Planet Waves O port

[mchalebk]

Originally Posted by steveyam

BTW, does anyone know what the two size sound holes dimensions are for the so called small and large units? The Planet Waves web site is far from clear. It simply says (copied and pasted here):

Fits Soundholes from 33.75" - 35" (85.73 cm - 88.9 cm)

Wha? that's a BIG guitar?! Notwithstanding the fact that those ludicrous measurements still don't mention TWO sizes. You just can't get the staff..

I need the sizes (with allowable variation) for TWO soundholes please.

Looks like that page has a decimal point misplaced, plus only lists one of the two sizes. A Google search turned up the following page:

http://www.planetwaves.com/PWOport.Page

Here's an excerpt:

Available in two sizes to accommodate large and small soundholes
Large Size - Fits 3.875 inches - 4 inches (9.843 cm - 10.16 cm)
Small Size – Fits 3.375 inches - 3.5 inches (8.573 cm - 8.89 cm)

[steveyam]

Originally Posted by mchalebk

Looks like that page has a decimal point misplaced, plus only lists one of the two sizes. A Google search turned up the following page:

http://www.planetwaves.com/PWOport.Page

Here's an excerpt:

Bless you matey! many thanks!

[Frets100]

I did try the O Port on several of my guitars.

For the Maton EBG 808 and Norman Rodriquez classical guitars, I found that the O Port improves the bass.

However, when I tried it on the Taylor 714CE ltd edition with Spruce top and Cocobolo back and sides, I did not notice any significant difference for the bass.

The O Port comes in two sizes - one for Acousctic guitar and the other for classical guitar sound holes. So check your sound hole sizes before buying. They come in two colours - black and white.


Try it for yourself if you find that your guitar lacks the bass. If your guitar has a pretty good bass response, then it may not be worth getting the O Port.

[steveyam]

Originally Posted by Frets100

I did try the O Port on several of my guitars.

For the Maton EBG 808 and Norman Rodriquez classical guitars, I found that the O Port improves the bass.

However, when I tried it on the Taylor 714CE ltd edition with Spruce top and Cocobolo back and sides, I did not notice any significant difference for the bass.

The O Port comes in two sizes - one for Acousctic guitar and the other for classical guitar sound holes. So check your sound hole sizes before buying. They come in two colours - black and white.


Try it for yourself if you find that your guitar lacks the bass. If your guitar has a pretty good bass response, then it may not be worth getting the O Port.

I'm getting kinda the opposite from all the posts and videos. Larger guitars with a good bass will 'stand' the damping ie they don't become overdamped as a result of fitting the device, whereas smaller volume guitars become overdamped and the already smaller bass output is diminished further. But hey, I haven't even tried one yet, so I'm sure you have a valid point, and thanks for that. I am going to get one and try it in my guitars. As has been said, at £18 it's not a lot of money and I can always sell it for half price or something, so it works out about the cost of a few pints!

[mitchl33]

I actually won one in a drawing and tried it for several months. I couldn't tell a difference when comparing before and after.

I had a drawing and gave it away to another person on the forum.

[guitararmy]

I obtained a large and small O-Port from some generous people on AGF to try out.
I put the large one in a Rogue budget dreadnought. It seemed to tighten up the bass and make the guitar a bit more clear in the midrange.
The small size fits my Baby Taylor. Same thing--provides a bit more clarity and less muddy bass.

I haven't tried the larger one in any of my other more expensive guitars because I didn't think they needed any improvement....

[steveyam]

Originally Posted by mchalebk

Looks like that page has a decimal point misplaced, plus only lists one of the two sizes. A Google search turned up the following page:

http://www.planetwaves.com/PWOport.Page

Here's an excerpt:

Just measured up my guitars. The one I wanted to try it on most, my Landola 12 string, has a soundhole of 9.4/9.5cm. So neither fits!

Most of my others, the Yamahas, are a microtad over 4 inches, so the larger one should be fine.

[steveyam]

One seller is saying this in their ad - not sure if it's a copy of PW wording, but anyway:

"The tonal enhancement provided by the Planet Waves O-Port is particularly pronounced when the acoustic guitar is plugged in and amplified, resulting in a much fuller sound, a stronger signal to the internal pickup, and significant feedback control."

I don't get that. As an acoustic device, I would have thought that its effect would have been more noticeable 'acoustically'. After all, the pickup (more often than not an under-saddle piezo) - to a large extent - is still going to pick up the string and top vibrations which are less affected by the O port as are the modified sound waves coming out of the soundhole. I'm not saying that the pickup is not affected, it's all interactive for sure, but I struggle to see that it is more noticeable (well, "particularly pronounced") than the acoustic sound.

[JanVigne]

The ad copy could just be a retailer making up stuff. I know who writes the copy for most retailers.


The O-Port does negate the use of a sound hole pick up. It would be nearly impossible to use the two devices simultaneously. If a piezo under bridge were used, I really can't say I understand how the O-Port could affect what the pu retrieved - with one minor exception mentioned later If a capsule type mic were used inside the body of the instrument, then the O-Port would probaby have a noticeable effect on what the mic capsule retrieved as turbulence inside the guitar body is smoothed by the addition of the O-Port.

Most noticeably, feedback should be suppressed by the directionality of the O-Port. By way of the horn type loading of the O-Port, the guitar should - it's difficult for me to tell while I'm paying my guitars - have a similar effect to a horn loaded driver. One advantage to a horn is its directionality and, therefore, its ability to place sound in specific locations while being exclusionary to others. Horns tend to focus their output directly in front of or on axis with the horn's throat. This should account for the claim of lowered feedback when using the O-Port. That would make it poorly written but feasible that, "resulting in a much fuller sound, a stronger signal to the internal pickup", was meant to say you can play much louder before feedback sets in. This would be a useable benefit even with the piezo pu.

[Azi]

Does it work? Yes.

I bought one to help a friend who wanted an increase in projection from his guitar. He has a 20 year old Epiphone which is a beater in more ways than one.

After hearing the before and after, my ears were convinced. After installing it, there was more pronounced bass and a very noticeable increase in projection.

[rsqdvr]

Originally Posted by JanVigne

God! I hate it when people start claiming 'snake oil" without ever trying the component in question! Please, leave your belief engines at the door and wipe your feet before entering an opinion.


I assume it was my post which mentioned the O-Port and which spurred this thread. I use the O-Port in two of my guitars, a Martin DM and my Little Martin travel guitar. I prefer the benefits afforded those two guitars with the device in place. If you read my post in the "effect of soundhole" thread, you'll see the basic description of what effect the O-Port is intended to have. You'll also see a description of how the O-Port is intended to operate - the basic physics of the device. If you do not understand the body of a guitar as a Helmholtz Resonator, then you might have problems understanding the simple physics of the O-Port. But that is what is at work here, simple physics which date back to the Greeks.

Since arriving at this forum I have detected a certain snobbery about how instruments sound along with a lack of clear understanding as to how they sound that way. Threads which ask basic questions answered by laws of physics or materials knowledge seem to be full of all sorts of mumbo-jumbo about woods and variables which are a mystery to be brushed aside in a sentence or two claiming its all about what anyone likes. I'm not about to imply the O-Port's effect will not result in a subjective impression of liking or disliking the sound. But, gentlemen, the effect is created by physics and it is easily understood if you just refer back to your high school education or know a bit of history. For one thing, such devices have been incorporated into guitars for at least the last 150 years.

Without trying to sound as if I am a shill for Planet Waves, the effect of the O-Port is similar to a tuned port on a loudspeaker. The enclosed cubic volume of a cavity when vented forms a simple Helmholtz Resonator which on its own has a system resonant frequency. The volume of air enclosed within the resonator cavity is excited into motion by the pressurization resulting from the movement of the guitar's body. With a fixed low frequency cut off created by the lowest frequency produced by a six string guitar, approx. 80Hz, the cubic volume of the cavity will reach dimensions which will provide either overdamped, underdamped or critically damped values. Those values will affect what is called the "Q" of the system. When the system is underdamped the frequency response of the system will tend towards a lumpy bass with a slightly rising frequency response above system resonance. This creates what we normally term "BOOM". Think of the example I provided in my post, a Gibson Jumbo. But this is what guitar builders were trying to create as they gradually increased the volume of the cavity in larger and larger instruments through the first half of the 20the c/. Boom stood out and made the acoustic guitar a viable solo instrument in the days before amplification. However, and I'm sure many will disagree, BOOM is a very desirable quality if you are looking for an evenly balanced frequency response which also favors the mids, highs and the attack and sustain of those notes. BOOM is the opposite of what is desired in a recording studio due its tendency toward obscuring those upper frequencies. Therefore, BOOM is a trade off which can be unacceptable to some listeners but it is created by the simple physics of an underdamped system.

An overdamped instrument would have mostly the opposite frequency response with a bit of a dip just beneath system resonance. This would lead to a slightly "jangly" sound quality from a small bodied guitar where the low frequencies have been slightly depressed in level relative to the mid and upper frequencies. The shape of the cavity is not that important other than in discussing how the shape can affect the movement of the air mass out of the cavity, the shape of the vent's throat is of primary concern. So manipulating the cubic volume of the upper and lower bouts of the guitar serves to move the air mass in desirable ways and adds to the amount of low frequency heft we hear from small parlor guitars.


If you have a half way decent audio system with vented speaker cabinets, go stick your finger in the port of your bass reflex speakers. You should feel a tube with a described volume and length. This is used to tune the cavity's resonant frequency and adjust the "Q" of the system. Without this port -which has volume and length, the speaker would just have a simple hole which would allow for the enclosed volume of air to escape the cavity. This simple hole-in-the-box would be the speakers which existed before mathematics became the accepted norm for defining a speaker's system resonance, the old fashioned one note boom boxes. By adding the tuned vent to the enclosure the designer is able to create a system with repeatable results and manipulate the "Q" of the system. Many cheap speakers have been sold with a high "Q" system resonance which results in a boomy, jump off the shelf advantage over more accurate speakers. Boom sells. Think of all the dreadnoughts which emphasize bass heft lining the walls of any Guitar Center in the US. For more on why this is, read the description of the human ear's perception of bass and high frequencies as predicted by the Fletcher Munson curves as I outlined them in the post in "effect of sound hole size".

The point to remember is the cavity and its vent act as a system. With a low frequency cut off defined largely by the length of the lowest string, the designer has one less variable to deal with. Now, think of blowing air across the top of an open bottle. With an empty bottle you'll have the system resonance of the full cavity which will be somewhat low in frequency. Add some water and you've changed the system resonant frequency by decreasing the cubic volume of compressed air but not changing the volume of the vent. This is the essence of what the sound hole enlargement accomplishes and this is what the O-Port also accomplishes. By adding a defined volume and length to the vent of the Helmholtz Resonator (the guitar body), the O-Port acts as a tuned port would in a loudspeaker. It's primary function is to tune the "Q" of the resonator. This changes the frequency response either just above or just beneath the system resonance of the cavity. The O-Port, however, is a simple product with defined volume and length in its own right. Therefore, it cannot be all things to all guitars. Whether the addition of the O-Port creates an over damped, underdamped or critically damped system will depend first on the cubic volume of the cavity. The addition of the O-Port will in some cases be beneficial strictly in terms of how it affects the "Q" of the system and in some cases it will not be a good fit. The O-Port does, however, come with a money back guarantee so the idea anyone is selling "snake oil" is just simply BS. Get over yourself if that's your idea. If it doesn't work the way you would prefer with your guitar, return it and get a full refund of your money.

In addition to the tuned port concept of the O-Port, its shape also acts as a horn loading device which will have its own benefits - many of which I described in the sound hole thread. When it meets the right cavity, the O-Port will be beneficial. When it is used in the wrong cavity, it will not.

Whether the O-Port is beneficial to you or not would be a subjective determination which is nothing more predictable than which instrument or which strings you would prefer. Where one person will hear a less bassy sound, another person will hear a more defined sound throughout the frequency range after the insertion of the O-Port into any specific guitar. There is no way to predict what anyone will prefer when it comes to sound quality. What can be considered though, is the reticence some folks have to anything which is unfamiliar or unknown to their belief engine. Some folks are just a little too quick to start insulting others when what the other person represents is something they fail to understand and do not wish to make the attempt to understand. On this forum you'll discuss strings and woods and all forms of subjective values with little real knowledge of their effect other than you like or dislike them. Yet, when a product such as the O-Port comes along, you're very quick to complain rather than spend a few refundable dollars to try a device which might actually make your high end instruments sound even better than they already do. The physics of the O-Port make it not exclusionary to a high end instrumental, only to an instrument with which it is not a good match due to the cubic volume of the Helmholtz Resonator you own. This is, indeed, a tough crowd.

Really??? Your opinion is of more value than anyone else"s????? You assume you are the only one to try this device??????? Perhaps you should heed your own advice!!!!! Control your belief engines & wipe your feet before YOU make an assumption....... Snobbery and arrogance look the same as ignorance......................

[steveyam]

I got one. Fitted it quickly to my FG-140. It was a quick thing as I was about to leave the house for a couple of days. Anyway, as it was me playing the guitar, it's not the perfect place (far from it) to judge the effect of an O port which projects sound forwards towards the listener, not the player.

A couple of points. The large size is a bit sloppy in Yamaha guitars with soundholes that are a tad above 4". There are guitars with soundholes that fall between the large and small sizes, so no O port will fit them..

From the few minutes that I had to play the FG-140, it did seem to have greater volume and projection, although I am a fan of 'lifted', even somewhat 'boomy' bass, so until I can do further tests, I'm certainly in no position to say any more than what I have just. I may prefer it, I may not. But it did seem to be louder with more projection.

I have a couple of FG-360s that sound very similar, so those pair will be my 'test bed'. Obviously the effect on each type/model of guitar will be different.

One more point, the choice of black or ivory is obviously better than nothing, but a colour more like aged spruce I suspect would suit a great many guitars out there. The ivory one doesn't even match new (spruce) guitars that well, it needs to be darker for most. So, I suggest make the 'ivory' one darker or leave it as it is and make an 'aged spruce' one.

[JanVigne]

Thanks for the try, steveyam. It's great to see anyone who keeps and open mind regarding "tweaks". Possibly, we could next discuss the importance of a good cable to the sound of an amplified acoustic.

LOL!

[hyenik]

here is my small test of O-port with Cort MR-E. Microphones and line too.
http://soundcloud.com/hyenik/sets/o-port-test/

[steveyam]

Originally Posted by hyenik

here is my small test of O-port with Cort MR-E. Microphones and line too.
http://soundcloud.com/hyenik/sets/o-port-test/

That is great. Well done tests and scope response scans too.

My own conclusion - after having used it on the FG-140, and also based on the above tests - is that I prefer the sound without the O-port. The effect of the O-port is guitar dependant (internal volume reacts uniquely with the port parameters), but for me, there's more bass without it (though it may well smooth out the frequency response) and the overall sound just seems better, more natural and less muddled without it.

I had an open mind, and I was quite ready to embrace the device and maybe buy some more for use with my guitars. But on balance, for me it's a "no". That's no real audible benefit and the looks downside of a white plastic ring around the soundhole. I just don't have a good reason to use it. It may well suit one of my guitars, and in time I'll experiment some more, but I've heard enough for now.

One more thing, the line inputs seem less affected than the mic'd ones. That backs up my earlier post about the effect of the O-port being less on amplified than on acoustic demonstrations - contrary to what I saw in one advert. Moral, don't always believe what you read in ads. People will lie to get your money. As if we didn't know that already..