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| Location of a sound port? http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=6630 |
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| Author: | Philip Perdue [ Thu May 11, 2006 5:00 am ] |
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Well I have progressed from the initial planning stage to the beginning stages. My wood is on its way from RC Tonewoods and a custom kit will soon be arriving from Blues Creek Guitars. Since this guitar will be a gift for my father and he has very poor hearing I am planning on putting a sound port on the instrument. The guitar will be a standard Dreadnaught as my dad is a flat picker. My question has to do with placement of the sound port. I believe the port would go on the upper bout. Is there a specific area of the upper bout to place the port that also maximizes the structural integrity? I would also think it would need some added support around the port like linen or a veneer. It has been suggested to me that linen would work well. Any pictures of you ported guitars would be appreciated. No tools, no skill, and no work space but I am in the game now. Thanks Philip |
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| Author: | LanceK [ Thu May 11, 2006 5:14 am ] |
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Timmy!!!!!!!!!!!!!!!!!!!!! Oh Timmy!!!!!! |
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| Author: | Dave White [ Thu May 11, 2006 5:38 am ] |
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Philip, I put mine here: 
I use wooden side braces and have a pair on either side of the port. I sometimes put thin veneers in between the 2 side braces for extra stiffening and also to add interest around the port when it is cut as I don't bind them. You can just about see the side braces and veneers in this photo: 
I have also used soundports with no extra veneers as well. Hope this helps. |
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| Author: | Alan Carruth [ Thu May 11, 2006 5:44 am ] |
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I spent some time a few years ago working out what I thought was the 'best' place to put a port. I used a classical guitar with 20 holes drilled in the right (upper) side, that could be plugged with corks. I did a bunch of measurements and listening tests over about a month, starting with taking the thing to the H'burg festival (where it was, hands down, the ugliest guitar there!). Here's what I found out. Whenever you put a hole in the side it changes the timbre of the guitar a little. The closer it is to the 'main' soundhole the less change there is. There is a _very small_ increase in output when you punch a hole of reasonable size (say, 5/8") in the side anywhere. A bigger port does not give you more output (surprise!) overall. It does change the timbre more. The port raises the pitch of the 'main air' resonance, and that's one of the major influences on the change in timbre. Again, larger and farther from the main hole gives a greater effect. You can decrease the size of the main hole to get things back to where they were, but it's a little hard to say exactly how much to decrease it by. One thing you could try: make the main hole smaller than you think it will need to be, and leave a wide margin around it with no inlay. You can use a marking gauge to enlarge the hole a little at a time once you've got it together and strung up. The 'best' place to put it is probably somewhere near the shoulder on the upper side, so that it points toward the player's face. Since different people hold their guitars differently the 'sweet spot' might change a little. For classical players it works well to put it just above the wide part of the upper bout. My tests indicated that the base of the neck was one of the _worst_ places for a port, as it makes a lot of change in the timbre and doesn't direct much sound to the player. On the 'corker' I just reinforced the areas of the holes with cloth tape before drilling them, and it's been fine for the three years or so that I've had it. When I put a port in a customer's guitar I use either a piece of 1/32" basswood plywood (from the model airplane shop) or a thicker piece of some other wood that's run cross grain. I'm still working on getting it to look right. |
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| Author: | Kim [ Thu May 11, 2006 8:02 am ] |
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Dave, Looking at your guitar bracing suggest to me that as a child, you would have made the best kites in Great Britain.  I really do like your work, very clean and practical but always innovative.
Cheers Kim |
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| Author: | Michael Dale Payne [ Thu May 11, 2006 8:29 am ] |
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Or do like Allen and put them everywhere and use cork plgs on the ones you dont want to use  
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| Author: | tl507362 [ Thu May 11, 2006 9:18 am ] |
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Here is a pic of a sound port I did on a bouzouki I'm just finishing up. I have already strung it up and played it in the raw, and I must say that it is the loudest instrument I have ever heard from such a small box. When I cover the soundport and then uncover it, I can hear about a 10% gain in volume from the players standpoint, but from the person listening, it is more like 5% change in volume or less. The best spot I think is between the waist and the peak of the upper bout, but very close to the peak of the upper bout, just before it crests. In these pics you will see that I used a maple/dyed black maple veneer to reinforce the area. I glued this in after the sides were bent by using a clamp with the soft styrofoam that will conform to any shape. Hope this helps, and good luck! Pic of the port: 
Here is a pic of the reinforcement: 
Tracy |
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| Author: | Michael McBroom [ Fri May 12, 2006 2:21 am ] |
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Here is a closeup of one of two soundports I installed in a client's guitar (on either side of the neck). I pretty much followed the guidelines that Robert Ruck, a highly respected classical builder, uses in the size and placements of his soundports. I used alternating white/black veniers to give the port a bit of visual interest. 
Best, Michael |
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| Author: | Darin Spayd [ Fri May 12, 2006 3:31 pm ] |
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Has anyone tried one in the lower bout? Last weekend I was playing my low-end (laminated b&s and neck) Martin, and held my ear to the side in various places along the side as I awkwardly strummed a chord. It seemed that the loudest sound came from just about even with the bridge. Is this a false impression? |
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| Author: | Billy T [ Fri May 12, 2006 6:01 pm ] |
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Dave: That's very nice! Is that Walnut on Maple? Billy Dean |
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| Author: | Dave White [ Fri May 12, 2006 8:04 pm ] |
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Billy, it's maple with curly koa binding. |
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| Author: | MATTRIX72 [ Sat May 13, 2006 2:31 am ] |
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hey dave, what are the sound advantages of the x-bracing style on your guitar verses the lateral braceing? I was just currious as to the differant styles,by the way that sure is a beautiful guitar you have there............  i hope mine looks as good as yours opon completion. & nbsp;
this style x - bracing verses 
this style lateral? thanks |
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| Author: | Dave White [ Sat May 13, 2006 4:26 am ] |
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Matt, I went to the hybrid X/ladder braced back about 8 builds ago. I was looking for a more consistent arching for the back without having to "force" the front to back arch by gluing the back to the shaped sides. I also like the way the braces lock and that there are only 4 notches to make in the side linings. Soundwise I think it gives slightly better overall projection of the guitar. Al Carruth uses forms of X braced backs as he says he can get a better back "tuning" that way although I don't conciously do this. |
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| Author: | Alan Carruth [ Sat May 13, 2006 8:26 am ] |
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I checked the lower bout positions in my 'corker' experiment, to see what they did to the sound. The only general answer I can give you is; 'it depends'. Putting a side port in the guitar changes the timbre, because the port 'vents' the 'main air' resonance, changing it's pitch, and it also 'hears' internal air resonances that aren't normally heard. Both of these things change the balance and overall tone of the guitar. Generally speaking, the farther from the 'main' soundhole the port is, the greater are both effects for a given port size. If you're using the port as a 'monitor' you want it to be fairly small, reasonably close to the main hole, and pointed at the player. This, along with a reduction in the main hole size, will preserve the sound you've come to know and love, compared to your 'normal' guitars, and work well. If you're using the port to remedy some problem with the tone of a particular instrument the 'best' place will depend on what's wrong and how the guitar works otherwise. I can't give you any general help with that: it's too variable. I did put a port beside the tailblock of one guitar in an effort to fix a specific problem, and it _almost_ worked. Sigh..... |
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| Author: | Billy T [ Sat May 13, 2006 9:38 am ] |
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[QUOTE]it's maple with curly koa binding.[/QUOTE] Uuuuummmmmhh!!! KOA!! Nice looking! Billy Dean |
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| Author: | MSpencer [ Sat May 13, 2006 3:49 pm ] |
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Dave, I like your bracing and thanks for the info, looks great! Mike White Oak, Texas |
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