Flared round vs Slotted ports

capitolj80 · Post by **capitolj80** » Tue May 22, 2012 1:54 pm

Sometime in the next month I'm likely to get a day off and I intend to use it to build the ported box for my rsdc's that i've been wanting for months now. I've made two designs: a 1.75cu (per sub) slotted with a 2x12" openening tuned at 30hz and a 1.75cu with a 4"(ID) flared round port tuned at 30hz. What are pro's and cons? Seems like building the round ported box would be a little less work, but cost a little more to buy the ports. Any opinion on how i should proceed?

Post by **ttocs** » Tue May 22, 2012 4:53 pm

I think flared is supposed to help prevent port noise.

capitolj80 · Post by **capitolj80** » Tue May 22, 2012 6:13 pm

that's true but I was planning rounding off the slot edges if I went that route. also the slotted would have about a 25% larger opening. i dunno...i just notice that it seems like most people are using slot ports and didn't know if there was supposed to be a real advantage to it or not. if a 4" flared round port in this application would sound just as good as the slotted counterpart, i'd probably go with the round...

Mr. Wild · Post by **Mr. Wild** » Tue May 22, 2012 8:38 pm

I prefer round ports for the simple reason that they have the least amount of port opening edge. Its turbulence near port opening edges that creates port noise.

Slot ports are easy to make if you're building the box anyway.

zeropoint0.5 · Post by **zeropoint0.5** » Tue May 22, 2012 11:13 pm

and the best way to found out......

build both boxes and listen to both......

make sure they are exactly calculated......

I have always heard, in sounding it will not make so much difference,

but when the length is extremely long, it is better to go for a slot port.......

nutxo · Post by **nutxo** » Wed May 23, 2012 8:32 am

Flared ports are really nice and save a ton of space. If ports get to long just go to 3 inch.

00goobs · Post by **00goobs** » Wed May 23, 2012 8:05 pm

The slot port with more area allows the air to flow in and out slower, hence less port noise. Funny thing, my old Pioneer house speakers, 15" woofers had a 1 1/2" diameter 4" long port facing the rear. It made a lot of noise, but in the house, it was loud and low compared to a sealed 12" house speaker...

I like the round PVC pipe option, quick, easy and adjustable. You could have the entire or part of the port length outside of the box to route through the rear deck or something cool...

Mr. Wild · Post by **Mr. Wild** » Wed May 23, 2012 11:22 pm

A slot port is no magic bullet. You can make a round port bigger too, you just have to go round corners like a slot port.

capitolj80 · Post by **capitolj80** » Thu May 24, 2012 6:30 am

thanks for the input guys! i think i'm gonna try out the round flared port

Post by **Eric D** » Thu May 24, 2012 10:05 am

I prefer round ports, and really like the "aeroport" product. I don't know if you can buy them any more. They were made by PNR I think, and for some time Rockford sold them as well. They have the lowest noise I have come across, and are easy to work with. You should use a router though to bevel their mounting edge, or to flush mount them (which helps even more).

I don't rule out slot ports though. With a lot of SPL designs which need big area ports, and long lengths, slot ports are the way to go. When big enough and long enough, they don't really make noise either.

90% of the time I go with the lowest noise option, sealed boxes...

capitolj80 · Post by **capitolj80** » Tue May 29, 2012 3:36 pm

A 3" flared port can handle the airflow of an RSdC12 at full power without getting noisy, right? cuz i discovered that there was no way of fitting the 4" tubes at 30hz tuning without adding an elbow, moving the ports to the sides of the box (plus removing the center divide), or going bigger with the box.