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jcham
Dodge Dakota
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1/31/2004
18:01:24
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 Subject: Will these dimensions work?
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Sorry about the length, but I have to set this up for you. I have a 10" RF Power HX2 Dvc Sub. It's going into a regular cab. I spoke with a guy at a local stereo shop about building a box for it and he quoted me a price of around $850. This was insane for a simple wedge-shaped box to go behind my seat. My problem is that I live in Southern Illinois, not exactly the hotbed of car audio innovations. Anyway, I called the other two shops in our area, and they won't do it or warranty the work because they dont't deal with Rockford Fosgate products. So, I went back to the first shop, and spoke to another person about some advice for building my own box. He gave me some dimensions, but they don't seem right. He said that for this sub I could build a box with the following dimensions: 41" Length. Top depth of 4". Bottom depth of 10". Box Height 19". Two 3" diameter, 11"Long Ports on each end. This would be constructed out of 3/4 MDF. What struck me as weird is that when this shop put my first sub in my truck, the box ran the width of the cab with almost exact same depth and height measurements and there was a lot smaller sub in it (10" Punch XLC.) Were they giving me the wrong advice or could this set up work. One note, the sub would be mouted "backward" in the box between the seats as I have removed my center console. Any help would be appreciated, I don't want to waste my time building a box that won't work, and I don't want to pay nearly 1,000 bucks to have it done for me. BTW the volume of these dimensions do not match up to Manufacturers Spec's, But when I asked the guy he said those numbers were guides and could be played with.
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DSW
Dodge Dakota
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2/01/2004
20:14:30
|  RE: Will these dimensions work?
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So what are the specs for this sub in a ported box? This box calculates to 2.19 cu ft. A 10" XLC would be swimming in this box since it's spec'ed out at .75 cu ft sealed and 1 cu ft ported. I have 2 of them in .70 cu ft sealed boxes and they sound great.
You can play with the air volume a little if it's within the subs range. The XLC's are OK from .65 to 1 cuft in a sealed box, but sound best at .75 cu ft. Same for other subs in sealed enclosures, but the air volume will be different. On the other hand ported enclosures need to be built with the correct air volume and port dimensions for the sub being used.
$850 for a box, I went into the wrong line of work. LOL Maybe he was quoting a glass box? Hope it wasn't for a MDF box cause this is a rip off, $50 for materials and maybe 1/2 day labor. The box seems big, was he quoting a enclosure for 2 subs?
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jcham
Dodge Dakota
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2/02/2004
13:08:49
| RE: Will these dimensions work?
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I hope I didn't confuse, the box will be for an HX2, not the XLC. My point was that the box for the XLC which is a much smaller sub than the HX2 has similar dimensions. The volums for a ported box for the HX2 is around 1.75 cu ft with three ports, not exactly sure I'd have to find my manual to see. The box he quoted me was MDF for a single sub. PLAIN.
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DSW
Dodge Dakota
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2/02/2004
15:36:42
| RE: Will these dimensions work?
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I just referred to the XLC's cause I have them, know their specs and you said the other box was for the XLC. Best thing to do is find the HE2 manual and build a box that's to RF's specs, air volume and port size. If RF says 1.75 cu ft and 1 or 2 3" ports at __ lenght then build the box to these specs. The box your shop said to build might work so-so, but RF gives you the optimal specs, so why go against the manufacturers specs in hopes that the box will work correctly.
Anyone can build a sealed box because they air volume can be off a little and not affect the performance of the sub that much. Ported enclosures have to be made to the correct specs. Too much or little air volume, wrong port diameter, lenght or location and the enclosure won't perform correctly. It might make bass, but it won't perform correctly.
Get the sub manual, bust out the calculator and figure out the dimensions of the enclosure needed for the correct volume. Don't forget to add in the air displacement of the sub (some where around .06 cu ft .07, .08) and add it to the air volume of the enclosure before figuring out the enclosure dimensions.
Best thing to do is go to www.rockfordfosgate.com and look at their section for building enclosures. They have all the information your going to need to build a good enclosure.
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jcham
Dodge Dakota
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2/02/2004
19:35:40
| RE: Will these dimensions work?
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Do I still have to account for sub displacement if the majority of my sub is going to be outside of the box. I am mounting the sub "backwards" because of the regular cab issue.
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DSW
Dodge Dakota
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2/02/2004
20:34:26
| RE: Will these dimensions work?
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Oh yeah, I forgot you were mounting it backwards, will it be "IN the box or OUT of the box. If it's backwards in the box subtract the cone volume from the the 1.75 cu ft , maybe a little less since the mounting ring is going to take away some air space. If it's backwards out of the box you should subtract the air volume of the round cutout and the cone's air volume. To figure the air volume of the sub's cone, line the sub cone with a trash bag and fill it with water, then use the amount of water to figure the volume of the cone. You can find water volume spec's online somewhere, I think it's like 5 or 8 galloons per cu ft. Don't remember since it was 5-6 months ago since I had to use this for a glass bottom box.
Yeah, this is getting pretty picky, but the closer you can get the actual air volume to 1.75 cu ft (or the subs optimal air volume) the better the sub is going to sound. The sub compresses the air, and uses the air as a spring, too much air and the spring is too weak, too little air and the spring is too stiff.
You will also want to put some fiberfill in the box to kill internal noise, but keep it against the walls and away from the sub and ports end. If it's a 3" port keep it 3" away from the end, 4" port keep it 4" away from the end. Sheet form like upholstery batting will work best since it's flat and you can cut it to match the inside of the box.
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jcham
Dodge Dakota
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2/02/2004
22:10:49
| RE: Will these dimensions work?
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As you can tell, this will be my first box that I have built, so I owe you many thanks. I do have another question. Is it even possible to mount the sub bacwards outside of a sealed box? I would like to do this if possible. My reason for this is because RF calls for three 3" diameter 16.5" long ports for a vented enclosure for my sub. I don't think I can configure the ports correctly, especially if the length and placement of the ports are critical to my sound. The manual doesn't give me any help in this area. Once again, thanks for your help and advice.
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DSW
Dodge Dakota
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2/02/2004
22:55:26
| RE: Will these dimensions work?
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It's possible to mount the sub outside the box from the exterior of the box, the critical thing is to get the sub completely air tight against the box. This means no air leaking past the gasket on the front of the sub.
Don't know If I have heard of anyone doing this with a sealed enclosure, or if I would do it, ported OK. But in a sealed box, I think this might mess up the sound since all the bass is coming fron the sub, there isn't a port to produce sound. The sub would be fighting against the basket and magnet to get the sound produced.
I checked out RF for specs on the sub, they say the 10" HE2 (2001) is recomended for a 1 cu ft ported enclosure with one 3" port 13.25" long. Should be realy easy to fit a 1 cu ft ported box into the SC with these specs.
Check out the manual at this URL, it might be the same as your manual. http://www.rockfordfosgate.com/rftech/library/2001/5_Subwoofers/LIT11416_DVCwoofers_MAN.pdf
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DSW
Dodge Dakota
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2/02/2004
22:59:40
| RE: Will these dimensions work?
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Aw crap, I looked up the wrong sub, but it's the same specs for the Power HX2 10" DVC.
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jcham
Dodge Dakota
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2/03/2004
00:22:45
| RE: Will these dimensions work?
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I printed the manual for the 2002 10" Power HX2 and it shows a 1.75 cu. ft. volume with three ports of the dimensions I said. I also got the manual from their website.
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DSW
Dodge Dakota
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2/03/2004
02:22:49
| RE: Will these dimensions work?
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I looked at the 2002 RF manual for the 10" HX2 and it shows the same specs that I mentioned, 1 cu ft box with one 3" diameter 13.25" long port. The most air volume you can run with this sub is 1.75 cu ft, but the optimal air space for the ported box is 1 cu ft.
Don't know where you see the specs for a 1.75 cu ft box with 3 - 3" 16.5" long ports, but it's not on thier website for the 2002 HX2. Here's the manual that I looked at for the 2002 10" HX2.
http://www.rockfordfosgate.com/rftech/library/2002/5_Subwoofers/LIT11487A_DVCwoofers_MAN.pdf
Someone else chime in here and back me up on the specs for this ported box.
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DSW
Dodge Dakota
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2/03/2004
02:35:20
| RE: Will these dimensions work?
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FK, Your right, I was looking at the HX2, not the Power HX2. This is a big box with a lot of port, but you got the right specs for the box, 1.75 cu ft with 3 - 3" x 16.5" ports.
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jcham
Dodge Dakota
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2/03/2004
12:50:33
| RE: Will these dimensions work?
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So, if port placement and length is so critical to the sound, my desired setup will not work, will it? The only way I could imagine it working would be to place the ports in the top of the box, but I don't know what kind of sound I'd be getting. I think I am going to have to sell this sub and go for something smaller. If anyone else can offer up a suggestion on a possible configuration please give some input.
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jcham
Dodge Dakota
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2/03/2004
20:27:22
| RE: Will these dimensions work?
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DSW, I think I was blinded by the power for the price, and bought the wrong sub for my Reg. Cab Dakota. I was reading around various other sites on the net and saw people talking about running 1 amp for each voice coil. Most had 1000 Watt Amps running this sub and I only have 500. I think I'm gonna go with something smaller and easier for my truck. Thanks again for all your input.
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DSW
Dodge Dakota
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2/03/2004
22:48:45
| RE: Will these dimensions work?
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Hold on there, you didn't buy the wrong sub, your just trying to build the wrong box, ported that is. If you go with a ported box then you need 1.75 cuft of air space.
Go with a sealed box, easier to build, flatter response curve, punchier bass and much smaller in size. RF's specs are .625 cu ft of air space for the sealed enclosure. That's less air space than your old XLC would run in. I personally like sealed enclosures better than ported enclosures, punchier bass.
The only down side I see to the Power DVC is that the puppy is realy deep for mounting an a RC, it's like 7" deep! You could try to mounting the sub at a 45% angle to the back of the truck. This would free up some space in front of the sub and also allow for the cooling vent in the back of the sub to be less obstructed by the enclosure.
Don't give up, just get creative.
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DSW
Dodge Dakota
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2/04/2004
03:36:22
| RE: Will these dimensions work?
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Dude, I got your the answer to your problem, well at least Stumper has it, check out his thread on "Center Console Box" and the URL he has at cardomian. You can easily put the HX2 into a box like this but it needs to be smaller than the 1.0 cu ft boxes he makes.
The air volume for the HX2 is .625 cu ft and the sub displacement is .115 cu ft (d@mn) so you will need a box .78 cu ft. This looks like a down fire but it could be a back fire, doesn't say. If you make a down fire, make sure you have about 1 1/2 -2" below the sub since the HX2 can travel 3/4" and 2-4" from the vent on the sub to the box. I would opt for a down fire box, but a back fire would get the sub into the truck also. Send Stumper an Email and see if he can make you a .78 Cu ft box, he was only charging $45 + shipping last year
Another thing you could do to get the box built inexpensively is have a wood shop build it for you. I had a custom MDF box made for $50 when I didn't have access to my tools. All I did was drew up some plans, took it to a shop I frequented, and they whipped it up in their spare time. Added a terminal cup and some carpet and I was in business, whole thing was around $70.
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jcham
Dodge Dakota
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2/04/2004
11:54:44
| RE: Will these dimensions work?
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Once agian, thanks for all the help. I don't know what the fk I was thinking by ruling out the sealed box. I'm definitely going to contact thumper and see what my possibilities are.
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