I've been searching through the articles on this site for information on selecting the position where the bridge should be. Obviously on an unfretted instrument you can move the bridge and experiment, but on a fretted guitar, once the frets are on and the neck is fixed that's it. You have committed yourself.

 

So is there any way to know on a box for box basis (not using formulas because I'm pretty sure that they are worthless unless you always use identical boxes) where the bridge should be to get the best results?

 

Now I've already done some test, but I don't know if they are the work of a visionary (don't laugh) or a pointless waste of time (odds on the latter). I was thinking that as far as the box is concerned it gets most of the string vibration through the bridge. If you want to simulate vibrations coming from the bridge can you use something else that will transmit vibrations and see (or rather hear) how they sound and make a choice based on that. I found a tuning fork and tried it at various places on three boxes that I intend to use soon.

The results from the three were quite different. Not surprisingly all gave the warmest and clearest sound in the centre of the box. The top one gave quite progressive results getting better quite gradually towards the centre. The left hand one was very even across it's width until right near the edge. The right hand one was a surprise as it sounded best right in the middle, tone falling off and getting soft of nasal even an inch away from the motif. Shame as I don't really want to put a bridge right on the motif but my tuning fork test suggests that it may be the best place.

 

So, finally, to the question. Has anyone done any tests - similar or otherwise - that give a good indication of where to put a bridge and that do not rely on ratios or formulas, but take into account the different characteristics of each box?

 

 

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Emmanuels guitars are clearly not typical acoustically I am sure, and on top of that it appears (and sounds like) he is using a sophisticated pickup, preamp and processing system to augment the sound as well. I am not intending to take anything away from his brilliant talent, just sayin' .... Hmm, why the headphones for a solo guitar performance?

 

I also have to respectfully disagree with Mark on the "flashy" comment. hang with me....

Back to using ZZ-Top/Billy Gibbons for an example to make my case. Yeah many of the songs are victim to a bit of goofy writing, but focusing on the guitar technique, I am a fan, and here is why. He nearly always used/uses simple riffs and makes the most of them, by delicate control and variation of his tone, instead of showy (and generally souless and tasteless) fingerboard shredding. What a tastefully applied bend, vibrato or harmonic touch applied here and there adds is far better IMO than speed and dexterity ever will be. Go to his early work, pre-Eliminator stuff, and check out his bluesy soulful bits, and rightious rocking out too. Play "Applogies to Pearly" for example. Tasty

 

And with that I will apologize for sidetracking a thread on design/building.

Sorry

Play nice and have fun!

Mark

Just my theory. I think he is so good that he is listening to the sports scores while playing.

Mark Bliss said:

 Hmm, why the headphones for a solo guitar performance?

LOL!

Well I must say that wasnt on my list of possibilitys!

Well, if you look at his expression part way through I think the team he supports must have just scored.

Mark Bliss said:

LOL!

Well I must say that wasnt on my list of possibilitys!

Having watched a lot of his other stuff I don't think his pickups or pre amp are doing anything especially fancy, I think they're just doing a fairly thorough job of picking up the sound being made by the guitar. Sure they're good pickup systems, but he's a remarkable player and I'm pretty certain he could get similar sorts of sounds out of a purely acoustic instrument (just at lower volume).

I guess he gets to play some very nicely made instruments and that can't do his sound any harm either.

Interesting that Australians are well represented among the the relatively small and select ranks of those who've done good scientifically sound research on guitar acoustics - I'm thinking for example of Graham Caldersmith, Neville Fletcher and the musical acoustics lab at the University of New South Wales.

Gents,

 

To get back to the original "zombie" thread topic for a minute, lookee here what I found, while getting materials for my Excel CBG soundhole optimization spreadsheet (from another thread):

 

http://physics.kenyon.edu/EarlyApparatus/Rudolf_Koenig_Apparatus/Tu...

 

Helmholtz and Koenig were doing experiments in the mid-1800s on tone. Note the use of spruce as the soundboard.

 

And on another link on the homepage of the above, this yittle gem (CBG fiddle, anyone?):

 

http://physics.kenyon.edu/EarlyApparatus/Rudolf_Koenig_Apparatus/St...

 

Both are fascinating finds, thanks for the additions Oily!

One thing that immediately caught my attention was that the resonator boxes appear to be sized (tuned) to the particular frequency, so they are great examples of why there is no fixed answer to our eternal question here. One may be best for treble tones, another for bass. Somewhere in between is a good comprimise.

 

So now we need a box of variable volume, and a moveable hole right? LOL! No seriously! Hey, maybe a tuba horn flare and some plumbing might help too! Ok, that parts not so serious. But keep the mind rolling ok?

 

As of yet I have been unable to find a clear explanation of the tone bars function in the Viol family. If the top sound board transfers treble energy and the back sound board bass, why connect the two at a location near the treble side of the bridge? And why do luthiers consider its exact location a critical part of set-up? So far this just defys my logic! Unless maybe it flattens the response curve as in the previously mentioned comprimise. Hmmm, you know I think I might have just figured it out all by my little old self!

Michael, where are you, we need your guidance........

Oh yeah, build another guitar, just go do it.......

Mark,

Yeah, I immediately thought of this thread when I saw those. Re the box of variable volume and movable sound holes, been discussing ways to do that very thing in this thread:

http://www.cigarboxnation.com/group/superclass/forum/topics/soundho...

The way Antonio Torres Jurado apparently approached this, and apparently the way the guy behind RainSong Guitars does a similar-but-different thing (soundboard thicness), was to have soundboard templates with varying sound hole sizes. In tha above thread, I postulated trying 1) soundboard templates with variable sized sound holes and locations, given a "standard" box size, 2) variable size boxes, upon which these soundboard templates could be affixed, and the use of a sound level or dB meter to measure the pressure of the air being moved out of the box. Somewhere in this thread, there is a link to a finite element study on soundboard flex vs. frequency. One could do the same thing for sound hole design and location, test those designs, and then test the addition of variably sized tubes that extend into the box below the sound hole. Torres apparently began to experiment with that idea as well, but gave it up for some reason.

I've been working today on an Excel spreadsheet Helmholtz calculator for either frequency optimization and / or sound hole size optimization, while also relating these to string gauges and tunings. It's more than half done; another day or so, and I'll have a rough but usable version for y'all to play with / critique.

BTW, did you see the XXXL fedora link I sent you on the "Blues player" thread?

Oily
Watching... always watching...

I know this is an old discussion, but I finally have some good feedback.

I recently(last week) built a 3-stringer just for the look of the box, not really expecting anything but a good looking toy.

Much to my suprise, it sounds so good, I have added it to my personal collection. It is a 3 string fretless, and the box is solid spanish cedar. All of my builds are acoustic first, the piezo is just for playing in a crowded area.

My point is really simple, they all sound good, especially if you tune them DAD/CGC.

I will definitely need at least a half dozen for myself tuned differently so I can play anything I want just with the slider.

 

So you want to be the watcher do ya? LOL!

MichaelS Country Boy Guitars said:
Watching... always watching...

For me placement of the bridge is 3 inches from the end of any box. This will insure that there is enough tension over the bridge.

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