MrShiffles Posted March 28, 2018 Report Posted March 28, 2018 So I am debating on building a new box for my VCW 15. I am currently rolling a Kia Sedona minivan with this sub in a makeshift CRX style box(2.8 cube) and a JBL GTX500 amp powering at 2ohm..the sub is top mounted with the magnet/basket out and 2-4" pvc pipes firing towards the rear passenger side corner..I flared out the ports with a heat gun hoping for better low end (thinking that would reduce velocity) but i'm still not getting what i need below 30hz (my port sq in/cu ft is still pretty low, i know)..i've been playing with the numbers via Bassbox Pro 6 and Torres, and although making the box bigger (~3.5 cube) with a much bigger slot port gives better results in BBP6, i am torn between grabbing 2 sheets of mdf for a better ported(laying out the cuts on Sketchup dictates the second sheet) or scrapping the ported idea and either going with a massive T-line or even a Parallel-tuned 6th order (which models quite nice in BBP6, although the group delay plots arent what i would like My musical taste is all over the place, but i like rock metal hiphop (slowed music too) and reggae. Here is a screenshot of my present box stats:
Triticum Agricolam Posted March 28, 2018 Report Posted March 28, 2018 Normally I'm the port area police, but on the amount of power you are running your two 4" port are probably fine for port area. If you are looking to get more output below 30 hz, you should probably tune below 30 Hz. Increasing your box size would help too. Something like 4 cu ft tuned to 28 Hz would work well, though with the larger net volume I'd suggest adding more port area as well. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds:
MrShiffles Posted March 28, 2018 Author Report Posted March 28, 2018 yea i was planning on doing at least 3.5 cube tuned at 30hz with port area of about 15sqin/foot. So slightly bigger and tuned lower than that would be optimum then. A T-line (say @26hz) would be overkill? I would have to buy at least 2 sheets of mdf or birch anyway for the ported build...i have plenty of room
Triticum Agricolam Posted March 29, 2018 Report Posted March 29, 2018 Well a T-line (at least the type commonly done in car audio) is a totally different beast. Its going to be a lot different than the ported box you have in mind, but not necessarily better. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds:
MrShiffles Posted March 31, 2018 Author Report Posted March 31, 2018 I'm gonna follow your lead on this one, Triticum... looks like big ported tuned lower is the way to go.. I plotted out everything again at 4 cubes tuned around 29 and it looks like I should definitely benefit from it..i will probably add a little to the torres port length as i see a 5 inch discrepancy between the 2 apps...i might have plugged in something wrong on BBP 6, who knows...I factored in a 47HZ corner frequency for the van for the graphs (haven't tested it though I'm sure the bigger cabin of my van is gonna peak lower than say, a mid sized SUV)
Triticum Agricolam Posted April 1, 2018 Report Posted April 1, 2018 16 hours ago, MrShiffles said: I'm gonna follow your lead on this one, Triticum... looks like big ported tuned lower is the way to go.. I plotted out everything again at 4 cubes tuned around 29 and it looks like I should definitely benefit from it..i will probably add a little to the torres port length as i see a 5 inch discrepancy between the 2 apps...i might have plugged in something wrong on BBP 6, who knows...I factored in a 47HZ corner frequency for the van for the graphs (haven't tested it though I'm sure the bigger cabin of my van is gonna peak lower than say, a mid sized SUV) Looks good to me. The port length in BBP seems really long to me though. Generally Torres will tune you a bit on the low side as well. Based on my calcs, a 4 cu ft box, with a 3.5 x 15.75 port, the port will need to be about 31" long to tune to 29 Hz. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds:
Joe X Posted April 1, 2018 Report Posted April 1, 2018 OP you should consider that bassbox pro does not support slot ports, just square or rectangular non slotted ports. Can't compare results with Torres when using a slot ported box, on the top of that Torres miscalculates a slot port displacement altering tuning as a consequence, so it's a really useless comparison.
MrShiffles Posted April 1, 2018 Author Report Posted April 1, 2018 8 hours ago, Triticum Agricolam said: Looks good to me. The port length in BBP seems really long to me though. Generally Torres will tune you a bit on the low side as well. Based on my calcs, a 4 cu ft box, with a 3.5 x 15.75 port, the port will need to be about 31" long to tune to 29 Hz. Yep just ran through the numbers again and you are spot on! I appreciate your input and am impressed with your builds ? 1 hour ago, Joe X said: OP you should consider that bassbox pro does not support slot ports, just square or rectangular non slotted ports. Can't compare results with Torres when using a slot ported box, on the top of that Torres miscalculates a slot port displacement altering tuning as a consequence, so it's a really useless comparison. I wasn't aware before but I'm glad you brought that to my attention Joe...I sketched up a couple different box designs but torn between which arrangement will load off the rear corner better:
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