View Full Version : Box tuning and port length question

Dr. Slam
09-28-2011, 10:11 PM
Audioques website recommends a port lentgh of 22-24 inches for a slot ported box designed for hdc3s. The box I am going to build is 19" deep. Is tuning based on an exact port length based on port area? I searched this forum and googled but couldn't find a conclusive answer

db xTc
09-28-2011, 10:36 PM
If the enclosure volume and port area stays constant: the longer the port the lower the tuning.

If enclosure volume and port length stay constant: the larger the port area the higher the tuning.

All the measurements work in harmony: port area, port length, and box volume. A change in any of the three will impact tuning frequency.

Also, larger boxes will tend to have better low end response and the box will normally peak several hz above tuning with a wider response curve. Smaller boxes will typically have a higher resonance and the peak will be closer to the port tuning freq and the peak is much sharper.

Dr. Slam
09-28-2011, 10:50 PM
How would I calculate an exact port length for my specific build?

09-29-2011, 01:33 AM
How would I calculate an exact port length for my specific build?

There is a big long equation that you can do by hand...or you can use some of the available online calculators that do it for you. The12volt.com and carstereo.com have a pretty extensive collection of calcs to help you do nearly anything.

Dr. Slam
09-30-2011, 02:15 AM
I'm familiar with the calculators but if the calculator states that need 21" and I'm building a box with a depth of 19 inches, is there away I can still get my desired htz while keeping the box shallow? Or do I have no choice but to make a deeper box?

09-30-2011, 09:30 AM
I think you can turn the port against the back wall, can't you? Correct me if I'm wrong, but at like a 90 degree angle turn?

09-30-2011, 10:16 AM
Yes, angle the port. Its an L slot port. As long as you keep the width of the port the same size all the way thru the angle.

Dr. Slam
10-05-2011, 08:32 AM
Ok thanks, that's the answer I needed guys