We can see each device input and output signal graph in the below image. The heat dissipation is minimized in this class providing a low heat sink space. But, this class also have limitation. A very profound limitation of this class is the crossover distortion. As two devices provides each half of the sinusoidal waves which are combined and joined across the output, there is a mismatch cross over in the region, where two halves are combined. This is because when one device complete the half cycle, the other one needs to provide the same power almost at the same time when other one finish the job.
It is difficult to fix this error in class A amplifier as during the active device the other device remains completely inactive. The error provides a distortion in the output signal. Due to this limitation, it is a major fail for precision audio amplifier application.
An alternate approach to overcome the cross-over distortion, is to use the AB amplifier. Same as class B, it has the same configuration with two active devices which conducts during half of the cycles individually but each device biased differently so they do not get completely OFF during the unusable moment crossover moment. Each device does not leave the conduction immediately after completing the half of the sinusoidal waveform, instead they conduct a small amount of input on another half cycle.
Using this biasing technique, the crossover mismatch during the dead zone is dramatically reduced. But in this configuration, efficiency is reduced as the linearity of the devices is compromised. The efficiency remains more than the efficiency of typical Class A amplifier but it is less than the Class B amplifier system.
Also, the diodes need to be carefully chosen with the exact same rating and need to be placed as close as possible to the output device. In some circuit construction, designers tend to add small value resistor to provide stable quiescent current across the device to minimize the distortion across the output.
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The cookies is used to store the user consent for the cookies in the category "Necessary". For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best valve amplifiers see valve audio amplifier. This led audiophiles to believe that "tube sound" or valve sound had an intrinsic quality due to the vacuum tube technology itself.
In , Matti Otala published a paper on the origin of a previously unobserved form of distortion: transient intermodulation distortion TIM ,  later also called slew-induced distortion SID by others. TIM did not appear at steady state sine tone measurements, helping to hide it from design engineers prior to Problems with TIM distortion stem from reduced open loop frequency response of solid state amplifiers. Further works of Otala and other authors found the solution for TIM distortion, including increasing slew rate , decreasing preamp frequency bandwidth, and the insertion of a lag compensation circuit in the input stage of the amplifier.
This new idea helped audio design engineers to better evaluate the distortion processes within an amplifier.
Important applications include public address systems, theatrical and concert sound reinforcement systems , and domestic systems such as a stereo or home-theatre system. Instrument amplifiers including guitar amplifiers and electric keyboard amplifiers also use audio power amplifiers. In some cases, the power amplifier for an instrument amplifier is integrated into a single amplifier "head" which contains a preamplifier, tone controls, and electronic effects. These components may be mounted in a wooden speaker cabinet to create a "combo amplifier".
Power amplifiers are available in standalone units, which are used by hi-fi audio enthusiasts and designers of public address systems PA systems and sound reinforcement systems.
A hi-fi user of power amplifiers may have a stereo power amplifier to drive left and right speakers and a single-channel mono power amplifier to drive a subwoofer. The number of power amplifiers used in a sound reinforcement setting depends on the size of the venue. A small coffeehouse may have a single power amp driving two PA speakers. A nightclub may have several power amps for the main speakers, one or more power amps for the monitor speakers pointing towards the band and an additional power amp for the subwoofer.
A stadium concert may have a large number of power amps mounted in racks. Most consumer electronics sound products, such as TVs , boom boxes , home cinema sound systems, Casio and Yamaha electronic keyboards , "combo" guitar amps and car stereos have power amplifiers integrated inside the chassis of the main product.
From Wikipedia, the free encyclopedia. Audio amplifier with power output sufficient to drive a loudspeaker.
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