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I've been putting it on the top, under the strings, for the wise guys out there, but I'm more interested in what distance it is placed from the neck joint of the guitar. Is there an agreed upon distance? I've seen references to placing 'x' bracing such and such a distance from the sound hole but no mention of where the sound hole 'should' go.

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I like to put mine pretty far north. My theory is that this increases the most active vibrating area of the top, which I envision as a roundish plate surrounding the bridge. I also design my body shapes with the waist pretty far north for the same reason. Notice in the top photo that the neck joins the body at the 15th fret, and yet the bridge is near the center of the lower bout and there's a lot of distance between the bridge and the sound hole. Very different from a conventional guitar.





Or even:

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Not having the hole under the strings has the added advantage of making it a lot easier to access the inside of the guitar; the strings aren't in the way.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Thanks Todd, LOVE to see different ideas.

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On the top..... Sorry couldn't resist.....

In our repair biz we at times see holes on the back, sides, etc. but I suspect that they were unintended....

Not having the sound hole in the traditional location also can introduce some servicability issues as well....

For example try regluing a brace south of the traditional sound hole location when one can't get their arm in the box and that far back.... It can be done mind you, think McPhearson..., but it's more difficult. Even pup installation can be more difficult with the sound hole in non-traditional locations.

Just some food for thought.

Thought I had the 'on the top' guys covered with the OP but apparently not and Hesh to repeat my question where is the "traditional location"?

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Hi Larry,
One answer is "near the end of the fingerboard". Even on traditional models the soundhole has moved as fretboards have gone from 18 to 20 fret boards.

I put it wherever it looks right

For this small classical, the top edge of the hole is under the 19th fret. Basically as high as I could comfortably get it, because the guitar it's based on only had 18 frets, and I wanted 19, but wasn't ready to try a contoured end with partial frets yet.


And here's a steel string with 14 fret neck, 20 total. Fingerboard end segment is a little longer, and the board is narrower and hole larger, but similar looking intersection between the hole and the board end curve.


And a harp guitar. With partial frets and contoured FB end, make sure the soundhole top falls between two frets. I actually probably should have put it a couple mm higher on this one. The last whole fret here is 19 (there are 24 total). The neck is 12 frets to the body.

I'm pretty loose about where they go, depending on the body style. L-00s, for example, have them pretty far south, with a 19-fret FB, uncovered by the fretboard extension, which makes the rosette more of a challenge. My Opus shape follows the L-00 in some respects.



Alan Carruth has done some research and I believe has found that moving it north enhances response in the lower pitches.

Pat

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formerly known around here as burbank
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Back about 14 years ago I was taking some readings on a Classical guitar using a small accelerometer, driving it with a sweep signal from the computer, and recording the output of the device. I got such a neat series of peaks I went looking for them with Chladni patterns. I was able to find most of them in top of back resonances, but there was one, at A=440, that didn't show up. Driving at that pitch and sniffing around with a microphone showed that it came from the soundhole, but there's not supposed to be an 'air' resonance at that pitch. Well, it turns out there is one, but...

Basically, what seems to be happening is that there's an interaction between one of the internal 'air' resonances, and a top resonance, that causes a 'split' in the air mode IF you have a body with a pronounced waist, AND the hole is centered just above the waist. Dreads generally don't show this, nor does it show upon guitars with the hole up in the corner, like Todd's. Since that 440 pitch is right in between a couple of 'normal' resonances on most Classical guitars it helps to enhance the output of notes around the fifth fret on the high E string, which might otherwise be weak. Under the circumstances,it doesn't look like an accident, and may be one reason the 'normal' layout and shape are so popular.

The research that showed the variation in pitch with location was done by William Allen, and published in 'American Lutherie'. It's in the first 'Big Red Book'.

Do you move the crossing of the X brace along with the location of the sound hole when you "move north"? If so, that might explain why the lower pitches are enhanced since you've (theoretically) freed up the lower bought to move more freely, right?

Also, your rosette's are lovely. The one on the steel string is really nice. The whole thing looks great for that matter!

In response to the OP, the "usual" location is about 4" from the top of the body to the top of the hole, measured on a dred and a jumbo.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

Such interesting responses proving once again that there's more than one way to do things.

This video is one reason I ask the question. The braces on the Martins are placed 'x' distance from the sound hole, but it looks more like that's where they end up, not where they are measured from.

https://www.youtube.com/watch?v=ZgrP2Hcvxv4

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Anywhere from here...



...to there...

Hesh's point is well taken. That said, I would also add that the side sound hole provides advantages for repair (just being able to see in through the side is a huge advantage, plus you can reach in through there with tools) that, IMO, outweigh any disadvantage caused by the northward location of the main sound hole.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Absolutely and the advent of acoustic guitars with f*ctory equalizers or control panels on the sides has gone a long way too toward making it far easier to do repair work in the inside. Removing the eq panel permits clamps to be passed though the side as well.

The enhanced bass you get with the more 'northerly' soundhole location is due mostly to the lowered pitch of the Helmholtz air resonance. Allen found that moving the hole from the center of the top to the end of a guitar sized box dropped the Helmholtz air pitch by about 25%. I've done experiments with one of my test mules that has a larger soundhole than usual. By inserting a plug with an off center hole of normal size you can drop the 'air' pitch, and it will vary more than you might think if the hole is 'up' or 'down' on the top.

It's very interesting to see the various approaches to sound hole location. I think this will prove to be a very informative thread.

To Todd Rose: Very luscious shapes on your guitars. I have always been curious about how one would brace a top for an off-center-line soundhole. I don't mean to hijack the thread, but I'd sure like to see just one picture of the bracing pattern.

Thanks,
Patrick

Thanks, Patrick!

When you look at this top bracing, bear in mind that, with this design, the fretboard extension floats rather than bearing on the top, and the body is braced to fully carry the load of neck under string tension (I'll include a couple photos of the back-and-sides assembly, too, so you can see what I'm talking about). Therefore, there is no structural need for an upper transverse brace, which, on a conventional guitar, plays an important role in carrying that load.

A side note -- You'll notice how I kind of scalloped the braces at each of the two X intersections. This is a new idea I'm trying on this guitar, which arose from my thinking that the area of an X intersection, with the braces at full height, is an extremely stiff area of the braced top. I do want added stiffness in front of and behind the bridge, to resist the distortion of the top that results from the bridge being torqued, but it seems to me that a full-height X intersection is probably overly stiff.

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Good thinking, Todd.
Exactly why I have gone over to ladder bracing again (modified). X-bracing seems WAY to stiff at the intersection to me. There are other ways to tackle bridge/top distortion besides X bracing. I like what you are doing though, and please let us know what you think about any tonal differences perceived from full X.
Really like to see internal experimentation!

Sorry about the pun but " thinking outside the box" occurred to me. Good stuff guys!

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