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The more I build (and repair), the more my perception of the influence of the back and sides on the overall voice and timbre of the guitar's tone evolves. Currently, I'm feeling like it has a greater effect than I have given it credit for in the past. I've long held to the idea that the "protein" of the recipe is the top and its bracing, and the back and sides are the "spices" that give the guitar a particular flavor.

I'm just interested in a general conversation about how folks perceive the influence of the back and sides on the overall tone and voice of the guitar. Looking forward to your responses.

Ken


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This is one of those things that is just too difficult do scientifically (with the resources most of us have). I think the first step would be to figure out how you wanted to define the differences you would expect so you can figure out how to measure them and test them. After all the first baby step is proving that there is a difference, defining it and predicting it is way down the line. Let's say you decide what you want to test for and can measure it and make the assumption that enough people will be able to hear the differences in the real world, you have to be able to isolate back and side material as the only variable in the signal chain. You can't really make two guitars that are identical except for the back and side speceis let alone build enough to eliminate the natural variation inside a species. So you are left with the strategy of making even more guitars as similar as possible so you can hope to find trends in the not perfectly controlled guitars. If you manage that do that and determine there is a repeatable predictable effect from back and side wood, you are left with the fact that it only really applies to that building style. It very well may be that one maker will work the backs to a certain stiffness regardless of timber, one might go for a particular tap, another might just go by thickness and probably 100 other subtle variations in deciding how to treat the back and side wood during the process.

All that is really hard to do. It is a lot easier to employ confirmation bias and lean too heavily on small samples and anecdotal observations. Failing a bunch of robust systematic experiments, we can have this conversation and take in as many opinions as possible and see if any kind me of consensus forms. But I would 't hang my hat on the results. But, some good conversation will ensu and many (myself included) will further develop their understandings of how these guitar things work. I look forward to reading it.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Thanks, Bryan, however, your first paragraph is exactly what I'd like this conversation to avoid -- pseudo-scientific hyperbole. I'm much more interested in folks' general feeling about B&S influence on tone. Sometimes there's learning to be gained from speaking in general, anecdotal terms.


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Woods with higher damping, ie a 'cardboard' tap tone yield guitars with more fundamental, less harmonics.

Woods with less damping, ie a 'pinging' tap tone yield a guitar with more overtones.

It is my opinion that woods with high damping 'wick' out the high freqs, while woods with low damping allow the high freqs to pass through and be recirculated back into the systems energy pool to continue to add sound. Or something like that. Even if that's not what 'actually' happens, guitars behave like that is true, so good enough for me.

If you had a guitar made of marshmallow back and sides and a guitar with peanut brittle sides, you would expect different results.

I think it's pretty obvious what the overall tone any given back and side set will lend, just by the tap tone.

This is of course after you have most other things down to a fairly consistant process, which will allow the back and sides wood to contribute the most that they can. That's how it works in my guitars anyway. Things like double sides and laminated linings could very well change that.

Thinking about the effects of B&S wood on the overall tone based on the mechanical properties of the wood rather than on what particular species it is makes a lot of sense. Is there a table somewhere that lists species and their damping properties either relatively or quantitatively?

It would be interesting to see how well the info in such a table would match up with people's anecdotal experience.

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Oops, I misread the title of the thread as asking for scientific (skimmed over the "non-," sorry about that. Though I'm not sure how attempting to empty the scientific method would be called "pseudo-scientific hyperbole!"

However, I think we both agree that this will be a good discussion.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Very interesting, medd, that you see it as so absolute. I built a guitar with b&s that tapped like wet cardboard, yet has very crisp trebles and lots of overtones. Would it have had even more overtones if made from rosewood? Maybe. Hopefully we can dig deeper into our perceptions of what influences a guitar's tone. I'd love to hear other opinions.


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I am just starting to build my first guitar, but I have played everything from a $200 Cordoba to a $30K Ruck. In my player's perspective, B&Ss define articulation of fundemental and overtones.

I'll describe the guitars I have played in the hopes it will add to this discussion. I have "tap tested" all the B&Ss, so I can give my subjective annotation.

75 year old Martin classical 00 - solid cedar top, solid mahogany B&S - a no frills model with wood that at the time was considered mediocre. The top was individually voiced.
- tap tested very warm but with rapid decay
- this guitar sings with choice overtones yet has amazing articulation
- crystal clear trebles and robust bass
- the beauty of tone is really hard to describe except "delicious"
- very easy to extract concert quality tone

Cordoba C3M - solid cedar top, laminate mahogany B&S - student grade instrument
- tap test sounds like plastic 2L jugs
- tone is way too bright, articulation is student grade muddy, overtones are confused and decay rapidly to fundemental
- loudness achieved
- impossible to extract concert quality tone

Yamaha Gaki - 55 year old classical made by Japanese luthiers - solid cedar top, laminate mahogany B&S - considered a student grade instrument
- tap test is heavy and dead like thumping a watermelon with rapid decay
- tone is muted with unresponsive trebles and warm basses and minimal sustain
- overtones are actually really nice and would be radically improved by better sustain
- difficult to extract concert quality tone

Delfy D00F - AAA solid cedar top, laminate Sapele B&S - student grade instrument
- tap test was warm and resonant with long sustain
- tone is a warm combo of fundemental and overtones with long sustain
- inarticulate and muddy - impossible to play flemnco on but great for the right songs like Tarrega's Study in E Minor
- concert quality tone achieved on certain songs else muddiness interferes.

Rodriguez Model FF Sabicas Tribute - solid spruce top, solid cypress B&Ss - low end concert quality instrument
- tap test sharp and snappy with rapid decay - sounds pleasing
- tone has strong basses, crystal clear trebles, beautiful overtones
- very articulate and can handle the most rapid passages with perfect clarity, but decay is rapid so not at it's best for songs like Tarrega's Study in E Minor
- concert quality tone easily extracted for all material, better with flamenco songs.

Ruck formerly owned by Rey de la Torre - yeah, I know the new owner - solid cedar top, solid Brazilian Rosewood B&S - obviously one of the best concert instruments on the planet.
- tap tone is luscious, warm, with amazing sustain for "golpes" on the B&S.
- tone is perfect with perfect balance across all frequencies, warm resonant basses, cystal trebles, monster midrange.
- so articulate that every nuance is audible simulataneously with ample and robust overtones that evoke spiritual emotions, assuming you have the ear to hear it!
- impossible NOT to extract concert quality tone - this instrument delivered massive tone no matter what plucking technique I deployed at all intended forces and volumes.

So, intuitively, the B&S "tap tone" of the finished instrument, for me, gives a great indication of what to expect. My intuition is confirmed when I play the instruments and make mentalnotes of the B&S tap tones I experienced.

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If thee meddle with dragon kin, thou will become crunchy and good with ketchup.

my observations are similar to meddling's, although the difference is subtle. drier tone with cardboard tap, and more note separation, more reverby with glassy / pingy tap tones, with notes carrying and blending into each other. I find them equally enjoyable, sort of like two superb singers with different voices.

I think the back and sides and how they are prepared are a big deal and play a huge role or maybe as important in the over all sound as the top wood is. I look at the box more as a reverb chamber with eq dampening qualities. The density of the wood and how porous it is I think really draw a guitar to sound one way or the other. For instance, in my mind maple being a really tight grained dense wood reflects sound absorbing very little, producing a bright full guitar. Where mahogany which is much more porous and softer does absorb taking away some of the higher frequencies, producing a darker moodier guitar. I think scraping the inside which compresses the wood fibers or sanding which is much rougher have a subtle affect in either direction as well. I think of it like going into a crowded restaurant with bare walls and ceilings or going into the same restaurant and now they've got foam on the ceilings and some curtains.

I wish I had the time and money to build the same guitar each with an adirondack, sitka and cedar top with a maple, indian rosewood and mahogany back & sides.

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Somogyi makes an interesting point in that you're wasting your money with Brazilian rosewood if the guitar is played mostly while standing. Your body damps out the back and it can't contribute anything to the back and forth of the top and back.

Shame nobody told Tony rice the above.

With my very limited experience of building and pretty wide ranging experience of playing I'd have said mahogany guitars have more cut and clarity. Clarity possibly as opposed to luscious sounding or complex. Rosewood has a more even response as in more depth to the trebles and more treble to the bass which makes the bass appear richer and possibly louder. Something like walnut seems to be in between but in my experience the worst of both. Just a blended homogenous voice which can sound boring next to the characterfull nature of mahogany and less beautiful than rosewood. The tone of maple can be a bit stingy to my ears.

All the generalisations obviously have exceptions. I believe the scientific approach to be of limited value due to the complex and chaotic nature of creating vibration. Added to the fact our ears and brain process sound in a complex and possibly indefinable way. Playing and listening to guitars is by definition subjective. Many of the relations between dimensions and sound production are clearly non linear. Also I believe a focus on data and and measurements risks not utilising the experiential and intuitive information built up in the less conscious parts of the brain.

But what do I know? Probably not a lot.

The brain is a very complicated and powerful influence on what we think we hear. I have two guitars that I made that are shop display models. One is Rosewood and one is Maple. Both have really good tops with very similar material properties, and both are tuned with the top and back fundamentals nearly identical. When listeners are asked to make a completely blind determination of which one is which (listener has never seen either guitar), the Maple guitar is identified as Rosewood about half the time. But when listeners are asked which guitar has better bass/ more warmth while looking at the guitar, the Rosewood is chosen most of the time. I'm pretty sure this is because players have been told for years that Rosewood is supposed to sound a certain way and Maple is supposed to sound a certain way. My own feeling is that the material properties of the top and the tuning of the fundamentals have a lot to do with how any guitar sounds, other factors notwithstanding.

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It will probably be alright.

Being a wood dealer (and guitar maker), I have people who either build instruments, or are having an instrument built, ask me questions related to this topic on a daily basis. Questions like: if I use this wood what sound can I expect, if I pair it with this top, what sort of volume, tone, articulation, etc., etc., etc., etc... This is my extremely non-scientific thought on this subject: You can take all of the most high grade, most resonant, most perfectly cut materials (wood), and if you don't know how to use them to their best potential, you can still have a crappy sounding guitar. Its like saying that if you had the best paint, the best canvas, the best brushes, and the best idea of what painting you wanted to create is all you need to paint like DaVinci.. Nope, sorry, it doesn't work like that.. To me building a great instrument is an art form. And like any other art, you have to have a great sense of how to use whatever medium you are using to create your art. The best art is the type where the artist uses his or her senses. Being able to FEEL, HEAR, SEE what each piece needs along the path of creation is more than just a paint by numbers project. This being said, if you have materials less than choice, if you have an understanding on how to use them, you can still create something excellent.. I have seen some incredible instruments made from materials that most "traditionalists" would never consider using.. You can take a scientific, technical approach to instrument making, using numbers and whatever else as a guide if that is what floats your boat, and there is nothing wrong with that, but have you ever heard someone say "I really want a guitar that sounds really technical"? I haven't.. What I do hear is "I want a guitar with soul, flavor, color, articulation...", etc..
To answer the question does choice of the back and side wood make much of a difference on the tonal personality of an instrument, I think absolutely it does. No question. But to find the personality and potential of those woods takes an understanding on how to find it..

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I make my back & sides as thick as I can.
No matter what wood I'm using or size of the guitar.
I want the top to do most of the work & let the body add flavor .

usually .095(2.3+)for sides & 3.0mm for a back.
Unless I'm making a period instrument.

I agree with Aaron also!

Mike

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Mike Collins

Blind tests don't work that well in my opinion. Players just don't know that much about tonal qualities generally. They just wan't what their idea of tone is. I used to bring 3 nearly identical mandolins to festivals, one red spruce, one Italian and one German spruce with red maple backs. Folks just picked the one that was right for them. Nice thing about F5 mandolins is they mostly use maple for backs. That said, sugar maple is quite different from Euro or red maple, sound wise. Didn't matter if I told them what wood was what. They picked the tone.

What I learned from building mandolins and guitars is that roughly 80% of the tone comes from the top & bracing, and the back is a 20% modifier of that tone. I never cared much for the explanation of why a wood sounds the way it does, I just noted the tone. A BRW guitar with red spruce will sound quite a bit different than one with German spruce.

The major makers all have published wood performance generalizations (Taylor has several articles and sales pitches) of what can be expected from a guitar that is a certain shape and made of certain woods. No need to re-invent -- but you may or may not agree with the consensuses. (or things posted at forums) So I have always been of the opinion, if you like a particular guitar -- try and copy it. On the other hand millions of great sounding guitars have been produced in factories and in the small shops simply using popular tried and true construction parameters. Some builders like me suggest lean toward "tight and light" other not so much.

We have the luxury of Eldery's here in Michigan --- no kidding I have listened to and played some beautiful looking $7000+ guitars that to my ear sounded no better than some of the common moderately price factory models.

And another thing --- sift through the various construction and gallery posts, while its easy to find comments where the maker was disappointed in his or her craftsmanship you are not likely to see "man did I ever waste my time this thing sounds like crap."

All I am saying is, to me its much better for the new comer to get to making --- paralysis by analysis is not very rewarding.

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Ken Cierp

http://www.kennethmichaelguitars.com/

This would take a life time of building for one man to figure out on his own . I will say this . I built 2 Mandolinetta's , One with Padauk b/s One with Oak b/s the Tone on the Padauk is far brighter . The Oak is nice mellow sound . Both have a nice tone . I guess for me , there is so much that goes into building and so many variables that I " Take what results I get " and decide if i am going that route again .

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This is my current line of thinking as well.

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George :-)

I've never played a maple guitar that had the relaxed fat bassy part of the tone. I love my maple dreadnaught for its cut-through-the-mix power, but it doesn't have the full bottom end found on well-made mahogony or rosewood guitars.

Oh I have. Maple when done right has a very warm and woody but still crisp sound that I really like.

However, factory maple guitars do tend to be bright and bass shy, probably cuz they dimension the sides and back the same for all guitars. My theory is that going slightly thin on the sides but thick with the back is the key. I've not tested it though. While I have made and compared identical dulcimers in both hog and maple, my only direct guitar experience with maple was two frankenstein rebuilds where I replaced both front and back plates.

I am up to 70 guitars now, mostly Mahogany or some kind of Rosewood. A couple of Maple OMs as well.
Tops have been Sitka, Adi, or Lutz.

For me the Rosewood is a little more lush but I just build em' and hope the customers hear something they like.

I will say that double sides no matter what the wood, have done something to the sound that people seem to like.

I'd say top 80%. B&S's and stuff like bridge wood, neck reinforcement, and hide glue or similar in the fret slots the other 20%

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I am sure everyone here has taken a piece of wood (back or top) held it in their fingers at a node point and tapped it and listened to it ring. Pretty sure anyone that has done that has taken the same piece of wood that was joined together with its mate and braced with spruce (or whatever flavor of brace wood you prefer) and tapped it again. Did you hear the same ringing tone that you heard with the bare plate? I doubt it. So the bracing does do a lot to change the resonant frequencies and dampening of the plates.



Tap tone of a back of one of the guitars I built. Notice the big hump at around 275 Hz. That is the lower bout. Tap the back of your guitar, you probably have two main resonances, one for the lower bout and one for the upper bout. I can't remember exactly but my guess is that the 800 Hz hump is the upper bout resonance. The lower resonance is about 15-20 dB higher than the rest of the spectrum. Guess what you are going to hear more of in the character of your sound? Might be a place to start a serious look at what your back is doing. Changing the back thickness and brace it differently and you will greatly effect the sound. Given different pieces of wood have different properties even if from the same tree I am not sure we can generalize on the tone of the wood without including the size of guitar and bracing. Leave the back thick enough and heavy braced you will not hear much going on. May need to think of it as a system.

Oh, where to begin ?? The Torres paper mache guitar. Greven says nothing replaces Braz Rosewood. Sergei De Jonge says it doesn't make a whole lot of difference.
And, Jose Romanillos(?) says he prefers a Spanish guitar made with Cypress over rosewood. Go figure.

Brent

A man hears what he wants to hear and disregards the rest, mmm mmm mmm, hmmm hhmmmmmhmmmmm....