Search results
Results From The WOW.Com Content Network
Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity. The fundamental frequency of this sound is usually double that of fundamental 50/60 Hz , i.e., 100/120 Hz, depending on the local power-line frequency .
Some sound system components have ground lifting switches at inputs, which disconnect the ground. One problem with this solution is if the other ground path to the component is removed, it will leave the component ungrounded and stray leakage currents may cause a very loud hum in the output, possibly damaging speakers.
The torsional deflection of a simple cylinder cannot radiate efficiently acoustic noise, but with particular boundary conditions the stator can radiate acoustic noise under torque ripple excitation. [8] Structure-borne noise can also be generated by torque ripple when rotor shaft line vibrations propagate to the frame [9] and shaft line.
The ground lift switch eliminates unwanted hum and buzz by interrupting the ground loops between equipment, preventing current flow along the cable shield between two devices. The switch disconnects pin 1 on the XLR jack, which is connected to the braid or foil shield in the cable and acts as the ground point of the circuit.
The amplifying devices in audio and radio equipment are vulnerable to a variety of feedback problems, which can cause distinctive noise in the output. The term motorboating is applied to oscillations whose frequency is below the range of hearing, from 1 to 10 hertz , [ 3 ] so the individual oscillations are heard as pulses.
The braking effect is critical to speaker design, in that designers leverage it to ensure the speaker stops making sound quickly and that the coil is in position to reproduce the next sound. The electrical signal generated by the coil travels back along the speaker cable to the amplifier.
Block diagram of the signal-flow for a common feedback loop [1]: 118 . Audio feedback (also known as acoustic feedback, simply as feedback) is a positive feedback situation that may occur when an acoustic path exists between an audio output (for example, a loudspeaker) and its audio input (for example, a microphone or guitar pickup).
Similarly, a relay may be connected to interrupt its own actuating current, causing the contacts to buzz (the contacts buzz at line frequency if powered by alternating current) Often these units were anchored to a wall or ceiling to use it as a sounding board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made.