Hey, I'm JR, training manager here at Crutchfield, and in this video we're going to talk about
amplifier classes. If you're shopping for an amplifier to power speakers in your car or in
your home, you might come across things like Class A, or Class AB, or Class D amplifiers, and hopefully
we're going to make some sense of what those classes mean and why they're relevant to you.
To understand amplifier classes, we should first break down basically what an amplifier is, and we're not
going to get super technical here, we just want to make sure you understand what an amp does. An
amplifier combines input voltage; in a car that's about 12 volts, in your home that's about 120 volts.
Input voltage is combined inside of an amplifier with musical signal. It comes in on some inputs.
It combines the voltage and the music to produce output power, measured in wattage. That power gets
sent over speaker wire to your speakers, and it makes them move in and out, which is how you hear
music. So now that you know how an amplifier works, it stands to reason that different amplifiers are
more efficient at converting input voltage into output power, and that's where amplifier classes
come into play. First we're going to talk about Class A amplifiers. They're often referred to as
amplifiers that are "always on." The parts of the amplifier that are responsible converting that
input voltage to output power are always on, and as a result they are actually very inefficient
but sound really good. They waste away about 75 percent of that input voltage as heat; the other
25 is warm, fuzzy music that sounds amazing. You're gonna find Class A amps in high-end home audio,
headphone amplifiers, phono preamps, and guitar amps. Guitarists love Class A amplifiers because
they sound so warm and fuzzy. They sound great, but they're very inefficient. That's why we
don't see them at all in car audio. Next up is Class B, which is really not much of a thing in
the world of audio. Class B amps, those parts that convert power into music are off until
they need to be turned on, and that switching on and off is horrible. It creates distortion.
It is more efficient, but it's just not good enough to use in any home or car audio application. Next
up, we're going to talk about Class AB amplifiers. They combine the benefits of both Class A
and Class B amplifiers. Those little parts of the amplifier that convert input voltage
to output power, they're never fully off like a B amplifier, but they're not always fully on like an
A amplifier. They're somewhere in between. They're always on, but just a little bit, so they're ready
to go to make power, to make output, to make music, and they're roughly 60 percent efficient at doing
that, so most of the input voltage is converted to music, and you get to hear it. Now they're not fully
efficient, right, there's still about 40 percent of that power getting wasted away as heat, so
they're a little bit larger. They need heat sinks to dissipate that heat. Positioning in car audio
is very important, but they're fairly common in car audio and in home audio. Next up is Class D. Quickly
becoming the most popular, the most common style of amplifier because they're highly efficient
and can be made much smaller, and they produce a lot less heat. One misconception: they're not
digital; Class D is not a digital amplifier, it's just another class. They're roughly 90 percent
efficient at converting input voltage into output power, wasting away only about 10 percent as heat,
so they can be made much smaller. They can be fit into smaller nooks and crannies in your car,
they can be used on your desktop to power some headphones or some speakers, and because they
are so small and so efficient they're used all over the place. Most car amplifiers are now Class D
amplifiers. Many home amplifiers are Class D. If you have a portable Bluetooth speaker like this
one, there's a Class D amplifier inside of there powering these speakers, because it's small and
it doesn't get hot. That's the last thing you want in a Bluetooth speaker. So Class D: the most common,
and they sound great. They've come a long way. At first, Class D amplifiers were really only good for
powering subwoofers where distortion really isn't a concern. However, now they are really good enough
to be used in very high-end home gear, headphone amps, PA systems, car amplifiers, and pretty much
anywhere amplification for audio is needed, you're probably going to find Class D amplifier options.
You might also see some other amplifier classes as you're shopping for amplifiers, like Class G,
Class H; you might see other terms that seem like they are proprietary technology for a particular
brand of amplifier, and that's really all they are is variations on these different amplifier classes
with some proprietary special sauce mixed in to make sure you
know that their amplifiers do a great job at converting input voltage into output power.
So do you need to care about amplifier classes? Probably not. Here's what you do need to care about:
does it have enough output power to really drive your speakers? Does it fit where you want to put it?
Obviously, that's very important in car audio where space is limited. What really makes a lot more
difference is the quality of each component in the amplifier, and as you spend more each component
gets better and the amplifier does a better job of giving good, clean audio to your speakers. So
get the right amp, but you probably don't need to worry too much about what class the amplifier is.
So if you have any questions about amplifiers, get in touch with us. All of our advisors are trained
on this stuff, and they can really help you out. Go to crutchfield.com/contact to talk live with one
of our folks, either on the phone or chat with them online. You can also post your questions
here on this YouTube video. We do look at those and we will respond accordingly. And as long as
you're here, go ahead and like, subscribe, and turn on those notifications. Thank you for watching.