Official Luthiers Forum!

Just think of me as the H.L. Mencken of lutherie and it will all be fine...

I think a little controversy might be a good thing around here...

Rick first I would like to thank you for taking the time and effort to respond. Even though participating here could be considered time well spent ( a gutsy form of advertising where your ideas and ways of presenting yourself are put in the open for critique or affirmation,(more relevant as the forums exposure grows)),you could be doing those things that support your family in a more direct way. There is no way that I can ever express my gratitude and respect deeply or often enough to you and others for that participation.

Those that craft guitars for a living are a big part of the life blood of a forum such as this. It is only natural that marketing be a part of many discussions.

My original intent on asking your help was on the chance that you had experience with a specific guitar, Ry Cooders,
built by a respected Craftsman that took on the challenge of using ladder bracing in a large body guitar. That did not turn out to be the case. Because you chose to make a living crafting instrument the breadth of experience you have gained allowed me to gain some valuable insights from you any way.

I feel my purpose in using ladder bracing is I would be able to get evenness of response and tone also clarity
(through fewer overtones) than I would be able to with x bracing. I felt the larger the body then the more the designs limitations come in to play, but I needed a lager body for a darker sound hence my interest in modified/hybridized L.B>

I was trying to get as much info as to how people think ladder braced guitars work in order to refine/ validate/invalidate my own without having to put them out. being around the amount of experience here can be intimidating. Conjecture about how something works
from me feels slightly pretentious.

My last post was a poor attempt to steer things towards theory rather than marketing issues while thinking about the limitations of approach. I thought the obvious inference would be that my approach benefits greatly from your(and others) input.

I think I understand what changing bridge plate grain orientation might help accomplish.

There was one ladder brace weiss I think?

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

Niche market; I resemble that, my first inspiration to build myself instead fixing and modifying cheapies was Homer Ledford!

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

I worked for a while between major lutherie efforts in many aspects of the building trades.   At one point we were putting an addition onto a house and talking to a very wise roofer about how to prevent leaks when marrying new construction to old.   He said, "Think like water." That was the key to knowing where the roof was likely to leak first.   Absolutely freaking perfect... Zen and practical all the way.

So if you want to know how a string is going to sound coming through the transformative medium of a guitar top and body, think like a vibrating string.   That will help you imagine how vibrations get into, propagate through, shake, and vibrate a guitar top and thus move air. Understand that what goes into the string and how the string wants to react to that pluck is greatly modified by the time it is transformed (not amplified...) by the guitar's structure and enclosed air chamber.   Think about how the tensile forces of the string act upon the saddle, the bridge and the top.

Don't get to hung up on a micro or nano scale version of it, though do know that all transforms take time, and do pay attention to the kind of work that Al Carruth has done to literally map out what the top is doing at different frequencies.    

Bracing basically controls how a top moves in and out of phase with itself at different frequencies. Guitar tops do not operate in a nice piston mode, loudspeaker-like manner. What we can do is to use bracing and top graduation to shape and prioritize non-linearities in how a guitar body transforms Pythagorean harmonic series' string vibrations into unique tone.

And ladder bracing tends to do that differently than does "X" bracing.   You got a problem with that? :-)

""
So if you want to know how a string is going to sound coming through the transformative medium of a guitar top and body, think like a vibrating string.   That will help you imagine how vibrations get into, propagate through, shake, and vibrate a guitar top and thus move air. Understand that what goes into the string and how the string wants to react to that pluck is greatly modified by the time it is transformed (not amplified...) by the guitar's structure and enclosed air chamber.   Think about how the tensile forces of the string act upon the saddle, the bridge and the top.

Really Really close to my approach to design but the filter I put it thru has much less experience.

""
do pay attention to the kind of work that Al Carruth has done to literally map out what the top is doing at different frequencies.     

That is why I asked about glitter patterns and the is direction I was hoping things would go.

""
What we can do is to use bracing and top graduation to shape and prioritize non-linearities in how a guitar body transforms Pythagorean harmonic series' string vibrations into unique tone.

Could you rephrase that so I can make sure you are saying what I think you said?

""
And ladder bracing tends to do that differently than does "X" bracing.   You got a problem with that? :-)

Aha the crux of the matter. When talking about one of the most important matters there is it can be like getting secrets from the C.I.A. or very contentious when you finally get talking about specific ideas in bracing.
When a Professional puts his bracing or bracing theory out there for critique or study it could affect his/her lively-hood. Keeping that in mind could help keep things at the debate level.

I guess what I need to do in order to learn is gut up a little and take some time to put my thoughts on how I think ladder bracing works and why in a comprehensible form and present them.

Fear that I may have held on to some fallacies and worrying about sounding pretentious for my experience level have kept me from doing so.

Growing in public has the potential of being painful.

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

The guitar (to narrow the field) does not "amplify" nor "transform" the string signal in a linear mode, either in frequency or phase.   The guitar changes the emphasis of the harmonic content, and it delays the delivery into acoustic energy of much of that frequency content at different rates at different frequencies. Each guitar has its own signature of non-linearity, and that defines its "tone".

We should look at the signature tone of any guitar as being the result of its "transfer function"...the rate at which it transforms a relatively coherent, multi-harmonic input signal from a string into an acoustic output.

Here's the thing...aside from the specific input force vectors of the string, it wouldn't matter if the input signal were from a string or from a fart. An input signal is an input signal, and the structure...the guitar itself...will impose an transform function on that input signal, thus defining the "sound" of that guitar.

Every mechanically vibrating structure has a definable "sound".   It could be a piano, a trumpet, a guitar, a banjo (NO!), an accordion, or whatever. If you put a certain signal into it, you'll get a different signal out of it. That's the very sound of the instrument...that's the very definition of the instrument's "tone".   And that can be represented as a digital algorithm. (with apologies to any Luddites here...) That digital algorithm is just a representation of what already is. It can be a recording, if you will, of the necessary clues to identify a particular instrument. The real point is that tone is ultimately definable.   

Are we there yet in being able to show all of this?

No, but we're a lot closer than we were ten years ago.

Though this is not the subject of this particular thread, I have to say now that I think the science inside lutherie will continue to advance inexorably toward understanding of how things like "X" vs. "Ladder" actually work. There's a point where the Genie is out of the bottle, and to welcome the Genie is to move forward with fewer impediments...

Wow its getting late I do not have to work tomorrow but I bet you do so thanks the for responses and I think I should hit the sack.
                     

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

Didn't Billy post a pic on the "Off Topic Discussion"? 

_________________
Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Hesh just think you could accomplish this while the tops are being given your methane treatments. With your prior experience I am sure we would all benefit from a toot-torial.
Did you ever find out if cups are flammable?

Who is H.L. Mencken-

""
Of all the classes of men, I dislike most those who make their livings by talking—actors, clergymen, politicians, pedagogues, and so on. All of them participate in the shallow false pretenses of the actor who is their archetype. It is almost impossible to imagine a talker who sticks to the facts. Carried away by the sound of his own voice and the applause of the groundlings, he makes inevitably the jump from logic to mere rhetoric.

""
All men are frauds. The only difference between them is that some admit it. I myself deny it.

""
Conscience is a mother-in-law whose visit never ends.

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

"The ill wind which blows no man to
good."  Henry IV, Act 5.     

_________________
Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Or, as Zilch the Torysteller would say, "Hark, what wind by yon lighter breaks?"  Jomeo & Rulliet, Part I 

_________________
Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

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[QUOTE]it wouldn't matter if the input signal were from a string or from a fart. [/QUOTE]

    Woah! I never thought of that! Hesh's guitars are vibratory and chemically preseasoned! Brilliant!

    I can see the AG publication now - "Sulphur Dioxide and Your Next Guitar"! Probably cause quite a... buzz!       

_________________
Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

[QUOTE=Rick Turner]
....
Here's the thing...aside from the specific input force vectors of the string, it wouldn't matter if the input signal were from a string or from a fart. An input signal is an input signal, and the structure...the guitar itself...will impose an transform function on that input signal, thus defining the "sound" of that guitar.
....
[/QUOTE]

Rick, hypothetically speaking, suppose you gather guitars that everyone or most agrees are great sounding guitars. Then with each guitar attach a transducer to the bridge, or (whatever location is judged optimal), and drive the guitar with a known definite signal or an impulse function. Record then deconvolve the known input signal from the recording, leaving the guitars instrument response plus some recording equipment responses etc. which could also be deconvoled. What's left would be some reasonable representation of the guitars response (transform function). Then build a library of great transform functions and use it to provide an analytical source of comparitive design.

For example: Unkown builder guitar A. has an instrument response most resembling a Torres guitar B. with the exception of a missing resonance at 700 Hz and phase difference at 200Hz.

I'm guessing you will say it's been done and doesn't work, but why?

Colin wrote:
".....none of the people I regularly talk to would concur with Mace. It may have been due to the local environmental conditions or the fact that early 17th century lutes were, not to put too fine a point on it, not very good!"

Or it could be all of those amateur repairs by gentlemen like Mace! :)

Thanks Rick. I keep trying to tell folks that the guitar is _not_ an amplifier. Maybe they'll listen to you....

That 'transfer funcion' that Rick talked about is a very interesting thing to look at. I've been messing with those for several years. The neat thing is that these days, it so easy to do: if you have a computer with a sound card, you can look at them. Sadly, I don't have the time to go into the methods at the moment. The basic one is aclled an 'impulse spectrum' and maybe you could finsd something under that head with a search. Othwerwise, I'll be happy to detail it tomorrow if anybody wants.

On X vs ladder:

Braces add a lot of stiffness along their length. If you insist on having the strings attached to a glued-down bridge, and want to keep the top from folding up under string tension, and at the same time you want it to be light enough so that you can hear the guitar, you'll need some bracing. Bracing along the line of the strings adds the most resistance to static deformation for the given weight.

However, you also need to think about the different ways the top can vibrate and what that does to the tone. Unlike a loudspeaker, the guitar top doesn't simply move like a piston. As you go up in pitch it breaks up into smaller vibrating areas. When you have two of them (a 'dipole') the two areas will be out of phase with each other, and, if they have the same area, and move with the same amplitude, they will mostly cancel out. It's possible for the dipoles to radiate a bit in one or two directions, and they can couple with other things to become more producticve (in some cases, two negatives really can make a positive!), but, in general, they won't be as effective at turning string energy into sound as the the loudspeaker-like 'main top' resonance.

As you might expect, there are two major 'dipole' top modes; a 'cross dipole' where the treble side moves 'up' while the bass side moves 'down', and a 'long dipole', where the fulcrum of the lever is the line of the bridge across the top, and the area in front of the bridge moves out of phase with the area behind.

The frequency relationship between these two modes will depend in some degree on the way the top is braced. The more 'across' the top the braces go, the higher the pitch of the 'cross' dipole mode relative to the 'long' one.

The long dipole pitch seems to often come in at around the same pitch on many guitars. This may have to do with the fact that this sort of motion is what the bridge torque is trying to do, and we build tops to have a certain level of resistance to bridge torque. Guitars without enough stiffness along the grain will have low 'long dipole' pitches, and may also collapse from the bridge load in a hurry. There's more to it than that, I'm sure, but this will do to go on with: we can think of the 'long dipole' pitch as more or less 'fixed' (at around 350 Hz, say F or F# on the high E string?), and look at the way the 'cross dipole' relates to it.

On classical guitars the 'cross dipole' picth is usually fairly low; averaging about 260 Hz on a sample of 30 I've tested. On a smaller sample (19) of my own steel string guitars it averages about 325 Hz.

Because it is less effective at putting out sound than the 'main top' resonant mode, the 'cross dipole' often acts as a 'cuttoff' to it: the cross dipole pitch is a dip in the spectrum just above the peak of the 'main top' mode.

Meyers found that, on classical guitars, those that had very narrow spectral peaks for the 'main top' mode tended to be percieved as 'harsh', 'forward' or 'thin' sounding. They often 'cut' well, and had good 'definition', but are not 'full'. Sort of the 'Broadway Belt' tone. Placing the cross dipole mode to low in pitch will have this effect. Since nylon strings lack high end energy compared to steel, a bit of this can be a good thing, adding 'clarity' if it's not over done. Thus we find that classical guitars tend to have the cross dipole pitch a bit higher than Flamencos, which really need that extra 'cut'.

With steel strings the added cross grain angle of the X brace moves the cross dipole pitch up, and yeilds a broader 'main top' peak in the spectrum. This is associated with a 'fuller' tone, in general, and steel strings can use that boost.

Ladder bracing boosts that 'cross dipole' pitch even higher, if I'm to beleive the small sample of guitars I have that used it. If Meyers is right, this ought to boost the 'fullness' even more, but, perhaps, at the expense of 'clarity' .

Of course, much will depend on just where the braces are relative to the bridge, for example. A brace very close to the bridge will tend to raise the impedance of the top, giving less volume and, maybe, more highs. Too far from the bridge and the top will not have much resistance to the torque.

More could be said, but I've got to go.       

Because of the dipole cancellation, acoustic guitar tops impose a "smiley curve" mechanical EQ to the string signal through that midrange cancellation.   Hence the usual desire to do the electrical equivalent of that when amplifying with undersaddle pickups...

We tried deconvolving impulses and found the results to be less than useful without a lot of tweaking. There's nothing like a plucked string to drive a guitar top in all of it's modes in the correct proportions.

Al picked up on something I said which important to know: a guitar is not an amplifier. The electrical equivalent of a guitar is a transformer. The guitar is a lossy and non-linear impedance matching device that is attempting to transform acoustically inefficient string motion into diaphragmatic motion that can move air molecules. Amplification involves harnessing an outside source of energy and modulating it so the output is a perfect analog to the input but is working at a higher energy state.

Considering just the bridge brace would another effect of moving the bridge brace closer and closer to the bridge in effect be creating an unbalanced dipole that as you bring the brace forward becomes more unbalanced becoming in effect a half-phase dipole?

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

I don't see the phase of the areas changing; it's just how large the areas are.

Ladder bracing could change the relative amount of frequency doubling from the z axis tension modulation, too.

Sorry did not say what I meant to say, at times I have severe concentration problems.

I meant to say monopole not half phase dipole.

unbalanced as in resonant frequency of the legs of the dipole.

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

I think it's getting to the point where the only way to find out more is to do some glitter pattern testing.   We can talk this to death and not really get much further.

Rick In reading my last two post I realized that I may in my inability to say things quite they way I mean to that I my have given you the Impression that you have been wasting your time talking to some one that is talking through his fart hole.

I want you to know this is not the case. I have days sometimes weeks where coherent though and effective communication become difficult even my ability to spell is affected. At these times I have usually avoided posting or even talking to others. I admitted a little of this in the off topic section a while ago.

I do feel that there is a little more to be gained but that you are basically correct, I feel a little less than capable of framing my thoughts on complex concepts enough to continue effectively anyway.

I have gained MUCH.

THANKS to all.
               Kirby    

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

P.S. am a huge Fleetwood Mac admirer.

P.P.S. Can I trade(unload on you) a 17.6 year old that takes joy in being a total b**h*** for a double horseshoe pickup?

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

For any one curious here is a link to a site that shows the bracing of a Kalamazoo KG-14

_________________
"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...