Sub box design

[LsGuy]

Hello all, another question about my system.

The sub in question is a Pioneer shallow mount 8 inch 250 watt rms sub powered with ~200 watts rms.

I am attempting to build a sealed enclosure for it. Trunk isn't an option, I dont think the sub would get loud enough to mount there, and I can't afford to lose any trunk space or my fold down seats. Rear deck mount isn't providing me what I want. Volume is fine, but bass isn't tight enough for me and theres a ton of rattle. Building an enclosure under the deck would require extensive modification (torsion bars directly under sub). Seats sit too low to fit the sub under, and at my height if I raised the seat my head would hit the roof. The one area I could sacrifice space is the passenger floorboard. Total working room here is 4.5 inches tall, 19 inches wide and 10 inches long. This is plenty of room for this sub as it has a mounting depth of only 2 5/8 inches. However, I want to go for a stealth look. Top of the box even with the door trim, carpet over the top.

I have found 2 methods to achieve this, but I dont know which would be better.

Option one up firing. Build the box to the floor, 3/4 inch wood on top to be weight bearing. Sub inset into the top of the box 3/4 of an inch, and build a weight bearing grate that would be inset into the box probably 1/4 inch to be flush. This would leave 1/2 inch for upward sub travel. Small sub with low wattage, this may be enough clearance but not sure. Carpet would lay directly over sub. Sub would sit 1/2 inch off of base.

Option 2 down firing. 1 inch gap between box face and floor. If using 1/2 inch wood inside dimensions would only be 2.5 inches, sub would be roughly 1/2 inch from the wood on the back side. Braced solid 1/2 inch weight bearing top. This is easier because I wouldn't have to figure out a grating system. Issue is, with a 1 inch gap there would only be an opening on one side, of about 18 inches. Would this be enough for the bass to come through? The up side is it would be aiming undernearh the drivers seat, so to the front of the cab.

Thoughts?

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[Kybasshead75]

Hello all, another question about my system.

The sub in question is a Pioneer shallow mount 8 inch 250 watt rms sub powered with ~200 watts rms.

I am attempting to build a sealed enclosure for it. Trunk isn't an option, I dont think the sub would get loud enough to mount there, and I can't afford to lose any trunk space or my fold down seats. Rear deck mount isn't providing me what I want. Volume is fine, but bass isn't tight enough for me and theres a ton of rattle. Building an enclosure under the deck would require extensive modification (torsion bars directly under sub). Seats sit too low to fit the sub under, and at my height if I raised the seat my head would hit the roof. The one area I could sacrifice space is the passenger floorboard. Total working room here is 4.5 inches tall, 19 inches wide and 10 inches long. This is plenty of room for this sub as it has a mounting depth of only 2 5/8 inches. However, I want to go for a stealth look. Top of the box even with the door trim, carpet over the top.

I have found 2 methods to achieve this, but I dont know which would be better.

Option one up firing. Build the box to the floor, 3/4 inch wood on top to be weight bearing. Sub inset into the top of the box 3/4 of an inch, and build a weight bearing grate that would be inset into the box probably 1/4 inch to be flush. This would leave 1/2 inch for upward sub travel. Small sub with low wattage, this may be enough clearance but not sure. Carpet would lay directly over sub. Sub would sit 1/2 inch off of base.

Option 2 down firing. 1 inch gap between box face and floor. If using 1/2 inch wood inside dimensions would only be 2.5 inches, sub would be roughly 1/2 inch from the wood on the back side. Braced solid 1/2 inch weight bearing top. This is easier because I wouldn't have to figure out a grating system. Issue is, with a 1 inch gap there would only be an opening on one side, of about 18 inches. Would this be enough for the bass to come through? The up side is it would be aiming undernearh the drivers seat, so to the front of the cab.

Thoughts?

you will want the subwoofer as far away from the listening position as possible, if placed in the middle of the listening area it will not sound right. It's really not as hard as it seems to gut the deck and frame it and attach the box to it for real. It will also have the horn effect with the sub facing the glass directly well worth the work.
I mean hell you could even get a Sono tube and glass it and set the circular enclosure behind the passenger seat, until you deal with the rear deck you will get rattles

 

[LsGuy]

you will want the subwoofer as far away from the listening position as possible, if placed in the middle of the listening area it will not sound right. It's really not as hard as it seems to gut the deck and frame it and attach the box to it for real. It will also have the horn effect with the sub facing the glass directly well worth the work.
I mean hell you could even get a Sono tube and glass it and set the circular enclosure behind the passenger seat, until you deal with the rear deck you will get rattles

Its not the gutting of the rear deck that bothers me, its the torsion bars that would need removed. In order to hook up gas shocks ill need tools that I don't want to purchase currently since my garage is still being built. Theres no good spot to mount them, would need to reinforce an area and probably weld them in place. Already pulled the carpet and checked it out, that's plan B. I'm not sure I understand the sound stage problem. People put subs under seats and behind seats all the time. Why won't it work here?

 

[Kybasshead75]

Its not the gutting of the rear deck that bothers me, its the torsion bars that would need removed. In order to hook up gas shocks ill need tools that I don't want to purchase currently since my garage is still being built. Theres no good spot to mount them, would need to reinforce an area and probably weld them in place. Already pulled the carpet and checked it out, that's plan B. I'm not sure I understand the sound stage problem. People put subs under seats and behind seats all the time. Why won't it work here?

Its not the gutting of the rear deck that bothers me, its the torsion bars that would need removed. In order to hook up gas shocks ill need tools that I don't want to purchase currently since my garage is still being built. Theres no good spot to mount them, would need to reinforce an area and probably weld them in place. Already pulled the carpet and checked it out, that's plan B. I'm not sure I understand the sound stage problem. People put subs under seats and behind seats all the time. Why won't it work here?

I just drilled a hole and installed a metal bar to prop up the trunk instead of using the hydraulics or torsion bars, problem solved.
Placing the subwoofer furthest away from the listening position into an area that it can load onto will concentrate an accelerate the air being displaced by the subwoofer much more efficiently than the subwoofer playing in the middle of the listening area a favorite trick for figuring out where your speakers go in the house or car is to get a small sub and have someone move it around until it sounds best to you while you sit in the listening chair.
I have found through experimentation that The Sweet spot is always where a subwoofer directs its energy the most efficiently. If you said it in the middle of a room the energy dissipates in all directions as a circular wave and its energy will not be concentrated into the listening area whereas a subwoofer aimed perfectly and in the right spot will immediately sound much better. Placing the subwoofer in the rear of the vehicle allows the wave to move in one direction forward eliminating the dissipation of the energy into all directions but rather concentrating it into the one direction forward into the seats.
A great example of this is when people move a single port from The middle of a surface like the back glass to the passenger side which is loudest to the driver because it loads the corner and the corner then bounces the energy into the drivers area then when you move the port to the driver's side it becomes louder to the passenger again because you're concentrating the airflow and wave energy of the subwoofer into a certain direction.
While various subwoofer locations will work and you will have base after some experimentation you will find The Sweet spot is always furthest away from The Listener and usually loading onto a surface that bounces the sound waves in the direction of the listening seat.

 

[Kybasshead75]

I just drilled a hole and installed a metal bar to prop up the trunk instead of using the hydraulics or torsion bars, problem solved.
Placing the subwoofer furthest away from the listening position into an area that it can load onto will concentrate an accelerate the air being displaced by the subwoofer much more efficiently than the subwoofer playing in the middle of the listening area a favorite trick for figuring out where your speakers go in the house or car is to get a small sub and have someone move it around until it sounds best to you while you sit in the listening chair.
I have found through experimentation that The Sweet spot is always where a subwoofer directs its energy the most efficiently. If you said it in the middle of a room the energy dissipates in all directions as a circular wave and its energy will not be concentrated into the listening area whereas a subwoofer aimed perfectly and in the right spot will immediately sound much better. Placing the subwoofer in the rear of the vehicle allows the wave to move in one direction forward eliminating the dissipation of the energy into all directions but rather concentrating it into the one direction forward into the seats.
A great example of this is when people move a single port from The middle of a surface like the back glass to the passenger side which is loudest to the driver because it loads the corner and the corner then bounces the energy into the drivers area then when you move the port to the driver's side it becomes louder to the passenger again because you're concentrating the airflow and wave energy of the subwoofer into a certain direction.
While various subwoofer locations will work and you will have base after some experimentation you will find The Sweet spot is always furthest away from The Listener and usually loading onto a surface that bounces the sound waves in the direction of the listening seat.

Pardon the massive grammar talk and text mistakes lol

 

[LsGuy]

I get what you are saying, but my down fire box design from the rear drivers floorboard would have the opening pointing forward under the drivers seat with all other directions closed off by the foot well. Would this not concentrate the sound waves forward in one direction?

Im not set on any one placement or design yet. I can't use a prop rod for the trunk, being my work vehicle my hands are almost always full when loading the trunk. I was actually considering installing one of those foot sensors to open the trunk so I wouldn't even have to use a hand to push the key fob button. Loading and unloading my trunk are a daily occurance. I was looking at it again yesterday, and I may be able to use extension springs to open and hold it. This would require no drilling or welding. It would be trial and error to find the correct spring weight. I'm thinking at the angle they would pull, 40 lbs on each side may do the trick. Finding a 6 inch extension spring that can extend a further 6 inches is tricky though.

 

[Kybasshead75]

I get what you are saying, but my down fire box design from the rear drivers floorboard would have the opening pointing forward under the drivers seat with all other directions closed off by the foot well. Would this not concentrate the sound waves forward in one direction?

Im not set on any one placement or design yet. I can't use a prop rod for the trunk, being my work vehicle my hands are almost always full when loading the trunk. I was actually considering installing one of those foot sensors to open the trunk so I wouldn't even have to use a hand to push the key fob button. Loading and unloading my trunk are a daily occurance. I was looking at it again yesterday, and I may be able to use extension springs to open and hold it. This would require no drilling or welding. It would be trial and error to find the correct spring weight. I'm thinking at the angle they would pull, 40 lbs on each side may do the trick. Finding a 6 inch extension spring that can extend a further 6 inches is tricky though.

Hey that down firing box is legitimate actually you might enjoy having it close to you as it resonates I loved my four tens right behind the seats in my single cab S10 that system would beat your guts out I think it would be the quickest and easiest option also I would go with that myself then you would have your trunk to use easily and less work to do downfiring is always good from what I've seen

 

[LsGuy]

Hey that down firing box is legitimate actually you might enjoy having it close to you as it resonates I loved my four tens right behind the seats in my single cab S10 that system would beat your guts out I think it would be the quickest and easiest option also I would go with that myself then you would have your trunk to use easily and less work to do downfiring is always good from what I've seen

Roger that, that's what I'll go with then. I know a lot of people say downfiring a car sub can be bad because of the weight of the speaker, however the box that pioneer makes for this sub is a downfiring box, so I'll assume it should be just fine.

 

[LsGuy]

Pioneer TS-SWX2002

Shallow sealed enclosure with 8" TS-SW2002D2 subwoofer

www.crutchfield.com

Here's the pioneer box. The legs on that look to be about 1 inch tall, so I'll assume my box being 1 inch up will be fine. I'm going to guestimate that since that box is 5.5 inches tall, with 1 inch being in the legs the actual box its self is 4.5 inches tall. My box will be only 3.5 inches tall, but like 20 inches wide and 10 inches long so I should actually get more internal volume. I think it will work out. Only thing that worries me is their design leaves gaps on all sides under the enclosure whereas mine will have it only on one side. Hopefully itll be enough for the sound to escape.

 

[LsGuy]

Then again their longest sides are only 11 3/4, so my one opening will be roughly the size of their 2 long sides combined. Should work ok hopefully.

 

[Kybasshead75]

Roger that, that's what I'll go with then. I know a lot of people say downfiring a car sub can be bad because of the weight of the speaker, however the box that pioneer makes for this sub is a downfiring box, so I'll assume it should be just fine.

I've heard people say that for years but the fact that pioneer designed it to be down firing should tell you they know what they're doing and empirically I have liked every downfiring box properly built that I've ever heard of the best base I ever heard in a home theater system was a single 18 inch cerwin Vega that had the subfiring down to the floor and the port loading into the corner of the wall.
what those people don't talk about is the phenomenon of cone reinforcement when the cone is close to a surface to load onto it will keep its shape better resulting in less distortion and Spike the impedance up to your amp a little bit forcing it to work harder also which means a little more juice and less distortion. A good formula is using the radius of the active cone area as the distance from the cone to the floor.

 

[LsGuy]

I've heard people say that for years but the fact that pioneer designed it to be down firing should tell you they know what they're doing and empirically I have liked every downfiring box properly built that I've ever heard of the best base I ever heard in a home theater system was a single 18 inch cerwin Vega that had the subfiring down to the floor and the port loading into the corner of the wall.
what those people don't talk about is the phenomenon of cone reinforcement when the cone is close to a surface to load onto it will keep its shape better resulting in less distortion and Spike the impedance up to your amp a little bit forcing it to work harder also which means a little more juice and less distortion. A good formula is using the radius of the active cone area as the distance from the cone to the floor.

I've heard that formula a lot, but the radius of the active cone in this is probably around 3 inches. There's no way that would fit, and if you check the box I linked here from pioneer you can see the dimensions. Theres no way that box is anywhere near 3 inches off the ground.