w8 740c enclosure

[eag]

I'm looking for a volume to build a box for this sub. I tried to do it myself in winisd but I'm not too good at that. The sub has the serial name above and its parameters should already be in winisd. I would use the sub for HT(bruckheimer-esqe)/ music (mostly alternative). I have 70w plate amp to push it.

Thanks

[need4speed]

im pretty sure winisd has an option for the optimal box size as does unibox...or check the manufactures website..they often make recommendations as to what size box to use

[Cal Weldon]

I have mine in approx 1.6cu ft (50 L?) box with two 8" passives and it seems more than big enough.

[pjanda1]

You want an extended bass shelf alignment with this sub, which the programs won't give you when you click the optimal box. EBS alignments trade efficiency for extension. This driver won't really be a sub in a sealed enclosure, as it will be -3db around 70hz due to it's low Qts.

With a 70W amp, you may want to consider something like a .5 cu ft vented box tuned to 30hz. You can get more extension out of a larger box. 1 cu ft tuned to 21hz looks nice, but you lose efficiency. Also, the bigger enclosure/lower tuning won't work that well if your crossing to the mains above 50hz or so.

Those low vent tunings in little enclosures require either a port made with a couple of elbows, a slot port or a passive radiator. The ports can be calculated with winisd. If you are going the passive route, check out the 10" unit at creative sounds. Passives add some cost, but they are nice because you can adjust the tuning as needed by adding and subtracting weight.

http://www.creativesound.ca/details.php?model=BXP10

[eag]

I may sound dumb but how do I "tune" a box to a frequency? Sorry you don't have to explain you can just point me to a link or something. Thanks

[need4speed]

tuning a box is done by adjusting serveral variables:

port diameter
number of ports
length of ports
enclosure volume

a change in any one of these will change the tune or Fb, which is the resonant frequency of the system. you can play with these variables in winisd or unibox and you will be able to see how it shifts that frequency left or right, depending on what changes you made. Ideally you will want to tune the box to get the flatest repsone graph. some prefer to add some boost (looks like a hump on the graph) at the bottom end to compensate for the human ear, but room gain will usually take care of that...or you can use a quality parametric eq later on to make a house curve.

here is a link to show the relationship between some of these variables:

http://www.usenclosure.com/Enclosure%20Formula's/enclosure_formula.htm

[eag]

Ok, so I went through those equations and got a vented volume of 663in^3, and a port length of 39". I posted recently on getting a very long port length like that but according to those equations the box should be vented. What should I do?

[eag]

I can't find an answer so I guess I'll just go with sealed

[Khron]

You might want to try a Linkwitz Transform circuit (bass extension for sealed subs)

http://sound.westhost.com/project71.htm

[Cal Weldon]

Have you considered using drones cones aka passive radiators?

If so I recommend a single 10" or two 8" in a 1 - 1.5 cu ft. enclosure