Multiple port tuning.

[dopey 0]

Copied mostly directly from Jl audio.

Multiple Ports

There are two widely used methods for calculating multiple ports for a single chamber. Only one method is correct but unfortunately it is the least commonly used.

The first and incorrect method takes it's thinking from the original port formula and says basically that if we take two ports and sum their cross-sectional areas, we can just plug this total into the port formula for Av to get our port length. This would sound reasonable, but it can lead to serious mis-tunings in some cases as we'll see in an example below.

The second and correct way to figure out how long each port should be follows this simple three-step procedure: