Where stuff happens
Bryan Galloup July 12, 2021
Those scalloped, tapered supports do way more than just keep your flattop from caving in.
Acoustic guitar bracing is something the general guitar-buying public rarely considers. And why would they? A guitar’s braces are hidden on the inside of the instrument and, with the exception of the back braces, are never seen at all. However, the fact remains: When a bracing system is combined with the soundboard’s material, it has the single most profound effect on the performance of a guitar. At their best, a guitar’s braces help to offer superior sound, response, and reliability. At their worst, they are either overbuilt, which makes a guitar feel laborious to play, or are underbuilt and fail prematurely. Guitarists simply need an understanding of what the various bracing styles are communicating, how they affect the soundboard, and what that might mean to the player.
Early Spanish-style classical guitars used gut strings. These low-tension strings allowed the soundboards and bracing to be thin and light. In the mid-1800s, the Martin Guitar Company worked to increase the stability of their soundboards, which ultimately culminated in the creation of the X-bracing pattern. At the birth of this innovative design, X-bracing was offered on gut-string guitars. As steel strings became more popular, X-bracing was recognized for its ability to ideally accommodate the increased tension. This marked a clear break between Spanish-style classical instruments and what would soon become the modern flattop steel-string guitar.
When a bracing system is combined with the soundboard’s material, it has the single most profound effect on the performance of the guitar.
As flattop builders worked to perfect the stability of this newfound bracing pattern, they continued to improve upon the sound of their guitars. Through shaping braces to lighten the system and by changing carving techniques, instrument makers found they were able to control soundboard flexibility. Many different bracing shapes emerged over time, each of which possess unique perks.
The most celebrated vintage steel-string bracing system is the scalloped brace. Guitars with scalloped braces are voiced by removing material in a scooping motion from the center of each brace. This makes the tops more flexible in the center, primarily underneath and directly behind the bridge. These guitars typically have a lower fundamental with a round and full high end.
Shortly after the end of WWII, makers began tapering their braces, which resulted in a shift that defiantly changed the sound and feel of these bracing systems. Guitars with tapered bracing have material removed from the perimeter of the braces, thereby “tapering” these braces back toward the bridge. Unlike scalloping, tapering shifts flexibility to the perimeter of the guitar. These tops routinely have a higher voice, giving the instrument a more responsive and defined sound that’s quicker to the touch.
I grew up on a 1957 Martin D-18, which was a great example of what tapered braces had to offer. Over time, I picked up a 1941 D-18 with scalloped braces. Even though these guitars were identical models, I had a preference depending on what style I was playing. In time, I perceived that I liked the 1957’s tapered brace sound for flatpicking due to its quick response and separation of notes. But my 1941’s lower fundamental was killer for rhythm accompaniment, something I found myself doing a lot of in the shank of my playing career.
Other options to consider were models like Martin’s D-35 or Gibson’s Country Western. Both of these guitars used lighter and smaller bracing absent of any scallop or taper. Instead, the smaller braces evenly dispersed the load throughout the top. While these lightly braced guitars confused many die-hard dreadnought players, the lower resonance and softer feel proved to be notably popular with fingerstyle performers and electric guitar players looking for an acoustic instrument with a lighter feel.
At this point, I should note that I’m referencing and comparing long-scale guitars. Even though it’s true that the lower string tension on a shorter scale might simulate some of the topics I’m referring to, that is a topic unto itself. Regardless, don’t be influenced by the hype surrounding bracing styles and become convinced it’s a feature you must add to your collection. Instead, consider some of these observations to help you find a guitar that optimally complements your playing style.
Bryan Galloup April 12, 2021
While there is no such thing as a “wrong” guitar, just consider what the right guitar could do for your playing.
When buying a new guitar, trying to differentiate between what you need and what you want can be a tough gig. What many do know, however, is that they aren’t looking to just buy another random guitar. They are looking for an instrument that will help them achieve a new level of musicianship or address a particular music style. I’ve been around quality instruments since 1975, so my personal preference for tone and feel in relationship to application has become very clear. It’s a process, but it’s one worth spending the extra time to get right. We’ve discussed body size, scale lengths, and string tension in previous columns. This month, we’re going to consider response and application—both incredibly important to consider when purchasing your next guitar.
First of all, resonance and response in relationship to any musical instrument are two sides of the same coin. It’s the balance of these two that greatly defines an instrument. Resonance, which is mostly heard and felt in your body, is set primarily by the instrument’s body geometry and flex. On the other hand, response is largely set by plate tension and material, both of which affect high end and attack. When these two are balanced correctly, that’s when the magic happens.
With any one particular type of guitar—such as a dreadnought, for example—there is a level of feel and responsiveness that defines the instrument, but those same qualities will still vary from one guitar to another. This can be confusing at first to the average player, but the good news is that having a better idea of what you’re looking for can quickly narrow the choices. Even better, it can significantly increase your chances of ending up with a guitar you’ll really enjoy playing.
When I think about the flattop steel-string guitar market, I think about three primary categories: the fingerstyle guitar, the high-power guitar, and the jack-of-all-trades guitar. The fingerstyle guitar is an easy one to talk about because the requirements of a fingerstyle guitarist are unique and defined. They are primarily after quick response with even balance from string to string and note to note. Additionally, they are looking for an efficient sound that comes to volume quickly, so headroom and raw power are not on their radar. This means that while a fingerstyle guitar is incredibly fun to play and easy on the hands, it will hit its maximum volume quickly when driven hard.
This means that while a fingerstyle guitar is incredibly fun to play and easy on the hands, it will hit its maximum volume quickly when driven hard.
On the other hand, the guitar typically desired by bluegrass players is a high-power instrument that offers lots of headroom. What you gain in headroom, however, you lose in response and feel, so that power comes at a price. Plus, it takes a lot of conditioning to develop the hand energy to drive these tops and keep them moving.
Finally, there is what I think the majority of players want: a guitar that will cover a wide range of music styles and one that is relatively quick to the touch. It has a respectable low-to-mid range response and is commonly found in medium to larger body sizes. That said, picking this guitar out of the crowd can be a challenge.
Remember that low end is mostly generated through body geometry, so, in the beginning, compare guitars of the same general body size to keep the decision making to a minimum. Once you’ve narrowed the field down to three or four prime candidates, ask the store owner or dealer to put new strings on all of them. This will serve as an effective way to compare the high-end and high-midrange response between the guitars.
And once your desired response has been identified, you can start comparing different body size options by going through the same process. By switching back and forth between, say, a dreadnought and an OM, you will find the low end you prefer to match your preferred response. Personally, I’m drawn to larger guitars with higher-tension soundboards. They are quick to the touch and require low hand energy, which allows me to play for hours without getting worn out. That said, everyone has their own perception of what is best for them.
The takeaway: Top response is a key element for every acoustic instrument that you should be mindful of when choosing your next guitar. With the correct guitar in your hands, you might find yourself able to break barriers you’ve been struggling with for years. I’ve seen it happen time and time again—when a player finally gets matched with the correct instrument, it can be a magical thing.
Would You Like Your Guitar Roasted, Toasted, or Baked?
“Torrefied” or “torrefaction” are words you’ve likely heard pretty often in the past few years in the context of musical-grade tonewoods. They refer to a heating process that changes the material properties of wood. The process was first developed to produce biofuel, and later to make construction lumber weather resistant. Because this process made wood lighter and more resistant to moisture, instrument makers took notice and began to explore the possibilities of applying the process to tonewoods.
When I first heard the term torrefaction applied to tonewood, I had a “hold-on-a-minute” thought: If it’s torrefied (which makes it water resistant), then how are you going to glue it together with standard water-based, guitar-making glues like hide glue or aliphatic resin? The answer is you can’t. So, what we’re most likely dealing with in treated musical-grade lumber is a unique process that would use cook times and temperatures different from those used for construction-grade lumber. This means that tonewoods are not truly torrefied, but rather thermally modified.
To make matters more confusing, each manufacturer uses its own trade name for thermally modified tonewoods in an attempt to carve out a unique slice of its marketing value. I’ve seen heat-treated tonewoods referred to as aged tone, specially aged, VTS roasted, toasted, baked, etc. I hope one day someone will discover how to cut the processing time and temperatures by 50 percent, so we could call it “half-baked” tonewood. Now that would be cool.
To grasp the basic process of thermally treating wood, we need to understand that wood is essentially a composite material made up of three main organic polymers: cellulose, lignin, and hemicellulose. When heated, these polymer chains begin to break down and the wood off-gasses some of these molecules. This makes the wood slightly weaker and less dense. Depending on the time and temperature, this process can improve the stiffness-to-weight ratio of the wood. But if wood is heated too long or too high, its stiffness-to-weight ratio can actually degrade. If done correctly, however, this process can imitate the effect of naturally aging wood.
But as of yet, there’s no substantial data available to back the statement that just because a piece of wood has been heat treated, it’s going to make a great guitar.
There are methods for altering tonewoods through thermal modification that have been patented by Yamaha and perfected by smaller boutique makers around the country, but again, these are not the same as the processes that are being widely described as torrefaction in today’s guitar market.
Another factor to ponder: The net gain from thermal modification is very small, generally in the range of about 10 percent. This means that through this process, the wood is either getting lighter or stiffer, but either way, we’re talking about very small amounts of positive gain. This also includes any changes in the damping factor within tonewoods, so to say that applying these techniques to tonewoods is going to make a massive difference in the overall sound or volume of the finished instrument is, well, highly questionable.
That’s not to say that thermally modifying instruments doesn’t have its place in our industry. The first time I saw a piece of what was referred to as “roasted maple,” I thought it was beautiful. Since then, I’ve seen instruments with thermally modified backs and sides made by Dana Bourgeois and bass necks by Roger Sadowsky, all of which were stunning.
So, why would you want to thermally modify a piece of wood? The goal would be to make a substandard piece of wood better, or to make a good piece of wood great, right? But as of yet, there’s no substantial data available to back the statement that just because a piece of wood has been heat treated, it’s going to make a great guitar.
In the end, even though we have a handful of pioneers like Bourgeois spearheading our understanding of this science, the jury is still out concerning the pros and cons of thermal modification. One thing for certain is that nothing will ever beat an already great piece of tonewood supplied to us by Mother Nature. It’s been proven through centuries of application that good ol’ high-grade tonewoods are the way to go for longevity and great sound for your guitar.
Just Say No to Cracks
In my last column [“Humidity—Friend and Foe,” March 2018], we defined the parameters of the “safe humidity zone.” And its importance was stressed because humidity control is the single most crucial step a guitar owner can take to protect instruments. But wait! There is more sad news. Stuff is going to happen to your guitars, and discovering a crack can be absolutely heartbreaking. Fortunately, damage is often repairable to keep your instrument stable and ready for action, but understanding what you are dealing with is key to making the best decisions during the repair process.
Lack-of-humidity cracks and impact cracks are without a doubt the two most common types. Lack-of-humidity cracks typically run along the grain of the wood. As wood shrinks in low humidity environments, it eventually reaches a point where the wood can stretch no further and, well, it cracks. Guitars with lack-of-humidity cracks generally show up in my shop around mid-October, which is about the time people turn on the heat in their homes and the relative humidity drops below 40 percent. These cracks aren’t hard to spot. Most often they’re located just behind the bridge on the top, but they can show up in other places. Another defining factor of lack-of-humidity cracks is separation in the guitar’s top—as much as 10 to 15 thousandths of an inch.
The fix is in. Impact cracks, which occur when a guitar takes a hit, are not open. They do, however, typically break the wood along the grain as well. (Photo 1). And most of the time, impact cracks go right back together with minimal effort (Photo 2). There’s a scenario where the guitar has a lack-of-humidity crack that separated in the winter but closed back up in the summer, and has the appearance of an impact crack. Regardless, these cracks can be repaired the same way as impact cracks.
By touching or rubbing the crack, you are working dirt and oils into the area, and this can make things much more difficult when gluing the guitar back together.
So what can you do if an unnerving crack shows up on your guitar? The first and most important thing to do is not freak out. Whether the crack is caused by humidity or by impact, there is no immediate danger to the guitar. Second, if you notice a crack, your first instinct may be to touch or rub it. Tip: Don’t do this! By touching or rubbing the crack, you are working dirt and oils into the area, and this can make things much more difficult when gluing it back together. For lack-of-humidity cracks, you should take quick action and re-humidify your guitar with a soundhole humidifier as soon as possible. This will—more often than not—close the crack. If you ignore this scenario, however, the wood could take a memory over time and will be much more difficult to repair down the road.
Visit the doctor. The next step is to see the repairperson. Between the two of you, you should identify what type of crack you are dealing with and determine what the next best course of action will be. If it’s an impact crack, a simple re-gluing usually does the trick with no need for further action.
In the case of a lack-of-humidity crack, the technician will usually continue re-humidifying the guitar until the crack closes. Only then will the crack be ready to be re-glued. Again, most of the time, the glue will be enough to hold the wood together. But a qualified repair person should advise you on how to better humidify your instrument to prevent the crack from returning in the future.
In either case, the glue seals the crack to protect the wood once it’s repaired—at least from a structural and sealed standpoint. But now you are likely thinking about the finish and if the repaired crack needs inner support. Here’s where I’m going to suggest that you relax and weigh your options. Both backers and finish touch-ups are what I consider to be phase two of the process, and are not always a necessary step in a repair.
When touch-up work on the finish is performed, it’s done to try to make the crack look better. It does not make it more structurally sound, and unless the guitar is almost brand-new—when finishes are more easily re-bonded—a finish touch-up on an older instrument generally looks, well, terrible. As someone who has been around world-class acoustic guitars and guitarists for over 40 years, a cleanly repaired crack is what I’d prefer to look at. As for backers or cleats, they are often not necessary to further stabilize the already re-glued and stable crack. So be sure to discuss this with repairpersons to ensure they aren’t making any moves that can’t be undone once in place.
Top 25 places to buy custom
Galloup Guitars has been chosen as one of the top 25 places to buy custom hand made guitars.
Having a custom guitar means that it is made exactly to your specifications. The shape, hardware, colors and other components are chosen by you so that it fits into your hands like a glove. There are several companies who have an excellent reputation for making guitars.
The Best Places To Buy Custom Guitars Online
We chose these award winners based on the following criteria:
Craftsmanship of guitars
Uniqueness and variety of guitars
Website layout and use
Uniqueness and story behind brand
Response times of customer support
THERE ARE HUNDREDS of places to buy custom guitars online. As a result, this made it difficult for us to pick our top choices. However, after extensive analyses and looking at hundreds of places to buy custom guitars, YOU WILL FIND BELOW THE TOP 25 PLACES TO BUY CUSTOM GUITARS ONLINE:
Humidity—Friend and Foe
What is the biggest cause of premature death for acoustic guitars? No, it’s not rambunctious children or spurned lovers. It’s humidity. And storing a guitar in an environment with improper humidity will not only shorten the life of an instrument; it’s certain to cause problems with playability and tone along the way. I consulted with Sam Guidry, our senior instructor/luthier here at the Galloup School of Guitar Building and Repair, on this very important, but generally overlooked topic. And the following is our take on what you should know to protect your guitar from humidity-related issues.
An acoustic guitar needs to live in a relatively stable environment. Most acoustic guitars are built in climate-controlled shops that maintain approximately 40 to 50 percent relative humidity. As the guitar goes out into the world, it should be kept in a range no less than 45 percent and no greater than 75 percent relative humidity. When the guitar is left outside that range for a prolonged period of time, strange things begin to happen. Recognizing the symptoms can save you from a trip to your repair shop, or worse.
The time of year is the first clue that you should monitor the humidity for your guitar. In northern climates, when the temperatures drop and the heater in your home begins to run, it will dry the air in your home and create an unfriendly environment for guitars. When this happens, it’s really time to start thinking about humidification.You may think that simply raising the saddle a bit will fix the problem, but the real issue is that your guitar needs supplemental humidification.
When wood dries out, it shrinks. This can be observed in several ways. First, you may notice that you can begin to feel the fret ends protruding slightly from the edge of the neck. This is because the fretboard is drying out and shrinking, but the metal frets do not. Another symptom is that your guitar will start to buzz. When an acoustic guitar’s top dries out and shrinks, the dome of the top will lessen, and this causes the string action to change. You may think that simply raising the saddle a bit will fix the problem, but the real issue is that your guitar needs supplemental humidification.
If left unchecked in a dry climate, an acoustic guitar will eventually crack. This most commonly happens along the grain of the top or back, but the fretboard and bridge can also suffer a similar fate in extreme conditions. If caught soon enough, many humidity-related issues can be repaired. But over time, the area around the cracks can develop a memory, and repairs will be much more difficult (Photo 1).
While dry conditions are the most problematic for us in the northern climates, areas like the Southeast U.S. have the opposite problem: too much humidity. Wood swells as it takes on humidity and this causes a guitar’s top to expand. Also, acoustic instruments will sound less responsive or dull when they take on too much moisture. So, while not as destructive as being too dry, a humid environment can definitely change the way your instrument sounds and plays.
You can’t change the weather, but there are steps you can take to ensure your acoustic guitar is properly protected through humidity fluctuation. First, keep it in the case when not being played. This is the single most important thing you can do to protect your instrument. There are also several products available to humidify the inside of acoustic instruments. Some devices feature a sponge that’s wetted and then placed in the soundhole while it’s being stored. These devices can do a lot to stabilize the humidity of your guitar. As the sponge dries and hardens, it’s telling you to add more water. Simple! Other more hands-on units offer the ability to both humidify and de-humidify, but these systems do have a life span and need to be monitored often. We also recommend that you invest in either an old-school sling psychrometer or a more modern digital psychrometer (Photo 2) to ensure you are getting accurate humidity readings in your environment.
Humidity should be a prime concern for anyone who owns a wooden musical instrument, but with a little knowledge and foresight, you can take comfort in knowing that your guitar isn’t in danger of an early demise.
The start of a long month of re-fins.
I found this photo, it’s from a few years back but it was a fun month. 61 Strat, 65 Strat, 72 Strat and a 50’s P Bass.
Gibson plastic bridge replacement
OK, here’s the deal. Yes, there are many issues in a coupled acoustic system that can lead to better tonal possibilities. First and foremost is the top or sound board of any acoustic instrument. It needs to be the most responsive element of the guitar for it to sound great. With that comes the importance of the bridge. The bridge is a pretty big deal given that 100% of the kinetic energy transferred into the string has to then be transferred through the bridge to drive the top, allowing “the magic” to happen. So choosing a solid material for the bridge that is of the right weight and density is ideal to do the job correctly. The saddle in a flat top style bridge system should also be a material that can move kinetic energy correctly to the bridge. Again, this energy needs to be dispersed to the sound board. This material can be many things but the best choices for tone always seem to have a similar weight and density.
Over the years I have settled into a pattern of not changing anything on an instrument, if at all possible, but this has not always been true. I have experienced some tough lessons in the past of what is the best choice, even though the general standard is to do something different.
The Gibson Adjustable Bridge brings up one such issue. The general consensus is, if the 1/4 inch adjustable saddle is changed to a 1/8th inch bone saddle, it sounds better. Well, I’m not so sure about that. I have made this alteration several times over the years, and I was not totally convinced it sounded better. In fact an alteration where the adjustable bridge is removed and replaced for the sole propose of installing a 1/8th inch slot is a mistake in my mind. There is probably not much chance that all of that new wood and glue will sound as good as the older, well seasoned original stock system. Noting that it’s not the vintage Brazilian bridge and hide glue joint that’s in question, it’s the adjustable saddle.
But what about those big ½ inch nuts and brass inserts bolted to the top with those adjusting posts screwed into them, those can’t be good, right? Well, not so quick, let’s look at these. What do they weigh, and how much does this weight affect the pitch of the top. Where is the top tuned? Maybe the top is tuned high enough that a little extra weight drops the pitch to better couple with the air resonance and the back of the guitar. These are important issues to look at if you are going to alter a vintage instrument from its original factory specs. I can tell you that the last such alteration I performed did not sound better, and in fact, it changed the guitars tone in let’s say “not a positive way”. I wished I had never touched it, and it was the last time I ever changed anything from vintage stock without some extensive research to back up such a decision.
And the last piece of the puzzle is…………….it looks terrible. Vintage factory specs are the correct look and it should be kept in tacked at all cost. When I look at a 1965 J-50 ADJ, I want to see the adjustable saddle not some aftermarket alteration.
So that brings us to the mid 60’s Gibson injected plastic molded bridge. I’m going to go on recorded and say (and you can quote me) this was not a good idea. There is nothing good about it from beginning to end. It definitely is bad for tone, and it did not hold up well over time. I have no problem replacing these systems with wooden replicas, (with the key work here being replica) that will retain the era correct adjustable saddle and look. In addition, there are a few little tricks I’ll do along the way that will most likely contribute to better kinetic energy transfer to hopefully improve tone.
Here is the suspect; you can see it a mile away. The first giveaway is that the fret board is rosewood and the bridge is black. It’s common that in most cases that the fret board and the bridge are made of the same material. Not true with an injected plastic molded bridge, they’re always black.
As we can clearly see this low quality plastic bridge is cracked and has over the years lost its original form. The first step is to remove the strings in preparation of removing the bridge itself.
Next step is to unbolt the adjustment screws until the saddle and screws simply fall out. Then you can reach inside with a ¼ inch wrench and unscrew the bridge. This entire process takes about 5 minutes.
OK, this is an injected molded plastic bridge, so this means that every one is exactly the same. No matter the time frame or model of guitar, they are the same footprint, height, pin spacing, saddle placement, everything no exceptions. This was a perfect opportunity draw this up in CAD and cut in on my CNC. This way whenever I need another (or anyone else) I’ll simply cut it and away I go.
Here is a prototype made from pine to check the fit and outer footprint. This fit perfectly in all dimensions and will look exactly like the wooden version also produced by Gibson around this same time frame.
If you notice we also left the wooded nibs were the screws would have fastened. This will locate the bridge and fill the holes all at once.
On the Brazilian Rosewood replacement we also added the ¼ inch holes to accept the pearl dots that were common on all Gibson bridges. This will not only be vintage correct by look, I will be able to add the small screws and nut as would have been installed from the factory; laying on the guitar it looks correct.
To glue it up I place a custom made wax paper covered backer inside that has two holes to accept the nuts of the adjustment system and I pushed a little wax into the adjustment holes to stop any glue from oozing in. The wooden plugs we left on the bottom on the bridge will act as the locators so this is good to go. I mixed up hide glue and clamped it up.
The wooden plugs we left on the bottom on the bridge will act as the locators so this is good to go. I mixed up hide glue and clamped it up.
Here’s the bridge glued up and it looks right, no question there. One thing I forgot to mention, before I removed the original plastic bridge I checked the intonation. I used my Peterson strobe tuner to see if it was even in the ball park and it was pretty close. On some of these jobs I’ve made a custom bone saddle replica of the original ceramic that was intonated for each string. This is a great thing for nailing the intonation and it doesn’t hurt the vintage value. It’s a direct replacement that looks right, you just inform the customer to hold onto the original. Huge improvement, no harm no foul.
It’s still a little rough, so I’ll move on to final stages.
Gibson routinely used two screws to the outsides of both E strings as fasteners. If you’ve ever seen the ¼ inch pearl dots on Gibson bridges, those are covering those fasteners. We programmed and cut these ¼ inch holes so we’re good to go to install the vintage style screws.
First drill the holes for the screws, and then I can choose the correct style and size screws for this vintage.
This not a big deal, you can find these anywhere, but I have a nice little collection I’ve acquired over the years. In this series of photos you can see I’m using a Philips head screws but I’ve seen both Philips and single blade heads throughout the years with single blade being the most common. Once fitted, I installed and tightened them into place.
The final touch is the ¼ inch pearl dot to cover the heads of the screws. I made these by gluing bulk pearl to the end of a ¼ inch wooden dowel and sanding them to the correct size. Then I glued them into place.
This is what the vintage system should look like from the inside.
The final product looks vintage correct, there’s no question there. Yes, I do understand that some will argue that a fixed bone saddle sounds better but I’ve been on both sides of that fence and I did not hear much of a difference if any either way.
If you want to improve tone one trick is to place a hard wood shim of the correct thickness under the ceramic saddle so when tightened down firm the entire saddle area is making good contact with the top. There is a steel spring under the vintage saddle that may have to be removed to pull this off but in this case all I had to do was tighten it down it was correct with the steel spring left in place. This trick increases the saddles contact area and significantly improves the kinetic energy transfer. Just by doing this alone I have noticed improvement in tone.
The Shape of Things
In my previous column [“The Name Game,” December 2018], we talked about tonewoods and how they might affect both the sound and longevity of an instrument. I also stressed the importance of understanding their material qualities, to help avoid the hype generally associated with tonewoods. We will definitely be revisiting these topics, but we should first look at how body sizes and their resonances affect the sound of an instrument. Once you have a better idea of what you are dealing with, you can make better choices to suit your playing style.
Guitarists often find themselves attracted to certain body sizes because they seem to fit their playing style. This isn’t just coincidence. Body size and shape play a role in the sound of an instrument by affecting its resonant frequencies. And a guitar’s resonant frequencies act somewhat like a notch filter that boosts output in the frequency range in which they are active.
The guitar has three main low-frequency resonances: the air resonance, the top resonance, and the back resonance. Large, deep-bodied guitars put the emphasis on the lower end. Smaller, shallower guitars have less low-end response, which makes their lows tighter and more defined. This doesn’tmean the smaller guitars have less volume. They are in fact the same volume within their resonant range, but just can’t pump the bottom.Yes, larger guitars have been made, but these two models define what players prefer for that big, acoustic sound.
Body sizes are commonly referred to in terms used by well-known instruments, like the Martin dreadnought and OM (orchestra model), or, for you Gibson lovers, it’s the Jumbo and L-00. When looking for low-resonance body styles or instruments with a big bottom, people are generally drawn to guitars in the vein of Martin dreadnoughts or Gibson Jumbos. Yes, larger guitars have been made, but these two models define what players prefer for that big, acoustic sound. In the case of the dreadnought, its 15.75″ bout and deep sides lower the air resonance to around 95 Hz, while the Gibson’s full 16″ bout can drop the resonance below 90 Hz for its classic boom. This is why some players like the Martin for its more-defined low end, while others prefer the Gibson for its smoother, lusher bottom.
Mid-resonant body styles such as the Martin OM and the Gibson L-00 are smaller in width and depth, resulting in higher resonant frequencies—with air resonances ranging between 100 Hz to 115 Hz. Their slightly higher resonances are preferred by fingerstyle players for excellent separation of notes and tonal balance.
The Guidry (left) shows deeper sides and a wider bout when compared to the Martin, which is a common design many modern boutique fingerstyle guitar makers use to boost low-end frequencies.
Even higher-resonance guitars—commonly known as parlor guitars—achieve air resonances ranging between 110 Hz to 125 Hz. While their bass response is limited, the clarity is unique and defined. No, a parlor guitar probably wouldn’t be your first choice if you’re limited to just one guitar, but many players have parlors in their collection to round out their sound.
On the other hand, the Gibson J-185, for example, is a model that bridges the gap between jumbos and OMs. Its shape is the same as a J-200, but it’s sized down from 17″ to 16″ at the bout, which kind of makes it the J-200’s little brother. Between the Martin OM and the Gibson J-185, these two models inspired the modern fingerstyle boutique market. For one example, our senior builder Sam Guidry pulled inspiration from both models in designing his SG-2 guitar. When it’s viewed next to a Martin 000-18 [Photo 1], one can see that even though the SG-2 model was designed deeper to lower the air resonance, the body styles have a similar footprint.
What seems to be true with all makers, big or small, is that while they might play around with the subtleties of the shape, in the end it’s the air resonance that separates the classes between a jumbo, OM, and parlor. When you understand there are defined, measurable differences between body styles, it helps you appreciate why certain classes of guitar are so prominent, and why they have earned their place in the market.
Scale Length and String Tension
Scale length can be a confusing topic. It’s commonly known that some guitars have shorter scales while others have longer scales, or, in other words, frets are closer together on some guitars and further apart on others. What the debate seems to be is how this impacts a guitar’s tone, response, and playability.
Players often dismiss short-scale guitars because they feel they might not be as powerful as long-scale models. The truth is that I have encountered plenty of short-scale guitars that were incredibly loud, and long-scale models that were not. Over time, I’ve perceived that it’s actually more of a type of tone issue rather than power. Vocalists, for example, might prefer short-scale instruments for their open, relaxed tone, while soloists tend to gravitate toward long-scale instruments for their authoritative and defined sound.
In relation to what impacts these things the most, the scale length is a secondary issue to the stringlength. It’s the tension created by the total string length being tuned to pitch and the tension placed on the soundboard that defines the tone, response, and feel of the instrument. On a 25.5″-scale instrument strung with standard medium-gauge strings, the tension created is around 189 pounds. A shorter-scale instrument strung with the same medium-gauge strings has approximately six pounds less string tension pulling on the soundboard. This directly affects the tone and response of the instrument enough that most players can hear and feel the difference.This directly affects the tone and response of the instrument enough that most players can hear and feel the difference.
In the early days of stringed instruments, even the ones that were plucked did not have frets. The players themselves brought an instrument into pitch by finger placement on the fingerboard. Over time, instrument makers developed the “Rule of 18,” an equation that located the correct positions to play in tune, which laid the groundwork for fret placement.
And when frets were added to the already established string lengths, modern fretted instruments were born. Today, we have adjusted the Rule of 18 to sweeten the scale, and, along with some creative nut placement and saddle adjustments, modern instruments play much more in tune than their predecessors.
Traditional classical guitars had measurements of 640 mm, 650 mm, or 660 mm, and many instrument makers that migrated to the U.S. also calibrated by these metric measurements and guidelines. Over time, companies such as the Gibson Mandolin-Guitar Mfg. Co. used imperial standard measurement, which accounts for their 24.75″ and 25.5″ scale lengths. The Martin Guitar Co., on the other hand, likely advertised their instruments by string length rather than scale, which explains their 24.9″ and 25.4″ short and long measurements. I have measured many “untouched” vintage Martins and their short scale, for example, measures around 24.75″ with a string length of 24.9″. The reason for the longer string length is to accommodate for string action that pushes the saddle back, thereby keeping the instrument from playing sharp. This is true on all fretted instruments: Even Gibson’s instruments will measure around .125″ longer than the advertised scale length.
Tip: If you want to find the actual scale length of any guitar, simply measure from the leading edge of the nut to the 12th fret (Photo 1), and then multiply that by two. If you measure from the leading edge of the nut to the center of the saddle between the 3rd and 4th strings (Photo 2), this is the string length. Of course, the saddle angles back as it moves toward the 6th string, which accommodates for string diameter.
With both longer and shorter scales, there are always trade-offs. This is why many custom-guitar builders have incorporated multi-scales (aka fanned frets) into the list of options for their customers. The most popular configuration is 26″ on the bass side and 25″ on the treble side, which effectively bridges the gap between longer and shorter scales. Performers who tune to DADGAD or other alternative tunings like fanned frets because they help prevent the low end from getting loose, which can cause the notes to become undefined and buzz. Meanwhile, the high-end tension drops into the range of a Gibson short-scale, thereby offering the sweet high end so many players like.
Matching the scale length to your playing style is one of those factors that’s subjective, although it is common that certain music styles do gravitate toward one scale length. I personally have scales that range from 24.75″ all the way up to a 28.75″ baritone. My current go-to guitar is, of course, one of my 25.5″ scale G.2C models, but that could change at any moment. I’ll keep you posted.
Bling Versus Sound and Feel
n my September column, “Scale length and String Tension,” I referenced my 1938 000-42 (Photo 1) as an example of a shorter, 24.9″-scale Martin. I recently pulled it out of the vault, put on new strings, and started playing it again. And while looking at the pearl detail and other appointments, I was reminded of how I felt back in the ’70s when I first saw these pearl-embellished instruments from 1930 to 1940. The magic of seeing a blinged-out instrument for the first time really stuck with me. Just recently, while hanging out with George Gruhn at his shop in Nashville, I picked up a 1942 000-45, which re-instilled the feeling of awe in me for the art of guitar making.
The art of guitar making is something that has captured the imagination of both luthiers and players for centuries. Luthiers were conservative in the early days, so embellishments were limited. Originators of the acoustic guitar, such as Torres and Ramírez, followed tradition by focusing on instrument making, but limited artistic elements to simple rosettes, purflings, or proprietary peg-head designs. It’s interesting that more modern instruments from the 1950s and 1960s—such as Martins, Fenders, and Gibsons—were often straightforward, clean, players’ models. Check the history books and you’ll see that even the great musicians gravitated toward basic guitars that would simply get the job done.
Over time, embellishments broadened production that pushed the boundaries of art and instrument making. Shell inlay on guitars like Martin’s 42 and 45 models was obviously popular. Then there is Gibson’s beautiful cremona-brown sunburst that became so common among country music stars. The thing to note with these examples, however, is that they were all great musical instruments first, and any appointments were in addition to their musicality.There certainly are makers who have achieved a balance of musicality and art.
There certainly are makers who have achieved a balance of musicality and art.
Somewhere along the line, the perception of musical instruments changed. It was likely due in part to the advent of television exposing the public to Gene Autry’s decked-out Martin and Hank Williams’ sunburst J-45. The buying public’s perception shifted, and they started paying more attention to the persona that accompanies making music, rather than the music making itself. When a customer pays more attention to the look of the wood and appointments than what an instrument sounds like, the scales tip and the instruments then have the potential to become less and less musical.
This is not to say that embellishments don’t have their place. There certainly are makers who have achieved a balance of musicality and art. One of my personal heroes is luthier Grit Laskin, who has seamlessly bridged art and music by making instruments that are truly inspiring. Tyler Robbins of Robbins Acoustics is also pushing the boundaries of art, music, and technology by producing some of today’s most exciting embellishments (Photo 2). The prime thing to note about makers like these two, however, is that they had their instrument-making chops down long before worrying about adding any embellishments to their guitars.
Then there are the inlays specialists such as Aulson Inlay. While they may not be luthiers, they have contributed greatly to the advancement of art and lutherie. As a gun for hire, the company is frequently commissioned to design artistic inlay projects to be incorporated into a luthier’s current build. For inlay artists such as Aulson, their focus is only the inlay: It’s entirely up to the luthier to tie it together with the instrument.
There are a handful of innovations in the appointments category that have now become commonplace, such as cutaways and armrests. Cutaways essentially evolved out of necessity, and the armrest is a comfortable option that customers like for several reasons. These extras need not be a concern, but past that, things start to get sketchy. As a musical-instrument builder, I, too, delved into the options and appointments category, but soon realized that getting back to my roots and delivering a world-class, concert-level instrument is what needed my attention.
In the end, whenever you’re looking to buy an acoustic instrument, remind yourself that it has to be a musical instrument first. Musical instruments will continue to evolve, and luthiers will continue to push the boundaries, but the fact is—in its purest form—the guitar’s original design has performed as intended for centuries. It’s the core instrument that lives closest to the truth, and the prime objective should always be tone, response, and reliability—not glitz.
Keep this in mind and never let the musicality of the instrument take a back seat to the embellishments. It will greatly increase the chances for a lifetime of bliss with your new guitar, while decreasing the probability of finding yourself in the dreaded position of having buyer’s remorse.
Sure, Your Acoustic’s Woods Are Important—But Is Its Bridge Plate up to Snuff?
It’s no secret that the soundboard is the key element for quality tone on an acoustic instrument. However, components attached to the soundboard, such as bridge material, bridge-plate material, and brace stock, will enhance or dampen an instrument’s performance as well. Through the balance of these secondary components, luthiers control the instrument’s voice. So it stands to reason that these items must also be of the highest quality and used correctly for the best possible outcome.
In the coupled system of an acoustic guitar top, the ratio of weight to strength is the result of the combined collaboration of all of its parts. For the style of sound a luthier is shooting for, there is an ideal balance for desired tone and response. The weight or strength is going to be either in the top or the braces, and borne in the bridge or bridge plate.
Let’s say the maker wants to use X-braces and scallop them to recreate a classic, vintage tone. Luthiers have to select an appropriate soundboard to collaborate with the scalloping process—the same goes for other bracing patterns and voicing styles—so they can mold the instrument’s tone for different players to achieve their ideal sound.
Early nylon-string instruments had thinner tops and lighter bracing, since they could accommodate the lower tension of nylon strings. These instruments used a pinless bridge, and their bridge plates were most commonly made of spruce and were fairly small. Once higher-tension steel strings were introduced, this meant soundboards had to be thicker, bracing had to be beefed up, and bracing patterns moved from fan bracing to the modern-X style. Additionally, bridge-plate materials shifted to harder woods, such as maple or rosewood, to accommodate the pinned-style bridges that anchor the ball ends to the bridge plate (Photo 1).In an attempt to keep up with the high demand, material quality was compromised as manufacturers started using weaker, heavier tops.
In an attempt to keep up with the high demand, material quality was compromised as manufacturers started using weaker, heavier tops.
Somewhere between 1920 and 1945, steel string guitar makers hit their ideal stride by balancing top thickness, brace voicing, the bridge, and bridge-plate size to form the tone of some of the world’s most iconic instruments. By the early 1960s, the popularity of steel-string guitars grew exponentially due to the folk-music boom. In an attempt to keep up with the high demand, however, material quality was compromised as manufacturers started using weaker, heavier tops.
Soundboard failures soon followed, so bracing and bridge-plate sizes were then increased in an attempt to stabilize the lower-quality soundboards. But because the overall weight of the tops increased and stiffness decreased, these moves compromised the instruments’ stability and lowered the quality of the tone and response.
Bridge-plate sizes, for example, shifted from small, vintage-style footprints and thinner profiles to a footprint that was twice the size and double the thickness. By the 1970s, some makers moved to plywood bridge plates in an attempt to remedy some instruments’ structural issues. Unfortunately, the addition of a large, thick bridge plate to make up for poor material choices was an ill-advised move. It only dampened the instruments’ performance as they continued to routinely fail.
When tuned to pitch and operating correctly, a bridge pin’s job is to hold the ball end in place under the bridge plate. When it’s not operating correctly, the ball end is allowed to sink into the bridge plate (Photo 2), which will distort the bridge pin and cause a number of woes, such as tuning issues and tonal distortion. Not surprisingly, when lower-quality bridge-plate materials were introduced, we started seeing an increase in this type of failure, which eventually needs repair or replacement. It’s a very advanced repair, and if not performed correctly it can severely damage a guitar’s soundboard.
Fortunately, our industry has revisited the quality craftsmanship that produced those iconic vintage guitars, spearheaded in part by luthiers such as Bill Collings, who practiced time-tested building approaches using quality materials. This allows luthiers to once again focus on smaller, lighter components that significantly increase an instrument’s response, as they are significantly better positioned to withstand string tension and humidity fluctuations. From a repairperson’s standpoint, focusing on the maintenance of high-quality, great-sounding guitars is much more rewarding work than major restorations to stabilize failing instruments.