Diy sub -3 point?

[Toast_Master]

when measuring a finished diy subwoofer😀, how do you determine the -3 frequncy point on my graphs?

thanks in advance

 

[SpeakerBob]

Measure it outside, away from buildings. It should look fairly flat then roll off at the bottom end. When the plot is 3dB down, well, thats your F-3.🙂

Rob.

 

[Toast_Master]

Yeah but, where I might get -3, might be actually +3 if you know what i mean.....like where do I rule the line to say

 

[SpeakerBob]

plot a line straight through the average of all the little peaks / troughs.

Rob

See what Linkwitz does:

http://www.linkwitzlab.com/models.htm