I dont think I have covered this before, but thought I would for those interested.
The class ratings are all about the power supply designs and amount of distortion the amp puts out at any given point.
The best way to describe how this works is with a water spigot on a sink.
Class A, you basically turn on the water as high as it will go. We are cooking eggs on these amps.
Class AB, you turn on the water as high as it will go, but you move your hand through the water from side to side. These amps run much cooler at the same output levels.
Class D You turn the water on full, and hold your hand in the stream with all your fingers open. These are very power efficient.
Class A is the cleanest you can get but you get clean at a high cost. The power demands for this design are very high and most cars could deal with (1) 2 channel 25 x 2 class a amp.
Class AB is a switching power supply design. That means it is cutting the power on and off all the time. This makes the amp more efficient but at a cost of adding distortion to the sound. There is a night and day difference between the sound quality of a Class a vs Class AB design amp. There is also a night and day difference in the cost.
Class D uses what is called a digital power supply and uses the least amount of power draw to make the same amount of power. The sound quality between the class AB and Class D is negligible. There is a difference but some sacrifices have to be made to accommodate the amount of power you have available to power the amp.
80% of all amps are Class AB and that number is changing in lieu of the Class D design. When Class D first came out it was only good for subs, because anything over 500hertz had massive distortion. That is no longer the case, and class D design from a sound perspective is just as good if not better in some cases than Class AB. While I am not referencing that here, there have been may test to prove this point.
Many audiophiles argue on this point. There are those that live and breath by the tube or class A design. And they would be right, they are the cleanest sounding amps available. The problem your car is not powered by a nuclear generator. Our cars have small alternators and 1 class AB designed amp would probably be ok if properly reinforced, 2 would be pushing it depending on the power output of the amp.
The Class D amps are designed from everyone these days including, ARC aduio, Pioneer, Kenwood, JL Audio, Alpine(My Choice) to name a few.
Additionally, the Class D vs Class AB or Class A are much smaller because of the design requirements. As we have small cars with small charging systems, The class D will suit almost all of the demands you could have for your system.
As an example, the Alpine PDX-V9 Amp, here are the specs, this is a class D design
Power Requirements: 14.4 V.DC (11-16 V allowable)
Input Sensitivity (RCA Input): 0.2 - 4 V (CH1/2, CH3/4), 0.1 - 4 V (Subwoofer)
Input Impedance: >10k ohms
Frequency Response (+0, -3dB: 1W into 4 Ohms) for CH-1/2/3/4: 3 - 100k Hz
Frequency Response (+0, -3dB: 1W into 4 Ohms) for Subwoofer: 3 - 600 Hz
THD+N (10W into 4 Ohms) for CH-1/2/3/4: <0.005 %
THD+N (10W into 4 Ohms) for Subwoofer: <0.006 %
THD+N (Rated Power into 4 Ohms) for CH-1/2/3/4: <0.03 %
THD+N (Rated Power into 4 Ohms) for Subwoofer: <0.05 %
Damping Factor for CH-1/2/3/4: >500 into 4 ohms at 100Hz
Damping Factor for Subwoofer: >1000 into 4 ohms at 100Hz
Signal to Noise (Rated Power into 4 Ohms) for CH-1/2/3/4: 112 dB
Signal to Noise (Rated Power into 4 Ohms) for Subwoofer: 119 dB
Weight: 2.7 kg
This is one of the cleanest sounding amps available by any measure.
Audiophiles also disagree on the point of Class D being as good as Class AB. Every amp I have ever used save one system has been Class AB. Pioneer in their ODR systems offered Class A designed Amp, but even though I owned 2 ODR systems in vehicles, I never used the Class A amps, because of the car I was using and the power requirements of those amps. Everyone I knew that did use the Class A amps, had to upgrade their cars electrical systems with multiple batteries and upgrated alternators with caps.
So when you are going to get an amp for your ride, give the design consideration. It is my opinion, that with the way the industry is going, Class A/B design is going away in lieu of the Class D design.
The class ratings are all about the power supply designs and amount of distortion the amp puts out at any given point.
The best way to describe how this works is with a water spigot on a sink.
Class A, you basically turn on the water as high as it will go. We are cooking eggs on these amps.
Class AB, you turn on the water as high as it will go, but you move your hand through the water from side to side. These amps run much cooler at the same output levels.
Class D You turn the water on full, and hold your hand in the stream with all your fingers open. These are very power efficient.
Class A is the cleanest you can get but you get clean at a high cost. The power demands for this design are very high and most cars could deal with (1) 2 channel 25 x 2 class a amp.
Class AB is a switching power supply design. That means it is cutting the power on and off all the time. This makes the amp more efficient but at a cost of adding distortion to the sound. There is a night and day difference between the sound quality of a Class a vs Class AB design amp. There is also a night and day difference in the cost.
Class D uses what is called a digital power supply and uses the least amount of power draw to make the same amount of power. The sound quality between the class AB and Class D is negligible. There is a difference but some sacrifices have to be made to accommodate the amount of power you have available to power the amp.
80% of all amps are Class AB and that number is changing in lieu of the Class D design. When Class D first came out it was only good for subs, because anything over 500hertz had massive distortion. That is no longer the case, and class D design from a sound perspective is just as good if not better in some cases than Class AB. While I am not referencing that here, there have been may test to prove this point.
Many audiophiles argue on this point. There are those that live and breath by the tube or class A design. And they would be right, they are the cleanest sounding amps available. The problem your car is not powered by a nuclear generator. Our cars have small alternators and 1 class AB designed amp would probably be ok if properly reinforced, 2 would be pushing it depending on the power output of the amp.
The Class D amps are designed from everyone these days including, ARC aduio, Pioneer, Kenwood, JL Audio, Alpine(My Choice) to name a few.
Additionally, the Class D vs Class AB or Class A are much smaller because of the design requirements. As we have small cars with small charging systems, The class D will suit almost all of the demands you could have for your system.
As an example, the Alpine PDX-V9 Amp, here are the specs, this is a class D design
Power Requirements: 14.4 V.DC (11-16 V allowable)
Input Sensitivity (RCA Input): 0.2 - 4 V (CH1/2, CH3/4), 0.1 - 4 V (Subwoofer)
Input Impedance: >10k ohms
Frequency Response (+0, -3dB: 1W into 4 Ohms) for CH-1/2/3/4: 3 - 100k Hz
Frequency Response (+0, -3dB: 1W into 4 Ohms) for Subwoofer: 3 - 600 Hz
THD+N (10W into 4 Ohms) for CH-1/2/3/4: <0.005 %
THD+N (10W into 4 Ohms) for Subwoofer: <0.006 %
THD+N (Rated Power into 4 Ohms) for CH-1/2/3/4: <0.03 %
THD+N (Rated Power into 4 Ohms) for Subwoofer: <0.05 %
Damping Factor for CH-1/2/3/4: >500 into 4 ohms at 100Hz
Damping Factor for Subwoofer: >1000 into 4 ohms at 100Hz
Signal to Noise (Rated Power into 4 Ohms) for CH-1/2/3/4: 112 dB
Signal to Noise (Rated Power into 4 Ohms) for Subwoofer: 119 dB
Weight: 2.7 kg
This is one of the cleanest sounding amps available by any measure.
Audiophiles also disagree on the point of Class D being as good as Class AB. Every amp I have ever used save one system has been Class AB. Pioneer in their ODR systems offered Class A designed Amp, but even though I owned 2 ODR systems in vehicles, I never used the Class A amps, because of the car I was using and the power requirements of those amps. Everyone I knew that did use the Class A amps, had to upgrade their cars electrical systems with multiple batteries and upgrated alternators with caps.
So when you are going to get an amp for your ride, give the design consideration. It is my opinion, that with the way the industry is going, Class A/B design is going away in lieu of the Class D design.