port calculator, diamond audio D310d2

This particular sub is a poor choice for a ported enclosure due to a large resonant magnitude at a relatively high resonant frequency. This sub has been intentionally engineered to have a very narrow bandwidth and to depend heavily on the cars transfer function in order to have decent lower frequency response. This was done in an attempt to make this sub function in a very small sealed enclosure. If you model a vented enclosure for one of these subs you will find that the vent length to enclosure size ratios are always ridiculous. This is because the engineers veered drastically from normal designs in order to accomplish adequate performance in tiny sealed enclosures. I personally am a big fan of vented design. Years of experience with this particular line of subs though have taught me that this sub is limited to sealed enclosures. In the event that you decide to give it a go anyway (nothing wrong with that) let me clue you in to what you will find. As you shorten the port Fb will rise. Port lengths will always be long for this sub. If you increase the box size the port length will decrease but the subs out put will drop dramatically defeating the vents effectiveness. If you stick with a small enclosure and a very long port you will get a low Fb but in the process will again end up with very low efficiency. This sub must have a minimum 3” diameter vent or you will have port noise even at moderate volume levels. I hope this information some how helps.   

speakermakers wrote: This particular sub is a poor choice for a ported enclosure due to a large resonant magnitude at a relatively high resonant frequency. This sub has been intentionally engineered to have a very narrow bandwidth and to depend heavily on the cars transfer function in order to have decent lower frequency response. This was done in an attempt to make this sub function in a very small sealed enclosure. If you model a vented enclosure for one of these subs you will find that the vent length to enclosure size ratios are always ridiculous. This is because the engineers veered drastically from normal designs in order to accomplish adequate performance in tiny sealed enclosures. I personally am a big fan of vented design. Years of experience with this particular line of subs though have taught me that this sub is limited to sealed enclosures. In the event that you decide to give it a go anyway (nothing wrong with that) let me clue you in to what you will find. As you shorten the port Fb will rise. Port lengths will always be long for this sub. If you increase the box size the port length will decrease but the subs out put will drop dramatically defeating the vents effectiveness. If you stick with a small enclosure and a very long port you will get a low Fb but in the process will again end up with very low efficiency. This sub must have a minimum 3” diameter vent or you will have port noise even at moderate volume levels. I hope this information some how helps.

Thanks for the very detailed answer. You did help me greatly with my decision. I also found out i have more like 3.5cu ft for the box (going under the back seat of a 00 silverado extended cab) i'm starting to fade away from the port idea now, although i may speak directly with diamond and see what their tech says on port length and what not. anyways, thanks again!