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I have been planning to cut a soundport into the side of a guitar I am building, and I have been thinking and doing some research on the topic. I have noted that most of the soundports on acoustic guitars are located on the upper bout, sometime from just beyond the waist to others being closer to the neck. I have been wondering if placeing a soundport on the other side of the waist, on the lower bout, would maybe be a more effective maneuver. Most of the sound energy is generated from that end of the guitar, and in my thinking it would make that part of the side a much more efficient place for a soundport. I would like to know your opinions on such a design, and your input if you have tried such a thing.
I also have been unsuccessful at finding approxamate dimensions for soundports. I really have no idea as to how big the hole needs to be for proper functionality. Any recommendations would be greatly appreciated.

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Jake Archer
~~Make a joyful noise unto the Lord~~

You could always to this:

http://www.alcarruthluthier.com/guitars/corker.htm

I think Al recently wrote an article about sound ports, maybe you can track that down.

My very scientific reason for placing my soundports in the upper bout are as follows:

'Cause Al said so.... yep, that's a good enough reason for me.

Seriously, if you get your hands on his article, he pretty well pointed that out as optimum placement. Most builders (some following his lead, some blazing their own trail to the same conclusions) have pretty well followed suit. One exception is the way-cool Ryan Bevel Flutes. Several others use dual ports in both the upper and lower bout. I'm sure every approach is good in its own right. Some strike me as simply an attempt to be different and recognizable (like the Ryan) but in a market where so many builders are putting out awesome guitars these days, I have no problem with that. Another topic for another thread, I guess.

If for no other reason, the upper bout port just "looks" right to me.

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Wes McMillian
Santo, TX
http://www.wesmcmillian.com

Jake,

I'm in the middle of doing my first with a sound port, and decided to use 2 sound ports: one on the upper bout for my left ear, and one on the lower bout (but not so far down that my arm will cover it) for my right ear. I also tilted the orientation of the ports, with the right sound port closer to the soundboard, and the left sound port closer to the back. That was after noticing that when I play, my head is almost never perpendicular to the guitar body.

I wish I had the chance to play Al Carruth's "corker" to confirm my hunch, but I followed gut instinct with the dual ports to see how she sounds.

Please let us know what you do, and then report back how it works out for you.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I tend to put my ports in the wide part of the upper bout because that seemed to work about the best. I had a number of people try different things at H'burg one year, in the raucous main display area, and that placement won by a small margin. Subsequent testing in my shop confirmed that it was at least as good as anything else.

Yes most of the sound does come off the lower bout of the top, but that doesn't mean that's the best place for a port. It comes down to two things; which internal air resonant modes the port will 'hear', and how active they are at that particular location. Further down on the lower bout, for example, with certainly get more energy out of the 'main air' mode, and you get the most from that with a port at the tailblock. Is that what you want?

If you're looking to get the 'out front' sound at the player's location, then the best port location is right at the same height as the main soundhole. This 'hears' more or less the same internal modes that the main hole does, with some notable exceptions. Depending on how you hold the guitar this may or may not direct the sound toward the player. Remember that the sound coming from the hole is not a narrow 'beam'; it spreads out in all directions, so that pointing the hole right at your head is not needed.

Any port will change the timbre of the guitar. Any air mode it 'hears' will have the pitch raised some, and, of course, many of the modes a port picks up don't normally put out much sound through the main hole. If you like the timbre, and particularly the bass balance, of the gutiar without a port, I'd suggest finding some way to reduce the size of the main soundhole to preserve the 'main air' pitch. A short sleeve, say a hlf inch deep or so, would probably do it. you could experiment with paper and cut it down until you get what you like, then make one of something more permanent.

I have to say that my experiment involved using small holes, and I think they are perfectly adequate if what you're looking for is a 'monitor' in a noisy/dead room. I don'thave as much experinece with ports larger than about 1" diameter, and can't say whether there is asome qualitative difference. When I tried oncorking most, or even all of the holes, in the 'corker' I did not get any increase overall in the sound output compared to two holes or four, but, again, that my be an artifact of the way I did the experiment. I will say that I have not been particularly impressed by most of the guitars I've tried with really big ports; or, rather, that they sound pretty much the way I'd expect them to, and I am not attracted to that sound.