Class A B AB D & H Audio Amplifiers Explained

Ever read audio equipment marketing literature and not know what the heck they are saying? Class A...huh? Class D? See links to more information below.

[jimmyv]

I was hoping for a little more info on the class D but I guess I’ll look elsewhere. Thanks

[bradmodd]

You forgot Class I, Class AB+B and Class G. These are crown, crest, yamaha, qsc marketing terms, technically speaking they are probably all class H.. I assume so anyway.

[edwardfanboy]

Class AB and class D amplifiers are the most common, not class A. Also, you didn't explain the unique characteristic of class D: Instead of the transistors controlling the current flow continuously, they switch the current flow rapidly (at 200+ kHz) on and off. This creates a small amount of noise, but it allows much more output power: A 15W/channel (peak) class D amplifier is smaller than a 3-watt-per-channel class AB amplifier.

[stevensmith]

Glad to see you back, hope every things ok with you.

[justinhiggins]

Car audio amplifiers are by lightyears the most powerful amplifiers ever made

[tortillaman]

I’m building a time machine. This video will help me.

[ThinkingBetter]

The description of Class D amplifiers is totally nonsense. He says "Class D uses output transistors". Actually use of transistors has nothing to do with Class D. You also have output transistors in the other types. Well, you can use vacuum tubes also for all of them. Rather class D is a type of amplifier where energy is conserved by not attenuating the output voltage over resistive transistor/vacuum tubes but rather through low-pass filtering (using capacitors/inductors) a high frequency switched digital signal to make it appear analog. As the (ideal) capacitor and inductor operate without energy loss, the efficiency of a class D amplifier can be more than 90%.

[Oystein]

Class A is not the most common. Class AB is the most common... And class D has also become very common in later years. But a class AB often sounds better than a class D. Atleast it used to.
And some amps even start as a pure class A and then switches over to class AB at higher power outputs.
A class AB is generally 50-60% efficient while a class D is about 90% (+/-)
And class A, B, AB etc all normaly have solid state transistors unless they have tubes. Some can also have both solid state and tubes.

[flyhouseoftruth]

I thought class ab amplified the signal as is, as it comes into the amp, and then the class d filtered out the high FQ before amplifying it allowing only the low FQ to be amplified. Making it more efficient if your using it for subs only. Some class ab amps allow for a low or high pass, but the whole signal gets amplified, anything filtered out is wasted power. That's why they told me if I was only driving subs, class d is the way to go.

[nickr]

Good to hear from you! Hope everything worked out in your personal life. Or is in the process of working out for the better.

[MatthewSuffidy]

A is probably is the best though, but not the most efficient.

[johnrobertbarela]

What does it all means?but, after i watch this video i know nothing...lol

[bloodlord]

What about tube pre-amps or is that a different category?

[JFK]

Class D was incorrect. It does not use transistors it uses MOSFETS. They can switch a lot faster than transistors and it modulates the audio via driver chips that uses a pulse with modulation to turn on and off the MOSFETS. The MOSFETS do not operate as linear devices they operate as high speed switches. The audio is fed into the chips and converted into digital pulses that turn the MOSFETS on and off creating a digital pulse width train. After the MOSFETS amplify the modulated digital signal you then filter out the high freq. components before it goes to the speaker and you are left with the reconstructed audio signal.

[alexandremarus]

class D uses MOSFETs on the output not transistors just pointing that out

[AltMarc]

Class A 50lbs, class B 20lbs, class D 2lbs and class H …still too heavy….