port too big??

[rv1890]

I ordered a pair of Precision Ports from Parts express. They are the 2 inch ports flared on both ends. I have made the Zaph L18 project to specs, and im going to being these ports. The only trouble Im having is that they seem awfully big for the enclosure. My calculations tell me to have a port length of 7.6 inches. Maybe its just me, but the port just flat out looks to large. Im i doing this properly??

[kelticwizard]

I am unfamiliar with Zaph's L18 project.

The only thing I can tell you about the Precision Ports is that it is recommended that a port flared on both sides should be one flare length longer than the what a straight pipe would be.

The flare length for the 2" Precision Port is 1 1/8" long.

So if the project calls for a 2 inch diameter pipe 4 inches long, and you use a port flared on both ends, your port should be 5 1/8" long. If the tuning requires a 6 inch long piece of straight pipe, the flared port should be 7 1/8" long. And so on.

If you have a link to Zaph's L18 project, perhaps I can give you more info.

[rv1890]

The web site link is
http://www.zaphaudio.com/audio-speaker17.html ...really cool website.

I have also accounted for the flared ends already. The physical size of the port being there just seems to big. Maybe ill post a pic of what im talking about.

[kelticwizard]

The Precision Ports flare out to something like a diameter of 4.5 inches. That's the principle they wortk on-to provide a gradual transition for the air to go from the small, crowded port to the large room.

I'll admit that when you put them on the ends, they look mighty big.

If it makes you feel any better, the straight pipes themselves take up 22 cu inches of space, the ports-even if they were cylinders 1 1/8" long by 4.5" diameters-would only take up 35 cu inches. That's 57 cu inches of space, your box is around 800 cu inches, so the ports take up less than 7% of the box volume. Which is essentially negligible.

But yes, they do look large, especially for a half cu ft box.

[rv1890]

aight that makes better sense. Thanks for taking the time to explain. I wasnt thinking about it in terms of volume. I guess its not so bad. thanks

They are sure are nice looking too.

[kelticwizard]

Yes, they are nice. Good luck with them.

A friend just bought a pair and installed them. Using the formula you are using, he got the tuning within 1 Hz of what he was aiming for.