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OK....I THINK I want to add a sound hole to my newly finished Hauser classical. Probably would be better had I done it before finishing...but I think I can pull it off.
By looking at the super O'Brian video of the guitar festival, it seems sound portals are abundant and placed about everywhere in all shapes and sizes. It would seem to me that the basic shape of the guitar and the soundboard is the proven form of resonance. Does a side sound port hamper the way the sound waves bounce inside the guitar and deter from the front projection?.....or does it just allow the player to get more out of what he is playing? Does size and shape matter? Most sound ports seem to be in the upper bout near the players head. However, I am seeing them place just about anywhere.
Kent Bailey

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Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com

The biggest question I might ask would be what you expect to gain from adding a sound port in the side of the guitar. Is it lacking something you were expecting? Will a sound port solve the problem? Is it just an experiment?

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I'm not sure what sound is missing on my first build or needed. It seems to sound better each day I play it. I have 4 classical guitars. One old...one fairly new custom built for me (with a sound hole in upper bout) another really old one I plan to put a new top and fingerboard on and my new build. They all sound different. The concert guitar I have (with the sound hole) does project sound towards me ...but I don't know if that detail has compromised the sound to others listening.
I'm just curious about the builders trend to add sound holes in all shapes and sizes. Do they really know what effect it has on the guitar sound...or is it just aesthetic. I see them all over the place. What data is there about their usefulness, placement, shape..etc.?....or what documented effects they have on the projection from the front of the guitar? I can't help but think that they must interfere with the front projection in some manor. I don't see many old school concert guitar makers using them.
Kent

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Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com

Exactly! What do they do. Al Carruth has discussed them at length in a few threads here on OLF and on other guitar forums, but the verdict is not a clear one. It does raise the body resonance of the instrument, when you cut one, and that could change the sound some, but the question of whether it makes it louder, or not is an argument. I don't want to put words in anyone's mouth, but my take on all the discussions is that it changes the sound, and that makes people think it's louder, but it's more the change that makes them think that, initially. After listening over a period of time, that effect seems to go away, and it doesn't seem to have made much difference. Just my take on it. It does provide a bit more feedback to the player, but whether it's good feedback is debatable. If it doesn't provide the full spectrum to the player, he could misinterpret what his audience is hearing, and change his playing in the wrong way, assuming the player can interpret such things. Some can't.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I am not an acoustic engineer nor a physicist, but I would hazzard a guess (please someone with more scientific knowledge correct me if I am wrong) that in the simplest terms, it will partly depend on effect on rigidity of the box as a whole that a sound port effects - if reinforced and the effect on the total rigidity of the box is negligable then surely given that the sound ports are usually small and thus there will be a minimal loss in mass of the sides etc that the tonal effect will be minimal?

In terms of volume since the sound hole is only there to let the sound 'out' it may well be louder in total as we sometimes see with steel strings with the 'larger' soundhole? Bviously to the player it will 'appear' louder anyway as the sound is also directed straight up to the player, but does this reduce the out put to the main sound hole ? facinating stuff and Would be interested to hear from someone who understand sthe physics of this because without that maybe alot of the thoughts will be based on opinion - eg what one person considers loud will not be for another ...

I don't know if this works, but here is a result of a search for "sound port", and "Alan Carruth". If you read all this, it may well answer your question. The OLF archives are full of these discussions, most all of them good.

search.php?keywords=Sound+ports&terms=all&author=Alan+carruth&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Hi Kent,

I have made guitars both with and without sound ports. I like the effect of the sound port as it seems to provide better feedback to the player. Robert Ruck pioneered sound ports as an option on his classical and flamenco guitars. It was one of his with sound ports that I first tried. It made me fill like I was being enveloped by the sound of the guitar when I played it. Any effects to listeners is a subject of much debate. Some say it actually improves it and others don't think so.

Robert does 13/16" holes about 2" to either side of the heel. He feels this is less obtrusive than the in the top of the bass side upper bout.

Regards,
Max

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Max Bishop
Brighton, Michigan

There is no doubt the player gets a warm fuzzy when playing with a portal near the players head. I just want to see some data before cutting a hole or 2 into my new project guitar. I guess, with most everything, an experiment always tells you one of 2 things.
Thanks for the info. and the link....study time.
Kent Bailey

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Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com

Despite a fair amount of study expended on the subject, there still seem to be some loose ends to nail down. Why am I not surprised. First, to restate what I think I know at this point:

1) Adding a port will raise the pitch of the 'main air' resonance.
2) Adding a port changes the directionality of the sound in the high frequency range. Even a small port will radiate some high frequencies that would not normally be going out in that direction. How big the effect will be, and what constitutes 'high' depends...
3) Adding a port will alter the spectrum and thus the timbre of the guitar to some extent.
4) Adding a port does increase the output of the guitar in certain sorts of tests in certain ranges. Most of the increase seems to be right at the 'main air' pitch, with some at the 'main top' pitch, and a bit at other pitches.

Here's the can of worms.
1) R.M. Motolla's very well constructed test showed that players could not hear a difference between 'port open' and 'port closed'. There were limitations in his test, as there are in all tests: in particular I don't think he ran any trials in a large, 'dead' room with background noise, where I would expect the port to be most beneficial. The ports he used were smaller than most people put in their guitars.
2) Even though the port can give greater output at some frequencies in some tests, it is not altogether clear whether that's useful in the real world. It's possible (I'd say likely), for example, that any increase in volume comes at the expense of sustain: there's only so much energy in the string and if you dump it faster it won't last as long. We need to address the issue of whether there's an increase in efficiency. I've got an experimental rig that could look at that, but whether I can find the time is another matter.
3) In the end, this is almost totally subjective. The port does change the sound, and if you like the change, then that's what counts. Claims about 'increased efficiency' or whatever will eventually sort out on the basis of reality: if they are true then the guitar will work better and the feature will be widely adopted for that reason. Measurements such as I make, or tests like Motolla's, might help sort things out a bit quicker, but this is a complicated field, and there are lots of folks who just won't accept 'science' at any level.

Messing with a perfectly good sounding new guitar does seem a bit risky. Especially, since it really hasn't had time to develop it's own sound yet. I have also heard that it is possible that you may produce a "wolf tone" in some cases by adding a portal. Wolf tones are rare in guitars ...mostly violins and cellos but very difficult to get rid of once you get them.
Ok....I need to back off extreme analysis and either cut a small hole or forget it.
I already have enough info. to make a sleepless night thinking about it.
Thanks to all
Kent

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Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com