4th order tuning question

[vetkilr01]

So finally got around to doing some testing with the im-sg. Here are my results for seeing how my boxes useable bandwidth is:

The Fl came out 44hz at around 6.5ohms

The Fh came out to 63,5hz at around 8ohms

and the Fb came out to 50hz at around 3.2 ohms.

My useable bandwidth is 44-63hz if I did this correctly.

So is this telling me my ported side is tuned to 50hz or 44hz ???

Thanks for the help.

[Kyblack76]

Then slowly raise the frequency until a first peak in impedance is found. If you go too far and pass the peak, just back down the frequency until the peak in impedance is found. Let us call this frequency peak fL. See figure 6

6. Continue increasing the frequency slowly until a second peak in the impedance is found. Let us call this frequency peak fH. Single reflex bandpass enclosures have two impedance peaks, see Figure x.

7. Now slowly decrease the frequency, you are looking for the minimum impedance that is between fL and fH.

8. The frequency at which this minimum impedance occurs between fL and fH is called fB. This is the tuning frequency of the ported chamber.

fL and fH tell us about the usable bandwidth of the system. Output of the subwoofer will start to decrease at frequencies below fL and subwoofer output will decrease at frequencies higher than fH.

[vetkilr01]

Thats what I did. So is the FL where the ported section is tuned to and rolloff begins under that?

[CleanSierra]

Thats what I did. So is the FL where the ported section is tuned to and rolloff begins under that?

By definition, yes.

[Kyblack76]

The ported section is your Fb

Roll off below Fl and above Fh