I have a Powerbass M-12 sub, and a Sub Zero ported box. my box volume is 1.5 cu ft and the sub's optimum ported box spec says 2.0 cu ft so I was wondering if I mounted the sub backwards(magnet facing out) so that the magnet/basket weren't taking up space in the box if that would help SQ and SPL at all?

Please do not just tell me to buy a new box as I spent about $100 on this one so I want to make it work as best as possible.

Sub specs:
http://www.powerbassusa.com/products...bwoofers.html#

 

Is the port length "fixed" or can you change it?

What you gain by mounting sub "backwards" you lose by mounting the sub backwards, unless you are clam shell mouthing it over another sub.

If port length is adjustable mount sub and box in car, using the amps x-over network and adjusting port lenght and "tune" the box for best performance, no you can not just slide the port in and out of the box, port needs to be shortened a little at a time, possibly a longer port is needed, you will need a box program, box gross volume, port area and the theil/small parameters of the sub to find port length, [volume]. 94

 

no my port is not adjustable, and I don't understand what you mean "What you gain by mounting sub "backwards" you lose by mounting the sub backwards"

 

I think what he means is that volume of sub box = "oompf" and when you gain volume of box you gain more output, but reverse mounting a sub causes a lower output than a regular mount sub with equal overall sub box volume. So while you are gaining volume of the sub box you are losing output. So it really doesn't gain anything.
You should just mount it regularly since you don't want to get a new box and you probably don't have the means to "port tune" your box.
I doubt you would notice the difference in volume anyway. Cars aren't exactly an optimum stage.

 

What mrdeadman said^^^.

Install the sub, [the proper way] and see if you can get it to work to your liking, if not you may need to remove existing port and replace it with one that will work. 94

 

I physically cannot change the port it is a slot port built into the box

 

It could be made longer, [more volume]. 94

 

Are you saying that if I make an extension to the outlet of the port that it would = more volume? But, would it not also make the port frequency lower?

 

What I am saying is that if the sub does not work in the box, your only option is to lengthen the slot port, [inside or outside] and yes it will change things, but if the sub will not work, other then getting another box, it's your only option.94