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View Full Version : help designing Box for two Sa-8's at 30 Hz



Pyrofan
10-05-2013, 01:45 PM
I listen to mainly rap and country ( depends on the day) and little dubstep. Im doing a vertical box in the back ( going to be like a console.). My dimensions are 14x15x26. Subs will fire forward and ported forward ( was told side port for my truck was better but whatever )

14 is front to back.
15 is side to side.
26 is max height. ( the lower the better.)

anyone provide and free help?

Sa-8s are getting 1000w rms at 1 ohm

Pyrofan
10-05-2013, 07:23 PM
anyone?

thatguy12
10-05-2013, 08:34 PM
download torres box calculator and map a design up. then download google sketchup and some youtube videos on how to make a subwoofer box in google sketchup (mark on caraudiofabrication has an awesome one). there's many tutorials on how to use torres box calculator. i know you want someone to design you one but its more satysfing when you design and build yourself, but if you don't want to design it you usually should pay a reputable person on here, the world is not free in any aspect sadly.

Pyrofan
10-05-2013, 08:59 PM
download torres box calculator and map a design up. then download google sketchup and some youtube videos on how to make a subwoofer box in google sketchup (mark on caraudiofabrication has an awesome one). there's many tutorials on how to use torres box calculator. i know you want someone to design you one but its more satysfing when you design and build yourself, but if you don't want to design it you usually should pay a reputable person on here, the world is not free in any aspect sadly.

I have made a box before and I have used sketchup for years. Are their no boxes people have already made? The only reason i dont want to design one is because I dont want to mess it up. Sealed is easy but calculating a port is hard to me.

thatguy12
10-05-2013, 09:05 PM
there is in the stickies in enclosure help but i dont think there is for eight inch subwoofers.

Pyrofan
10-05-2013, 09:23 PM
Would this work

ImageShack® - Online Photo and Video Hosting (http://imageshack.us/photo/my-images/62/125cubes32hz21sqin4qf.png/)

bbeljefe
10-05-2013, 09:31 PM
Sundown recommends .5 to .75 per sub @ 35 Hz. I'd go with 1 cube (.5 per) and 16 square inches of port. With the 13.5" width you have, a bottom mounted slor port would be 1.18" (1 3/16") tall and 25" long. The total volume of that port would be .37 cubes and the drivers displace .16.

So, you'd need a total internal volume of 1.53 cubes. Using your available outside dimensions, that would be 15 wide, 14 high and 16 tall.

Pyrofan
10-05-2013, 09:36 PM
Sundown recommends .5 to .75 per sub @ 35 Hz. I'd go with 1 cube (.5 per) and 16 square inches of port. With the 13.5" width you have, a bottom mounted slor port would be 1.18" (1 3/16") tall and 25" long. The total volume of that port would be .37 cubes and the drivers displace .16.

So, you'd need a total internal volume of 1.53 cubes. Using your available outside dimensions, that would be 15 wide, 14 high and 16 tall.

Here is my idea. with that 16 high it may work better. Would 35 Hz sound good for Rap? most people seem to be running like 30-32

oxsign
10-05-2013, 10:21 PM
I would actually have the port turned the other way firing under that rear seat. Anywhere from 32Hz-34Hz is where I tune mine for daily.

bbeljefe
10-05-2013, 10:24 PM
30-32 will sound more like 25-28 in the vehicle and those drivers do not do well tuned low. At least, in my experience, I've not been able to model a large enough box tuned below 35-38 Hz that yields a smooth curve. They always have a horrible dip from just above tuning to about 100 Hz. I've experienced that with most of the SAs and frankly, most of Sundown's woofers in general.

Not to mention, 35Hz is a good frequency for lows in a vehicle and the SAs are near bullet proof so you don't really have to worry about them unloading below tuning.

Pyrofan
10-06-2013, 12:19 AM
30-32 will sound more like 25-28 in the vehicle and those drivers do not do well tuned low. At least, in my experience, I've not been able to model a large enough box tuned below 35-38 Hz that yields a smooth curve. They always have a horrible dip from just above tuning to about 100 Hz. I've experienced that with most of the SAs and frankly, most of Sundown's woofers in general.

Not to mention, 35Hz is a good frequency for lows in a vehicle and the SAs are near bullet proof so you don't really have to worry about them unloading below tuning.

Box to your quotes. Look good to you? It doesnt seem like the subs fit. At least stacking them.

Imageshack - ost4.png (http://imageshack.us/f/11/ost4.png/)

( zoom in to see better)

bbeljefe
10-06-2013, 12:56 AM
on a 15" x 16" baffle they will fit diagonally.

Pyrofan
10-06-2013, 10:13 AM
on a 15" x 16" baffle they will fit diagonally.

I cant get it to fit. The one on the top left will be flush with the port and side when mounted. The other one cannot fit without over hang. When you say 15'' and 16'' do u mean total box or just the mounting area.

here is a pic to show. http://img692.imageshack.us/img692/4457/688u.png

bbeljefe
10-06-2013, 11:32 AM
I meant the total box but I wasn't thinking about the port. So in reality, you have about 13" in height and 15 in width.

Do your circles represent the outside diameter of the sub or the cutout diameter? Even with the port there, I would think it should fit but maybe I haven't had enough coffee this morning.

Another option is to put the port in the bottom left corner of the box with the subs mounted as you have them shown, only higher. In that case the port would need to be either 4" x 4" or 3" by 5 5/16".

Pyrofan
10-06-2013, 02:07 PM
I meant the total box but I wasn't thinking about the port. So in reality, you have about 13" in height and 15 in width.

Do your circles represent the outside diameter of the sub or the cutout diameter? Even with the port there, I would think it should fit but maybe I haven't had enough coffee this morning.

Another option is to put the port in the bottom left corner of the box with the subs mounted as you have them shown, only higher. In that case the port would need to be either 4" x 4" or 3" by 5 5/16".

Circles are cut out. Im still a little confused. The smallest area i seem to be able to fit them in is 1'3'' x 1' 4 11/16''. Thats a little to wide. Rather have it taller. Is my port the right size and dimensions? Wish someone would just design me quick one.

bbeljefe
10-06-2013, 02:33 PM
Circles are cut out. Im still a little confused. The smallest area i seem to be able to fit them in is 1'3'' x 1' 4 11/16''. Thats a little to wide. Rather have it taller. Is my port the right size and dimensions? Wish someone would just design me quick one.

Well then, it won't work I suppose. I didn't model the box for fitment but since you did, you have the answer. As for the port, it looks correct, although your measurements are hard to decipher, given that there are no visible indications of exactly which measurement applied to which portion of the box.

Perhaps that's not the case on your screen but it is on the photos you shared.


Oh and, on other idea (if feasible) would be to place the port at the bottom and load one driver in the front and one on the top. Or, vice versa, by adding a few inches of height to the side panels and getting the bottom face up off the floor a bit.

I wouldn't mind designing you one if I was a Sketchup guy but I'm not. I'm old and I use pen and paper to sketch my boxes and I don't make cut sheets, I just build.

EDIT: So basically, in the time it would take me to draw a box on Sketchup, I could build two of them, lol.

Pyrofan
10-06-2013, 02:42 PM
Well then, it won't work I suppose. I didn't model the box for fitment but since you did, you have the answer. As for the port, it looks correct, although your measurements are hard to decipher, given that there are no visible indications of exactly which measurement applied to which portion of the box.

Perhaps that's not the case on your screen but it is on the photos you shared.


Oh and, on other idea (if feasible) would be to place the port at the bottom and load one driver in the front and one on the top. Or, vice versa, by adding a few inches of height to the side panels and getting the bottom face up off the floor a bit.

I wouldn't mind designing you one if I was a Sketchup guy but I'm not. I'm old and I use pen and paper to sketch my boxes and I don't make cut sheets, I just build.

EDIT: So basically, in the time it would take me to draw a box on Sketchup, I could build two of them, lol.
Well, im going to pen and paper now. Ill come back with the new revision.

Pyrofan
10-06-2013, 05:06 PM
Ok, so i got a box that may work. I did the math i think its all right. The only problem is port speed. Its WAY to fast. like 160 ft/s. Does that mean this isnt gonna work? Its SHOULD be 1.3 ft^3

Pic of the box.

ImageShack® - Online Photo and Video Hosting (http://imageshack.us/photo/my-images/849/uph3.png/)

ImageShack® - Online Photo and Video Hosting (http://imageshack.us/photo/my-images/7/gmfn.png/)

bbeljefe
10-06-2013, 06:59 PM
Honestly, I've been building boxes since 1987 and I've never, ever wondered or worried about port speed. Port area, on the other hand, is important and it changes with the piston displacement of the driver(s). As for how fast the air moves through the port, that depends on the speed of sound and the amount of restriction the port provides.

Only thing that doesn't look right with that box is that it looks like the end of the port is too close to the side of the box. It really needs to be at least one full port length from the side wall.

Pyrofan
10-06-2013, 07:16 PM
Honestly, I've been building boxes since 1987 and I've never, ever wondered or worried about port speed. Port area, on the other hand, is important and it changes with the piston displacement of the driver(s). As for how fast the air moves through the port, that depends on the speed of sound and the amount of restriction the port provides.

Only thing that doesn't look right with that box is that it looks like the end of the port is too close to the side of the box. It really needs to be at least one full port length from the side wall.

So if my port length is 26, then their needs to be 26in from the end of the port to the side. Is that even possible

bbeljefe
10-06-2013, 07:41 PM
So if my port length is 26, then their needs to be 26in from the end of the port to the side. Is that even possible

No no... port width, not length. ;) If your port is 1 5/16" or whatever we came up with, you need that amount or more between the end of the port and the side of the box.

Pyrofan
10-06-2013, 07:49 PM
No no... port width, not length. ;) If your port is 1 5/16" or whatever we came up with, you need that amount or more between the end of the port and the side of the box.

When i did the math myself, my width was 1.25. the distance from the end of port to wall is 1 in. Is that .25 gonna matter that much?

EDIT: So, i revised the box so that it wouldnt be closer then 1.25in. Its even. The box is about 1.46 ft^3. little on the big side but do yall think it will work?

bbeljefe
10-07-2013, 12:38 AM
When i did the math myself, my width was 1.25. the distance from the end of port to wall is 1 in. Is that .25 gonna matter that much?

EDIT: So, i revised the box so that it wouldnt be closer then 1.25in. Its even. The box is about 1.46 ft^3. little on the big side but do yall think it will work?

Yes, it will make a big difference in that it would introduce turbulence and thus, noise. You're better off with higher tuning than noisy lower tuning. And if you mean the net volume is larger, that's too much of an increase for those subs. Your tuning will likely be lowered to the point that you have a nasty dip above Fb and too much peak at Fb.

Pyrofan
10-07-2013, 09:31 AM
Yes, it will make a big difference in that it would introduce turbulence and thus, noise. You're better off with higher tuning than noisy lower tuning. And if you mean the net volume is larger, that's too much of an increase for those subs. Your tuning will likely be lowered to the point that you have a nasty dip above Fb and too much peak at Fb.

That 1.46 is after displacement. So great. i dont think the box can go any smaller. I did what the tutorials said.

bbeljefe
10-07-2013, 10:31 AM
Not great. Here's the response curve for what you've drawn:

http://i596.photobucket.com/albums/tt42/bbeljefe/SA8Mess_zps7e06b797.png

Remember me saying you'll have a nasty dip above tuning? That dip starts at 34Hz and goes almost -3dB throughout the entire bass range above it. And it falls off like a wall below tuning. Essentially, that's a 30Hz burp box with no acoustical gain.

Do what you want but again, those drivers do not do well in large boxes. One cube is about the max they're gonna be happy in and that's at 35Hz.

Pyrofan
10-07-2013, 10:34 AM
Not great. Here's the response curve for what you've drawn:

http://i596.photobucket.com/albums/tt42/bbeljefe/SA8Mess_zps7e06b797.png

Remember me saying you'll have a nasty dip above tuning? That dip starts at 34Hz and goes almost -3dB throughout the entire bass range above it. And it falls off like a wall below tuning. Essentially, that's a 30Hz burp box with no acoustical gain.

Do what you want but again, those drivers do not do well in large boxes. One cube is about the max they're gonna be happy in and that's at 35Hz.
Back to the drawing board! The biggest problem is port length. Some are want very long ports.

EDIT: im getting a port length of 33. Seems like that gonna be to long

bbeljefe
10-07-2013, 11:15 AM
Back to the drawing board! The biggest problem is port length. Some are want very long ports.

EDIT: im getting a port length of 33. Seems like that gonna be to long

Again... one cube tuned at 35Hz. Port length as stated previously (25" iirc) and ~16in˛ of port area. ;-)

Pyrofan
10-07-2013, 11:45 AM
So, i got 1.05 net volume ( using Torres)

Port area- 18.13
port length-34.10
34.86 hz.

Please say this will work

http://img203.imageshack.us/img203/9744/q9fw.png

ImageShack - SketchUp 2013-10-07 10-39-47-89.bmp (http://imageshack.com/i/nh09xfp)

jdawg90
10-08-2013, 01:00 AM
I've been designing a box for my sa-8's myself. I've done a TON of searching.

That port area sounds small. What I have gathered on here is you want 15-18 inches PER SUB (I think it was buck that said that but I'm not 100%). With the small space requirements of these subs that results in a port length of around 50 inches giving each sub ~.6 cubes.... yea fun I know.

I thought that sounded like a lot so I mapped out the vent velocity in BBpro and the velocity was pretty close to the velocity of an sa-12 in the recommended box size with 14 inches of port a cubic foot (what I read they like).

Pyrofan
10-08-2013, 10:21 AM
I've been designing a box for my sa-8's myself. I've done a TON of searching.

That port area sounds small. What I have gathered on here is you want 15-18 inches PER SUB (I think it was buck that said that but I'm not 100%). With the small space requirements of these subs that results in a port length of around 50 inches giving each sub ~.6 cubes.... yea fun I know.

I thought that sounded like a lot so I mapped out the vent velocity in BBpro and the velocity was pretty close to the velocity of an sa-12 in the recommended box size with 14 inches of port a cubic foot (what I read they like).

Yea. I talked to Buck also. My port is 41in long tuned to about 34-35hz. The box is about 1.5 cubes with is the smallest it can be in my layout. Finishing up my box today.

Pyrofan
10-08-2013, 07:26 PM
So, its built. Its a little off but no more that 1/16. So, where should i face it. Foward, left, right, or back? Is a different in truck?