port length/ physical port length

[Go-N-Def]

Can someone explain why we enter a certain number but, the physical (actual) port lengths are different on torrez.

[Markous]

Any change in direction causes more resistance to airflow.

In my trade we refer to it as total equivilent length when dealing with fittings for pipe for calculating friction losses.

[bkolfo4]

Because you have what is referred to as "end correction factor".

Different port configurations (slot port with 1 or more common walls, flared ports, etc.) respond like they are a different length than their actual physical length.

[Go-N-Def]

Ok, I just made a box this weekend and realized I made the port from port length, it doesn't sound good so when I went to review my measurements I noticed I didn't use physical length.

[Joe X]

The number you enter as port length is the number you use to do the box, the end correction is none of your business, the program uses it under the hood to calculate tuning.

[Go-N-Def]

Physical port to the right side is incorrect for tuning. the number I entered as port length is what I should make the box with. Is this right?

[Joe X]

Say I entered 31" in Torres for port length then I measure the center line end to end of the port to be 31" SO in the diagram below 10 3/4" + 20 1/4" = 31" that's it, you don't have to care about anything else.

[Go-N-Def]

joe x, i was talikng about how port lenght is 20'' but physical is 15'' this is what messing me up. but you say dont worry about the 15''.

[Joe X]

Torres calls physical port length the distance you see in red:

Physical port length = L1 + L2 + 3/4"

Torres never documented to my knowledge what it was but he has explained in various threads, it's meant to be some help but you can basically ignore it, you need to know ho to interpret it in case of a double baffle, no need for it, simplest way is like in my last post IMO.

[Go-N-Def]

Got it