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View Full Version : HELP ME I'M DROWNING; Making my first box



iiJonathan
08-09-2013, 03:06 AM
So, to start this thread off, I have a regular cab f150 (2000) which I plan(ned) on installing 3 SA-8 V2's at 33hz. The max dimensions I have behind the seat are 43 Width, 14 height, 9 depth at base, and 5 depth at the top which comes out to 1.65 Cu's. (This is a wedge style design as I have a bench seat)

The problem; I wasn't thinking about bracing, sub displacement, or wall displacement while laying out my audio-build please forgive me, this is my first time. (3) SA's will come out to .24 Cu3 displacement leaving me with 1.41 Cu, already less than minimum for 3 Sa's (1.50) However, I am running a BRX.2000 to them and at 1.37 Ohms, they'll be receiving slightly over their 500 RMS rating. around 570. I'm not sure if that'll compensate for my loss there, but we still haven't calculated the port wall displacement. I've been playing around with torres, and I'm coming to the conclusion that this becoming more and more impossible with my size box and Hz.

Options; Unless someone here has a secret, or knows a builder that could potentially help me (I'm willing to pay) I'm facing downgrading to 2 subs, at 1 Ohm flat they'll receive 1k RMS each which I'm sure they can handle, but I really really really really really don't want to downgrade. I may actually create a box to sit in between the dash and seat on the trans column.

My thoughts; I'm thinking the 33 Hz is actually what's killing this plan, no matter what I do I can't seem to get my Hz down without killing the air space. What's an acceptable port width? It seems the only way I can achieve 33 Hz is with a 1" port width, but that doesn't seem right. What is an acceptable port length? I technically can make this work, because I can extend the box to a bigger width, but I'll need to extensively modify the plastic bodywork behind the seats which restrict the corners of the box (I'll get back there with a recip. saw) But I'd like to atleast try to not modify the interior too much.

Hopefully someone can help me, and thanks ahead of time if you do!

mylows10
08-09-2013, 03:11 AM
might try 2" aero or round ports ,see how that will work for you

iiJonathan
08-09-2013, 03:14 AM
Unfortunately, I'll have to look into that. I have absolutely no clue on how Aeros work, and how people even figure them out.

NIHL8ION
08-09-2013, 03:15 AM
You don't have enough space for 3 subs, I'd be looking at going with 2 if I was you, I just built a box for a reg cab 04' F150 for a single 12" sub with about 1.94 cu ft net tuned at 36hz (I went a lot taller than 14") and that was barely even possible keeping it behind the bench...

iiJonathan
08-09-2013, 03:16 AM
That's what I was really scared of. Atleast I haven't bought them yet!

Better-Action
08-09-2013, 05:01 AM
Thought about a external Aero?

Plugged the numbers in Torres and if you go with 2 3" aeros 20" long and about 14 of that external you got 1.5cf to work with after the port. That gives you roughly 33hz tuning and around 10" of port per cube.

iiJonathan
08-09-2013, 01:51 PM
I have looked into aeros, but I have no idea on how they work whatsoever. Externally, Im not sure how I could fit such a long tube, and me being a novice box builder I don't think the results would be good.

iiJonathan
08-09-2013, 02:01 PM
Thought about a external Aero?

Plugged the numbers in Torres and if you go with 2 3" aeros 20" long and about 14 of that external you got 1.5cf to work with after the port. That gives you roughly 33hz tuning and around 10" of port per cube.

Where would I find said aero?

mylows10
08-09-2013, 02:05 PM
Parts express or just go get some abs pipe at Home Depot

T3mpest
08-09-2013, 02:50 PM
If the port is facing a boundary that will drop the tuning a few hz as well. If you can get 36hz in a program, you'll be closer to 33 in a car.

Better-Action
08-09-2013, 09:53 PM
Aeros are simpler than slot ports imo. Less chance to **** em up. Torres has a aero calculator. The way I pictured it was the 2 external aeros on the driver side coming out the top of the box. 14" external so both the ports would go into the box only 6" and the other 14" would be sticking out.

In Torres where you put your slit port dimensions right under it is areo. Just add 2 as the number of ports and 3" as the diameter, and length. Then down by woofer displacement you'll see length of external port. Aero ports are so simple, its kinda hard to mess em up. Plus if you'd like to experiment with different tunings its so easy to just swap out a tube.

bubbagumper6
08-09-2013, 10:08 PM
You have to not only include the port wall displacement but also the port airspace as well, that's not usable airspace for the enclosure and must be subtracted from the gross volume.

iiJonathan
08-10-2013, 12:02 AM
Aeros are simpler than slot ports imo. Less chance to **** em up. Torres has a aero calculator. The way I pictured it was the 2 external aeros on the driver side coming out the top of the box. 14" external so both the ports would go into the box only 6" and the other 14" would be sticking out.

In Torres where you put your slit port dimensions right under it is areo. Just add 2 as the number of ports and 3" as the diameter, and length. Then down by woofer displacement you'll see length of external port. Aero ports are so simple, its kinda hard to mess em up. Plus if you'd like to experiment with different tunings its so easy to just swap out a tube.

You've actually clarified aero ports so much for me with just that statement. I'm definitely going to look into this, 33 hz isn't as important to me as it is having 3 subs.

---------- Post added at 11:02 PM ---------- Previous post was at 11:01 PM ----------


You have to not only include the port wall displacement but also the port airspace as well, that's not usable airspace for the enclosure and must be subtracted from the gross volume.

Are you talking about if I use an aero or slot port. If I use an aero there will be no "port wall" correct?

hispls
08-10-2013, 12:05 AM
The volume of air within the port is subtracted from net volume.

2 subs in correct size box will generally be better than 3 subs in too small of a space.

iiJonathan
08-10-2013, 12:09 AM
Now that I finally understand torres, I plugged in the Aeros, and I see how this can work! Will I have the port "noise" they talk about if I don't flange the ends? and will the 6" internal still need to be accounted for in terms of airspace? I'm not exactly sure if I should brace this style box, I'll probably use some 1x1's, and I won't need the 45's in the corners since its an aero. Bare with me please, these aeros are out of my knowledge range for now.

iiJonathan
08-10-2013, 12:14 AM
Does this look right? http://img405.imageshack.us/img405/4921/zfm9.png
Should the external port section be 20 or 14 since only 14 is outside the box.
The minimum for 3 Sa's is 1.50 :S I may be able to invert one in the center where the bench seat comes inwards for the console but that'd only give me an extra
.08. I'm not sure how much bracing is going to do me in for.

Edit: been playing with the dimensions and I've added like .5's to certain areas, and with .10 displacement I can pull a solid 1.50! My two questions now are; Will .10 bracing be enough, and since this is a wedge design box, the aeros will not be coming out of a flat surface, but rather the sloped part due to the actual top being underneath a rear firewall lip (stupid design) Will that affect what's going on?

Better-Action
08-10-2013, 01:33 AM
Doing the aeros like that shouldn't pose a problem. One thing I didn't think of is the mounting depth of those 8's.

I don't think you'd need much bracing for a box that small. Maybe just 2 1" round wooden rods going from the back wall to the front, know what I'm saying?

And only 14" of the port would be external so you have it right in the pic.

If that mounting depth on those eights kills it a good alternative would be a beefier single 10" mounted in the center inverted. In a single cab a decent box and a beefy 10 with some power on it will get you excellent output.

And Torres automatically deducts port space from volume. Change the length of the port and you'll see that the internal volume of the enclosure will change. Does it all for ya.

bbeljefe
08-10-2013, 01:44 AM
You should seriously consider losing one of the woofers. Those minimum manufacturer recommendations are for high SPL and power handling and don't consider much where sound quality is concerned.

Two SA8s on that power in a good sized ported box will be loud as hell and will produce good low end. Add a third and you won't get the lows you want.

Unless of course, you're building a burp box and don't care about sound quality...


Oh and, here's another option if you absolutely can't live without three woofers. Put two behind the seat and put one in the console box you mentioned building. Or vice versa, depending on how much space you have to build the console box.

Better-Action
08-10-2013, 01:51 AM
You should seriously consider losing one of the woofers. Those minimum manufacturer recommendations are for high SPL and power handling and don't consider much where sound quality is concerned.

Two SA8s on that power in a good sized ported box will be loud as hell and will produce good low end. Add a third and you won't get the lows you want.

Unless of course, you're building a burp box and don't care about sound quality...


Oh and, here's another option if you absolutely can't live without three woofers. Put two behind the seat and put one in the console box you mentioned building. Or vice versa, depending on how much space you have to build the console box.


Phase issues booooooo!!!!!

iiJonathan
08-10-2013, 01:57 AM
This is all very good advice, I'm currently in the denial stage of losing my third woofer, but I'm slowly coming to the realization that I won't be all that happy with a 3rd. I am however, going to use aero's for the two because I realize how much more awesome they are than slots. I'm definitely going for some SQ, and I hate the one note wonder burp boxes. In the end, I'd rather have two subs in a nice airspace than three crowded, but thanks for helping me out everyone, this really got me even more excited for my build and I definitely gained some knowledge.

Yeah, I was gonna use those rounded ones I see everyone use for bracing.
I'm thinking that the mounting depth will be alright, they are only 6 5/8th's, so if I'm starting with 10" at the bottom I should be alright.
With the aeros facing up I'll probably get some good bass. Do you think the fact that I'm in a small cab would add to the flex or take away?

Edit: You guys think I should put both aeros on drivers side or split them between the pass and drivers for better sound localization.

iiJonathan
08-10-2013, 02:09 AM
2 SA-8 V2's at 1 Ohm running 1k a piece in a 1.40Cu3 33Hz box it is.

bubbagumper6
08-10-2013, 02:27 AM
You've actually clarified aero ports so much for me with just that statement. I'm definitely going to look into this, 33 hz isn't as important to me as it is having 3 subs.

---------- Post added at 11:02 PM ---------- Previous post was at 11:01 PM ----------



Are you talking about if I use an aero or slot port. If I use an aero there will be no "port wall" correct?

There will be no wall but the volume inside the port CANNOT be counted towards the net volume of the enclosure. It's not usable airspace.

Better-Action
08-10-2013, 07:10 AM
This is all very good advice, I'm currently in the denial stage of losing my third woofer, but I'm slowly coming to the realization that I won't be all that happy with a 3rd. I am however, going to use aero's for the two because I realize how much more awesome they are than slots. I'm definitely going for some SQ, and I hate the one note wonder burp boxes. In the end, I'd rather have two subs in a nice airspace than three crowded, but thanks for helping me out everyone, this really got me even more excited for my build and I definitely gained some knowledge.

Yeah, I was gonna use those rounded ones I see everyone use for bracing.
I'm thinking that the mounting depth will be alright, they are only 6 5/8th's, so if I'm starting with 10" at the bottom I should be alright.
With the aeros facing up I'll probably get some good bass. Do you think the fact that I'm in a small cab would add to the flex or take away?

Edit: You guys think I should put both aeros on drivers side or split them between the pass and drivers for better sound localization.

Good choice. And with more airspace to play with you shouldn't have to go external port. I've been told that subs on passenger side and port on driver does great in trucks. And it wasn't wrong. Had a single 15" on 2k flexing my back window 2" and incredible lows in my extended cab s10 with it.

One idea is if you could shorten the box width wise about 3-4 inches you could do one large port firing out the bottom driver side towards the wall. Heard good things from that configuration as well. Like 1 6" Aero. I did this side firing port setup with 1 10" and a 4 inch Aero tuned to 35hz and it sounded great in a Dodge ram single cab. Very tight and punchy sounding.