Digital or Analog Amplifier?

[etosaiyo]

Is it worth buying the class D amp? Does is it really make a difference in sound quality?

[sientobente]

Hi, a class D amp isn't a digital amp but rather it is the topology used in constructing the amp. It is still an analog amp since it should accept analog signals. The difference between a class A and D if I can describe it properly, is like this. Imagine a 1 meter straight line.

Class A has a solid straight line.
_____________

Class AB might be solid on on the first 75% and dotted until the end
_______ _ _ _ _

while Class D is half solid, half dotted line.
_____ _ _ _ _ _ _

The solid line represents a straight clean signal, while the dotted line is processed signal.

This is one of the reasons, why class A or AB is still preferred for Audio. But don't get me wrong, there has been advancement on class D amps nowadays which can match some Class AB amps. So it would probably depend too on which particular class D amp are you looking at. The main advantage though why Class D is getting some popularity is because of efficiency.

[oj88]

The 'digital' nomenclature in Class D amps does not talk about the input or output but how this topology makes the transistors switch on and off very fast (PWM or some other types of modulation). The efficiency in Class D amps came from the fact that transistors don't waste much power when they're either passing current or blocking them (switched on or off). Transistors becomes lossy and lose efficiency if it is only partially passing/blocking signals (ie. Class A, AB amps).

Class D amps are ok typically for subs. Purists would still try to avoid them for any other purpose. Also, not all amps are the same. Some Class D amps lose more sound detail than others. Though, the filtering technology have vastly improved and is still improving.

[sientobente]

I agree. There are amps though that you might think are digital, like the Zapco Reference and Audison Prima because of their optical inputs, but in reality, these are still analog amps with a preamp stage that accept digital inputs and has it's own DAC to convert the signal back into analog when it goes into the amplification stage.

[etosaiyo]

Thanks guys for the reply. I was looking at the Alpine PDX V9 and based from your responses as well from a friend's advice, I think class AB would suffice although nowadays class D is getting more efficient.

For class AB amp, what do you recommend?

[sientobente]

I now get the confusion, because Alpine advertises that amp as a Power Density Digital Amplifier. That PDX V9 is actually one of the better Class D amps out there. I think it is now rare to get one of those.

[jhnkvn]

Alpine's are expensive locally due to the taxation laws. If you plan on using yours for personal use, it might be a better idea to import.