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 Post subject: Sound port
PostPosted: Thu Jan 04, 2018 1:44 pm 
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Cocobolo
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Sound port / beer holder... whatever.
So the basic process is simply to:
1- reinforce the area on the inside under the port
2- cut the port
3- dress it with binding or whatever.....

I mean it’s just a reinforced hole... right?


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 Post subject: Re: Sound port
PostPosted: Thu Jan 04, 2018 1:50 pm 
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Koa
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Correct. A cross grain reinforcement patch is what I use. I also put a "tube" in of fiber per the Jay Lichty article in the GAL magazine. I've only done this for ukes though.

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 Post subject: Re: Sound port
PostPosted: Thu Jan 04, 2018 1:58 pm 
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Koa
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Here are some pics of one I did awhile back. Note the cam clamp makes a nice platform for the template to clamp to. That’s from the GAL article. I used SM FB polish to shine it up. Doesn’t take much!

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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 11:31 am 
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Cocobolo
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bcombs510 wrote:
Here are some pics of one I did awhile back. Note the cam clamp makes a nice platform for the template to clamp to. That’s from the GAL article. I used SM FB polish to shine it up. Doesn’t take much!

Image

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What is the “horn” made of? That plastic part.. and why


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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 12:23 pm 
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The tube is fiber, not plastic. Black fiber, 0.020. You can get it here: http://rctonewoods.com/RCT_Store/fiberv ... -p-87.html

If you get the magazine from the GAL, you can see the article in this issue: http://www.luth.org/search/contemporary ... soundport/

For the why - The hole needs to be bound either way. Jay's reasoning is that having a tube gives the port a look of "purpose". Rather than looking like a hole it has depth and looks like a "port". I like the look as well so I stuck with it. It's super easy to scarf the fiber board and get a nice joint along the port.

You could just cut the hole and bind it which is what just about every guitar I've seen has.

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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 12:38 pm 
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Of course it begs the question - What does it do to the sound?

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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 1:01 pm 
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Koa
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sdsollod wrote:
Of course it begs the question - What does it do to the sound?


The port? Not sure... it stands to reason that the sound coming out of it would be different than just a bound hole. Maybe? The loudspeaker premise? Who knows.

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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 1:21 pm 
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sdsollod wrote:
Of course it begs the question - What does it do to the sound?


You had to do it...



These users thanked the author Michaeldc for the post: bcombs510 (Fri Jan 05, 2018 1:34 pm)
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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 1:50 pm 
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bcombs510 wrote:
The tube is fiber, not plastic. Black fiber, 0.020. You can get it here: http://rctonewoods.com/RCT_Store/fiberv ... -p-87.html

If you get the magazine from the GAL, you can see the article in this issue: http://www.luth.org/search/contemporary ... soundport/

For the why - The hole needs to be bound either way. Jay's reasoning is that having a tube gives the port a look of "purpose". Rather than looking like a hole it has depth and looks like a "port". I like the look as well so I stuck with it. It's super easy to scarf the fiber board and get a nice joint along the port.

You could just cut the hole and bind it which is what just about every guitar I've seen has.


I'm actually headed to Tryon to hang with Jay and Corrie the middle of next month.

I've *not* been binding mine. Instead I'm using my building forms clamped in a vise and custom a clamp cull to create a decorative plywood layup. It's usually 4-plys of the same species as the back and sides with a contrasting cross veneer. That part is trimmed to fit between the linings and then back beveled on each end exposing the contrasting layup when viewed through the soundhole. This is obviously done before closing the box. Ends up looking very elegant if well executed.



These users thanked the author Michaeldc for the post: bcombs510 (Fri Jan 05, 2018 1:58 pm)
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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 1:55 pm 
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I believe that the tube will raise the main air frequency in comparison with a port without the tube.

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These users thanked the author Rodger Knox for the post: bcombs510 (Fri Jan 05, 2018 1:59 pm)
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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 2:01 pm 
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Koa
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Michaeldc wrote:
I've *not* been binding mine. Instead I'm using my building forms clamped in a vise and custom a clamp cull to create a decorative plywood layup. It's usually 4-plys of the same species as the back and sides with a contrasting cross veneer. That part is trimmed to fit between the linings and then back beveled on each end exposing the contrasting layup when viewed through the soundhole. This is obviously done before closing the box. Ends up looking very elegant if well executed.


This sounds nice. Any pics of an example? I thought of the soundport the same as the soundhole that you would want to cover up any endgrain, but I like your approach. I bet it looks great.

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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 2:08 pm 
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Koa
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There is one thing that Jay mentions in the article that is worth mentioning. When you bend the reinforcement patch, under bend it. It's much easier to clamp into place if you are pushing it down in the middle than if you are trying to clamp the ends that are curling up. It really does help.

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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 5:38 pm 
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Koa
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"I believe that the tube will raise the main air frequency in comparison with a port without the tube."

That's what I was talking about. I have put soundports in a few guitars and I know how it adds ambience to the players ears. It also seems to give a little more low end... So, the tube would raise the air frequency? ...Does that mean less lower end than without the tube?

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These users thanked the author sdsollod for the post: bcombs510 (Fri Jan 05, 2018 5:45 pm)
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 Post subject: Re: Sound port
PostPosted: Fri Jan 05, 2018 6:00 pm 
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Koa
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bcombs510 wrote:
Michaeldc wrote:
I've *not* been binding mine. Instead I'm using my building forms clamped in a vise and custom a clamp cull to create a decorative plywood layup. It's usually 4-plys of the same species as the back and sides with a contrasting cross veneer. That part is trimmed to fit between the linings and then back beveled on each end exposing the contrasting layup when viewed through the soundhole. This is obviously done before closing the box. Ends up looking very elegant if well executed.


This sounds nice. Any pics of an example? I thought of the soundport the same as the soundhole that you would want to cover up any endgrain, but I like your approach. I bet it looks great.


Sorry for the poor quality photos.


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These users thanked the author Michaeldc for the post (total 2): J De Rocher (Fri Jan 05, 2018 7:03 pm) • bcombs510 (Fri Jan 05, 2018 6:01 pm)
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 Post subject: Re: Sound port
PostPosted: Sat Jan 06, 2018 12:47 am 
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bcombs510 wrote:
There is one thing that Jay mentions in the article that is worth mentioning. When you bend the reinforcement patch, under bend it. It's much easier to clamp into place if you are pushing it down in the middle than if you are trying to clamp the ends that are curling up. It really does help.


I laminate the patch on the outside surface of the side before cutting the hole. This gives it the correct shape with just the right amount of under bend.



These users thanked the author saltytri for the post: bcombs510 (Sat Jan 06, 2018 7:18 am)
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 Post subject: Re: Sound port
PostPosted: Sat Jan 06, 2018 2:57 pm 
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Mahogany
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Rodger Knox wrote:
I believe that the tube will raise the main air frequency in comparison with a port without the tube.


It's actually the other way around, putting a tube in will restrict the port and lower the main air frequency.


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 Post subject: Re: Sound port
PostPosted: Sat Jan 06, 2018 3:07 pm 
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jeffhigh wrote:
Rodger Knox wrote:
I believe that the tube will raise the main air frequency in comparison with a port without the tube.


It's actually the other way around, putting a tube in will restrict the port and lower the main air frequency.
That makes more sense to me.


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 Post subject: Re: Sound port
PostPosted: Sat Jan 06, 2018 3:18 pm 
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Mahogany
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In the same way that adding a tornavoz to the soundhole lowers main air frequency


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 Post subject: Re: Sound port
PostPosted: Mon Jan 08, 2018 3:32 pm 
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Koa
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I believe (without being an expert) that there was concern that opening a second hole in the box could raise the main air frequency such that it might create wolf tones especially with the open D string. Adding the tornavoz to the sound hole would help counteract that. At least that was my understanding from a post many years ago on the MIMF site.

That said, I also believe Alan Carruth's answer was to make a guitar with dozens of sound holes plugged up with cork to see if he could slowly increase the opening and see at what point it made a significant difference to the main air frequency. If I understood him correctly, a standard 1"-2" opening had little effect, and he offered that a simple opening enough to give the player some feedback could be added without affecting the guitar's tone too much. That implies that the sound hole tornavoz is probably not necessary.

*All the usual disclaimers of passing this information on and not being the originator. I could be totally backward in what I understood Alan C to say. I hope not, because I put a 1.5" round soundhole in all my guitars! :-)



These users thanked the author rlrhett for the post: bcombs510 (Mon Jan 08, 2018 4:07 pm)
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 Post subject: Re: Sound port
PostPosted: Tue Jan 09, 2018 1:15 pm 
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Actually, the 'corker' was my first foray into ports; I was just trying to get a reading on what a hole in any given place would do, and where the 'best' place might be for one. I've made two other 'test mules' to check out different aspects of the port question, and learned a few more things.

Basically, any hole you punch in the side is going to raise the 'main air' resonant pitch. It's difficult to predict how big the effect will be. Basically, the larger the port and the further from the 'main' sound hole the more pitch rise there will be. Even a small hole in the tail block (say, an open jack hole) will make a difference. The port also makes the 'main air' resonance stronger. A pair of ~1" holes at the base of the neck can increase the output at the (higher) main air frequency by as much as 7 dB, while a hole of the same area in the 'usual' place, at the wide part of the upper bout on the bass side, increases it by 3dB or so, and doesn't raise the pitch as much. Note that over all the power output of the guitar does not increase with a port: there seems to be a broad band decrease above the 'bass reflex range' that balances it. It makes some sense: there's only so much energy in the string signal, and the port doesn't make the thing more efficient.

As jeffhigh said, adding a sleeve to the port lowers the 'air' pitch. I don't know offhand whether you could cancel out the rise from adding the port by putting in a deep enough sleeve, but it might be possible. If it worked that might be useful in preserving the tone of the guitar while gaining the benefit of the port.

The main use of the port is as a monitor. The low-end sound of the guitar, say up to about the open G pitch, tends to go out about equally in all directions, so the player hears it about as well as the audience. As you go up from there the instrument becomes more directional, so that by the sound goes off the top and out of the hole toward the audience. The player mostly hears this through room reflections, so if you're in a large, dead, or noisy room ( think 'restaurant gig') you won't hear much of the high end. A port you can look into directs some of that sound toward the player. It's not ;the same; sound that coming out of the main sound hole; again, the closer the port is to the main hole the more alike the sound will be. At any rate, if you tend to play in noisy places a port can help. I've also heard from customers with high frequency hearing loss that it comes in handy for them as well.

As always with the guitar, it can get as complicated as you care to make it, but that's the précis.



These users thanked the author Alan Carruth for the post (total 3): TimAllen (Sat Jan 20, 2018 11:58 pm) • Ken Jones (Tue Jan 09, 2018 10:44 pm) • bcombs510 (Tue Jan 09, 2018 9:28 pm)
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 Post subject: Re: Sound port
PostPosted: Thu Jan 18, 2018 9:45 am 
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Rodger Knox wrote:
I believe that the tube will raise the main air frequency in comparison with a port without the tube.

Actually the tube will lower the frequency. The effect on the sound should be similar to that of a tornavoz in a classical guitar. The idea is a good one I suspect.


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 Post subject: Re: Sound port
PostPosted: Thu Jan 18, 2018 11:32 am 
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Brazilian Rosewood
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Just to add another tip here, friendly plastic is a wonderful thing for clamping the plywood sandwich up to reinforce the port hole.


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 Post subject: Re: Sound port
PostPosted: Mon Jan 29, 2018 11:23 am 
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Cocobolo
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Here’s how it turned out.
Thanks for all the tips folks:)
Image
Image


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 Post subject: Re: Sound port
PostPosted: Mon Jan 29, 2018 11:44 am 
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Koa
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SnowManSnow wrote:
Here’s how it turned out.
Thanks for all the tips folks:)
Image
Image


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Looks good!!

Looking forward to seeing it in finish...


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