Beginner's Guide Series - The Inside and Outside of an Amplifier

                     Beginner's Guide Series - The Inside and Outside of an Amplifier

When entering the world of home theater, you'll always encounter a large, unavoidable black box, usually the central hub of the entire system, covered with various knobs and interfaces – this is what we commonly call an AV receiver. What is an AV receiver? An AV receiver is short for "power amplifier." As the name suggests, its core and fundamental mission is to "amplify power." The audio signals from Blu-ray players, game consoles, or TV boxes are actually very weak, with insufficient energy to drive the speaker units in the speakers that need to vibrate back and forth to produce sound. The "amplifier" module in an AV receiver is responsible for receiving these weak signals, amplifying their power, injecting them with powerful energy, and then transmitting the amplified power signal to your speakers. Only in this way can we hear powerful explosions, clear dialogue, and detailed environmental sound effects. It can be said that without "power amplification," a home theater is impossible. But an AV receiver does much more than that. It also processes video signals, connects all your audio and video source devices, performs audio decoding and sound field processing… It's like the "Swiss Army knife" of the audio-visual world—decoding, processing, amplifying, connecting… it can do everything. But just as the small scissors on a Swiss Army knife can't compare to a real pair of large scissors, AV receivers, in order to achieve "integration," have to make some compromises in certain aspects, especially in their most fundamental amplifier section.

Amplifier Tuning

Have you ever wondered why amplifiers from different brands, even with similar specifications, can sound completely different? Behind this lies a concept called "tuning." Some well-known manufacturers frankly admit that they intentionally tune the signal processing links (especially the preamplifier section) of their AV receivers to make their sound style sound either warm and relaxed or bright and prominent. This leads to an interesting phenomenon: even if you connect a standalone power amplifier with a "neutral" and "transparent" sound characteristic to these AV receivers (where the AV receiver is only used as a preamplifier decoder), and even if all other equipment and settings (including room calibration) are exactly the same, the final sound will still have a continuous and subtle difference.

From the perspective of pursuing "reference playback"—that is, the most realistic and accurate sound reproduction—this kind of "tuning," whether intentional or unintentional, may deviate from the ultimate goal. You might ask, "Can't powerful room correction functions (such as Dirac Live) correct this problem?" The answer is: not entirely. Room correction mainly addresses frequency response and transient response issues caused by the room's acoustic environment (such as standing waves and reflections), but it's difficult to eradicate the inherent "timbre" or "flavor" of a sound system or amplifier. Room correction corrects the errors of the "room," not the personality of the "equipment." Of course, there are many variables involved, and they are interconnected, but as a possibility, it constitutes the first important characteristic of AV receivers—they may have their own "sound personality," rather than absolute neutrality.

Power Reserves & Volume: 

AV receivers attempt to cram too much into a single chassis: preamplifier, video processor, audio decoder, and driving an ever-increasing number of channels (from 5.1 to 7.1.4 and even more). All these components draw power from a single shared power supply and a single power cord.

The laws of physics and the amplifier's own power efficiency determine its upper limit on output power. The key limitation is that the total capacity of this shared power supply is finite. It's like a reservoir that needs to supply multiple outlets simultaneously. While a manufacturer might label it "150 watts per channel," this doesn't mean it can simultaneously provide 150 watts to 7 or 9 channels while playing a movie. When all channels require high power output simultaneously (such as during a large explosion scene), this shared power supply becomes a bottleneck. Of course, not all AV receivers are created equal. Entry-level models typically have weaker amplifiers and power supplies; while high-end models are equipped with better components, larger, more stable power supplies, and more powerful amplifiers. This allows them to provide a cleaner electrical signal at higher volumes when multiple channels are working simultaneously and is prepared to deliver a wider dynamic range during large dynamic scenes in movies. 

Regardless of the amplifier's level, the power demand increases dramatically when you turn up the volume. Here, it's important to understand two different power requirements: 

1. Continuous Power: This refers to the continuous power required to play an entire soundtrack at a specific volume. 

2. Peak Power: This refers to the maximum instantaneous power required during the dynamic peaks of the soundtrack (such as explosions or impacts).

Movie audio is always dynamic, with both sustained, stable sections and sudden booms and explosions. Typically, amplifiers operate at a stable power level, leaving a certain margin to handle sounds with very high peak power. The difference between these two can be several decibels or more, posing a significant challenge to the amplifier! Some inexpensive amplifiers may not show a difference in average power compared to high-end amplifiers, but their shortcomings will be exposed when faced with sudden high sound pressure levels. Amplifiers usually use a "capacitor pool" to handle peak demands; the larger the capacitor, the longer the peak power can be sustained. However, if the instantaneous power demand exceeds the supply, the amplifier will first lose control of the bass unit, leading to power compression. The bass quantity and extension will decay faster than the mid and high frequencies, making the sound "thin" and lacking foundation, and distortion will increase sharply. 

Damping Factor: 

This is a controversial topic, but the "damping factor" is an important part of amplifier specifications. It defines the amplifier's ability to control the speaker unit, especially its ability to control excess vibration after the unit has emitted sound.

Imagine you tap a drumhead; the drumhead vibrates to produce sound, and then slowly stops. A good amplifier, like a strong hand, can instantly "press" down on the speaker diaphragm after the signal ends, stopping it instantly and decisively. This control is closely related to the damping factor. AV amplifiers typically have a low damping factor, around 50, while excellent independent power amplifiers start at 150-200, or even higher. There is much debate about whether this parameter affects the sound. Generally, a higher damping coefficient results in a shorter ringing time and stronger control, leading to a tighter and clearer sound. It's important to note that the actual damping coefficient applied to the speaker is also affected by the speaker cable resistance, but starting from a higher base (i.e., a high damping coefficient from the amplifier itself) is undoubtedly more advantageous. 

From all-in-one to separate amplifiers: 

For entry-level users, the all-in-one design of AV amplifiers offers great convenience and cost-effectiveness, suitable for scenarios with limited space or budget. However, as users' pursuit of sound quality, dynamics, and system versatility increases, the limitations of all-in-one amplifiers will gradually become apparent.

When the pursuit of sound quality reaches a higher level, many enthusiasts naturally turn their attention to separate power amplifier and preamplifier solutions, mainly for the following reasons: 

● Stronger driving force and control: Independent power amplifiers typically have larger power reserves and higher damping coefficients, providing cleaner and more abundant power to the speakers, especially excelling in multi-channel, high-dynamic-range scenarios. 

● Pursuing a more neutral and realistic sound reproduction: A separate power amplifier solution bypasses the inherent "tuning" style of the AV receiver, achieving a sound closer to the original recording or a more personalized sound.

● System upgrade and expandability: When you want to upgrade the amplifier's performance, you only need to replace or add a power amplifier, without replacing the entire AV receiver system, allowing for more flexible expansion.

● Suitable for high-end cinemas or multi-purpose spaces: In high-end home theaters, private cinemas, and professional listening rooms, a separate power amplifier solution is almost standard to meet higher sound quality and system scale requirements. Whether it's a large cinema needing to drive multiple channels, or a music/movie space with extreme demands for dynamics and sound quality; whether it's a multi-room system requiring flexible expansion, or a professional listening room aiming for reference-level reproduction, a separate power amplifier solution is a highly favored choice.

Amplifier Tuning

Have you ever wondered why amplifiers from different brands, even with similar specifications, can sound completely different? Behind this lies a concept called "tuning." Some well-known manufacturers frankly admit that they intentionally tune the signal processing links (especially the preamplifier section) of their AV receivers to make their sound style sound either warm and relaxed or bright and prominent. This leads to an interesting phenomenon: even if you connect a standalone power amplifier with a "neutral" and "transparent" sound characteristic to these AV receivers (where the AV receiver is only used as a preamplifier decoder), and even if all other equipment and settings (including room calibration) are exactly the same, the final sound will still have a continuous and subtle difference.

From the perspective of pursuing "reference playback"—that is, the most realistic and accurate sound reproduction—this kind of "tuning," whether intentional or unintentional, may deviate from the ultimate goal. You might ask, "Can't powerful room correction functions (such as Dirac Live) correct this problem?" The answer is: not entirely. Room correction mainly addresses frequency response and transient response issues caused by the room's acoustic environment (such as standing waves and reflections), but it's difficult to eradicate the inherent "timbre" or "flavor" of a sound system or amplifier. Room correction corrects the errors of the "room," not the personality of the "equipment." Of course, there are many variables involved, and they are interconnected, but as a possibility, it constitutes the first important characteristic of AV receivers—they may have their own "sound personality," rather than absolute neutrality.

Power Reserves & Volume: 

AV receivers attempt to cram too much into a single chassis: preamplifier, video processor, audio decoder, and driving an ever-increasing number of channels (from 5.1 to 7.1.4 and even more). All these components draw power from a single shared power supply and a single power cord.

The laws of physics and the amplifier's own power efficiency determine its upper limit on output power. The key limitation is that the total capacity of this shared power supply is finite. It's like a reservoir that needs to supply multiple outlets simultaneously. While a manufacturer might label it "150 watts per channel," this doesn't mean it can simultaneously provide 150 watts to 7 or 9 channels while playing a movie. When all channels require high power output simultaneously (such as during a large explosion scene), this shared power supply becomes a bottleneck. Of course, not all AV receivers are created equal. Entry-level models typically have weaker amplifiers and power supplies; while high-end models are equipped with better components, larger, more stable power supplies, and more powerful amplifiers. This allows them to provide a cleaner electrical signal at higher volumes when multiple channels are working simultaneously and is prepared to deliver a wider dynamic range during large dynamic scenes in movies. 

Regardless of the amplifier's level, the power demand increases dramatically when you turn up the volume. Here, it's important to understand two different power requirements: 

1. Continuous Power: This refers to the continuous power required to play an entire soundtrack at a specific volume. 

2. Peak Power: This refers to the maximum instantaneous power required during the dynamic peaks of the soundtrack (such as explosions or impacts).

Movie audio is always dynamic, with both sustained, stable sections and sudden booms and explosions. Typically, amplifiers operate at a stable power level, leaving a certain margin to handle sounds with very high peak power. The difference between these two can be several decibels or more, posing a significant challenge to the amplifier! Some inexpensive amplifiers may not show a difference in average power compared to high-end amplifiers, but their shortcomings will be exposed when faced with sudden high sound pressure levels. Amplifiers usually use a "capacitor pool" to handle peak demands; the larger the capacitor, the longer the peak power can be sustained. However, if the instantaneous power demand exceeds the supply, the amplifier will first lose control of the bass unit, leading to power compression. The bass quantity and extension will decay faster than the mid and high frequencies, making the sound "thin" and lacking foundation, and distortion will increase sharply. 

Damping Factor: 

This is a controversial topic, but the "damping factor" is an important part of amplifier specifications. It defines the amplifier's ability to control the speaker unit, especially its ability to control excess vibration after the unit has emitted sound.

Imagine you tap a drumhead; the drumhead vibrates to produce sound, and then slowly stops. A good amplifier, like a strong hand, can instantly "press" down on the speaker diaphragm after the signal ends, stopping it instantly and decisively. This control is closely related to the damping factor. AV amplifiers typically have a low damping factor, around 50, while excellent independent power amplifiers start at 150-200, or even higher. There is much debate about whether this parameter affects the sound. Generally, a higher damping coefficient results in a shorter ringing time and stronger control, leading to a tighter and clearer sound. It's important to note that the actual damping coefficient applied to the speaker is also affected by the speaker cable resistance, but starting from a higher base (i.e., a high damping coefficient from the amplifier itself) is undoubtedly more advantageous. 

From all-in-one to separate amplifiers: 

For entry-level users, the all-in-one design of AV amplifiers offers great convenience and cost-effectiveness, suitable for scenarios with limited space or budget. However, as users' pursuit of sound quality, dynamics, and system versatility increases, the limitations of all-in-one amplifiers will gradually become apparent.

When the pursuit of sound quality reaches a higher level, many enthusiasts naturally turn their attention to separate power amplifier and preamplifier solutions, mainly for the following reasons: 

● Stronger driving force and control: Independent power amplifiers typically have larger power reserves and higher damping coefficients, providing cleaner and more abundant power to the speakers, especially excelling in multi-channel, high-dynamic-range scenarios. 

● Pursuing a more neutral and realistic sound reproduction: A separate power amplifier solution bypasses the inherent "tuning" style of the AV receiver, achieving a sound closer to the original recording or a more personalized sound.

● System upgrade and expandability: When you want to upgrade the amplifier's performance, you only need to replace or add a power amplifier, without replacing the entire AV receiver system, allowing for more flexible expansion.

● Suitable for high-end cinemas or multi-purpose spaces: In high-end home theaters, private cinemas, and professional listening rooms, a separate power amplifier solution is almost standard to meet higher sound quality and system scale requirements. Whether it's a large cinema needing to drive multiple channels, or a music/movie space with extreme demands for dynamics and sound quality; whether it's a multi-room system requiring flexible expansion, or a professional listening room aiming for reference-level reproduction, a separate  r solution is a highly favored choice.

When you feel your system performance is always "just a little bit off," and you encounter a bottleneck in your pursuit of higher sound quality, a separate power amplifier is often the key to unlocking a new world. It will provide your speakers with abundant, pure power and unparalleled control, and also provide the most solid and neutral working foundation for your advanced room correction system (such as Dirac Live), allowing it to focus on solving room acoustic problems rather than compensating for amplifier shortcomings. It's a fun and engaging journey of discovery. Whether you're a beginner or a seasoned audiophile, understanding these principles will enable you to build the ideal system best suited to your needs.

发送反馈