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View Full Version : Need some help with first box build. RE SX12



sound giant
04-23-2009, 02:12 PM
I have a crappy looking car that im putting it into....Cutlass 1999, the one that looks like i fly from the back haha. Any way ill have a Hifonics 2006D with the RE SX12 D4 wired at 2 ohm. So I get close to say 1100-1300 watts or is that amp overrated that much? Ok so i need some tips on a ported box. I want around 32-35 hz tuning. 2.0 is the rec from RE but what about larger, will that equal better? I want to keep quality im not trying to just get stupid loud.

sound giant
04-23-2009, 02:14 PM
Port length matter? port size? shorter deeper box or taller wider box? port facing? double baffle? sub location? etc

help me out here plz

DNick454
04-23-2009, 02:19 PM
The larger, lower tuned boxes will have better low end extension and a decently flat sound curve. I wouldn't go any bigger than the recommended volume though. That amp should be perfect for that sub, keep in mind, RE rates their RMS ratings "thermally". As in, thats what the voice coil can handle temp. wise. If you're getting full excursion off 600-800 watts or whatever, don't drive it any harder. But yeah, take it easy with that amp until you get a good idea of where your box cuts off at the low end.

I'd say 2 to 2.25 cubic feet with a port tuned to like 32 Hz would be great. I'd say for a 12" SX in a 2 cubic foot box, you'd want like 40 sq. in of port area.

DNick454
04-23-2009, 02:22 PM
Port length matter? port size? shorter deeper box or taller wider box? port facing? double baffle? sub location? etc

help me out here plz

Length width, and height don't really matter, as long as you've got enough volume, the port is atleast it's own width away from a wall in the car, and the sub isn't hitting any walls, and has some space to breathe in the box.

Since you're driving a cutlass, a box with sub(s) and port facing back would be best.


And yes, port length and size matters A LOT. That is what determines entirely what the enclosure sounds like.

sound giant
04-23-2009, 02:37 PM
The larger, lower tuned boxes will have better low end extension and a decently flat sound curve. I wouldn't go any bigger than the recommended volume though. That amp should be perfect for that sub, keep in mind, RE rates their RMS ratings "thermally". As in, thats what the voice coil can handle temp. wise. If you're getting full excursion off 600-800 watts or whatever, don't drive it any harder. But yeah, take it easy with that amp until you get a good idea of where your box cuts off at the low end.

I'd say 2 to 2.25 cubic feet with a port tuned to like 32 Hz would be great. I'd say for a 12" SX in a 2 cubic foot box, you'd want like 40 sq. in of port area.
how do i know where my box cuts off at low end?

40sq in of port area, can you give me an example like 1.5x10x25 or something?


Length width, and height don't really matter, as long as you've got enough volume, the port is atleast it's own width away from a wall in the car, and the sub isn't hitting any walls, and has some space to breathe in the box.

Since you're driving a cutlass, a box with sub(s) and port facing back would be best.


And yes, port length and size matters A LOT. That is what determines entirely what the enclosure sounds like.

thanks for the help.

should i double baffle the front?

DonH
04-23-2009, 04:03 PM
ok man sq inches is LxW now if you want to get a quick and somewhat reliable specs go here:
http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

plug in data accordingly.

DonH
04-23-2009, 04:04 PM
should i double baffle the front?

not necessary but always a nice touch.

dnick454 is a good guy seen him do some free design before. also if you have any question bro feel free to pm me

DNick454
04-24-2009, 09:47 AM
not necessary but always a nice touch.

dnick454 is a good guy seen him do some free design before. also if you have any question bro feel free to pm me

Double baffle is a nice touch, not necessarily needed for a single 12" as far as structural integrity goes, but, if you have enough space to make it a bit bigger because of the volume it takes up... then you can do a flush mount fit with the woofer (assuming you have a router and a jasper jig.)

And thanks for the complement d_man1 :D


EDIT: Lol I just realized how lame I am... in school posting on ca.com at 8:40 in the morning... /sigh :laugh:

bustaplz
04-24-2009, 10:49 AM
Double baffle is a nice touch, not necessarily needed for a single 12" as far as structural integrity goes, but, if you have enough space to make it a bit bigger because of the volume it takes up... then you can do a flush mount fit with the woofer (assuming you have a router and a jasper jig.)

And thanks for the complement d_man1 :D


EDIT: Lol I just realized how lame I am... in school posting on ca.com at 8:40 in the morning... /sigh :laugh:

9:49AM at work reading your post. Couldn't help but laugh with you.

sound giant
04-24-2009, 08:23 PM
hey dnick, when i get home i'd like to share with you the dimensions on my box design, if you would look it over for me later? I think i got like 38in of port length or something like that, ill post it here when i get it.

DNick454
04-25-2009, 12:00 AM
hey dnick, when i get home i'd like to share with you the dimensions on my box design, if you would look it over for me later? I think i got like 38in of port length or something like that, ill post it here when i get it.

Yeah, I'll take a look at it. As far as the port length goes, it's hard to say what that will equate to. 38 of port length doesn't mean anything definite without knowing how big the box is and how large the port is area wise, if it's a really tiny port, 38 inches long could be tuned to like 20 Hz for all I know. But yeah, post up the dimensions and I'll calculate the specs out and make sure they're what you were wanting.

sound giant
04-27-2009, 09:32 PM
So this is the dimensions i got

height 19"
width 29"
depth 15"
wood thickness .75"
port width 3"
port length 22"

according to the REcalc that is 2.576 cube and tune to 35hz with port area of 52.5

Dnick and anyone else tell me this is ok or not. Should i make the box 2.2-2.3 cube and tune lower?

I prob wont do the front double baffle since someone said its not really needed with a single 12"

DNick454
04-27-2009, 10:22 PM
Yeah, that might be a little big on the volume end. Tuning is ok. If you wanted to go lower you could, but 35Hz pretty much is a well rounded cover-all tune. If you could fiddle with the box and get it closer to 2 to 2.25 cubes at like 34 Hz, because sub will displace a bit of volume and raise the tuning, that would be a good start. 52.5 sq. in of port area is also more than enough. So if you make the box a little shorter or something, no need to make the port larger to make up for lost area. Also, a little shorter would be better for a trunk car. Since the subs and port are facing back into the trunk, if the box is really tall, the trunk takes all the waves and the box blocks it from entering into the cabin. If it's shorter, the sound waves resonate in the trunk and go over the box into the cabin space and it will get louder.

Just try and slim the box down height wise to reduce a bit of volume and fiddle with port length to get around the same tuning. Good luck :)

sound giant
04-28-2009, 03:20 AM
thanks that post helped me out alot.

just one more thing.... should i lower the port area from 52.5?

sound giant
04-28-2009, 03:41 AM
27.5 width
15 height
18 width
3.25 port width
20 port length
43.875 port sq area
2.331 cubes
33.5 hz tune

sound giant
04-28-2009, 03:44 AM
27.5 width
15 height
18 width
3.25 port width
20 port length
43.875 port sq area
2.331 cubes
33.5 hz tune

DNick454
04-28-2009, 09:03 AM
27.5 width
15 height
18 width
3.25 port width
20 port length
43.875 port sq area
2.331 cubes
33.5 hz tune

Sounds spot on. If you used the RE Calculator, I'd say go ahead and print that off with the cutsheet and start building. Once you put the sub in there, it should drop the volume inside the box to about 2.25 cubes and the tuning would bump up a tad, probably right around 34Hz flat. That should sound really nice.

sound giant
04-28-2009, 10:52 AM
and port area is all good.... thanks dnick youve been a big help. Ill update you on my box build. Im gonna use titebond or something like that cuz ive seen alot of people rec that glue. Screws on the outside (not risking screws on the port walls)?? Probably just spray paint the exterior.

DNick454
04-28-2009, 02:04 PM
You can put screws into just about anywhere on the box so long as you pre-drill correctly, and don't put the screw really close to the end of a piece, because it will split easier.

As far as glue goes, Titebond wood glue is a good choice. If your cuts are straight and at 90 degree angles and you put clamps on the wood, then those joints will cure almost as strong as the MDF itself.

And yeah, please make a build log, I'd like to see your progress as you build it. And if you have any questions or concerns while building, anyone here can guide you in the right direction.

Good luck with the build :D Looking forward to seeing some results.