Hello,

I was wondering whether it was possible to use two different port length on a same box:

For example I need 31.5 inch of port length total for 2 x 3" round ports.

Can I make one 14" and the other 17.5"???

It's just that it is quite difficult for me to fit those two ports inside the box, outside would be possible but aestethically wouldn't be good.

Thanks guyz,

Kelvin

Hi Kelvin,

I'm afraid it doesn't quite work like that. Each individual port, being of different lengths, will behave as a Helmholtz resonator at different frequencies. It is not the approach you would really want to take, in my opinion.

Have you considered building a slot port? Cross-sectional area is easily achieved and you can easily construct a long port by utilizing 90 degree bends or "L" ports.

If your talking about wanting two different tuning frequencies on the box that can be done through interchangeable ports, basically you have a large square cut in the box with the port mounted to a plate slightly larger than the hole, then screwed in the hole, sealed with weather stripping, then make a plate of the same size with the other port length for the other tuning freq and you can swap these out when you want, just screw the baffle with the tuning freq you want in.

I hope that made sense, there are good how-tos on this subject and im sure there are others that can do a better job explaining

Actually, I wanted to use round ports because I wanted to do be able to use some plugs.

Meaning, daily driving with a sealed box and when "showing off", unplug the ports and -voil

I haven't ever seen a sub that modelled well in a sealed and ported environment of the same internal volume. In your case, I would make a removable port and have two different tunings. One real high for max output and another for daily listening.

Actually, I was thinking of using the exact same sub that you have: 2 x RL-i8s.

Website's recommend for car use if I remember correctly 0.5 cuft sealed and 0.3 cuft tuned to 35Hz ported.

I thought that 1 cuft sealed and ported was doable...

Not in the same box, unless you are going to use an external port...

So you think I would be better off using some external ports?

You do realize that a port for a single Rli8 in a box that small can easily be over 100" long? For example, my Rli8 (which is in a bigger box so it has a shorter port by far) is .65cuft tuned to 30hz but the external dimension of the box is over 3.5cuft.

In other words, it isn't going to work.

humm... I guess I have to rethink about the built then... Thanks

I was actually wondering how you did your box: being only .65

So you used an external slot port?

No, his is completely internal... it isn't interchangeable either.

I suggest not trying to make it dual purpose.

I haven't been in Car Audio for very long but I do like browing forums. LOVE CAR AUDIO... fun but expensive lol

Wanted to try a sealed/ported setup because I came by a man that did it and stated that it sounds good... Not sure how good, but not crap, heh

Here's a pic of his box:

So, what do you guyz think?