Digital amplifiers?

December 13, 2012
 by Paul McGowan

Whenever a conversation comes around to Class D amplifiers, they will inevitably be referred to as digital power amplifiers; a common mistake. They are not digital power amplifiers. They are as analog as class A and Class A/B amplifiers and it’s important to understand the distinction lest they get a bad rap merely by their name (although it’s still a mystery to me why “digital” associated with an amp is looked down upon).

What one can say about a Class D amplifier is their method of operation is clearly different than that of a traditional power amp and, of course, they are far more efficient because their transistors are either on or off (like a digital amp), yet they are still analog. What gives?

How could a power amp whose output transistors are either on or off (and no where in between) be classified as analog which, by definition, means the sound is not broken up into small defined quanta or bits?

This new series will explain this great mystery and set the record straight for those of you interested. But first I want to start with what we consider a traditional power amplifier and then we’ll move on to Class D.

Tomorrow we’ll start with an overview of the many classes of amps and what they mean.

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3 comments on “Digital amplifiers?”

  1. Now the mainstream Digital Amplifier is PWM based?? At the very beginning of SACD launch to the market, sharp made a Amplifier do Digital Amplification in 1-bit Delta-Sigma format, by using non-standard connector, sending DSD stream out to Amplifier to do direct amplification with DSD signal. I hope we will have direct DSD PWM amplifier very soon, so not converter required to reach purest form of amplification.

  2. I am sure one thing we’ll agree on, no matter what the amplifier topology, no matter what devices are use,d no matter what principle it’s based on, no amplifier can be better than its power supply. I hope you will spend some time talking about the parameters that power supply are judged by such as line and load regulation, slewing rate, energy storage, output impedance, etc. These basics can spell the difference between excellent and mediocre amplifiers of whatever type you like best.

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