which freq to tune ports to? read ahead... (1 Viewer)

[Mike SJ]

ok say I have a 4 cubic foot (128 liters) sealed sub with 2 10"s and I get a gradual increase in SPL from 20Hz@75db's to 100Hz@100db's. Should I increase the box dims and tune the port below 20Hz? or keep the same size and tune the port @ 20Hz? Suggestions please? and If you give one, please explain what the effect will be. thanks

 

[Ryan Schnacke]

So you're seeing a 25dB increase from the tuning point at 20Hz to the upper end at 100Hz? Doesn't this seem like a lot of slope? I would probably raise the tuning point and/or enlarge the enclosure until I got more like 5 to 10dB of slope.

I know that room gain will fill in the bottom end to some degree, but even with a really small room I wouldn't count on 25dB of room gain.

 

[Mike SJ]

"Doesn't this seem like a lot of slope?"

Well yes, yes it does, that is why i am posting this question. So say I increased the box size to 6 cf or 168 liters, that would help with the 100Hz to 40Hz range and then if I ported it and tuned it to 20 Hz, then that would help in the 40Hz to 20 Hz range, right? of course all these are approximates.

 

[Brian Bunge]

Without knowing exactly what drivers you're using, and their parameters, any suggestions we make are purely guesses. You really should give us the info. on the drivers if you want a more accurate answer.

 

[Mike SJ]

well winisd showd how well 2 3' long ports would do in the same size enclosure. it would flatten the whole thing to 30HZ then a easy rolloff to 15 Hz.

so its just about right