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I am in the process of designing a parlour sized guitar, and have a quick query about the lower bout tone bar. I have seen examples where the tone bar intersects the X on the bass side and slants downward towards the treble side or alternatively starts intersecting the x on the treble side and slopes down towards the base side.

Can anyone please educate me as to what difference this would make to the sound of the guitar. Is it a way of making either the bass or treble more defined.

Thanks

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Nick

Follow my musings on getting started in luthiery http://www.tredwellinstruments.co.uk

None, apparently.
"Tone" bars are used to increase cross grain stiffness. It seems to be that the angle (and number) are more important than the side to which they are fitted.
Several people on this forum have built them the "wrong way round" due to a popular plan showing the bracing pattern (unconventionally) from the outside of the soundboard, and they, with others, have commented that it seems to make no difference.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

They also help with the position of the tonal node. How and where they are peaked.
This is where the fun in building can start. To learn what these little nuances do to the tone. One thing , is that changes can be good or bad. You are making a guitar and tone is subjective. There is no right on wrong , there is just different.

Here is a link to a library of guitar tops spanning many years.
http://www.youtube.com/watch?v=NFkXpoWTBzk
link edited

I personally am very traditional and place the tone bare off the treble as Martin does.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

John, I have no idea what that means. Would you like to re-phrase?

Also puzzled by the relevance of binding jigs to brace placement.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Oops!
Mistake with copy/paste?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

http://www.youtube.com/watch?v=wvJAgrUBF4w

how you place and where you place the braced effect the top. Some people call them patterns some tonal nodes just a nomenclature thing. Here you can see the patterns on a plate with different HZ.

https://www.google.com/search?q=guitar+ ... 40&bih=762

The point to be made without getting into a lot of technical language is that braces will affect the top and how it moves. Learning what this means is how you can make your guitar sound the way you want it to. Tone is subjective , and like a cake , there is a process , and how we control the process dictates the outcome.
Learning how the braces work and what they to tonally gets you that much closer to being able to repeat tone on a guitar . Took me a few years to get this all figured out. Keep a good build log and don't make a lot of changes from one build to another and you will soon understand the cause and effect.
Mr Carruth will be sure to post more detailed information but how you control the top is how you control the conversion of the string energy to the top.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

i'm embarrassingly un-scientific about this, but i kinda go the same way too. you can certainly tune them to alter the pitch of the top. unfortunately i don't have scientific data (charts, graphs, patterns, etc..) to prove this to anyone and i'm ok with that. maybe someday i'll rub the edge of a plate with a bow and sprinkle poppy seeds on it to see what it looks like but for now my ears are pretty good.

if they were just cross grain straps one would slap a strip across the top and call it a day. there is a reason they are "tuned" and this is one of the finer areas of building. for example, on my tops i go for an extremely even response in every area of the plate and i can shift "nodes" so to speak around by shaving and scalloping the tone bar or bars. i also feel (again with no real proof) that one can direct the vibrations from the bridge and bridge plate to a favorable area of the top. for this reason i tend to anchor one end of a tone bar at the bass side of the bridge with the hope of driving some low frequencies to a wider section of the top.

i also suspect they can control bridge rotation to a small degree.

tuning to a pitch and tuning to patterns is a different thing. taking wood off at any random point on the braces will change the note of the top but shaping the brace to tune into the chladni patterns is different technique all together.

http://www.physics.ucla.edu/demoweb/dem ... plate.html

there are many ways to voice the top. What I have found after 170 guitars is that as you work your process , you will get to a point that by habit or design you start to form patterns. I pre shape braces before I put them on the top and back . I do tap for the top and back key and get them at least a semi tone apart and don't voice the top much until it is on the guitar.
There is no one perfect way , as we all are using subjective input . Getting balance across the tone spectrum is what you want. I don't like all bass nor all treble , I want it balanced , and I want it as even up and down the neck as possible. Tuning a top will help you gain this. Using any method. It is about controlling the process.

Keep a building log is my best advice . You don't need to know the physics all you need is to understand the cause and effect relationships.
keep it simple

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

OK. So what you actually meant was that where you place the braces changes the shape and frequency of the modal resonances. At least I think that's what you meant!


So John, what do you tune to?

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Thank you for your responses, I will have a more in depth look over the weekend as I am away on business.

But the first question I have is Colin, you mentioned that



I don't suppose you could please point me in the direction of any more info about this?

_________________
Nick

Follow my musings on getting started in luthiery http://www.tredwellinstruments.co.uk

Woah! wrong person for - I am not experienced, only built a few SS, (OM and SJ), so I am in no position to guide anyone in design especially parlor.
I'm just on my first parlor build, and I believe they can be difficult to get to sound balanced.
Have a look at this thread http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=42762 for the tips/pics/build manual generously given by Terence Kennedy, who has built several similar parlors.
All I can tell you is the closer the tone bar is to across the grain, the stiffer the top and vice-versa. Also, the more tone bars (of a similar size) the stiffer the top, but the more weight - basic stuff really.
Also read this, it may give you some ideas?
http://www.frets.com/FretsPages/History/Martin/MartinBraces/martinbraces.html
Look at the part about the D-! and DM models.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

i tend to divide the area up equally with whatever amount of tone bars the size of the guitar calls for. i don't like to bunch them together as it makes for a an unnecessarily stiff localized section. other opinions differ.

I'm just going to pop this up here for more experienced folks to either agree or disagree with, and for discussion. I am an amateur and these are not my ideas. I heard this from a video of Richard Hoover (founder of Santa Cruz Guitar Co.) discussing bracing. I know that this is one luthier's take on how bracing affects tone, and that some might not agree, but I thought it was interesting and would be fun to discuss here.

The way it was described made it sound to me as though Martin usually has the tone bars start from the treble side (left side when viewing the bracing, the side of the soundboard that will be closest to the treble strings) and they slant across the lower bout toward the bass side.

Richard uses the analogy of a graphic EQ when talking about voicing the top. According to Richard's explanation, "stiffness promotes treble, flexibility promotes bass". The left/treble side is stiffer because there is more bracing located in that area, including part of the X brace, finger braces, and the ends of the tone bars butting up against the leg of the X brace. If you leave more mass on that side it will promote the treble side. If you scallop it out, you will bring the "volume" of the treble down, making it less bright or "chimey" in the trebles. Also, the right/bass side of the bracing it is fanning out - the two tone bars and the leg of the X brace have space between them, meaning that it is not as tight in that area. He showed two dread tops, one with pre-war style scalloped bracing (we've all seen pics of this style) and the other was what I think some people call parabolic bracing where the braces are not scalloped, but have been shaped and tapered in areas to promote different sounds. According to Richard, the pre-war style bracing favors the low end, where as the parabolic had more mass in the treble side, and the tone bars were tapered down to nothing at the other end. He described the second as being more balanced.

He stated that it's also possible to do things that would fall "in between" the two styles and guitarist Eric Skye who was on the tour said that they had made a hybrid braced dread for him that he loves.

When it came to tuning the top, Richard used a really interesting analogy to describe how they do things at Santa Cruz. He said that if they were to pre-shape all of the braces and place them on the top, he said it would be like "throwing rocks at a keyboard on a piano" and that you might get lucky and have the rocks hit the right keys and have resulting notes that "agree" with one another, but that it's unlikely. He said that by tapping the top in different areas and listening, you can hear different "notes" and can tell if they agree with one another or not. They shape theirs so that the notes agree with one another. He stated that it didn't matter what the notes were, just that they agree with one another, which he believes results in the top moving in complimentary ways that create nice overtones.

**Now my thoughts**

I know a lot of this isn't directly related to the question you asked, as it goes into voicing quit a bit. However, it seems to me that if he is right and mass promotes stiffness and flexibility promotes bass, then I would want to mimic Martin also and have the tone bars meet the leg of the X on the treble side. It seems like it would be easier to promote the bass response if there was less mass on the bass side of the soundboard. I started a thread a week or so ago about avoiding thin/glassy tone in small bodied guitars. I'm building a Martin style OO and want the fullest bass response I can get to balance the small body sound out a bit. Really, I'd like it to be very balanced overall (I own a dread, I don't need another).

I feel that the ideas of mass promoting treble and flexibility promoting weight is probably correct, based on the responses I got from the kind folks who responded on the avoiding thin/glassy sound thread. Most of them cautioned me to not "overbuild" the top of the guitar, as it would emphasize the treble.

I'm interested to hear everyones thoughts on this.

Justin, I took the tour at Santa Cruz last year. It was guided by Richard Hoover and I found it very interesting. For what it's worth, my biggest takeaway from the experience was that Mr. Hoover is a very savvy marketer.

Charlie,

Are you suggesting that the information above is incorrect? I will not be offended if that is the case, and I do think that Richard is very savvy when it comes to finding ways to market what they do.

I really posted that to get people's input on whether or not the idea of having the ends of the tone bars butt up against the X brace on the treble side made it easier to achieve the desired sound from the guitar by shaping them when they are in that position.

I feel like it makes more sense than saying that you tune all of your tops or backs to a particular note(s).

I believe it has been disproven that the guitar has a specific 'bass side' and 'treble side'. The top vibrates as a single unit. The bass is produced by the whole top moving up and down as one, while the treble notes cause the top to break up into smaller areas of vibration, much like the video of the plate John put up. The higher the frequency, the smaller the vibrating areas and the closer together the nodes are. In my thinking, symmetrically bracing the top, for example using lattice or fan bracing instead of the tone bars, will produce better trebles, because the whole top will be vibrating the same way, if that makes sense...

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Hey Justin - I don't mean to question Mr Hoover's knowledge of lutherie, but I do think some of his comments are more directed toward guitar buyers than luthiers, if that makes sense.

I'm far from being an expert but I agree with what PeterF said about the way tops vibrate. If you want to learn a ton about the way guitar tops work and vibrate and how bracing, stiffness and mass affect tone, check out the books by Gore and Gilet. They're not light reading but are extremely enlightening.

http://www.goreguitars.com.au/main/page ... rview.html

Thanks for the replies Peter and Charlie.

I will look into the Gore and Gilet books over the weekend. I have Cumpiano's book and it has been interesting to reference, but I've heard that Gore and Gilet are the go-to for diving deeper into these matters.

On a related note, since I was watching John's video of bracing the top, I noticed that the glue he uses is a "fish" glue. Does anyone else have experience working with this stuff? I am not sure that going the hot hide route is something that I'm really ready to do, and the idea that the fish glue has less of a dampening effect on the top sounds appealing to me.

The Cumpiano / Natelson book has been the standard for years, and justly so, but the Gore / Gilet books really open up a new world in terms of understanding how guitars work and how we as luthiers can control the tone and consistency of our guitars.

A lot of folks are using fish glue because it offers most of the same benefits of hide glue but without the very short open time of hide. Fish glue is actually just the opposite...lots of open time but that means long clamping time. I believe it dries to the same degree of hardness as hide glue and is reversible as well. And fortunately it smells nothing like fish. I think most people get it from Lee Valley. http://www.leevalley.com/US/wood/page.a ... 65&p=20019

Justin, no offence meant, but did you mean to write ?
Thinking soundboards/bracing (or top thickness) I would be more inclined to say something like - increased stiffness (or reducing weight) produces higher frequencies and lower stiffness (or extra weight) produces lower frequencies.
Hope I got that right!

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

While I basically agree with Hoover's observations as you present them, mass is not the correct term. It is the stiffness of the brace which promotes treble, that it also has mass is irrelevant as far as that goes.

Mass (or 'weight') in itself tends to favor bass.

In a somewhat nerdy analogy that will make sense to some: I see mass as equivalent to inductance, in other words it's a low pass filter. Stiffness is like capacitance, or a high pass filter.

Colin - I meant to write flexibility promoting bass. It's what Richard Hoover said about top bracing.


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Greg,

Let's try and simplify the terminology a little. My understanding (and I could be wrong) is that the more material left on the brace the less flexible it is. The less flexible it is, the less the top moves. When you say that it is the stiffness of the brace that promotes treble, I agree, but all things being equal the more wood left on that brace the stiffer it will be. That being said, I'm not sure how this is "irrelevant". More wood = stiffer brace, right? That's what he meant by "mass".

In the avoiding thin/glassy tone thread that I started, more experienced builders than myself cautioned me to not overbuild the top. They said keep the bracing light, and you will achieve greater low end, and in this particular instance since we're taking about a small bodied instrument, would result in a more balanced sound. Do you disagree?

In the video tour that I saw, when Richard was explaining this (and as some others have mentioned it was probably worded more for players than luthiers) his point was that there was a greater amount of bracing converging on one side of the sound board, and traditionally that's on the left side - the same side that the treble strings are on. Others here have said that this is irrelevant as the top moves as a single unit up and down. I can understand this, but if the placement is irrelevant, I wonder why it has been the standard placement for so many years. There have been so many variations on so many different things in modern guitar building, from playing with different radii for tops and backs, slanting back braces, cutting a channel in perimeter of the top to "free it up" to move more towards the edges, solid wood kerfing instead of traditional. But from what I've seen the placement of the two tone bars seems to be pretty consistent when a forward shifted X bracing pattern is being used. I know there are other patterns that can be used, but I'm interested in understanding why these braces continue being placed in the same position by most major builders of guitars. Mike Baranik makes some really nice guitars, and doesn't stick to tradition. His back bracing is angled in a really interesting pattern, and he even describes the body on his PX (parlor) as being "asymmetrical". Yet when you look at photos of the top bracing, the two tone bars are in the same place as Martin, Taylor, Santa Cruz, etc. etc. etc.

I am not a physicist, but basic logic dictates that the more wood there is glued to an area the less likely it is to vibrate when compared to an area where there is less wood. This is why "pre-war" style bracing is something that is still being talked about as a desirable feature in a guitar.

As always, I appreciate anyone willing to talk about this stuff with me, as I am really interested in it, and in understanding why things are done the way that they are and I want to build the best sounding instrument I possibly can.

Hi Nick:

Here's a bit of a different point of view than what you may have received so far.

Lots of times on Lutherie forums folks, newer builders may ask questions that do not have a simple answer. Tone and all things related often fall into this category.

You will get many points of view here and already have but there is another way forward too that you and only you have complete control over. And... that is doing some testing and experimenting on your own. From testing glue joints to determining for yourself with a bathroom scale if the clamping pressure of a go-bar changes with deflection there is, in my view, no substitute for doing some experimenting on our own and noting the outcomes.

After my first five guitars one of my primary goals was tone related so I took three months off from building and built 10 different tops often braced differently, etc. What I learned was beyond my own expectations but more importantly what I retained years later seems to be more complete than anything gleaned from someone else telling me the answers or what they believe to be the answers.

You will find builders who thrive on empirical data, testing, science, physics, etc. And you will find folks who may see Lutherie as an escape from the fast pace of technology and instead an opportunity to transport oneself into another time past. Some of us may be attempting to be what I affectionately call a Luthier who has a feel for Lutherie.

In my neck of the woods is the University of Michigan and as such we have access to lots of papers that have been written by graduate students who attempt to apply science and math to tone. Interestingly though the conclusions reached may not always pass muster and instead it's possible that those with lots of experience and the ability to stop and smell the roses with the power of observation throughout their years of experience may produce killer instruments as well.

You might want to pick-up some tops that are seconds with cosmetic defects and try some of the things that you have questions about for yourself. You also might want to build a mule, a guitar engineered to be serviceable and taken apart and put back to together many times and try some of the tops on it. That's exactly what I did and it helped me beyond measure. By the way my mule is my most played personal guitar and the blonde... on the right in my avatar pic.

There are countless ways to brace a guitar and what may work with one style may not with another style. And that my friend is part of the beauty of Lutherie for many of us - you will never exactly know what you are going to get BUT when you start to develop a feel for this, gain experience, your guesses will improve greatly!

Hi Justin,
When speak of "prewar" bracing they are often speaking of Dreadnoughts with the scalloped bracing that Martin used. Scalloping braces reduces stiffness but leaves "mass" (on the peaks), both things that contribute to bass response. Slanting the tonebars probably reduces the propensity of the soundboard to flatten and crack under extreme low humidity conditions that cross grain gluing has. Varying the angle also allows some adjustment of the final stiffness of the top. It doesn't hurt to stick to a plan for your first few.