Amplifier classes may seem like a foreign language to those who are new to the audio industry, but they are essential to understanding the performance and characteristics of any amplifier. In this guide, we will break down the various classes of amplifiers and explain their differences, strengths, and weaknesses, providing you with the knowledge to make an informed decision when purchasing an amplifier.
Class A Amplifiers: The Quintessential Sound Quality Experience
If you’re looking for the purest and most natural sound, then Class A amplifiers are the ones for you. They are the oldest type of amplifier, and their circuit design has remained unchanged for years. Class A amplifiers operate by keeping the output transistors in the active region at all times, ensuring that the signal is amplified without any distortion. As a result, Class A amplifiers have the most accurate and transparent sound quality. However, they are also the least efficient, producing a significant amount of heat and requiring larger power supplies.
Class B Amplifiers: Efficient but With a Catch
Class B amplifiers are designed to be more efficient than Class A amplifiers, but they come with a significant tradeoff. Instead of keeping the output transistors active at all times, Class B amplifiers turn them off when there is no signal to amplify. This design allows Class B amplifiers to produce less heat and consume less power, but it also leads to a phenomenon known as crossover distortion, where the signal is distorted at the point where the output transistors switch on and off. The result is a slightly compromised sound quality, although it can still be impressive in the right circumstances.
Class AB Amplifiers: The Best of Both Worlds
Class AB amplifiers combine the best of both worlds of Class A and Class B amplifiers. They use two sets of output transistors, one for positive signals and one for negative signals, and they bias the transistors slightly into the active region, ensuring that they are always on but using less power when there is no signal. This design eliminates the crossover distortion of Class B amplifiers and reduces the heat and power consumption of Class A amplifiers, resulting in a high-quality sound with a reasonable level of efficiency.
Class D Amplifiers: The Digital Revolution
Class D amplifiers, also known as digital amplifiers, use a different technology than the previous three classes. They use pulse-width modulation to amplify the signal, which is essentially turning the signal on and off very rapidly. The result is a highly efficient amplifier that produces very little heat and can be very compact. However, this efficiency comes at a cost, and Class D amplifiers are known for producing a harsher, less natural sound than the previous three classes.
Class T Amplifiers: The Newcomer
Class T amplifiers, also known as Tripath amplifiers, are a relatively new addition to the audio industry. They are a hybrid of Class A and Class D amplifiers and use Tripath’s proprietary digital amplification technology. The result is an amplifier that is highly efficient, produces very little heat, and has a sound quality that rivals that of Class A amplifiers. However, they are relatively expensive, and their availability can be limited.
Class A Amplifiers
Class A amplifiers are known for their uncompromising commitment to sound quality, and they are often the first choice for audiophiles and professional musicians. Class A amplifiers operate by keeping the output transistors in the active region at all times, ensuring that the signal is amplified without any distortion. This design results in the purest and most natural sound quality, which is free from any noise or harmonic distortion. However, Class A amplifiers are also the least efficient, producing a significant amount of heat and requiring larger power supplies.
One of the most famous examples of a Class A amplifier is the Marantz Model 7. This amplifier was introduced in 1959 and quickly became a reference standard for audiophiles. It had a Class A design and a tube-based circuit, which produced a rich and warm sound that was highly sought after. Another notable Class A amplifier is the Pass Labs XA60.5, which is a solid-state design that delivers an impressive 60 watts per channel. It has been praised for its ability to reproduce music with a high degree of accuracy and detail, making it a favorite among audiophiles and music lovers.
The McIntosh MC275 is another iconic Class A amplifier that has been in production since the 1960s. It is a tube-based amplifier that produces a warm and natural sound that is highly regarded by audiophiles. The MC275 is also known for its distinctive design, with its signature blue meters and chrome chassis. It has become a collector’s item and a symbol of high-end audio equipment.
In recent years, Class A amplifiers have become less common due to their inefficient design and high production costs. However, there are still many high-end Class A amplifiers on the market, such as the Pass Labs XA200.8 and the Ayre Acoustics VX-5 Twenty. These amplifiers are designed for audiophiles and professional musicians who demand the highest level of sound quality and are willing to pay a premium for it.
Class A amplifiers are the gold standard for sound quality, and they have a long history of producing some of the most iconic and sought-after amplifiers in the audio industry. While they may be less common today due to their high production costs and inefficient design, they continue to be a favorite among audiophiles and music lovers who demand the best possible sound quality from their audio equipment.
Class AB Amplifiers
Class AB amplifiers are a popular choice for both home audio systems and professional music studios because they combine the best features of Class A and Class B amplifiers. They use two sets of output transistors, one for positive signals and one for negative signals, and they bias the transistors slightly into the active region, ensuring that they are always on but using less power when there is no signal. This design eliminates the crossover distortion of Class B amplifiers and reduces the heat and power consumption of Class A amplifiers, resulting in a high-quality sound with a reasonable level of efficiency.
One of the most famous Class AB amplifiers is the Adcom GFA-555. It was introduced in 1985 and quickly became one of the most popular amplifiers in the audio industry. The GFA-555 used a Class AB design with a high-current output stage, which allowed it to deliver a powerful and dynamic sound with excellent clarity and detail. The GFA-555 became a classic amplifier and was highly sought after by audiophiles and music lovers.
Another notable Class AB amplifier is the Cambridge Audio Azur 851A. It is a high-end integrated amplifier that uses a Class AB design with a dual-mono output stage. It delivers an impressive 120 watts per channel and has been praised for its excellent sound quality and versatility. The Azur 851A is also equipped with a built-in digital-to-analog converter (DAC) and a high-quality headphone amplifier, making it a complete audio solution for any audiophile.
The Rotel RB-1582 MkII is another Class AB amplifier that has received critical acclaim. It is a solid-state amplifier that delivers 200 watts per channel and uses a Class AB design with a large toroidal transformer for improved power handling. The RB-1582 MkII has been praised for its dynamic and detailed sound quality, making it a favorite among music lovers and professional musicians.
In recent years, Class AB amplifiers have continued to evolve and improve, with companies such as Parasound, Emotiva, and Anthem producing high-end amplifiers that use advanced Class AB designs. These amplifiers are designed for audiophiles and music lovers who demand the highest level of sound quality and versatility from their audio equipment.
Class D Amplifiers
Class D amplifiers, also known as digital amplifiers, use pulse-width modulation to amplify the signal, which is essentially turning the signal on and off very rapidly. The result is a highly efficient amplifier that produces very little heat and can be very compact. However, this efficiency comes at a cost, and Class D amplifiers are known for producing a harsher, less natural sound than the previous three classes.
One of the most well-known Class D amplifiers is the Hypex NCore NC400. It is a highly efficient and compact amplifier that is capable of delivering 400 watts per channel. The NCore NC400 has been praised for its high level of detail and accuracy, making it a favorite among audiophiles and professional musicians.
Another notable Class D amplifier is the NAD Masters Series M22. It is a solid-state amplifier that delivers 250 watts per channel and uses a Class D design with a modified version of the Hypex NCore module. The M22 has been praised for its excellent sound quality and versatility, making it a popular choice for both home audio systems and professional music studios.
The Benchmark AHB2 is another Class D amplifier that has received critical acclaim. It is a solid-state amplifier that delivers 100 watts per channel and uses a Class D design with patented THX-AAA technology. The AHB2 has been praised for its exceptional dynamic range and low distortion, making it a favorite among audiophiles and music lovers.
In recent years, Class D amplifiers have continued to improve, with companies such as Nord Acoustics, Bel Canto, and Purifi producing high-end amplifiers that use advanced Class D designs. These amplifiers are designed for audiophiles and music lovers who demand the highest level of sound quality and efficiency from their audio equipment.
In conclusion, Class D amplifiers offer a highly efficient and compact solution for amplifying audio signals. While they may produce a harsher, less natural sound than other amplifier classes, the latest Class D designs have greatly improved their sound quality, making them a popular choice for audiophiles and professional musicians who value efficiency and versatility.
Class T Amplifiers
Class T amplifiers, also known as Tripath amplifiers, are a relatively new addition to the audio industry. They are a hybrid of Class A and Class D amplifiers and use Tripath’s proprietary digital amplification technology. The result is an amplifier that is highly efficient, produces very little heat, and has a sound quality that rivals that of Class A amplifiers. However, they are relatively expensive, and their availability can be limited.
One of the most famous Class T amplifiers is the Topping TP60. It is a compact and affordable amplifier that delivers 50 watts per channel and uses a Class T design with Tripath’s proprietary technology. The TP60 has been praised for its excellent sound quality and value, making it a popular choice among audiophiles and music lovers.
Another notable Class T amplifier is the Sonic Impact T-Amp. It was introduced in 2004 and quickly gained a reputation for delivering high-quality sound at an affordable price. The T-Amp used a Class T design with Tripath’s proprietary technology, which allowed it to deliver an impressive 15 watts per channel with very little distortion. The T-Amp was a game-changer in the audio industry and paved the way for other Class T amplifiers to follow.
The Trends Audio TA-10.2 is another Class T amplifier that has received critical acclaim. It is a compact and versatile amplifier that delivers 2×15 watts per channel and uses Tripath’s proprietary technology. The TA-10.2 has been praised for its excellent sound quality and versatility, making it a popular choice for both home audio systems and desktop setups.
In recent years, Class T amplifiers have continued to evolve and improve, with companies such as NuForce, Dayton Audio, and Trends Audio producing high-end amplifiers that use advanced Class T designs. These amplifiers are designed for audiophiles and music lovers who demand the highest level of sound quality and efficiency from their audio equipment.
What are the main diffferences between each Class?
The main differences between each amplifier class are:
- Class A amplifiers – They operate by keeping the output transistors in the active region at all times, ensuring that the signal is amplified without any distortion. They produce the purest and most natural sound quality but are also the least efficient, producing a significant amount of heat and requiring larger power supplies.
- Class B amplifiers – They turn off the output transistors when there is no signal to amplify, resulting in less heat and power consumption. However, this design also leads to a phenomenon known as crossover distortion, where the signal is distorted at the point where the output transistors switch on and off. They are known for their efficiency but compromise on sound quality.
- Class AB amplifiers – They combine the best features of Class A and Class B amplifiers. They use two sets of output transistors, one for positive signals and one for negative signals, and they bias the transistors slightly into the active region, ensuring that they are always on but using less power when there is no signal. This design eliminates the crossover distortion of Class B amplifiers and reduces the heat and power consumption of Class A amplifiers, resulting in high-quality sound with reasonable efficiency.
- Class D amplifiers – They use pulse-width modulation to amplify the signal, which is essentially turning the signal on and off very rapidly. The result is a highly efficient amplifier that produces very little heat and can be very compact. However, this efficiency comes at a cost, and Class D amplifiers are known for producing a harsher, less natural sound than the previous three classes.
- Class T amplifiers – They are a hybrid of Class A and Class D amplifiers and use Tripath’s proprietary digital amplification technology. They are highly efficient, produce very little heat, and have a sound quality that rivals that of Class A amplifiers. However, they are relatively expensive, and their availability can be limited.
In summary, each amplifier class has its own unique features and tradeoffs, and the choice of which amplifier to use depends on the user’s priorities, such as sound quality, efficiency, cost, and availability.
Which Class is right for me?
The choice of which amplifier class is right for you depends on your specific needs and priorities. Here are some factors to consider when selecting an amplifier class:
- Sound quality – If the sound quality is your top priority and you are willing to compromise on efficiency, Class A amplifiers are the best choice. They produce the purest and most natural sound quality without any distortion.
- Efficiency – If efficiency is important to you and you don’t want to compromise too much on sound quality, Class B, Class D, or Class T amplifiers are the way to go. They are highly efficient and produce less heat and consume less power than Class A or Class AB amplifiers.
- Cost – Class A amplifiers are typically the most expensive due to their inefficient design and high production costs. Class D and Class T amplifiers are generally more affordable and offer a good balance between sound quality and efficiency.
- Availability – Some amplifier classes may be more widely available than others, depending on the brand and location. You may need to do some research to find the amplifier class that is right for you and fits within your budget and availability.
In conclusion, the choice of which amplifier class is right for you depends on your priorities and specific needs. Consider your budget, sound quality requirements, and efficiency needs to determine which amplifier class is best suited for you.