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Recently on one of the flamenco forums there was an extended discussion about the attributes of adding a soundport. The thread was initiated by one of the luthiers in Spain who had added a port to one of his flamenco guitars and explained how he felt it was an improvement for the player. You'll have to realize that even though many steel string and classical builders have embraced adding soundports, to flamenco purists this was equivalent to blasphemy and the ensuing discussion was both heated and open.

Many of us have added soundports to our instruments for a while now and have avidly listened in to the many, many discussions and also read the articles published in American Lutherie and others landing on both sides of the issue.

One of the participants in the above mentioned discussion was Jason McGuire, a professional flamenco player who is well respected amongst his peers. He is currently playing two ported instruments and to help support his position that the soundport was an improvement to the player, he took the time to record a YouTube segment with some of his uplevel recording equipment to show the differences of playing with a soundport open and closed. He also shows that there are differences depending upon where the mic is located; out in front or close to the port & player. This substantiates what Alan Carruth has said that the port is a monitor for the player, changes the timbre of the guitar to a certain extent and opens up the upper bout sound energy a bit.

Take a listen and see if you can tell the difference between the mic locations.

http://www.youtube.com/watch?v=hyOmGDoVVnQ

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Peter

Great video. The sound differences are quite distinct, even on my laptop speakers.

The 'player experience' part is especially enlightening, as the sound difference is very similar to what I'm used to in the 'in front of VS behind the guitar' situations.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Peter-

Can you show a link to this discussion please?

Thanks-

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John Lewis
Wannabe builder owned by 2 crazy dachshunds

I really don't hear much differance if any from the front. And I have pretty good speakers. I'm wondering if a hand is the proper think to cover the port with being it's not the same as wood. But the volume to the player is obvious which is also obvious if you ever played one.

I didn't hear any difference when the microphone was at the front of the guitar. I listened to the video with my eyes closed and I couldn't tell when he covered up the port. I could tell the difference when the microphone was near the port. With my eyes closed, it was a lot harder to pick out when he uncovered the port. Near the end of the video it was a bit easier.

I don't think he was trying to fool us but I wonder if he was attacking the strings the same way each time. It would be very easy to unconsciously play a bit louder when when the port was uncovered because a louder guitar is what you expect. R. M. Mottola's experiment had an independent 3rd party cover and uncover the sound hole while the player is blind folded. He found that most players couldn't tell if it was covered or not.

Very subtle if there was any difference at all. I have to agree with Mike that it seemed like the attacks weren't the same. I heard more difference in between arpeggios, specifically when he hit the low E within trials than between trials. i.e. I heard differences in low E tone even though he didn't remove his hand from the port. I couldn't hear any difference when he was doing the fast strumming at the end.

I have a gut feeling that he should have used cardioid mode for some reason though.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

If you have played a ported guitar then there is no denying that it is louder to the player. As far as the tone and out front sound that has a lot to do with the size of the port and it's position and the size of the sound hole which is what Alan Carruth's corker demostrated.

I thought so too until I tried to tell if the sound ports were plugged or not with my eyes closed. I couldn't do it. I did this experiment on Al's corker. The test was very disturbing since the differences were so noticeable when my eyes were open.

Maybe your brain is train to muffle out sounds when you close your eyes, like going to sleep at night?
Interesting to say the least.

Whether or not you can hear the difference in the video, there is a very real difference in person to the player. I would argue that the high frequencies are enhanced with the port open and I am pretty sure the physics will back me up...

I am sitting here with a Selmer style guitar I built with a larger-sized sound-port in the upper bout and the difference with the port covered or uncovered is quite remarkable. Anyone could tell the difference from the driver's seat. Granted the primary sound-hole on this guitar is smaller than a comparable Martin style guitar, so maybe the differences are more extreme in this case...

Regards, Peter

Based on tests I performed on several guitars that is not the best location for a soundport and that video is a good example of it. I would say that closer to the lower bout would be a more beneficial location.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

You don't hear things the same way a microphone does.

From what I can tell, a port does three things:
1) It increases the output of the 'main air' mode, and alters it's pitch,
2) it 'vents' higher order modes that may not contribute directly to the sound output in a 'normal' guitar, and
3) it alters the directionality of the radiation pattern at high frequencies.

The guitar is too small to emit the low frequencies in a directional manner; the lowest notes go out in all directions, and the player hears about as much of them as the audience. You don't have to go up too far for it to get more directional, though, and by the time you've got to 500 Hz or so, almost all of the sound is headed off the top and out of the hole, away from the player.

Normally this is not a problem: you catch the reflections from the room and your brain integrates all the information seamlessly. In a larger, or soundproofed, or noisy, room, such as a 'restaurant gig', you might not get much feedback from room reflections, and this is where the 'port' probably shines. This, IMO, was one of the issues with Mottola's study; had he included some bigger, 'deader' rooms, the result might not have been so clear cut. I can't fault him: he had enough to do with getting the data he got, and this is a usual sort of issue with such studies.

I did not watch the video: with my dial-up connection it's not worth the trouble generally. Most mics are more directional than your ears, though, and if he had the mic pointed at the port, it would probably pick up more high end with it open than with it shut. My own measurements did that. In some sense, the mic is always in a 'dead' room, and would pick up the difference, where your ears might not.

What your ears might well pick up on that a mic could miss is the different mix of high frequencies in the sound. I think this is what causes opening a port to give that 'wow' sensation: the sound changes in ways that your ears are designed to pick up on. Because of the change, you 'home in' on it, and it may well seem a lot 'louder' just because the change is interesting. But, of course, once you get used to the new mix, it goes back to being the same ol' same ol', and it doesn't sound so loud anymore. I noticed this in my own playing/listening tests at Healdsburg; the initial impression that the instrument was louder with the port open faded quickly.

As always, this stuff turns out to be far more complicated than it might seem at first, in some ways. In the end it's likely that neither the claims of the extreme enthusiasts ("makes every guitar better!") nor those of the extreme skeptics ("no real difference") will turn out to be wholly true. The big question will be whether it does something that is worthwhile. If it does, then ports will become normal design features, and if not, then they won't. Only time and the market will tell.

With my eyes closed, I also couldn't tell if the ports were plugged or not on the corker from out front.

On the other hand, there was a definite improvement in sound after the wine spill.

He had the mic in omni mode which should eliminate significant directional effects in micing. That's why I'm thinking that cardioid or even hyper cardioid (which is an available pattern on the C414) would be a better pattern to use when trying to demonstrate this with a mic.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com