Big port vs. Small port?

[Mike465 10+ year member]

Hmm this is the second instance I've noted that people who own RD subs were recommended by the manufacturer to use grossly small ports. For something along the 4 cubic foot volume with a SPL 15" woofer, I would say 50-60 sq. in of port. I don't understand why RD recommends such itty bitty ports, that's gotta choke the sub down like no other.

If you are using a 15" Sonance then your box needs to be 3.75 cubic feet with 30 square inches of port tuned to 35Hz. Having that small of a port does not choke RD subs. Me and Steve test again and agina on enclosures for his subs. I built a box for 2 HW 15's that had only 80 square inches of port and we can do 155's in the kiack all day long.

 

[Mike465 10+ year member]

rule of thumb is 16sq. inches of port per cubic ft iirc. remember you port to volume, not to sub size. me i slap the biggest port I can in/on and tune at either 33Hz, 35Hz, or 38Hz (38Hz for SPL)

Well if you try to have a huge port tuned to 33Hz when the sub plays that low you are going to loose controll of the cone and blow your sub. Plus, the larger the port you have you are going to have steaper and steaper roll offs above and below tuning. Yes, if you are making a burp box then it will not matter but far a daily box it will not work.

 

[Mike465 10+ year member]

I'm going low than with a large port.
Both MisterGrubbs and Steve from RD audio said that the Sonance series likes small boxes/ports for some reason. I dunno why, don't know enough about soundwaves and building enclosures to understand that. Right now my box is tuned at 32hz and it flexes my windows on 1 song, but it has a very small port and I would like more umph out of my sub.

Build the box to 3.75 cubic feet with 30 square inches of port tuned to 35Hz. You will not be disapointed

 

[DNick454 10+ year member]

Mike, you never answered my PM //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif and you're going against my "moar port = moar betta" theory. I dunno man, I'm losing faith I tell ya //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[Lakota 5,000+ posts]

I normally say big port...

 

[kush-divinity 10+ year member]

I have had decent sounding boxes with smallish ports. Like Mike said, you have a flatter response with a port on the smaller side. But you WILL lose max SPL. Nothing to care about if it is in a daily.

I'd prefer a flat box with exaggerated response around 25-40hz than a 50hz 1 note wonder fartbox anyday.