Understanding Tonewoods and Acoustic Guitar Parts

The acoustic guitar is a marvelous and perfect grab-and-go instrument for the company picnic, backyard barbecue, campfire gathering, and just about any informal social rendezvous.

Its portability and versatility make it a must-have model for every six-string hobbyist. But, with so many makes and models, how do you choose? That’s why I put together this short guide on what to look for when buying an acoustic guitar.

I’ve had three guitars custom-built. Two solid-body electrics and, currently, an electric bass guitar. While these aren’t acoustic guitars, many principles still apply, and the attention to detail is worth noting. I began my custom building research in 2018.

I was introduced to a local luthier and started doing my research—where much of the foundation for this article comes from. Of course, this was from an electric guitar perspective.

I’m considering a steel-string acoustic and returned to my old research and added some new research. For completeness, this is where I list largely overlooked acoustic guitar parts.
In talking to luthiers, I discovered this is the process artists go through when creating a signature model.

So, I put together this Understanding Tonewoods and Acoustic Guitar Parts guide for you, serious beginners and seasoned electric players, as you shop for a quality acoustic guitar. Especially if you’re a crossover player.

Crossover players are guitarists that are transitioning from electric to acoustic. This term also refers to steel-string players switching to nylon and vice versa.

Bottom Line Upfront

There are so many options for today’s players that it can be overwhelming when first purchasing an acoustic guitar.

The price and look are the determining factors for the average strummer and beginning guitarist. But, for the serious player (beginner, pro, or every level in between), choosing an instrument is an investment, and you want to choose wisely.

The construction of every part of the acoustic guitar affects the sound, feel, comfort level, and playability. And this is true for instruments of every class, style, and price point, from budget knock-around guitars to high-end vintage collectibles. If you’re serious about making a well-informed purchase, do your homework.

This article will give you an overview of the functions of the different parts of the guitar’s anatomy, the various kinds of wood used, and what to look/listen for. You don’t need to understand the math and science behind the construction and wood properties. This information is to help you label the sounds that you like.

And that’s the bottom line, let your ears and hands decide. Keep your heart and eyes in check.

My 3 Tips for Buying an Acoustic Guitar

These areas are largely overlooked, and I discovered their importance in my search for sound, feel, comfort, playability, and tone. Try many makes and models, and when you find something that creates a strong emotion (good or bad), make a note of it. The first three areas to focus on are the scale length, nut width, and body types.

Scale Length

The scale length directly affects the tension of the strings and how the guitar feels to play, and it can also affect the sound. The longer the scale length, the higher the tension to tune to the proper pitch.

Dreadnoughts and Jumbos are standard longer-scale length models. These measure between 645-650 mm (or 25.4-25.6 inches). These guitars are known for their low-end richness and are perfect for the campfire singalong.

Some Gibsons and Martins (000 and OM) models fall into the shorter scale category, measuring 628-632 mm (or 24.75-24.9 inches). Also, parlor and travel guitars can have even shorter scale lengths. These are sometimes called concert-size guitars and are my preference for steel-string acoustic body size.

Nut Width

This is a significant factor in any guitar’s playability, and acoustic guitars have many standard nut widths. Nut widths range from 41.2-47.6 mm (or 15/8-1 7/8 inches). And you’d be surprised about the difference that 1 mm makes in the feel.

Body Types

Finding a body type that allows you to sit and play comfortably is essential. Each body size has pros and cons, so you should consider your playing preferences (music style, fingers vs. pick, etc.).

In short, play a few different guitars keeping in mind the scale length, nut width, and body type. The last thing you want is an acoustic guitar that’s pretty but uncomfortable to play.

Tonewoods

The Top Wood

When choosing a tonewood, you must find the sounds your ear likes. Let’s begin with the top wood, which is responsible for the initial sounds you hear. It’s where the initial attack and vibration take place. So, the top wood is responsible for the response that you hear. You can think of the back and sides as the EQ.

Most acoustic guitars have a light-colored top made from a species of spruce. So, let’s look at the similarities and differences between the most common spruce species.

Sitka Spruce (Picea Sitchensis)

Found in the U.S. and Canada, this is the most common wood for acoustic guitar tops. Sitka Spruce is known for its strength, clarity, and dynamic range. This wood works for many different music styles and a variety of models. You can find Sitka Spruce on broad guitars, from cheap-and-cheerful models to top-line Martins.

German Spruce (Picea Abies)

Please distinguish German from the Engelmann Spruce (next entry). And, to add to the confusion, German Spruce is sometimes mistakingly called European Spruce—there are other varieties of European Spruces.

This wood is favored for classical guitars and violins. But, some manufacturers are having success using this for flat-top steel strings. Many believe that German Spruce shares many similar characteristics to Adirondack Spruce.

Engelmann Spruce (Picea Engelmannii)

This wood is native to the Western U.S. and Canada. It’s sometimes considered an upgrade to Sitka Spruce, while others will say that it’s different, not necessarily better. I side with the latter group. Engelmann Spruce is lighter and less stiff than Sitka Spruce. And, depending on the guitar, provides a slightly richer tone.

Adirondack Spruce (Picea Rubens)

The King of the Top Woods. I read that many years ago, but I can’t remember which magazine. Adirondack Spruce hails from the Eastern U.S. and Canada. It’s also called Red Spruce. This wood can be driven hard while retaining its tone and dynamic response. This is also the most expensive of the bunch.

What Do I Play?

A Taylor 312ce-N series Grand Concert. It has a Sitka Spruce top and Sapele back and sides—I love it.

All spruces are not created equal, and this short guide should help you understand (and listen for) the differences.

The Back and Sides

We all know that the back and sides influence the guitar’s tone. But how? And, more importantly, what do I look for? First, we need to understand the back and sides’ functions.

The back and sides direct the sound energy to the top, which functions as a speaker cone. I look at the back and sides as the EQ.

If the back and sides are soft and flimsy, they will absorb the energy produced by the string’s vibration. We want that energy directed into the top, and we want that top to dance up and down and push air. The back then reflects the air through the soundhole towards the listener.

The Anatomy of the Back and Sides

Bracing: The back of the guitar needs to be braced for strength. The top uses different bracing systems depending on makes and models, while the back uses a ladder bracing system.
Neck Block: The neck block is a vital component of the guitar body, and it’s either glued, crewed in, or both. The design depends on the neck joint (which I’ll cover next week).
Lining: This joins the top and back to the sides. These used to be long strips of wood with slits (or kerfs) cut along the entire length. The kerfs are machined and provide a light and flexible surface. The top, back, and sides are glued to the lining.
End Block: This houses the rear strap button/endpin while joining and strengthening the butt of the guitar.
Side Struts: Not all acoustic guitars have these, but they’re installed on some guitars to help prevent splits.

Back and Side Tonewoods

Here are some highlights and what to look/listen for when considering the back and sides.

Rosewood

There are a variety of species of rosewood, and it’s known for its rich and warm tone. Indian tends to be dark, Madagascar is lighter, and Cocobolo is highly figured. These sound warmer in low mids and have more presence in the trebles than mahogany. Brazilian (or Rio) rosewood is the big one and protected but the holy grail of rosewoods (if you can find it).

Mahogany

There is a misconception that mahogany is lesser of a tonewood than rosewood. It’s more accurate to say that it has a cleaner and more direct sound than rosewood. It has fewer mid-overtones but a pronounced bass response with solid trebles. Look for this paired with spruce. Also, mahogany is confusingly applied to many related woods from the Americas, Africa, and Asia.

Sapele

It’s similar to mahogany, just not as pretty. Sapele is an African wood that is in plentiful supply and sustainable.

Ovangkol

This is a rosewood alternative. Also, from Africa, that is lighter in color and less expensive. It’s a great all-around guitar-making wood.

Maple

This heavily-figured wood looks beautiful. It has a bright, punchy character with less warmth in the mids than rosewood or mahogany. If you’re a hummer and strummer, closely examine this wood.

Koa

This wood is stunning and sometimes used simply for its aesthetic. It falls tonally somewhere between mahogany and maple.

Walnut

Another beautiful hardwood. This fall somewhere tonally between mahogany and rosewood.

New Woods

Environmental concerns and legislation over the use of tropical hardwoods have several manufacturers looking for sustainable alternatives. So, don’t be put off by an unknown timber.

Laminates

These have received bad press over the years. But high-pressure laminates (HPL) are modern, sustainable, and share some of the tonal characteristics of the above.

Parts Largely Overlooked

You’d be amazed how the sum of every little detail affects the instrument’s tone, comfort, and playability. So, pay attention to these little details.

Neck

The neck needs to be stiff to transfer the kinetic energy of the string’s vibration to the bridge and top. Mahogany is one of the most common neck woods, with Spanish Cedar and Maple also used. Maple laminates are also typical in the marketplace.

Headstock

Carving the headstock and neck from a single piece of timber is expensive, wasteful, and inefficient. Many makers use a different headstock attached to a scarf or finger joint; some may have a volute on the rear to increase the strength at this weak point.

Also, the “ears” (outer edges) of the headstock are often glued on. The headstock is angled back to create down pressure as the strings cross the nut, which helps the vibration and sound. Many headstocks have a decorative wood overlay to match the fingerboard and bridge.

Nut

This can be made of various materials, and each alters the tone in its own way. Some typical nut materials are synthetic ivory, plastic, bone, Corian, Tusq, brass, etc. I spoke about nut widths above, and serious fingerstyle players prefer wider nut options, while strummers lean towards tighter or ‘standard’ nut widths.

Neck Joint

You should know about two types of neck joints: glued and bolted.
The glued (or dovetail) is a traditional method for attaching the neck to the body. A shaped tail is cut into the neck block and fitted with a corresponding pin on the end of the neck heel. Purists prefer these and say that it’s the best to join.

The bolted (or mortise and tenon) method uses two holes for an M6 bolt that goes into the neck. There’s also a fretboard extension, and under that sits a mahogany block with small brass inserts bolted from underneath.

This creates a solid joint that can still be taken apart in a few minutes if you need to do a neck reset or any other type of maintenance. Martin, Taylor, and Collings use variations of this method to name just three.

Fingerboard

Most acoustic use ebony or rosewood (and other similar sustainable substitutes with similar characteristics).

Ebony is a dense wood that accentuates the tone’s high- and low-end clarity compared with rosewood. In short, ebony sounds brighter. Also, the fingerboard radius on acoustics tends to be flatter than most electrics, between 15 and 18 inches.

Frets

Acoustics are usually fitted with thinner frets than many electric guitars, probably due to less need for string bending.

Heel

Similar to the headstock, the heel on high-end/vintage-style guitars is carved and sculpted from the same piece of wood as the neck. Heels vary in shape and size, and this is the most logical, structurally sound position to add your second strap button.

Trussrod

This functions in the same manner as on the electric guitar; the truss rod counteracts the tension of the strings on the neck. It’s usually adjusted from the headstock end (underneath a truss rod cover) or through the soundhole.

Understanding Tonewoods and Acoustic Guitar Parts: Conclusion

Learning about what to look/listen for when buying an acoustic guitar can be challenging. There are a lot of little details to consider.

I’ve also mistakenly purchased my first acoustics with my eyes and heart instead of my hands and ears. I’ve been enamored with brands and the guitar’s aesthetics. And have, subsequently, made regrettable choices.

Today, I take my time; I’m talking months before pulling the trigger on a purchase. I research and play before I make a purchase.

Some companies offer a restocking fee for internet purchases, and I like this option. When you consider gas, traffic, time, parking, etc., the restocking cost doesn’t seem like much. And I get to try out the instrument in the comfort and distraction-free environment of my own home.

Many of you are like me and have guitars that become part of your lifestyle. When I consider a new guitar, I intend to have that for years to come. So, hopefully, this article will help you make that next selection.

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Ed Lozano, Managing Editor, Guitar Space

Managing Editor at Guitar Space

"I’m amazed that I still enjoy sitting with a piece of sheet music and learning something new after all of these years.”

Ed Lozano is a professional guitarist, instructor and author. He earned a B.F.A. in Commercial Arranging/Professional Writing from Boston’s Berklee College of Music. Ed has worked with Bob Dylan, Paul Simon, Tori Amos, Stone Temple Pilots, ACDC, and many others.