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soundports

BrandonBrinley

By BrandonBrinley
in Acoustic Guitars

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Freeman Keller Apprentice

Freeman Keller

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Yeah, Tim is a great believer in holes in the sides of guitars. I've never done it and never really looked at one but my assumption would be that you would want to reinforce the thin curved side around the port with some sort of graft on the inside - I would be tempted use wood with grain running vertically on the sides. I would think you would want to prebend it to the curve of the side - might tend to split if you aren't careful. You could probably use a plunge bit on a router to make the cut as long is it didn't go into the waist of the guitar.

You might want to look inside a guitar with a Fishman style "barn door" electronics and see how the side was reinforced. I'm afraid the if you don't do something it will split.

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totamus Newbie

totamus

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Freeman is absolutely correct. You need to reinforce if it is a solid wood side. If it is laminate, not so much of a concern, get out your favorite implement of destruction and whack away (knife, chainsaw, tire iron, etc).

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tim Mcknight Newbie

tim Mcknight

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Here ya go. Send me an email if you have any questions.

Sound port installation instructions:

List of materials:
Dremel with router base
1/8" Downcut spiral bit (StewMac)
1/2" dia Dremel sanding drum
180, 220, 320 sand papers
Brush on super glue (Stew Mac)
2" masking tape

Tape the area off with two layers of masking tape. Be generous so you don't risk scratching the surrounding finished area around the port.

Look inside your guitar and see if there are any internal side braces. If so, transfer the brace locations onto the outside on the masking tape so they are visible from the outside. This is the area that your sound hole must be located [between] as you don't want to sever a brace. Stay well below the top and back kerfed linings too.

Draw out the port shape on the masking tape. Smooth designs seem to produce a better tone. I use a port roughly the size of a small egg. Remember the larger the sound port the higher pitch your guitar will be. Start out smaller and you can always make it larger.

Use the Dremmel , router base and down cut spiral cutting bit. Stay 1/16" inside of the line and cut the hole out.

Put the sanding drum in the Dremmel and now sand to the finished shape outline.

Use 180 sandpaper and round over the internal and external edges of the hole. Progress to 220 and finish with 320. Be very careful NOT to sand the finish on the exterior of the guitar.

Coat the edge of the hole with superglue. It will dry hard and shiny. Use the edge of the brush to apply the glue and make a circle around the freshly sanded edge.

Remove the masking tape. If the glue is rough (usually it isn't) you can smooth with 600 wet or dry sandpaper and then buff.

Get a glass of iced tea, kick back on the couch and let me know how big your smile is when you first hear your ported guitar.

Warning [read the fine print >] Even though this may seem like a simple modification please remember there is no way to reverse it once the port is cut. It took me about 9 months of continuous R&D to work out the ideal shape and location for my sound ports. I tune my sound box to a certain frequency and if the port is cut too large you will raise the Helmholz or main air resonance of the body. The result will be a loss of power and projection. If the port is cut to the correct size the sound port will actually produce a gain in forward and 360* projection. Good luck and enjoy the fruit of your work.

Tim

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Freeman Keller Apprentice

Freeman Keller

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Wow, Tim, thanks for the explaination. I am surprised that you don't reinforce it somehow. When I built the mando (remember the mando? As I learn to play it I really am glad I built it) I used the surgical gauze trick on the f-holes. I would have expected all kinds of splitting with a sound port.

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BrandonBrinley Newbie

BrandonBrinley

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well i did it with a hole saw sanding paper and masking tape :]
came out great lol no splitting
even though i did gouge a spot that was near the port but hey theres gouges like that all over this old parlor
and i also found out this guitar has a solid back top and sides which shocked me :]
i will put up pics tommorow along with the pics of the classical because i dont have my camera at the moment

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tim Mcknight Newbie

tim Mcknight

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Wow, Tim, thanks for the explaination. I am surprised that you don't reinforce it somehow. When I built the mando (remember the mando? As I learn to play it I really am glad I built it) I used the surgical gauze trick on the f-holes. I would have expected all kinds of splitting with a sound port.



Yes, I do remember the mando project ;)

All my newer guitars have "Double Sides" so there is no need to reinforce the sides (at least of my guitars). I have cut dozens of holes in single thickness sides with no il effects. It would be best to reinforce the area where the port will be cut but many folks simply don't have the tools or skills to attempt that. Since the majority of all single thinckness sides have some sort of side reinforcement in place already, be it wooden sticks or cloth tape, that is ample reinforcement to stop a crack from propogating.

The absolute safest sides to cut ports in are laminated sides because they are the most stable. There is always some slight risk when cutting into single thickness [solid] sides because you have no way of knowing how much stress or springback remains in the sides when the rim was assembled. There is a risk with these sides of the wood wanting to release some tension when the port hole is cut.

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