Acoustic Guitar Building Secrets...

[drbluegrass]

...What are some of the acoustic guitar building secrets that make guitars sound like those from Prewar Guitar Co, Merrill, B&H, Altman, Bourgeois, Collings, Santa Cruz, Mike Long, Thompson, Hooper, Caleb Smith, and other high end guitars? And, why don't most acoustic guitars sound like them? Are there really any "secrets" to acoustic guitar building? When you look them over most of the bracing, bodies, necks, bridges, etc., look the same. Just what makes an acoustic guitar sound really outstanding?

[charles Tauber]

A basic loaf of bread contains flour, water, salt and yeast. Using those same basic ingredients, a great loaf of bread can be made or a very mediocre loaf can be made and they can have an appearance that is very similar. The great loaf might cost $10 to buy, the mediocre one $2. Knowledge, technique and experience are among the things that go into what distinguishes the great loaf from the mediocre one. Intended consumer and target price also factor into it.

Guitars are similar, at least in some respects.

[drbluegrass]

Originally Posted by charles Tauber

A basic loaf of bread contains flour, water, salt and yeast. Using those same basic ingredients, a great loaf of bread can be made or a very mediocre loaf can be made and they can have an appearance that is very similar. The great loaf might cost $10 to buy, the mediocre one $2. Knowledge, technique and experience are among the things that go into what distinguishes the great loaf from the mediocre one. Intended consumer and target price also factor into it.

Guitars are similar, at least in some respects.

Yes but what, specifically, are some of those secret skills? And please, no..."if you knew, it wouldn't be a secret." responses. There must be some tricks of the trade that are commonly known among high end builders. What are some of those? Some kind of secret bracing? The way the bracing is carved? The way a bridge is placed? The way the top and sides are assembled? Yada, yada, yada.

[phavriluk]

It's all in the judgement, intelligence, experience, and wisdom of the builder. No book of secrets that anyone who has the book can execute.

Prior answer came from many years of experience and thought.

There's no tree of knowledge we can shake the fruit out of.

[Rodger Knox]

There's no real secrets, most of the high end builders are more than willing to share their knowledge. It's a combination of material selection, design, and construction sequence, and those factors vary from one builder to the next, there's many roads that will take you to the destination. Some measure material properties then use math and physics in the design, some build completely by feel. What the great builders cannot share is their experience.

My favorite answer to this question came from master luthier Bruce Sexauer. His answer was to build with integrity.

[Simon Fay]

You've asked a very reasonable question that is often met (and for good reason) with a somewhat opaque response from both builders and guitar players. Factory guitars from top tier manufactures (Martin, Taylor, etc.) can be amazing but generally they are just very nice. The guitars that take it to the next level are more vibrant, responsive, powerful/louder, and often have more tonal character. In short, the guitars just make music in a louder and livelier fashion and are just noticeably more "musical".

Here are some of the ways that a builder can reach that next level if they do their job well:

• Put a tone friendly finish on the guitar. This mostly means a thin film. Most finishes can be tonally neutral if they are not thick.
• Build the top to be ultra responsive. Herein lies the real answer to your questions but it isn't a straightforward process. You can have super responsive guitars that are balanced or unbalanced, have hot notes, long sustain or short sustain, etc... Getting the guitar to be more responsive is basically just allowing it to vibrate easier. To do that you need to make sure the bracing and top thickness (and weight distribution) are intelligently designed and optimized. The optimized part is where most good luthiers will see improvements over factory guitars. This also requires skill and knowledge on the part of the builder. There is a lot of information out there about how guitars and other similar instruments function and information on their basic modes of vibration (Google Chladni patterns). A bit of information and some good common sense can get you very far on this path and IMO, allow you to build a guitar that is noticeably better sounding that a typical factory instrument. Further improvements and achieving a very refined sound require more knowledge, experience, and effort/control to produce reliably and consistently.
• One other consideration is that the build components of a guitar can vary noticeably. In other words, every Sitka top is not going to be exactly the same. If you are trying to take your work to the next level, these variations must absolutely be accounted for. If the weight and strength of tops and guitar components can vary, this is a variable that must be controlled and understood.
• One other aspect is to build holistically. The guitar is a system and the top, back, sides, and neck vibrate together.

So the problem is that the building a great guitar relies more on knowledge and experience and effort. The effort must be directed towards controlling your materials and doing a myriad of small things that you think will help you make the guitar more efficient at sound production.

[Simon Fay]

So my response above is somewhat nebulous because a detailed response is just way too time-consuming to give. So how about I take you through my thought process if I were trying to address a specific problem in my guitars.

Let's say I liked my instruments but wanted to improve the note separation and balance of my guitars. A basic understanding of the vibrational mechanics of the guitar will point out a number of potential ways to address the issue. I would probably first look at the situation as being that the guitar was favoring certain modes of vibration and not vibrating well in others. It seems to me that a guitar that can easily vibrate in different ways/patterns would more easily produce sound at any given frequency. So maybe I need to free up certain regions of the soundboard or perhaps lessen vibration of a certain mode. Maybe I could add mass somewhere or build lighter in other areas. Those are all possibilities. So you make the best and most informed decision you can and tackle the issue by altering the bracing arrangement and profile or the strength and weight of the soundboard.

You try it and see what happens. It is necessary to try and maintain all other variables as best that you can. Then you listen to your results and make further refinements based on what you've heard.

On my path over the years to refine my guitars, I've changed the x-brace angle and location. Changed my bridge plate size and shape. Altered all the lower bout braces and locations dozens of times. I've changed how I graduate my tops. Changed my back bracing numerous times. Changed various aspects of construction. Every time I made a change in the hopes that it would improve specific qualities in my guitars. I've gone in certain directions and then gone in a different direction after I realized maybe doing something different would yield the results I'm after.

I tried to approach each of those decisions with a thoughtful analysis of what my guitars do well and how they could be improved. And I've thought about those things in the context of how the guitar vibrates and functions as a sound producer. Well, this was a bit more lengthy than I originally intened but hopefully, that might give a bit of insight into the process (or at least, the way I approach my work).

[printer2]

A small operation can tailor their process in ways a large company can not. If you are putting out five instruments a week rather than a thousand you can select your wood and exclude material which you do not think will fit your product line whereas if you made the thousand guitars you would be hard pressed to do the same. And then there is your market, the person spending $5-10k on a guitar is going to take a little more care of the instrument than someone plopping down $500 so you can take a few more liberties in the design. The mass market driven instrument has to take into account the materials and the way the guitar will be treated when deciding how much extra fat they have to leave in.

Go out and buy 100 sets of wood from a supplier that were from the same source. Start making the same guitar, over and over. At some point you will get better at it and the later guitars will probably be better than the first. You'll gain experience and get to know how much you can take away and where you have to leave in. And it might be different for the different pieces of wood. You may pair up one top with a different back than you would a different top. Or you may leave the brace a little taller on the one rather than the other. But until you have the wood in your possession and get the feel of it I doubt you can give a definite answer how much salt you need in this one as compared to how much pepper into the other.

Look at car engines, you have daily drivers and performance engines. The one engine is a 350 ci while the other is a 350 also. But one has been blueprinted while the other one has normal manufacturing tolerances. They are both the same design but one will outperform the other. Mind you the daily driver may last 100,000 miles while the other might not. There is something to be said about picking up your guitar and not finding a crack in it. I repaired two of mine after a dry winter. I have other guitars that I just had to let the fretboard drink up some moisture for the frets to recede.

Not much help getting your answer am I?

[mirwa]

The secret for me, it’s like cooking a great meal, you use the best ingredients you can find and assemble them with the greatest of care and respect.

Treat each part as if it was the final part, not simply part of the process to achieve an end goal.

Nothing more complicated than that.

If you are starting out, subscribe to Robbie O’Briens online building courses, I think he charges 100 dollars for complete video tutorials of every step by step process to build a guitar, well worth your money.

Steve

[Mbroady]

Originally Posted by Simon Fay

So my response above is somewhat nebulous because a detailed response is just way too time-consuming to give. So how about I take you through my thought process if I were trying to address a specific problem in my guitars.

Let's say I liked my instruments but wanted to improve the note separation and balance of my guitars. A basic understanding of the vibrational mechanics of the guitar will point out a number of potential ways to address the issue. I would probably first look at the situation as being that the guitar was favoring certain modes of vibration and not vibrating well in others. It seems to me that a guitar that can easily vibrate in different ways/patterns would more easily produce sound at any given frequency. So maybe I need to free up certain regions of the soundboard or perhaps lessen vibration of a certain mode. Maybe I could add mass somewhere or build lighter in other areas. Those are all possibilities. So you make the best and most informed decision you can and tackle the issue by altering the bracing arrangement and profile or the strength and weight of the soundboard.

You try it and see what happens. It is necessary to try and maintain all other variables as best that you can. Then you listen to your results and make further refinements based on what you've heard.

On my path over the years to refine my guitars, I've changed the x-brace angle and location. Changed my bridge plate size and shape. Altered all the lower bout braces and locations dozens of times. I've changed how I graduate my tops. Changed my back bracing numerous times. Changed various aspects of construction. Every time I made a change in the hopes that it would improve specific qualities in my guitars. I've gone in certain directions and then gone in a different direction after I realized maybe doing something different would yield the results I'm after.

I tried to approach each of those decisions with a thoughtful analysis of what my guitars do well and how they could be improved. And I've thought about those things in the context of how the guitar vibrates and functions as a sound producer. Well, this was a bit more lengthy than I originally intened but hopefully, that might give a bit of insight into the process (or at least, the way I approach my work).

I really enjoyed your 2 posts. Thanks for sharing.

[Alan Carruth]

There are no 'secrets'. It's all about knowing how the thing works at some level, and how to make whatever changes you need to get this set of wood to work better on this guitar. Since these are complex beasties what's 'right' in one case might be very 'wrong' in another, even though the wood can look similar. Smaller shops tend to have more leeway to make the needed changes, but it still takes a lot of time and experience to know what to do, and then you need the skill to actually do it.

[yellowesty]

Ha! Another refusal to divulge the secrets of luthiery -- and to brazenly deny that they exist. It reminds one of the earlier refusals and denials regarding the corporately-held 60 mpg carburetors that Detroit (in collusion with Big Oil) refused to share with the American public. I expect that we'll now hear denials about the luthiers' secret handshake as well. Sad.

[Wozer]

there are really no "secrets"...it's all out there on the internet

it comes down to various aspects:

1: actually trying to get it "right" (e.g. the proper attitude)
2: as has been already noted, each piece of wood is different (END OF DISCUSSION)...factory guitars are all made the same across a given model series, yet each piece of wood is not the same...when a luthier takes the time to analyze each piece of wood and use the results to determine what to do he/she is going beyond what the typical factory does
3: the luthier being "gifted" in being able to discern the minutiae with regards to the woods (and this rather correlates to #1 above)
4: years and years of experience (doesn't matter if the luthier is naturally heavily gifted in regards to the craft...the more experience the higher the chance he/she gets it "right")

[printer2]

Originally Posted by Wozer

4: years and years of experience (doesn't matter if the luthier is naturally heavily gifted in regards to the craft...the more experience the higher the chance he/she gets it "right")

Can't recall if I re-told the story on this forum or not. A man I knew was a target shooter and he told me about collecting his target and a spectator saying he was a very luck shot. He replied, 'Yeah and I get luckier the more I practice.'

[MC5C]

I think the reason that luthiery is filled with secrets is that so many of the details that make the differences in sound come down to intuition, feel, tactile response, hearing "something" that means "something" about tapping a plate. And an inability to transfer that knowledge with words. In an apprenticeship one can demonstrate often enough to teach, one can simply build a lot of guitars, pay attention and teach yourself what is important (and repeatable) to you, some people use engineering skills to reduce "feel" to deflection under load and vibrating patterns of dust, even then you need to be able to make decisions on what you learn from testing your wood.

I was watching the video of Anthony Bourdain with Rachel Rosenkrantz, and watched how she tapped the freshly glued soundboard. The difference is that she tapped it with a small hammer (very repeatable) and she said "two seconds. I like to hear between two and three seconds" or words to that effect. Light bulb went on for me - so THAT'S what she thinks is very important, I never considered measuring the duration of the resonance from the tap... But now I've learned - been taught - and I will tap plates that way - and my way - from now on. A secret may have been unveiled...

Brian