MIMF

I'm doing a pretty traditional 17" f-hole archtop and strongly considering an upper bout side port. The research I've done suggest they really can open up the sound not only for the player but general projection as well. I was planning to double the thickness of the side with a second layer of mahogany, so it would be .180" thick around the hole, and the hole would be fairly small. Looking at generating a true ellipse 3" by 1.5" and see what that looks like. Has anyone done this, are there any comments or suggestions?

Brian

I do put sound ports in my arch tops. Alan Carruth did a very extensive test on sound ports, and basically came to the conclusions that unless you make an enormous one it doesn't really affect the sound to the audience much. It does provide the player with a better sense of the sound. Arch tops tend to project a lot, and give little feedback to the player, or at least that is my personal experience. On the first one I did a sound port I started with a guitar with no sound port and cut one in. It made a noticeable difference to me the player. The guitar became much more enjoyable to play because I could hear the rich sound the people in front of the guitar were hearing.

As to reinforcements, there are several threads on sound ports in general. I put no reinforcement on the one I did after the fact, and have seen no problems. I just use a perfectly round sound port 1.5" in diameter. On others I have used two sheets of veneer backing as much for esthetics as anything. I suppose a crack could start at the apex of the oval. Even cloth reinforcement at the apex would probably be sufficient in my opinion.