The RE8 Speakerboxx Thread

[deltron]

Well since all of us will be getting our shiney new RE8s soon I think its time we start sharing our knowledge, or lack of it in my case, about the homes our babies will soon be living in.

I have a NBS EC and took the following measurements underneath my back seat today. I guess this is a start as to where to begin on box construction.



I am not really sure where to start since this is the first box i am attempting to build. I'm sure some of you are in the same boat, so lets put out heads together and make some kick-a$$ boxes!

[Jailer]

I presume you're looking at building a sealed box for the speakers. Here's a link to a sealed box calculator to figure out what internal volume you'll need for them. http://www.ajdesigner.com/downloads/ajsealed.exe There's also vented and bandpass box calculators available for download at http://www.ajdesigner.com/speaker/bcs.php if you need them. You'll need the specs for the speaker before you'll be able to calculate a volume for the boxes, I searched a bit online for them and couldn't find them.

[deltron]

I am leaning towards a sealed enclosure, both because it will probably be easier to build an because i want a decent sounding setup. RE sugggests 0.217 cubes per driver in a sealed, SQ setup. For "SQL" as they call it which I am guessing is a midpoint between SQ and SPL they recommend .5 cubes tuned to 32 Hz.

Here are some the specs on the RE8:

[code]
Fs 22.8 Hz
Re 3.2 DVC
Qms 4.21
Qes 0.38
Qts 0.34
Sd cm2 195
Vas 27.1 l
Xmax 1 way linear 12mm
BL 15.4
SPL 1W/1m 81.2
RMS 175 W
Max 250 W

Additional info

Cutout 7.25
Displacement 0.09
Mounting depth 4"
Weight n/a
[/code]

I don't really know what this stuff means, but I will be plugging it into one of thsoe box designing programs in hopes that I won't have to do much number crunching.

If anyone has a box built for 4 RE8s in an extended cab setup please post some pics or info if ya could..

[DemoN]

what you need to do is to take the total area that the sub requires for airspace and make sure your box is close to it. my understanding is that they want .37 cubic feet each.

[OKLAGMCRUISER]

what you need to do is to take the total area that the sub requires for airspace and make sure your box is close to it. my understanding is that they want .37 cubic feet each.

Don't forget to remove the displacement of the sub once it is in the enclosure...

[DemoN]

Don't forget to remove the displacement of the sub once it is in the enclosure...

psst, i wasn't going to confuse them...that number accounts for the sub ;)

[deltron]

since the sub has .09 ft^3 of displacement, you calculation would say it needs .46 ft^3 total. That is close to what the re site says with a ported setup. Is that what you are talking about and if so what do you tune it to? (Website says 32Hz)...

[joakwin]

re site says .25cu ft^3 sealed

with 4 re 8's
u would need 1.36cu ft^3 be4 displacement to have 1cu ft^3 after the subs are installed in the box

[deltron]

joakwin,
can the subs share the same air, or does each sub need to be isolated in its own space?

[beerbsct]

joakwin,
can the subs share the same air, or does each sub need to be isolated in its own space?

its best to have seperated. that way if something happens to one the box doesnt become bigger.

[DemoN]

its best to have seperated. that way if something happens to one the box doesnt become bigger.

well, in that exact situation...yes, seperate boxes would be better. but any other time, shared airspace is fine.

[beerbsct]

well, in that exact situation...yes, seperate boxes would be better. but any other time, shared airspace is fine.

yes thats right. but me id rather spend the time to make chambers than spend the money for blown subs.

[slaterbj]

Just as an FYI. I am going to fiberglass the bottom of the sub enclosure to fit to the floor and build a traditional mdf box for the rest. The 4-8's will be firing up into the rear seat. I have had that configuration for my 10's for a while now and love it.

[x6369x]

If I remember correctly, the rear seat of my NBS crew-cab is 54" wide. So let's say it's the same on the EC's.

So, I can take a wild guess on your airspace.

Divide up the boxes into 3 seperate chambers, then add them up:

passenger/driver's side:
7.5/9.5 x 10.75 x 19.00 => (8.5-0.75-0.75) x (10.75-0.75-0.75) x (19.0-0.75)
= 0.93^ft x 2 = 1.86^ft.
*Note: The width is only minus 0.75" for MDF instead of 2 0.75" pieces.

tranny hump area (width is width of seat minus passenger and driver's side width):
3.25/5.25 x 10.75 x (54.0-19.0-19.0) => (4.25-0.75-0.75) x (10.75-0.75-0.75) x (16.0)
= 0.31^ft.
*Note: The width doesn't take into account the 2 pieces of 0.75" MDF, because it's not needed.

So the approximate net volume is 1.86^ft + 0.31^ft = 2.17^ft.

[Exalted512]

well, in that exact situation...yes, seperate boxes would be better. but any other time, shared airspace is fine.

also helps with bracing...if youre going to have a box that spans the length of the back seat...its best to have some walls in there to prevent flexing...etc
-Cody

[deltron]

thanks for those calcs x6369x.

it doesnt look like i will be able to have the room to mount a downward firing sub between the hump and the seat. its 5.25" high, and with a sheet of mdf on the top and bottom, that brings down the height to 3.75.

I definitely have plenty of room under there for the speakers, im just trying to figure out the best shape and size for the box. does anyone have bass box pro, or is pencil and paper the preffered method?

[x6369x]

Build it according to your drawing and fire the subs forward:

So the approximate net volume is 1.86^ft + 0.31^ft = 2.17^ft.

If you factor in bracing and speaker displacement and a slight margin of error, you're prob gonna be close to 2.0^ft. So roughly 0.5^ft per RE8.

Now, to make the design as least complex as possible, I would divide the box in the middle, and put 2 subs per half, then you'll have about 1.0^ft per pair.

If you wanted to be crazy and put each sub in it's own enclosure, it'll take a lot of math/geometry skills to figure out where to put the dividers at. And because the box isn't a perfect square, it'll be a big PITA.

If you need to cut down the volume a bit, place chunks/blocks of MDF in the box to decrease the airspace.

[addiction2bass]

why not just ditch the back seat and go ported from what ive heard these realy come alive ported.
what ive wanted to do is line all the subs up on one side of the truck put the amp in the middle or on top of that box and then find a small bucket seat to put back thier so ya still got a seat for a 3rd passenger if you must! ;) but with my 10 RE10s i dont think ill have enough room unless i do a wall on one side of the truck.LOL

[deltron]

i definitely wont be ditching the back seat. and the .5 ft^3 per driver is only if its a ported enclosure right? on their website it says .217 for a sealed/sq setup.

[addiction2bass]

awwwwwwww.LOL

well you could always build the box so it comes out in the center and goes into your consol or a custom made consol for alot more box air space and definatly port them ;) anythings posible with just alittle work. ive seen some killer consols all custom made.

id like to make me a custom one like on the newer trucks but the only thing i wanna be able to lock up is my pistol sometimes i cannt carry it with me and right now i cannt lock it up in anything

just something to think about...