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resonate
09-07-2012, 12:38 AM
I designed a new one..scroll down to check it out!

Positive construction is great. ;) (For an SA-15, aiming for 3.5 @ 35 hz)

http://img525.imageshack.us/img525/1739/design2t.jpg (http://imageshack.us/photo/my-images/525/design2t.jpg/)

http://img507.imageshack.us/img507/5498/design2top.jpg (http://imageshack.us/photo/my-images/507/design2top.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

Now, there are a few things I need to clear up -

1) The height dimension excludes the top wall of the enclosure. So the total height will be 17".

2) The outer dimensions of the box are 17 x 17 x 29. That means the inner dimensions are 15.5 x 15.5 x 27.5, giving me an internal volume of ~3.8 cu. ft. Then, as displacement of the sub and port are subtracted, it'll leave me in the ballpark of 3.5 cubic feet.

3) I used Products Menu (http://www.psp-inc.com/tools.html) to find my port length, it's supposed to be around 35 hz with a 6" aeroport. Is this anywhere close? (Also, I know I don't have much room between my port and my rear wall, as shown in my second picture. Is this going to be a major problem?)

goingdef
09-07-2012, 12:44 AM
I'm not a designer but I have made a few boxes and I'm pretty sure you want the ports distance equal too or greater then it's opening from the back wall, you may have to use a 90% elbow in there to achieve the tuning you want.

RangerDangerV2
09-07-2012, 12:47 AM
go with a slot port. or fire the port to the side.

resonate
09-07-2012, 12:48 AM
I'm not a designer but I have made a few boxes and I'm pretty sure you want the ports distance equal too or greater then it's opening from the back wall, you may have to use a 90% elbow in there to achieve the tuning you want.

I heard it was you wanted the end of the port at least equal to the ports diameter (which is certainly not the case here, I'm aware). How would I elbow an aeroport? And how would that affect the tuning/sound?

---------- Post added at 10:48 PM ---------- Previous post was at 10:48 PM ----------


go with a slot port. or fire the port to the side.

Which side?

Toone
09-07-2012, 12:49 AM
port should be diameters distance away from back wall as said above, also no bracing?

resonate
09-07-2012, 12:51 AM
port should be diameters distance away from back wall as said above, also no bracing?

I've run multiple boxes, none of them ever had bracing, seemed to be fine. Then again, they were slot port boxes. I guess it never really came to mind, but I'm sure this isn't my final design. I'll add bracing when I redo the design for my port.

RangerDangerV2
09-07-2012, 12:52 AM
I heard it was you wanted the end of the port at least equal to the ports diameter (which is certainly not the case here, I'm aware). How would I elbow an aeroport? And how would that affect the tuning/sound?

---------- Post added at 10:48 PM ---------- Previous post was at 10:48 PM ----------



Which side?

experiment and see which one will get you louder.

goingdef
09-07-2012, 12:53 AM
I've always just built slotted ports there easy to get everything you want built right into the enclosure, I have only done one aero type port and it was to the passenger side as coming out the front wasn't an option but to add an elbow I don't know how you would add that in hvac work a 90% turn represents a 10' straight piece worth of pressure drop I don't know if things like that factor in here or not.

resonate
09-07-2012, 12:56 AM
I've always just built slotted ports there easy to get everything you want built right into the enclosure, I have only done one aero type port and it was to the passenger side as coming out the front wasn't an option but to add an elbow I don't know how you would add that in hvac work a 90% turn represents a 10' straight piece worth of pressure drop I don't know if things like that factor in here or not.

I do like slot ported boxes, but unfortunately I really just don't have the room to work with one. I'll do a new design to the side.

hispls
09-07-2012, 12:57 AM
Definitely don't want to crowd the port into the back wall! Bracing will always help.

pro-rabbit
09-07-2012, 01:09 AM
Pretty much what everyone else has said about the port.

The other issue if you port out the side is loading/unloading may become an issue.

resonate
09-07-2012, 01:13 AM
New Design!

http://img267.imageshack.us/img267/7528/design3b.jpg (http://imageshack.us/photo/my-images/267/design3b.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

I realize it's pretty close to the wall, but I really couldn't move it over much further because of the subwoofer. Better/worse than the first one?

EDIT: The 7 1/2 in. is for the SA-15s depth.

resonate
09-07-2012, 01:14 AM
Pretty much what everyone else has said about the port.

The other issue if you port out the side is loading/unloading may become an issue.

How's the new one look? And what do you mean by loading/unloading?

RangerDangerV2
09-07-2012, 01:16 AM
How's the new one look? And what do you mean by loading/unloading?

unloading is when the woofer loses pressure on the rear wave. it basically starts to move free air. from my understanding anyways. also I would swap to a single 12 and run it in the correct box..

resonate
09-07-2012, 01:19 AM
unloading is when the woofer loses pressure on the rear wave. it basically starts to move free air. from my understanding anyways. also I would swap to a single 12 and run it in the correct box..

But..but..I finally got my SA-15.. :crying:

And wouldn't I lose quite a bit of output? I do not want that.

pro-rabbit
09-07-2012, 01:29 AM
What is the net volume? I didn't catch that part. Also, if you can I would drop the port down and the sub cutout to where the sub sits just over the port...also, add bracing.

If you are short on volume, then yes, I would down grade..but I didn't do any math I'm on my way and I'm tired lol.

resonate
09-07-2012, 12:25 PM
What is the net volume? I didn't catch that part. Also, if you can I would drop the port down and the sub cutout to where the sub sits just over the port...also, add bracing.

If you are short on volume, then yes, I would down grade..but I didn't do any math I'm on my way and I'm tired lol.

IIRC, the box is aimed @ 3.8 gross, 3.5 net volume. The sub accounts for about .17 and the port ~.14 or so. I'd like to construct the box myself, but I'm not really sure how to add bracing. I'll look it up and make the box a little bigger to account for the brace.

resonate
09-07-2012, 04:24 PM
Here's a thought - think design #2 (http://www.caraudio.com/forums/usertag.php?do=list&action=hash&hash=2) would work if I inverted the sub and added bracing?

kushy_dreams
09-07-2012, 08:40 PM
My advice is to get an 8inch sonotube (cement form) from home depot for $5, get the one that 7 3/4inch wide or whatever the smallest is, do sub back, port to the side, you will need 24inches of length to get a 35hz tune with 3.5 cu/ft. If you go up in volume to 4 cu/ft, you can get the length down to ~20inches. If you went with 31 wide, same height at 16.25 and a little more depth, like 19-20, that should give you enough room after displacements for about 4 cu/ft. Bracing is done with simple dowel rods, at least 1inch in diameter.

Build this box, only use the smallest size of 8inch sonotube instead of 3inch aeros:

http://carphotos4.cardomain.com/images/0015/61/19/15941691_large.jpg