Sound port questions

[Harley90]

Hi, looking to add a sound port to my next guitar I'm getting built...looking to do a 0 or 00 Martin style guitar, likely rosewood (Maybe Mahog) body, ebony full scale neck.
The builder I'm discussing this with, jokes about a sound port, but I like most all guitars I've played with one and this is to be a couch, watching TV kinda of guitar.

He has never built one, so a bit hesitant on being the 1st one. Happy with the other guitars he's built for me but looking to add a few different specs this time around.

Thank for any thoughts or comments around this topic.

[TomB'sox]

Not sure why he would joke about it. They are not really controversial in the least anymore. If you like them, find someone who will do one for you. I kind of laugh that someone who has not done one before would be joking about it. I would take more notice if someone had done 50 and then decided they did not like them. I moved to Texas and all my friends were telling me they hated Texas and the people that live there, when I would ask when they had been there, invariably they all replied they never had. I rest my case.

Sound holes have been proven to aid the player in hearing the guitar and, unsuspected by most, to increase the forward projection of the guitar as well.

[K20C]

I’ve had 2 customs with sound ports and didn’t care for either. The sound I heard as a player was way different than what the listener in front heard. On one, the low E through the sound port was overpowering. I didn’t keep either guitar very long.

[fitness1]

I would be hesitant as well - and probably look for someone who has experience and understands the process or at least have him commit to speaking with someone who does.

I would also caution you, given the size of the prospective guitar, to keep the port very small.

Most of the time when folks think ports don't work, they are much too large and/or placed incorrectly.

[mikealpine]

I’ve got some with and some without. No way to know if the ones that have them would sound better without a port, or if the one that don’t would sound better with. If the builder is not comfortable on his particular guitars, then I’d stay away. Otherwise he is experimenting with your guitar and money. If you really want a guitar with a sound port, find another builder that cuts in sound ports and makes a guitar you like. In the end, my gut says that if you like this builder, get the guitar, no port.

[Tim McKnight]

We reduce the diameter of the main sound hole by the volume of the side sound port. If you don’t then the side sound port will raise the Helmholz (main air mode) of the sound box and the guitar will sound thin and treble biased or tinny sounding.

[Jamolay]

Originally Posted by Tim McKnight

We reduce the diameter of the main sound hole by the volume of the side sound port. If you don’t then the side sound port will raise the Helmholz (main air mode) of the sound box and the guitar will sound thin and treble biased or tinny sounding.

I read about people adding sound ports to already built guitars. This makes me think that is not a good idea. Are there adjustments that are made?

[justonwo]

Building with a sound port, in my opinion, is a bit of a holistic operation. Some guitars that are designed to have them sound fine with them (LeGeyt comes to mind). Others that don’t have them sound fine without them. I’ve even found they can be beamy/distracting in some cases.

I would definitely NOT push a builder into something they joke about. If they don’t embrace the concept wholeheartedly, don’t push it on them.

[Tim McKnight]

Jamolay,

It’s just physics and there are no free lunches.

[jcjenkins3]

What I know about sound holes I have learned by experimentation and trial and error. They do make a difference in the sound of the guitar. There seems to be a sweet spot for every guitar, where the area of all the holes in that guitar gives optimal sound for that guitar. Until that area of sound hole is reached, all holes in a guitar body act equally upon the sound, and are of equal importance. Once that sweet spot has been reached, holes in the top of the guitar have much more influence on the sound than holes in the side of the guitar. Almost all guitars, and pretty much every factory guitar has a sound hole that is too large for optimal sound. If you ask why the sound hole is the size it is, you will be told something like, "because a Martin 000 has that size sound hole." Of course the reason a Matin 000 has that size sound hole is because a man needed to be able to get his hand inside of it to work on it after it was assembled. Also, its body was smaller than a dreadnaught, so it was given a sound hole 1/8" less in diameter than a dreadnaught. A 00 has a sound hole 1/8" smaller than 000, and so on. There is no scientific basis for the size of these holes. Usually a sound hole 3 to 5 square inches smaller than a Martin 000 in a comparable size guitar yields much improved sound. I could go on, but you are probably bored, so that is enough for now.

[Cocobolo Kid]

I really like side sound ports. Both my Baraniks and my Kraut have a side sound port. I personally would not buy a guitar without one now.

Like others have said before, I would definitely choose a builder that has experience installing them and seeing how they affect the sound of their guitars.

[Bruce Sexauer]

I was hesitant myself, but now include them in most of my more contemporary work. I think it is very important to maintain the porting size of the box, so I diminish my sound hole by about the same amount as the side port represents. Many builders seem to over-port their guitars. IMO, of course.

[Eire]

I'd be leery of a builder doing his first sound port on one of my guitars, at least without some coaching and guidance. I've several different sound ports on my McKnight guitars and would follow Tim's guidance. My favorite is what he refers to as a "dual" sound port; you can see a photo of one of my guitars on the McKnight home page, and a better picture of what the "dual" ports look like under his "Options" menu. May just be psychoacoustics, but I feel like there's more of a stereo sound from the dual ports, as opposed to a single port. YMMV.

[fitness1]

Originally Posted by Eire

My favorite is what he refers to as a "dual" sound port.

Me too - I've had great results with that on a few guitars. As I said previously and Bruce said above, the key is the size. I put dual ports on a couple classicals and they were very small - the ones on this Solista were 7/16 each and extremely effective!

[sinistral]

Originally Posted by Bruce Sexauer

I was hesitant myself, but now include them in most of my more contemporary work. I think it is very important to maintain the porting size of the box, so I diminish my sound hole by about the same amount as the side port represents. Many builders seem to over-port their guitars. IMO, of course.

Alan Carruth wrote a paper back in 2009 describing tests he performed on an experimental guitar he built based on Carleen Hutchins’ ’La Grueyer’ violin, with ten pairs of 5/8” holes along the upper and lower bout, which he plugged with small corks.

Alan Carruth—Side Ports

He concluded much the same:

Some care must be taken with the size and location of the port if the normal timbre of the guitar is to be preserved, but fortunately it does not take a large port to make a useful monitor. Making the normal soundhole smaller on these guitars compensates for the expected shift in the A-0-1 mode pitch. I will note that it is a little hard to predict how much to reduce the main soundhole size when using a port, since the larger the port and the further it is from the hole the greater the pitch shift, in general.

To jcjenkins3, there is in fact a scientific basis for the optimal size soundhole for a given size box. What’s interesting is that luthiers long before Martin figured out the relationship, probably through trial and error. There’s a lot out there on the topic, but the discussions by Alan Carruth and Trevor Gore in this thread do a good job summarizing it.