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Sound Ports?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=19175		 Page 1 of 1
Author:  Frank Cousins [ Mon Oct 13, 2008 5:40 am ]
Post subject:  Sound Ports?
Hi

Having blunted tools, blistered fingers and cussed, laughed and finally enjoyed a rather nice 'wee dram' of 21 year old Laguvulin Islay malt with my mentor to celebrate completing number 1, number 2 has its back and top joined ready for thicknessing and the sides thicknessed and sized ready for bending.

My question is to sound port or not to sound port and if so when is the best time to do this? I have seen some of the beautiful guitars produced on here which have some lovely sound port designs so would like to have some tips if possible. I have not really played any guitars that have them, so dont ahve the knowledge as to what to expect and any impact they have on both overall sound quality or on what this does from a players perspective.

Any tip, help and advice greatly received.

Cheers

Frank
Author:  Peter J [ Mon Oct 13, 2008 6:40 am ]
Post subject:  Re: Sound Ports?
Frank,

There are extensive discussion threads in the archives about sound ports. Alan Carruth is our resident expert and technical advisor in this area. Check out his website where he describes an experimental guitar he built with sound port holes up and down the body. He "corked" them closed and only opened them one at a time while performing acoustic tests. Very interesting experiment.

If I remember correctly there was a very minor improvement in loudness.
Author:  Mike Collins [ Mon Oct 13, 2008 6:41 am ]
Post subject:  Re: Sound Ports?
Frank;
I bend my sides ,install linings ,which seems to help support the side when I drill a 1" hole in the upper bout.
I then bend a piece of left over side material (which I already drilled the hole in)to match the inside curve of the side & glue it with the grain running 90 degrees to the side grain.
Then i just sand the hole and taper it a bit.

A port seems to help the top to pump easier.
By reducing pressure inside the box.
I can hear the guitar better when playing it ,which I like allot.

[:Y:] Mike
Author:  gozierdt [ Mon Oct 13, 2008 9:33 am ]
Post subject:  Re: Sound Ports?
I drill the hole after I have completed the box. I add a cross-grain support
patch inside the upper bout from back to top lining, and approximately
3 inches long before I close the box. Then after the box is closed I drill the
hole carefully, using a sharp tubular holesaw. If I want it oblong, I extend
the hole with files after drilling.

If I wanted one of the fancier ports with multiple openings, I'd create it
just before I closed the box by drilling multiple small holes, and use a
coping saw to create the shaped openings.
Author:  Alan Carruth [ Mon Oct 13, 2008 12:56 pm ]
Post subject:  Re: Sound Ports?
As far as I can tell, a side port facing the player makes a nice little 'monitor, especially if you're in a noisy situation. The main change it makes in the sound is a rise in the 'main air' pitch, and some shifting around of peaks in the upper rnage. Making the main soundhole a little smaller (say, by about 1/4-3/8" for a 1" port at the wide part of the upper bout) gets the main air mode pitch back down to where it belongs.

I drill the port with a Forstner bit before I put on the top or back. The cross grain reinforcement is glued inside first. I like to turn a slightly tapered surround, wrap it with contrasting veneer, and glue it into the hole. Wrap the taper with sandpaper to match the hole taper to it, and trim it off after it's glued in.
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