Acoustic guitars are one of the most commonly used instruments in music today. These guitars have been used to play a variety of music genres globally and can come in a fairly wide span of shapes and sizes.
Acoustic guitars can be used in so many great playing environments, from studio recordings and concert performances to fire-side jams and intimate house shows. I’ve put together this brief guide to the different parts of an acoustic guitar to help you better understand how it works.
Acoustic guitar diagram
There are several types of acoustic guitars, but they all generally have the same parts. I like to break the anatomy of an acoustic guitar down into three primary areas:
- The body: The body is where the acoustic guitar generates sound and usually consists of a soundhole, pickguard, and bridge.
- The neck: The neck is supported by a truss rod and is home to the guitar’s fretboard.
- The head: Consists of the headstock, tuning pegs/machine heads, and connects to the neck through a joint called the nut.
Let’s take a closer look at each area of the acoustic guitar, including some of the finer mechanisms used in its construction.
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The headstock is the very top part of an acoustic guitar and is furthest away from the body. Most acoustic guitars have a headstock with three tuning mechanisms on each side. These mechanisms consist of smaller parts called the pinion gear, worm gear, and string post and are used to secure the guitar string and tune them to a specific pitch.
2. Tuning pegs
There are six tuning pegs at the head of the acoustic guitar. These pegs look like metal or plastic ears that you can rotate clockwise or anti-clockwise. Turning the pegs tighter will increase the tension of a guitar string and raise its pitch. Turning the peg the other way will decrease a string’s tension, lowering the pitch accordingly.
3. Machine heads
The machine head and tuning pegs often get mistaken for each other. However, the tuning peg is the mechanism that you physically turn to change the pitch of a string, whereas you can look at the machine head as the entire tuning mechanism.
The machine head is the small collection of parts located under the tuning pegs. When you twist a tuning peg, a pinion gear works with a worm gear to turn the string post (where the guitar string is tied off).
The capstan is another term for the string post, where the acoustic guitar strings are tied off at each machine head. The capstan looks like a small metal cylinder with a hole for threading and tying off the guitar string. These capstans are fixed to the guitar head with a thin metal nut and washer.
The nut of a guitar plays a vital role in the playability of a guitar, as well as its ability to hold tuning after frequent use. The nut is a thin piece of plastic, wood, or ivory and is slotted at the joint where the headstock meets the neck of a guitar.
The guitar strings run over grooves in the nut over a guitar, and its positioning determines the acoustic guitar string height (or action).
It’s always best to get your guitar’s nut adjusted by an experienced luthier or repair service. The slightest mistake could render your acoustic guitar unplayable.
The neck of a guitar is a long piece of wood that connects the headstock to the body. Most acoustic guitar necks are rounded at the back to fit the shape of your hand and have a fretboard on the front with 20-24 frets, depending on the size of the guitar.
Acoustic guitar necks generally have three curvature profiles: C-shaped, U-shaped, and V-shaped. Each shape is made to suit different hand shapes and preferences. Knowing which shape suits you best can go a long way in improving your left-hand technique.
Inside the neck of a guitar is a truss rod, which acts like a spine to give the neck structural support. The neck can be joined to the body using a variety of fixtures. Some of the more common fixtures are set necks, bolt-on necks, and neck-thru.
- Set necks: A simple fixture where the neck is glued directly onto the body of a guitar. Very common in acoustic guitars.
- Bolt-on necks: This fitting uses a bolt to screw the neck onto the body for additional support. This is most common with electric guitars.
- Through necks: Through necks have a fitting that runs through the body of the guitar. These are the sturdiest type of guitar neck but are also more difficult to repair and service.
7. Truss rod
The truss rod is a long piece of steel that runs through the neck of a guitar from the headstock to the body.
You can access the truss rod through the head of the guitar if you need to change its rigidity. Altering the truss rod will also affect the action of the strings, so be sure to get this done by an experienced professional.
The fretboard (sometimes referred to as the fingerboard) is the most used part of an acoustic guitar. This part is loced on the top side of the guitar neck and is responsible for a guitar’s pitch. When you play guitar, you push the guitar strings down onto different areas of the fretboard to change their pitch and to create melodies or chords.
Guitar fretboards are generally constructed using softer woods like maple or rosewood. These woods help reduce the excess vibration of strings when you press them down into the fretboard.
The fretboard is split up over specific intervals using a raised metal wire. These intervals are called frets and are used to map out each string’s respective pitch along the neck of the guitar.
Your guitar’s fret sizes will depend on the size of the guitar and will determine its playability and general tone.
Acoustic guitars generally have markings on frets 3,5,7,9,12,15, and 17 to help players navigate the fretboard. These markings, or inlays, usually consist of dots or small diamonds.
Some guitar manufacturers will use inlays as a space to mark their brand or logo, while other craftsmen create more intricate inlay designs like fire, flowers, dragons, etc.
The heel is on the back or curved side of the acoustic guitar and is the joint where the neck meets the body. These generally come in a standard shape and may have a strap button fixed on them to hang your guitar strap.
The body is the chamber that generates the acoustic guitar’s resonance when the strings are strummed. The body is generally the largest part of the guitar, sits below the neck, and consists of a flat top, curved sides, and a back.
Most luthiers or guitar service professionals split the guitar’s body up into three main areas. The lower bout is the bottom of the body and is the widest part. The waist is the middle part of the body and is where the body curves inwards. The upper bout is the top part of the guitar body and can sometimes feature one or two cutaways.
The soundhole of an acoustic guitar is a round opening on the body. It allows the sound produced by the strings to resonate and project outward, enhancing the guitar’s volume and tone.
The bridge is where the guitar strings are secured to the guitar’s body. The bridge sits below the soundhole on top of the guitar and is generally fixed to the guitar using a strong adhesive. Strings can either be tied into the bridge or plugged into the body using bridge pins.
The bridge is also responsible for moving the vibration of the string through the top of the guitar and into the rest of the body. A badly fixed bridge can severely affect your guitar’s resonance, so be sure to have this checked out whenever you get your guitar serviced.
The saddle works just like the nut of the guitar and sits on top of the guitar’s bridge. The saddle is slotted into the bridge to set the height of the guitar strings over the body and neck. Adjusting the saddle will affect the action of your strings, as well as their overall resonance.
The cutaway is found on the upper half of the body. As the name suggests, this part is a curvature that is cut into the body of the guitar to give the player easier access to the higher notes on the fretboards. Guitars can come in a single or dual cutaway, but most acoustic guitars don’t feature a cutaway at all.
17. Soundboard (Top)
The soundboard is another part of an acoustic guitar. It is a piece of wood that sits on top of the acoustic guitar’s body. The soundboard is used to fit the guitar’s bridge and also has the soundhole cut into it. The soundboard vibrates when you strum the guitar, so it has to have a certain flexibility in its properties.
Because of its purposes, the choice of wood in a soundboard, or top, is crucial, as it can largely determine the guitar’s resonance, tonal characteristics, and, ultimately, the quality of the guitar. The most common choice of wood for acoustic guitar tops is cedar, spruce, and maple for their durable but tensile nature.
Certain acoustic guitars may come with a circular pattern that surrounds the soundhole. This design is known as the rosette and can be used by the manufacturer as a personal trademark or to improve the guitar’s aesthetic.
The pickguard is a small, flat piece of material that is fixed to the soundboard just below the soundhole. The pickguard helps protect the body from scratches when you strum the guitar with a plectrum and can also add a nice visual touch to your guitar’s design.
20. Strap Buttons
As the name suggests, strap buttons are small steel buttons that are screwed into the guitar’s body and are used for securing your guitar strap. Not every acoustic guitar comes with a set of strap buttons, but a trained professional can install these.
Whether you’re an experienced player, beginner guitarist, or curious craftsman, it helps to know the various parts of an acoustic guitar and how each part functions. You can use this guide above to better understand the acoustic guitar and its fundamental mechanics.
What seems like such a simple instrument requires a fair bit of skill, knowledge, and craftsmanship to construct properly. It certainly makes me appreciate every chance I get to play a high-quality acoustic guitar.