[mjg100]

I have a small (11'-5" wide x 13'-5" deep with 8' ceiling) room. I have base traps in the corners and I have 12-2'x4'x3" thick sound panels on the walls. The sub that I currently have in this room is an old left over NHT SW2P. The NHT is a (external)16" x 16" x 16" cube with separate 80 wpc amp. I am wanting more bass, more impact, but with the current economy I want to keep costs down as much as posable. Building something is not a problem, I have all of the tools needed, but as I said I want to spend as little as posable. I was thinking about refitting this box with a new driver and replace the amp. For the driver I was thinking something along the lines of this: www.parts-express.com/pe/showdetl.cfm?Partnumber=297-460 . For the amp I could use a plate amp or an EP2500. If I reused the existing NHT box I probably would want to plug the port off. I like a sealed sub.


I have not used any of the programs to calculate box size needed, nor have I opened up the NHT to see how well (braced) the box is. Has anybody rebuilt an HNT before? Would I be better off building a whole new sub using a larger cheaper driver along the lines of this: www.parts-express.com/pe/showdetl.cfm?Partnumber=295-468 ? What do you guys think?

 

[Stephen Hopkins]

That driver performs fairly well in the box you described based on some rough calculations... the enclosure looks to be around 1.5 ft^3 and with that driver sealed you get an F6 of around 30hz. The EP2500 will be plenty of power/headroom even even with a ton of low-end EQ.


That said, by using a less expensive 12" or 15" driver in a larger ported enclosure you could get a ton more output and low end extension. Something like an Easy-Button Shiva-X would have the same driver cost and maybe $50 more for the enclosure. A Dayton 15" DVC or 12" Titanic with enclosure would cost about the same as just the HiVi driver you're looking at. A used SVS 12.3 driver (if you can find one) would lower your costs even more.

 

[mjg100]



Quote:
Originally Posted by Stephen Hopkins /forum/post/15472749


That driver performs fairly well in the box you described based on some rough calculations... the enclosure looks to be around 1.5 ft^3 and with that driver sealed you get an F6 of around 30hz. The EP2500 will be plenty of power/headroom even even with a ton of low-end EQ.


That said, by using a less expensive 12" or 15" driver in a larger ported enclosure you could get a ton more output and low end extension. Something like an Easy-Button Shiva-X would have the same driver cost and maybe $50 more for the enclosure. A Dayton 15" DVC or 12" Titanic with enclosure would cost about the same as just the HiVi driver you're looking at. A used SVS 12.3 driver (if you can find one) would lower your costs even more.

I like sealed better than ported. In my other room I have an 18" sub in a 4.5CF sealed box with 1,300 watts. I did not build the sub, so this is new to me. If you think i would be better of building a sealed sub not re-using my existing box, what would be your recommendations for 12" or 15" sealed with cost kept in mind. Don't worry about the cost of the box. I have MDF here at the shop that I can use. Also I am not that worried about the box finish. i could make it look like a piano if I wanted, but I do not want it to be seen or stand out as a distraction. It will be painted black to match my room. Room has black floor, walls and ceiling.

 

[Stephen Hopkins]

Once the Tempest-X becomes available again, that would probably be a good candidate. Same holds for an e5.12 or 16Ov.2 from eD. The main problem I see is that with almost any sealed arrangement you're going to need some sort of EQ to boost the low end, and that adds cost as well.


What is it about ported designs that you are not in favor of? Have you heard a properly designed ported DIY sub in this price range? If not, I think that would go a long way towards changing your mind. These aren't little 1.5 cu ft boxes with 2" cardboard ports that inevitably sound boomy and bloated... something like an easy-button slot-ported design with a Shiva-X would be very musical with much more output and low-end extension without the need for EQ to boost the low-end.

 

[mjg100]

Lets say I go with the Shiva-x driver and a slot ported enclosure. Why size amp and box size do I need? I know I need to take into account braces when calculating volume, but what about amp if I use a plate amp and what about driver volume? Where do i get the (volume) numbers for those two items?


As I said the room is small (11'-5"x13'-5"). The speakers used are five RBH WM30's. Here is a picture of the front wall. http://i243.photobucket.com/albums/f...o/PC050016.jpg Please excuse the poor pic. The spots are on the lens, not the room.

 

[mjg100]

I am thinking about using one of these two designs, but I will need to turn them on their side. www.audiocircle.com/circles/index.php?topic=51979.msg493407 I want to place the sub some where along my front wall and I only have 20-1/4" of clearance between the bottom frame of my screen and the floor. The flooring is 3/8" thick foam rubber exercise flooring. The room used to be our exercise room and I reused the flooring for the HT. I would place the port on the front baffle. Would you change anything from this design? Would you change anything location wise if placing on it's side? Also what size amp would be good to use in the second design? The first design it says a 300 watt amp would work well with it. Would that also work well with the second design or would I be better off going with a 500 watt amp? If I went with a 500 watt amp (2nd design) would I be ahead to go with some thing like the O Audio 500 watt amp with PE? www.oaudio.com/500W_SUBAMP.html Also how much stuffing would be needed for either of these two designs? Thank you for your help. Since I am new to this I would much rather use a proven design rather than try to come up with my own.

 

[mjg100]

Bump.

 

[Stephen Hopkins]

I'd put out a request for an Easy-Button design with 20" exterior height, 4.3 ft^3, tuned to 18hz. Chances are Dan will have you a rendering and cut-list extremely quickly, probably less than a day. This would mate very well with a Shiva-X and anywhere from 500-1000w (actually one of their reference designs). I wouldn't use the O-Audio amp for this design because of its filter settings, but something like the BASH 500w w/ a basic filter mod or the Dayton 500w plate amp would work fine. A EP2500 would be more than enough power but lack any high-pass protection. Placing the sub on its side will have no affect on performance.

 

[NEO Dan]

All my stuff is in storage, so It'll have to wait.


Use a PE Bash instead of the O-Audio BASH amp. The ammount of boost in the O-audio is tailored for sealed applications.


I really wouldn't do a 18hz tuned design and put my stamp of approval on it. The Shiva-X is capable of much lower extension.

 

[mjg100]



Quote:
Originally Posted by NEO Dan /forum/post/15507591


All my stuff is in storage, so It'll have to wait.


Use a PE Bash instead of the O-Audio BASH amp. The ammount of boost in the O-audio is tailored for sealed applications.


I really wouldn't do a 18hz tuned design and put my stamp of approval on it. The Shiva-X is capable of much lower extension.

I would be happy to go lower, I just do not know how to go about designing it. I have looked at the design programs, but I use a MAC not a PC. How low would you design for using a Shiva-X?

 

[Stephen Hopkins]

I reccomended the 4.3 ft^3 18hz recommendation due to the small room and somewhat limited space for the box. The Shiva-X can definitely go lower, but at the cost of box size.

 

[mjg100]



Quote:
Originally Posted by Stephen Hopkins /forum/post/15508239


I reccomended the 4.3 ft^3 18hz recommendation due to the small room and somewhat limited space for the box. The Shiva-X can definitely go lower, but at the cost of box size.

When you say 4.3CF are you referring to interior volume or exterior volume? If interior I know to subtract for the bracing and 0.15 CF for the driver, but do i subtract anything for the amp? If I do subtract for the amp how do i determine how much?


The only measurement that I need to hold is the height. I can go wide and deep. If the sub modeled well using exterior size of 19-7/8" height, 23-1/4" wide and 23-1/4" deep it would be nice because I could switch this with my sub in my larger room if I wanted to, but that is not a requirement that I have to hold if it is limiting the performance of this sub.

 

[Stephen Hopkins]

I'm reffering to available interior volume... you'll need to account for bracing, the driver, the amp. and the port

 

[mjg100]



Quote:
Originally Posted by Stephen Hopkins /forum/post/15508958


I'm reffering to available interior volume... you'll need to account for bracing, the driver, the amp. and the port

I knew about deducting for the bracing, driver and port. Those are no problem. What I have not been able to find out is the volume occupied by the amp. Where do I find this info for the 300 watt and 500 watt Bash amps? Thank you for your help.

 

[Stephen Hopkins]

The way those amps are designed (open back) I'd say the volume loss would be very negligible... maybe 0.05 ft^3 at the most?

 

[mjg100]

Kevin Haskins has sent me a proven sub design based on the Shiva-X. the sub is 20" wide, 27" deep and 27" in height. It uses two 4" ports 17" long. Sub has two braces. One horizontally in the middle and one vertically in the middle. Power will be from a 500 watt plate amp. Only question that I have now is how much stuffing is needed and where do I locate it?

 

[mjg100]

My Shiva-X is ordered.

 

[Stephen Hopkins]

That's a larger box with a lower tune and should make great use of the driver's capabilities. Since it's not one of the reference designs, I'm not sure how much fill you would need. You could probably even go without.

 

[mjg100]



Quote:
Originally Posted by Stephen Hopkins /forum/post/15514196


That's a larger box with a lower tune and should make great use of the driver's capabilities. Since it's not one of the reference designs, I'm not sure how much fill you would need. You could probably even go without.

I have been doing some studying on this and I think I will try it with out any stuffing. I can always add later if I want.