Bl sealed or high powered Q?

[shizzzon 461]

This is my original plan and am wanting to make sure this is my best option for Loud and clean bass.

I was used to running 1 Audioque 15" ported at 29hz in 7.5cu ft box off of 1400w, it was ungodly!

Current setup - 1 Audioque 15" Sealed in 2.2 cu ft off of 1400w.

It is a little less loud in the low frequency area due to a lot lower group delay as well but like how it sounds as well.

Anyways, my current project is to have 3 12" Qs off of 3 optidrive 2000ds. Each q would be wired to 0.35ohms all in a common chamber sealed box roughly 2-2.4cu ft stuffed with polyfill (emailed fi about this to see what they say bout the polyfill). Now, these amps are rated at doind 1,600w at 1 ohm but at 14.4v, i believe if i'm around 13v flat, it should drop the wattage right around 14-1500w so with the BP option, it should be a perfect max match. I use O-scopes as well so it would be pure power, no clipping.

I notice that the Qs vs the Bls are a lot less efficient and everyone is telling me that i may be pushing the qs too hard and get BLs, however i only have room to go sealed...

Fi specifically says not to use BL's in sealed boxes and i don't want to run 1 12" BTL either i know it can't handle 6K worth of amps.

So.... does the 3 12" Q sealed plan still hold as the loudest theoretical setup?

[///M5 2,833]

Why not 2 BL's ported then?

[Captain Kev 0]

Agreed with M5. 2 12" loaded BL's ported should outperform 3 12" Q's sealed in SPL.

[shizzzon 461]

i forgot to mention why not ported...

according to what i am seeing, the required port area for a 4,000w amp on 2 12s would require about 30-40" length port to keep the port velocity under 20% of the speed of sound, the lower the %, the better. less restriction.

However, i don't know how i would go about building the ported box because-

this box design takes up almost the whole trunk for just 2-2.4 cu ft. The rest of the space is taken up for 2 Kinetik HC2400s.

The only way to port would be to port straight up and i don't know if i can do that with that much length requirement.

I would still have to stuff polyfill in the enclosure to even reach ideal results.

If i port back, all the air would slam into the batteries and there is hardly any airspace left after the batteries are installed there resulting in a problem with the sound waves getting back into the cabin effectively.

I've tried doing ported designs in AutoCAD before and got a headache from trying too long and just decided to go sealed. But at the time, i never considered polyfill...

Some thing i was reading says that if i use 1 lb of polyfill for every 1 cu ft,the enclosure Net size should increase up to 40% larger.

Now, that would mean if i had a 2.0 net to start with, 2 lbs should get me up to - 2.8 which is where i wanna be.

According to WinISD, when it comes to tuning the box, the would be tuned at 39hz before polyfill, after polyfill - 31hz! It does have a nice flat response somewhat similar to a sealed box if not placed in a car.

The design looks good of course but trying to model it in AutoCAD is another story.

I'll try some more to try and get a ported design to fit in my hatch but last time i did that i gave up...

I'll let you guys know what i find out.

[///M5 2,833]

40% with polyfill is a joke...

[shizzzon 461]

40% with polyfill is a joke...

If that's true then it's even more improbable to go ported for 2 12s with that power

[shizzzon 461]

Here is what i have to work with for all those who may be better at this than i am-

Information-

Red line on left, dimension on rear seat layed back in default position.

Yellow line on left, dimension on rear seat tilted all the way back into cargo area.

red box enclosure outline (pay no attention to that)

All other lines below it, pay no attention to either.

Horizontal and vertical line to the right -

Vertical line marked at 20.25" allows 7" depth remaining in vehicle to install HC2400s in the rear.

Horizontal line - 12" height clearance, more detailed specs below

Main white outline - dimension of cargo area as follows-

Take for granted enclosure will sit against rear seat(rear seat's tilt back takes up 3" of depth in the cargo area.)

Depth of cargo area - 24.25"

Width of cargo area-

If staying no higher than 12", width is 42"

If staying no higher than 13", width is 38.5"

If going above 13" high starting from rear seat and working back-

maximum height from rear seat - 22.3" and gradually drops to 18" high 11.5" deeper from starting point.

After 18" high at 11.5" deep, height drops to 14.5" just after 0.5", drops to 13.5" high 3.5" further back and stays at 13.5" high for 2 inches deep, then drops to 13.0" 1" deeper, then gradually drops to 12" high going 4" deeper, then quickly drops to 10.0" high after 1.75" deep.

Gotta love AutoCAD,

anyways, those are the dimensions, this is everything goin in that area-

2 Kinetik HC2400s -

13" Long

6.7" Wide

8.5" High

Sub box - you figure it out,

1 large mono amp for 2 subs or 3 mono amps for 3 subs.

(If 3 monos, 2 are installed below the floor drawing, only 1 remains to be placed in the drawing area)

1 MORE amp for cabin door speakers.

Edited January 20, 2008 by shizzzon

[shizzzon 461]

They got back with me, it will be fine to use Polyfill or a variation of it, they suggested Polyfill in itself isn't as good as Dacron 2 or 3.

After visiting sites, Acousta-stuf seems to be pretty good. $9\per lb, they suggest that it outperforms dacron.

I was doin some more research, i am to put more and more in the box until it causes negative results. Crutchfield states it can make it up to 30% larger, that was my typo, that's where i read it at, not 40 but 30% larger.

As long as it doesn't get caught up in the Pole vent, i'm ok.... but according to install pics, that's gonna be tricky if i had to fill the whole box with it.

But still yet, gimme some ideas people and tell me the dimensions because i had done the work in autocad for over a month now so try and make me feel stupid by finding out a box style in 1 day that's better, hehe.

[Fi Car Audio 64]

BLs sealed are a no go. Qs with that much power would need the BP option... and I can tweak from there specifically for sealed if need be too. Itd loose some output near tuning, but would also dop deeper and have a little more output on the top end as well. For me, itd be the way to go by far. No easy way to run 3 amps on 2 subs ported... so you really would be about even in output near tuning with only 2 amps on the 2 subs... so no real gain there. Cleaner, easier setup overall...

Thanks,

Scott

[shizzzon 461]

i should end this topic i suppose, hehe.

After talking with my dealership, this setup will not be possible unless i spend $2,000+ on new suspension system!

Because of the added weight and just 1 passenger, the car will be over it's max load capacity.

Since i never anticipated on buying coil overs and new tires, i decided to force myself into finding a way to run 2 12" BLs ported off of a 3,000w amp and i found a way(like a patent miracle, hehe) so that will be the way i am going to go.

From what i see, i will tune it right around 35hz. I might still throw some acousta0stuf in this ported box because any extra room will be nice but the net volume i will have for the 12s is 1.35cuft per sub but for a common chamber. I know of a way of increasing that volume some more but i don't need to be super picky on detail right now.

Right now, Second Skin is awaiting a $500+ order in the near future.

By the time their stuff is installed,i should be able to crash into a wall and the only thing i should hear is my GPS rerouting my destination,