Official Luthiers Forum!

I've just started a series on my blog documenting how an idea of mine developed over a few years. It may be of interest to some of you, and may inspire one or two to look again at some of your past experiments you may have considered to be a bit of a cul-de-sac. It would be interesting to see what other ideas from others the series spawns.

I shan't spoil the ending, but it's a nice little tale. Next episode in a couple of weeks!

http://nkforsterguitars.blogspot.com/20 ... dea-i.html



nigel

http://www.nkforsterguitars.com/the-book

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nigel

http://www.theluthierblog.com

Cool sketch. Interesting idea. I'm looking forward to reading more.

Mike

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Mike Lindstrom

sounds ligical enough to give it a try.
good luck!

Oh I did! As you will see...anyone else tried a novel way around this problem?


http://www.nkforsterguitars.com/the-book

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nigel

http://www.theluthierblog.com

is that fretboard for playing past the sound hole? Could be interesting if it worked.

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"Preoccupation with an effect gives it power and enhances the error"
from "Your Owner's Manual" by Burt Hotchkiss.

Did you look at the rest of the drawings on the blog? The idea was to have a 1 piece neck from head to toe, with a soundhole cut into it, and for it to take the strain. The body was just a passive amplifier.

Worth a try? Mmm?


http://www.nkforsterguitars.com/the-book

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nigel

http://www.theluthierblog.com

Latest episode on the blog!
http://nkforsterguitars.blogspot.com/20 ... ea-ii.html



http://www.nkforsterguitars.com/the-book

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nigel

http://www.theluthierblog.com

Excellent work Nigel

Steve

Intriguing. How does it sound? It would seem to me that, by connecting the bridge to the fretboard and neck, you might be preventing free vibration of the bridge, and the soundboard.

How would you charactize the volume and projection of the guitar?

very interesting .......... I would love to hear a sound clip

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Interesting. I bet the soundport helps alot on that one. I like to rest my hand on the bridge when picking and seems like that would be hard to do with your design for me but i like the clean look of it. Is the neck cantilevered? Or is it glued down to the soundboard to transfer the string energy.

I think the blog answers most he questions folk. It wasn't supposed to work like a conventional guitar, the bridge wasn't to "work" the soundboard in the same manner, rather the super light soundboard would sympathetically amplify the vibration of the neck unit.

I'd love to see how others could develop the idea.







http://www.nkforsterguitars.com/the-book

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nigel

http://www.theluthierblog.com

It is still a very nice artwork. The path to innovation is littered with failed experiments. Onwards and upwards.

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Aaron Craig

That's awesome! The only thing I would say is that if that saddle, bridge, fret board end or what every you call it is actually hovering above the top it would be interesting to know what it would be like if it was coupled to the top to impart some string energy at that point.

There was a bolt attaching the soundboard to the underside of the bridge area. Rather like a Dobro. Didn't work. I tried having the whole neck touching but that was worse, then I tried a little bridge between the bridge and top which was much better but still too soft and quiet, and the soundboard was not braced in a way to resist down pressure so I knew it wouldn't last.

It may well work with the Howe Orme style soundboards I've been developing over the last couple of years. "Cylinder tops" I call 'em, it's a Howe Orme arch but with an X brace. Very strong and very light.

Now they way I think and work is not scientific compared to much of the folk who contribute to this forum, but it may be interesting to know what the "scientific view" of this "passive amplifier" way of building is. Even if I don't understand the answers, I may gain a new insight and a different take on things. Another, different idea may be born.

Anyway, another episode in a few weeks! Wait till you see what happened next!


http://www.nkforsterguitars.com/the-book

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nigel

http://www.theluthierblog.com

Your guitar design looks nice and would be better suited for electronics without the saddle and soundboard being connected.

Nigel,

You are always on the leading edge. Great concept and great work. I'm a fan.

Marc

I greatly appreciate innovation, even reckless innovation. One never knows what the boundaries are unless they are fearlessly trampled. And to restate and expand an idea on your blog, innovative ideas must be executed with flawless workmanship, so at the very least, no objections can be made on the criteria of craftsmanship. It seems you succeeded completely in this regard.

Having said that, I remain convinced that there is still much to be explored. The acoustic couplings you have tried did not succeed, but it seems there is a vast array of unexplored ideas. For example, you mentioned trying a bridge wedged in, but the question is, what kind of bridge? In violins, the bridge is the heart of the violin. Even within the narrow convention of the traditional violin bridge, the sound is changed greatly depending on principle bridge modes, mass, damping, etc. which are changed by removing wood in strategic places.

I would be inclined to continue to explore a bridge of some kind, perhaps a much wider one, similar in appearance to a convex brace, thus putting the contact points closer to the periphery, and variably positioned somewhere within an arc of perhaps as much as 120 degrees. This would put less stress on the top by applying force where the sides will contribute something in resisting distortion over time. Further, I would fashion the bridge such that it can be optimized by carving and tuning while in place. This will change the nature of the acoustic couple in real time, which is a tremendous advantage. Further, the legs might be equal, or one leg may well be longer than the other. The most challenging aspect will be in deciding how the bridge will attach to the neck end. This will take imagination and creativity of the same order as the whole guitar.

If top distortion under downward force remains an issue, how about a sound post or two directly under the bridge feet, to allow the back to contibute resisting strength? After all, you've got that handy side port for easy access. Why you practically anticipated the installation of posts : -)

That there is an optimal coupling of your string termination to the soundboard is an immutable truth, and so is the fact you have scarcely explored a fraction of the potential coupling systems.

Yes, excellent - plenty of food for thought there. But alas we can only be as wise as we are at the time, and it seemed that any tinkering with the transmission would make little difference at the time as the soundboard I made was not capable of standing much down pressure. If I go back to this design I may well experiment more with the transmission. But it dawned on me that the issue was also with the physical shape of the soundboard. Passive amplification didn't work in the way I had hoped.

Not to worry - all I wasted was my time. I whipped the soundboard off (still usable for one of my Howe-Orme style instruments) and removed and cut down the neck. The guitar became a rather fancy Model S advanced with a canted soundboard - rather like the classical Millennium guitar.

As you will read in the next few posts though, the design took a different but still related direction at this point.


http://www.nkforsterguitars.com/the-book

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nigel

http://www.theluthierblog.com

I wonder if trying a similar concept but with that extension essentially placed under the soundboard instead of on top would work? Vibrations would transfer to the box while a solid connection between neck and bridge would enhance stability (?). I always wondered whether a raised fretboard extension as used in many arch tops and some classicals was really effective. I also tend to question the concept of a top as speaker cone "pumping out" sound. Speakers have no holes, and increased air passage does not increase volume. We're talking sound waves here right? Not wind. Or does wind increase volume? I am just a novice here.

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"Preoccupation with an effect gives it power and enhances the error"
from "Your Owner's Manual" by Burt Hotchkiss.

Here's something I'm trying to take the string pressure off the top. Got the inspiration for it studying how pianos are made. The test models I built show a lot of promise. I ended up cracking the top while french polishing, it's lightly braced, and am in the process of making another. Gonna spray this one.

Okay, I tried to post some photos but it didn't work, I'll try again. Waiting________ It tells me the file is too big, so no picture . Ah, success at last

Interesting. It looks very strong. I take it that's the top bracing there.

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"Preoccupation with an effect gives it power and enhances the error"
from "Your Owner's Manual" by Burt Hotchkiss.

The brace in the lower bout is to keep it from spreading when the strings are tensioned, I'm going to be using a tailpiece which I'll probably have to build myself. I want a tailpiece that can be adjusted to regulate the force of the strings against the top. The hoop that runs around the inside is laminated out of mahogany, is really stiff and adds little weight. My idea was to build a strong frame like in a piano, thereby making it easier to construct consistent soundboards. I'm trying to get the soundboard to act as a diaphram as in a piano. I built a test frame of plywood, the shape of the guitar, stuck a neck on it and tried a few bracing methods. Ladder bracing has worked the best so far. I'm looking at making the bridge like a piano's, using offset steel pins to form the node instead of angling the strings over a nut, that will remove nearly all the downward pressure of the strings on the top. I wish now I had built an adjustable neck into the guitar, as it is I chose to use a shim between the neck and body to change the angle if needed. I just hope the finished guitar works as well as in the tests, I didn't have sides or a back on the test rig and it was loud and sensitive and sounded just right.

Isn't that downward pressure on the top what makes it transfer string vibration and thus sound? Hopefully your design doesn't kill resonance. Piano strings are quite larger than guitar strings. Hope it works though.

I'm thinking of going to the drawing board with a "through neck" type design inspired by Nigel's attempt. It got the creative juices flowing again. Just wish I could find a huge hunk of ebony like that on the cheap.

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"Preoccupation with an effect gives it power and enhances the error"
from "Your Owner's Manual" by Burt Hotchkiss.