I have a 12" sub, what volume box should i build so that it hits the hardest (this is for listening to rap)?

I have a 12" sub, what volume box should i build so that it hits the hardest (this is for listening to rap)?

I would go to the sub manufacturers web site, and see how much air is required for the sub to beat at its peak, then Iwould build the box acccordingly.

yes agreed. you need to check the specs on the sub and what box design is best.

as for hardest, do you mean loudest? a sub will hit harder in a sealed box, but will provide more volume (with less power) in a ported or vented box. a ported or vented box is usually a better design for rap or hip hop music that has the long extended bass lines.

Call the manufacturer and get their suggestion. Most people like ported boxes for Rap, with a low tuning frequency 30-40Hz. If they ask what order box, go with a 1st order. It's easier to build and only has one chamber (smaller). It helps if you have a fax number handy, because they can fax you a sheet with the cubic feet you'll need. Some manufacturers also give you sample dimensions to make it easier to build. You don't need to be really exact. For instance if they tell you to make a 15x20x18" box, it really won't matter if you use those as outside or inside dimensions. If the port seems really large though (or if you want to be exact), ask them on the phone if the suggested cubic feet includes the port and driver displacement, and if it doesn't include the driver displacement, ask them how much the driver displaces. Spending maybe $5 on this long distance phone call is your best solution. We really can't help you without knowing some basic properties of the woofer, which are called Thiele-Small parameters.

If they don't have the specs on a website, you probably should have bought from someone else. Build a slot ported box tuned to the subs Fs. There are plenty of enclosure calculators on the web if you can get the sub specs. You'll need Fs, Qts, VAS, Xmax, and driver displacement. Or use the vendor recommended enclosure and port specs if they have them.

what is your actual 12" sub. what amp will you use to drive it ? how much space would you sacrifice for bass ?

If you have no success with the manufacturer - I offer complete Thiel-Small measurement services as well as enclosure modelling and design. PM me if you are interested, my prices are very reasonable.