Hey, I have a Cadence Beast 15" sub that I was thinking of throwing a box together for. Cadence recommend 2.5 cubes vented, with a 6" diamer port, 10" long to give a tuning frequency of 50hz (-3 db at 38hz). I want a decent SQ sound, with tight bass and good low end. This is not for competing, just for daily listening. If I do a slot port 8" high by 6" wide by 14" long, this should give me a tuning of around 47hz, according to Bassbox Pro. Any idea if this will give me decent sound, and would anyone recommend different dimensions for port length/width etc? Thanks for your input.....

 

These are what the Vent Velocity and Response graphs came out to on my program, with the port dimensions I gave above:

 

For a daily driver with "some" SQ in mind...you're concentrating way too much on vent velocity. 6m/s is very low. IMO your tuning freq is much too high. Use a smaller diameter port and tune lower. A peak vent velocity of 30m/s is more than acceptable.

 

Sounds good, I got the same advice from another member on here. I think I will try to tune closer to 37hz, better?

 

Depending on the Fs of the driver, I would consider going a couple Hz lower with the tuning frequency if you want better low end and sound quality. Also the vent area might be a bit high for a box that is only 2.5ft^3.

 

Okay, so maybe try for 30hz? If the vent area is too large, what is the downside?

 

Agreed, this is normally my approach. Having too much port is a non-issue though because if he wants to lower the tuning, most likely he'll have to use a smaller diameter port.