Class B amplifiers have a very high efficiency but are impractical for audio work because of high levels of distortion ( See: Crossover distortion ).

Modern Class AB amplifiers commonly have peak efficiencies between 30 – 55 % in audio systems and 50-70 % in radio frequency systems with a theoretical maximum of 78. 5 %.

Commercially available Class D switching amplifiers have reported efficiencies as high as 90 %.

Amplifiers of Class C-F are usually known to be very high efficiency amplifiers.

Class AB is widely considered a good compromise for audio amplifiers, since much of the time the music is quiet enough that the signal stays in the " class A " region, where it is amplified with good fidelity, and by definition if passing out of this region, is large enough that the distortion products typical of class B are relatively small.

Class AB sacrifices some efficiency over class B in favor of linearity, thus is less efficient ( below 78. 5 % for full-amplitude sinewaves in transistor amplifiers, typically ; much less is common in class-AB vacuum-tube amplifiers ).

* Class D audio amplifiers, white paper-pdf

Of the two kinds of RF power amplifier, switching amplifiers ( Class D amplifiers ) cost less and use less battery power than linear amplifiers of the same output power.

For example, class AB amplifiers are around 25 or 50 % efficiency while Class D amps are much higher ; around 80 % or more efficiency.

Since an 800 watt amplifier built with standard Class AB technology would be very heavy, some acoustic amplifier manufacturers use lightweight Class D amplifiers, which are also called " switching amplifiers.

Since an 800 watt amplifier built with standard Class AB technology would be very heavy, some acoustic amplifier manufacturers use lightweight Class D amplifiers, which are also called " switching amplifiers.

Post World War II, the majority of valve power amplifiers are of the Class AB-1 " push pull " ultralinear topology, or lower cost single ended i. e. 6BQ5 / EL84 power tubes, but niche products using the DH-SET and even OTL topologies still exist in small numbers.

In the 1970s and 1980s, most PA amplifiers were heavy Class AB amplifiers.

In the late 1990s power amplifiers in PA applications have became lighter, smaller, more powerful and more efficient due to increasing use of switching power supplies and Class D amplifiers, which offer significant weight and space savings as well as increased efficiency.

Class 2, stations operating on clear channels are required to cease operation or operate under nighttime restrictions beginning either at local sunset ( for daytime class 2, stations ) or sunset at the location of the dominant class 1, station where located west of the class 2, station ( for limited-time class 2, stations ).

Some 45 frequencies are assigned for use primarily by dominant Class 1, -- A or Class 1, -- B clear-channel stations, designed to operate with adequate power and to provide service -- both groundwave and ( at night ) skywave -- over large areas and at great distances, being protected against interference to the degree necessary to achieve this objective.

Or a bored dog because you are more interested in something else -- maybe the way you look, or the date you have after the Class, or you are just doing this to please the parents.

Many adults showing at Westminster today are products of this Class.

It has been suggested many times that a Class be set up for the Juniors who are overage and cannot enter the Junior Classes.

For some time this writer has been suggesting a Junior Judging Class for Intermediates over 16 and under 20 years of age who are ineligible to compete in the Junior Class.

Class V resins are considered to be produced by a pine or pine relative.

Class I AC's are large cytosolic enzymes (~ 100 kDa ) with a large regulatory domain (~ 50 kDa ) that indirectly senses glucose levels.

The genes for Class II AC's are known as cyaA.

# Class I devices present minimal potential for harm to the user and are often simpler in design than Class II or Class III devices.

# Class II devices are subject to special controls in addition to the general controls of Class I devices.

Class actions are commonly referred to as class action suits ; however, this phrase is redundant as the historical distinction between " actions " at law and " suits " in equity is no longer recognized.

It was also revealed by Emma Frost that she and Professor X are both Omega Class Telepaths when she manages to detect the real Professor X.

Terms invented by Adams in relation to the strip, and sometimes used by fans in describing their own office environments, include “ Induhvidual .” This term is based on the American English slang expression “ duh !” The conscious misspelling of individual as induhvidual is a pejorative term for people who are not in the DNRC ( Dogbert's New Ruling Class ).

Listed below are the Divisions for Class 1 ( Explosives ):

* Class III: the struma is very large and is retrosternal ; pressure results in compression marks.

Their status is still undetermined, they could be the youngest low-mass Class 0 protostars yet seen or even very low-mass evolved objects ( like a brown dwarf or even an interstellar planet ).

In the current system of stellar classification, stars are grouped according to temperature, with the very young and energetic Class O stars boasting temperatures in excess of 30, 000K while the older Class M stars exhibit temperatures less than 3, 700K — a vast difference that has a huge impact on the star's luminosity.

In fact this situation has only been historically realized temporarily such as in the Israeli kibbutz or the very early Soviets before the adoption of state capitalism and entrenchment of the communist party as a New Class, or in isolated or preliminary form such as in the final phase of the Second Spanish Republic, or various experimental utopian communities ; although in embryonic form.

The boys soccer team participated in the very first Class C State Championship in 1974, losing 3-0 to Richmond High School at the University of Maine.

The tiny Class 1 railroad was very profitable and became known as the " Richest Little Railroad in the World.

Due to badly failure of government in providing the Education, the Elite Class Education System in Pakistan got successes very quickly.

As c2c is mainly a London commuter railway and the average c2c journey is between 40 to 70 minutes, c2c does not offer first-class seating, its Class 357s have standard high-density 3 + 2 Chapman seating to meet demand at peak times when the line is very busy.

Considered one of the most complex engine designs of its day, the Deltic was nevertheless very reliable, and was taken into service after the war as a locomotive powerplant ( in British Rail's Class 55 ) in addition to the torpedo boats, minesweepers and other small naval vessels for which it was designed.

* 1700 Class: This locomotive is very similar to the 1600 / 1800 in appearance but technically different.

* Class 8: Moderate impairments of the legs, ormoderate impairments of playing arm ( considering that elbow and shoulder control is very important ), ormoderate cerebral palsy, hemiplegia or diplegia with good playing arm.

Class III function very differently from class I and class II, but its locus occurs between the other two classes — on chromosome 6 in humans — and are frequently discussed together.

* Class I are subject to very high minimum investment requirements and are, therefore, known as " institutional " shares.

A very exceptional efficiency for a specific Class D amp, the ROHM BD5421efs, operates at 90 % efficiency.

These models are traditionally hand-made, but advances in technology have turned the industry into a very high tech process than can involve Class IV laser cutters, 5-axis CNC machines as well as rapid prototyping or 3D printing.

* Class System Variations – The classification system today is a very rough rule of thumb, particularly in the " readiness " category.

A very special Class of “ high-cube ” boxcar was the X60 class series 8 door type introduced in the mid 1960s on American railroads to haul bulky but light-weight automotive parts such as body panels and were a massive 86 feet in length.