RAM_Designs

Your box volume and port area is on the low side. Are you able to go any larger with the overall box size?

There's always ways to make it where the port isn't going to cause loading issue with the woofer, it's just hard to visualize some times.

Any reason why you put the internal port opening right behind the woofer like that?

Some company owner, I forgot who exactly(Maybe Jacob or Electrodynamic) was talking about it before, how adding the pole vent really does not much of anything for cooling with the woofers they were testing it on. But I do see your point, that if it is the only form of potential cooling with a given woofer, then I can see how it will affect it more greatly than on a sub that already has other forms of cooling.

What about motor force and the box design? Nah, not important at all.

Pole vents don't do a whole lot for venting. They're mainly used to reduce back pressure that can make the dust cap pop off. There are a ton of high power handling SPL subs that do not use a pole vent.

It's normally best to veer off from the standard enclosure specs that most companies give you.

It's a D motor, which is the same(or close) that they used in the 9500k woofers, if I remember correctly. Definitely not a 3500 motor of any kind.

You need to use the net volume when finding the needed port length, not the gross volume. Otherwise, you can make a situation where the port would need to take up the entire box and leave you with no chamber volume. Use the net volume you want to find port length, find the disacement of the ports, then work backwards to find the dimensions needed to give you that net volume after sub and port displacements.

I thought they were at H with the 9500 motors, so I don't think there is a K motor. Unless you're talking about the old DD K series subs from about 8 hears ago, but I only remember the 25k and 35k models. Could be wrong though. There's actually couple of the 35k 15's on the local craigslist.

For a pair of the 12's, I have had good results with 1.5-2ft^3 sealed and 3.5-4ft^3 ported with an upper 40's tuning. Mechanical power handling is mostly dependent on the sealed chamber volume.

I just ran the dimensions on the design you just posted because I knew the port area looked too large to be tuned that low with a 21" length. The box you have right now is 6ft^3 tuned to 41hz. 35"x33"x14" = 7.63ft^3 before displacements 4.75"x12.5"x20.75" = .713ft^3, 1.426ft^3 for both Subtract .25ft^3 for sub displacement, and you're right around 6ft^3 A 6ft^3 box with a pair of 21" long 12.5"x4" ports give you a 41hz tuning.

You simply don't have enough space. You can do the 15" version though.

I don't see it being a big issue, just the Qts and vas values want to pull the box size in opposite directions. I'll actually model it when I get home, if you'd like.

You only have to pay for the design itself. Once we get all of the details squared away, then I'll send a PayPal request.

These Obsidians are looking better every day it seems.

Judging from the vids I have seen so far, they sure will.

This is a tribute build for HelloMyNameIs on here. His brother passed away, and since four was his favorite number, why not cram four of the new Obsidian Audio 15" subs in the back of his Jeep...right? The box will be 12.75ft^3 tuned to 34hz via four 6" aeroports. The bracing was a little tricky as I had to avoid the aeros and brace the top as well. Needless to say it took a little planning to make sure everything would work out ok.

The port length given is for EACH port, so each port will need to be 36" long. Also, the volume seems to be a bit on the large side, might want to tone it down to 6.5-7ft^3 unless you're running less than rated power and need the efficiency via a larger chamber. The volume that you use in the port length calcs is the final volume after all sub and port displacements. Then you work backwards to find a suitable box size to give you that final volume after displacements.

It's actually rather odd for a 12" sub with a Qts value that low to have a Vas that high.

Qts is reasonably low, but Vas is rather high. Without modeling it I'd guess 8-9ft^2 with a 30hz tuning should work well.

Do you have any specs?

Jean Grae. Check the opening verse of "The Illest" with Immortal Technique and Pumpkinhead.

Could just be cancellation issues as well, either inside the box or out.

The exo seems pretty beastly.