Official Luthiers Forum!

Latest SM ad I received - "The O-Port will make any guitar, from beginner to custom, sound richer, fuller, and louder, with more clarity and better projection"
https://www.stewmac.com/strings-and-accessories/instrument-accessories/feedback-control/daddario-o-port/?utm_source=facebook&utm_medium=cpc&utm_campaign=pla&fbclid=IwAR17tdVQedkGwcuxLblSkybNxUzrqMRAXkEuhvSCv4VKkLh7qPb7PZZVbgg

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

woo hoo

_________________
Steve Smith
"Music is what feelings sound like"

I tried one in my Acoustic Bass, it did lower the note but it also lowered the volume.

You could probably save a few bucks and use one of these instead:
https://www.amazon.com/MyCableMart-Cut- ... JWN7&psc=1

A number of years back I built a guitar with soundholes similar to the layout Steve Grimes uses on his Beamer model. I inserted cable grommets in them which allowed me to vary the size of the openings. It did change the sound - as I closed them down the sound seemed to accentuate the bass but also added some "mud" into the mix.
The O-Port might improve a strident sounding guitar some, but the grommet could do much the same, and if you find one that allows you to vary the size of the opening you might be able to dial in the amount of "mud" you desire.
For smaller soundholes:
https://www.electriduct.com/Desk-Grommets.html

I have a client who insisted on installing one in each of his $7000 custom built Taylors as part of the setup. He was certain they lowered the resonant frequency and helped project the sound to make them louder.... Keep in mind he only plays them in the studio, and never live.

I thought they changed the sound from open to closed, and told him so. They were also a colossal PITA to install, and I followed the instructions to a T (in my opinion). I won't recommend or use them on any of my stuff.

_________________
"Act your age, not your shoe size" - Prince

Plastic reinvention of the Maccaferi Tornavoz!

a solution looking for a problem

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I ran an 'impulse spectrum' test an O-port in an OM size guitar a while back. The guitar was one of a 'matched' pair in mahogany and Red spruce that I made as an experiment. The test is a fairly standard way of seeing what the guitar is capable of. You tap on the bridge and record the 'thump', in a more or less standard manner and setting, so that you can compare the effect of changes directly. This tells you what the guitar does, which may not be the same as what it sounds like.

What the O-port did was to drop the pitch of the 'main air' resonant peak in the output by 8 Hz, from 100 Hz (between G and G#) to 92 Hz, just below F#. The power of the resonance was also reduced, relative to other higher ones that did not seem to be affected as much, by about 20%. What surprised me, though, was what happened to the 'main top' resonance: that dropped in pitch by a similar amount (201 Hz to 192 Hz), but was cut down in amplitude by more than half. Normally the 'main top' peak in the output is much higher than the 'main air', and that was so without the O-port. Whit the port in, the 'top' peak is much lower then the 'air' peak.

This is much different from the changes that one sees with a normal 'tornavoz' which has straight sides that are either nearly cylindrical to somewhat conic. The usual tornavoz drops the 'air' pitch and power, often by a lot, but usually doesn't affect the 'top' mode nearly as much. The flare of the O-port seems to alter the air flow inside the box so that it works almost oppositely from the usual soundhole restriction.

Again, this is an objective test, and only on the one guitar. I would not expect the outcome to be very much different in kind on another guitar; I have not had the chance to check that out. It doesn't say what the changes will sound like; to paraphrase: "there's many a slip between ear and brain". Microphones don't have opinions; they just tell you what's there.

There's a fair number of classical builders who use them, going back to the 1800s, Torres among them. Those went deep into the body, almost all the way to the back. A builder friend here uses them exclusively, but a shallow version made of spruce. His guitars are known for their bass.

_________________
formerly known around here as burbank
_________________

http://www.patfosterguitars.com

Absolute truth, Alan.

_________________
"Act your age, not your shoe size" - Prince

Check out the g*bson Mark series that Richard Schneider and Kasha collaborated with g*bson on to manufacture.

That's where this idea comes from.

PS: It didn't work back then either....

Oh, dear God. I've had a couple Mark series guitars on my bench.... Real oddballs.

_________________
"Act your age, not your shoe size" - Prince

Was it the 70's I think yeah they were weird with that megaphone as pictured here in the sound hole and a few other things like fan bracing or a hybrid of same. We have a few here that we take care of for their owners and one of them got his as a graduation present from High school. He always says that when he received it it was "state of the art, baby."

I always bit my lip and think yeah but it sounds like crap.