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The output (plate) impedance of the diode vacuum tube rectifiers in the power supply is high, so the increasing impedance of the filter capacitors at low frequencies can mean that low frequency swings in the current drawn by output stages can cause voltage swings in the power supply voltage which feed back to earlier stages, [2] [6] [4] making ...
From about 1900 to the 1950s, the "lowest frequency in practical use" in recordings, broadcasting and music playback was 100 Hz. [9] When sound was developed for motion pictures, the basic RCA sound system was a single 8-inch (20 cm) speaker mounted in straight horn, an approach which was deemed unsatisfactory by Hollywood decisionmakers, who hired Western Electric engineers to develop a ...
A rotary woofer is a subwoofer-style loudspeaker which reproduces very low frequency content by using a conventional speaker voice coil's motion to change the pitch (angle) of the blades of an impeller rotating at a constant speed. The pitch of the fan blades is controlled by the audio signal presented to the voice coil, and is able to swing ...
The high impedance of the line in circuit does not load down the output of the source device. These are voltage signals (as opposed to current signals) and it is the signal information (voltage) that is desired, not power to drive a transducer, such as a speaker or antenna. The actual information that is exchanged between the devices is the ...
Most professional audio power amplifiers also provide protection from clipping typically as some form of limiting. A power amplifier pushed into clipping can damage loudspeakers. Amplifiers also typically provide protection against short circuits across the output and overheating. Audio engineers select amplifiers that provide enough headroom.
For most audio applications more power is needed at low frequencies. This requires a high-power amplifier for low frequencies (e.g., 200 watts for 20–200 Hz band), lower power amplifier for the midrange (e.g., 50 watts for 200 to 1000 Hz), and even less the high end (e.g. 5 watts for 1000–20000 Hz).
The term loudspeaker may refer to individual transducers (also known as drivers) or to complete speaker systems consisting of an enclosure and one or more drivers.. To adequately and accurately reproduce a wide range of frequencies with even coverage, most loudspeaker systems employ more than one driver, particularly for higher sound pressure level (SPL) or maximum accuracy.
Carver's U.S. patent 4,218,660, first applied in his model M400 power amplifier, describes a power supply whose input switches on and off at an ultrasonic rate to adapt to the varying power demand of the amplifier. The innovation is in the power supply, not the amplification circuitry, and in the use of switching, not in the use of a coil or coils.