(under the class definition) Subject matter wherein the signal has a hum or noise component inadvertently introduced therein, as where there is ineffective filtering of a rectified A.C. power supply or bias, and wherein such objectional component is removed or reduced by the same hum or noise component introduced into the signal path of the amplifier in such manner as to oppose the objectional signal component, thereby removing it from, or reducing it in, the output signal.
(1) Note. Where such component is removed or reduced by negative feedback classification is elsewhere.
SEE OR SEARCH THIS CLASS, SUBCLASS:
75+, where such components of this subclass (149) are removed or reduced by negative feedback. See (1) Note above.
114, for amplifiers having unrectified A.C. power supply including those with means to eliminate hum.
118+, for push-pull amplifiers which include means for opposing noise, hum, or other unwanted components inadvertently present with the signal, and wherein the compensation is inherent in the push-pull arrangement, per se. 124+, for plural channel amplifiers including those wherein an unwanted component in the signal is separately amplified and opposes the unwanted component in a channel which includes the signal and the unwanted component.
150, for cascaded amplifying devices of different characteristics including those wherein the characteristics of one stage compensate for those of another.
151, for cascaded amplifying devices with means to by-pass a stage wherein a feed forward component may oppose the same component in the signal path.
199+, for amplifiers with power or bias voltage supply including filters to eliminate hum, etc..
296, and 297, for semiconductor amplifiers with bias or power supply circuitry.
SEE OR SEARCH CLASS
315, Electric Lamp and Discharge Devices: Systems,
94+, for discharge device load systems having cathode or cathode heater power supply, with or without anode power supply, but excluding control electrode supply, including those having means for hum elimination, etc..
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems,
549, for miscellaneous circuits with power supply and hum prevention or elimination means.
333, Wave Transmission Lines and Networks, 167+, for wave filters, per se, which may be used to eliminate a frequency component, particularly subclasses 181+, for smoothing filters for power supply.
363, Electric Power Conversion Systems,
39+, for electrical conversion systems including means to eliminate frequency components.
