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There was a discussion on a Ukulele forum that I thought would be of interest here. It has to do with a single soundhole vs. the double puka (two soundholes). The two soundholes placed high in the upper bout has several effects on the performance of the soundboard. It allows the transverse brace to be located much higher on the soundboard. The bridge now has a larger area of support on the soundboard. And of course this certainly frees up a much larger area for sound production. I would guess that the bracing could be a bit lighter too on both the soundboard and around the soundholes.

The photo is a guitar built for Keola Beamer by Steve Grimes from Maui. I have heard Keola play his several times and it always sounds great.

Philip

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aka konacat

If you think my playing is bad you should hear me sing!
Practice breeds confidence and confidence breeds competence. Unfortunately, I'm stuck in practice.

Many of the Arch Lutes and theobros used 3 sound holes in a cluster. I have one on the drawing board as my Arch lute build for next year, this would be the rose pattern.



Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

There is an interview of Steve Grimes in the Summer 2003 issue of AL, which includes him talking about this design. As always, there are tradeoffs. He evolved this design to deal with slack key guitars tuning the strings lower than normal. The design offers him a better bass response. He says the bass isn't louder, just richer. He also talks about trying not to lose the treble while enhancing the bass.

Thanks for posting this, it save me from having to. It seems to me that not enough testing has been done for optimum sound hole size and placement. You would think that this type of design would cause more soundboard vibration because there is more board under the strings which would cause longer sustain and possibly higher volume. I am just a newbie so I'm only looking at the obvious and I'm probably not looking at all factors here but I would be interested to here different opinions on soundhole placement and number of soundholes.

I made one like that some years ago: it was interesting, but not without problems.

First: read up on air resonances. Bill Allen's article in American Lutherie #1, now out in the first 'Big Red Book', is a great place to start.

Moving the hole up toward the top edge drops the 'main air' resonant frequency a lot if you leave the size the same. Making the hole bigger, or using two holes for more total area, would raise it again.

There are a bunch of air resonances in the box. Some of them can be heard directly through the 'normal' hole, and some can't. Some of the ones that can't 'talk' to the outside air directly still influence the tone by the way they interact with the top. Moving the hole(s) to the upper corner(s) changes which air resonances are heard directly, and how the top works with the air. Since a lot of that stuff has been worked out by cut-and-try methods over many years to give a 'good' sound you're sort of on your own when you make such a major change. Not saying it can't work, but don't be surprised if you lose something you liked!

One problem on the one I made had to do with one of those normally 'silent' air modes: the one where the air sort of 'sloshes' back and forth across the upper bout. This happens at about 700 Hz on most guitars, iirc. The holes in the corners could 'listen' to that mode nicely, and feed sound from it into the room. The problem was that they were out of phase with each other. They're far enough apart so that they don't cancel out except right along the center line of the guitar just in front, but they do tend to 'beam' that pitch out toward the sides. When playing I'd have my head right in that 'beam', and any note that had any of that pitch in it would sound LOUD. So I'd play it soft. The folks out front didn't hear it the same way, and wondered why I was playing so unevenly. Little did they know.

Ah, the unexpected pitfalls of science....

BTW, regular Martin style X bracing does a pretty good job of extending the vibrating area up. The actual soundboard area that you lose with the hole is not all that much, and I didn't feel that the game was worth the candle. You might do better, particularly if you can get the fingerboard off the top.