Physical Port Length vs Port Length

[Carroot1]

What is the difference between port length and Physical port length. In the box I am building my port length is 30" and my physical port length is 24.75" Which one is more important? I'm building a box with one common wall

Those are my calculations

It would be VERY helpful if someone came up with a picture perhaps in Google sketch up or something.

Thanks in Advance, any help is appreciated

[MrSkippyJ]

JL Audio port page.

If I understand correctly, the physical port length is less important than the port length. I assume that port length is the same as effective port length.

[Carroot1]

JL Audio port page.

If I understand correctly, the physical port length is less important than the port length. I assume that port length is the same as effective port length.

Well I need to know which one to build it by. Port length or physical port length. It cannot have both and what about end correction?

[Cashdollar2009]

Paint skillz...

[Carroot1]

Paint skillz...

i believe its the other way around. according to that jl audio link port length is the actual wood

[Cashdollar2009]

i believe its the other way around. according to that jl audio link port length is the actual wood

It's called "physical" because it is the part of the port that is "there." If you build the actual mdf piece 30", your tuning would drop, and according to your theory, your "physical" length would actually increase. Look at the picture, which line is longer? I have built a box or two bud.

And you are going to want to put "2" common port walls as the back of the box will be acting as a common wall when your port bends. This will add more volume to your box as there will be less mdf inside creating displacement, which will in fact play with your tuning slightly as well.

Edited October 3, 2010 by Cashdollar2009

[MrSkippyJ]

It's called "physical" because it is the part of the port that is "there." If you build the actual mdf piece 30", your tuning would drop, and according to your theory, your "physical" length would actually increase. Look at the picture, which line is longer? I have built a box or two bud.

And you are going to want to put "2" common port walls as the back of the box will be acting as a common wall when your port bends. This will add more volume to your box as there will be less mdf inside creating displacement, which will in fact play with your tuning slightly as well.

The JL site does say otherwise. JL says physical is the measurement down the middle. Doesn't mean they are right though.

[Carroot1]

The JL site does say otherwise. JL says physical is the measurement down the middle. Doesn't mean they are right though.

So I would want to build it to fit the physical port length right? the 30inches doesn't matter or is that the effective port length?

[Carroot1]

Hows this for a box eh???

[hdorre]

You have too much port area. I think you want 3 port walls for an "L" port