (US);
Edward Kelm, Pasadena, CA (US);
NAD International, Grafelfing, DE;
Abstract
A phonograph cartridge interface which enables any magnetic phonograph cartridge to be operated into its proper termination impedance. One embodiment of the device includes a capacitance test section which is used to determine the unknown capacitance of a tonearm cable. A termination network is then adjusted to provide a proper amount of capacitance in view of the determined capacitance and the value of total termination capacitance specified by the cartridge manufacturer. The network also is adjustable to provide the proper termination resistance in parallel with the capacitance. In a second embodiment capacitance matching circuitry is included which enables the total termination capacitance provided by the tonearm cable and termination network to be adjusted to a desired value. In this embodiment, actual measurement of the tonearm cable capacitance is not required. Either embodiment of the invention can be (a) configured as a stand-alone device for use with any phono preamplifier or (b) incorporates as an integral part of a phono preamplifier. An isolation amplifier is included in the stand-along version to eliminate effects of the input capacitance of the phono preamplifier to which the interface is connected.