How Do Acoustic-Electric Guitars Work? (Pickups, Amps & Mics Explained)

How Do Acoustic Electric Guitars Work

This is always helpful information to know before you buy. Rarely does a willy-nilly guitar purchase ever become a longtime, worthy buy.

You might want to know how an acoustic electric guitar works in order to maximize use and amplify acoustic harmonies.

You might just want to know how to make your guitar sound better plugged-in.

To keep things simple, we’ll take the stance of defining a stage-ready guitar (already factory-set with pickups/preamp) versus an acoustic guitar that’s going to be overhauled with custom electronics.

Without getting too wordy with jargon that can confuse the heck out of you, we’ll give it to you straight. Here’s how the cogs and gears work to bring about the awesomeness of music magic!

How Does an Acoustic-Electric Guitar Make Sound?

We have to start somewhere, so we may as well start with the fundamentals – the organic way sound is made. Since there are a lot of factors involved in the amplification part of an acoustic electric guitar, we’ll cover the basic idea of how sound works here and then cover the electrical components later.

First off, what makes the sound in an acoustic guitar? On both an acoustic and acoustic-electric guitar, you have the strings that create vibrations when plucked or strummed. That vibration reverberates across the span of the soundboard (top tonewood surface) and also travels down the strings to the saddle and bridge of the guitar. Those vibrations “move” air within the air cavity called the soundhole. The resonance created in the soundhole depends on its depth/size and the tonewoods used to make the back and sides of the guitar. Voila, you now have sound exiting through the soundhole of the guitar.

On an acoustic-electric guitar, additional electronic components are incorporated to convert string vibration into measured units of voltage. Those fluctuating frequencies of voltage are then, in a round-about way, sent to the amplifier for amplification.

acoustic electric guitar anatomy
Image Source:

When an acoustic-electric guitar is plugged in, you don’t need to soley rely on the soundhole or vibrations directly from the strings for projection. Instead, the electronics sense the vibration energy moving across the soundboard and body of the guitar.

This takes away the inconvenience of having to stand static with an acoustic guitar in front of a mic for performances, and it also reduces the need for a built-in mic in the soundhole that can often cause feedback, and you don’t need to strum and pick so hard to be heard.

So, what’s that round-about way we just mentioned, and what exactly are the electronic components? Now, you’re askin’ the good stuff!

The Transducer

On an acoustic-electric guitar, you’re going to need a transducer of some sort. It’s the device that picks up sound wave vibrations and converts it into an electrified form. You can have:

  • Magnetic/Soundhole pickups
  • Contact pickups/Soundboard transducers
  • Undersaddle transducer/Piezo pickup
  • Built-in mic
Pickup + Microphone: Image Source

Some guitars incorporate a “blend” of both magnetic and piezo pickups, and others may have one of these options with an internal mic. All nylon string guitars with the option of pickups will always have piezo pickups and/or a built-in mic because there’s no way to sense vibrations from nylon – a non-magnetic material. But, many acoustic electric guitars have steel strings, so what options can you expect with these?

Most of the time, you’ll almost always see a piezo pickup on an acoustic electric guitar with the addition of an on-board preamp. Typically, it will be installed underneath and in contact with the saddle on the bridge of the guitar where it can effectively pick up vibration energy. This specific type of device is called an active undersaddle transducer. This type of pickup is often paired with other pickups and microphones to provide versatility for sound options, and to produce a richer, more organic and natural sound. A piezo pickup and other types of electronic pickups are what we call active pickups.

Passive VS Active Pickups

Passive pickups are similar to internal microphones that essentially just pick up the vibrations and soundwaves and send it straight to the amp. You bypass the need for a preamp that means you typically lack the ability to enhance, shape, and change sound and tones. Simply put, if you just want the ability to plug in for acoustic goodness, a passive pickup is a decent device. However, if you want to achieve more controlled volume and other features, you’re going to need to install a preamp at some point or simply opt for a guitar with an active pickup.

Active pickups require a power source such as a battery, often seen in either AA or 9V sizes. Most of the time, you’ll see this on-board preamp on the top side of the guitar. There, you’ll be able to see if you have a blend of both a pickup and a mic option where you can either slide or switch between the two.

This preamp can also offer a gain control. Essentially, it’s what drives the power levels of the signals to the amp, but it can also boost volume. If the preamp doesn’t have a gain control, it can be assumed that it’s already factory-set to a certain level of gain. One way around the lack of a gain control is to use the volume control on the main amp. Either way, it’s very helpful when you find you need to compete in a multi-instrument band when you feel like you’re being drowned out or you’re experiencing unwanted feedback when you do try to vie for being heard.

Internal Mics

Built-in mics aren’t necessarily the budget option as they can be seen on some high-end guitars. They’re extremely helpful when you need volume but not so much where the acoustics of your setting, say in a concert hall, carries sound projection for you. However, the internal mic can raise problems for the performer as they’re prone to producing unwanted feedback. Multi-blend pickup and preamp systems allow you the flexibility to switching out from the mic when it proves to be problematic. However, if you’re going to install one yourself, look for one with a high feedback resistance of exceptional quality.

Acoustic Guitar Amps

Getting the right amp for your acoustic electric guitar is definitely something you want to think about. You can have a guitar that sounds stunning when plugged in, but not so much when playing acoustically. Reversely, you can also have a guitar that sounds absolutely beautiful acoustically, but sounds like a tin can when plugged in. Sometimes, this is just due to plugging into the wrong amp.

An acoustic guitar amp amplifies a guitar’s natural sound. You want to keep it clean but make it loud. Features you’d typically see on an acoustic guitar amp are:

  • Feedback control
  • Various built-in effects
  • Dual channels (at least for guitar and microphone)

There are still other factors that you may need to consider, such as type, power, and speaker size. For all of that kind of talk, amp out our “Amp Buying Guide” for all the tips you’ll need while shopping for one.

Acoustic VS Electric Guitar Amp

Yes, there’s a difference. Of course, you’ll need to evaluate your style of playing and what sounds you want to achieve from your guitar and amp. An electric guitar amp is typically designed to focus on the mid-range and treble frequencies while also aiming to achieve distortion effects so often heard in the rock genre.

Can you plug an acoustic-electric guitar into an electric guitar amp?

Yeah, give it a go! The amp may not reflect the pure sounds of your acoustic, and you’re definitely going to have to twiddle around to achieve acoustic attitude without feedback. It can be done. But, if you’re not too much into experimenting, just stick with an acoustic guitar amp.

Small Devices With Huge Impact!

As you can see, we didn’t really cover magnetic and soundhole pickups or contact pickups, simply because we kept it simple with acoustic-electric guitars that sport the typical electrical equipment. Keeping it simple helps you understand the fundamentals of how an acoustic electric guitar works.

For such small electronic devices, they certainly have a huge impact when it comes to sonic projection, sound versatility, and player confidence!