if i take the subs out of my auidbahn bandpass and put them in this box
<A Href="http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1319182617">HEre


Will they souind as good?

I'd be a bit wary of that box. It might be the picture quality, but it doesn't look like they used MDF. More like pressboard or something 'cause it's so grainy.

The seller didn't list the displacement of the box anywhere. You'd have to email him/her and ask what the volume of that box is. Then you'd have to check the specs of your subs to see if that box's volume complies with your subs' requirements.

Don't forget as well that changing from a bandpass box to a sealed box changes many things. For starters sealed boxes deliver more sound quality than bandpass while sacrificing some loudness in the process and they generally require less space. Also, you should find out whether the subs that you have are optimized for a sealed enclosure or whether they are geared more towards a vented or bandpass enclosure.

All of these factors play large roles in determining which box will sound better with your particular subs. If you do the research, you're more likely to be pleased with your decision.

the box is 5/8MDF

It would still help to know it's volume. Did he say anything about that?

And how about the subs you're using, what are they and do you know their requirements?

the volume is 1.25cubic feet/chamber,
i don't know what subs i'm gonna get yet, i have to sell the bandpass first

It's dual chambered? That's a pretty good selling point. Well, as long as you don't mind looking for subs to fit a box rather than the other way around, then it could work out nicely. Custom fit boxes are a lot cleaner than just making something fit. As lon as the subs you choose will work to your liking in a sealed enclosure with that volume, then you're good to go.

will most 12" subs that work well in selaed enclosures need any more than 1.25cu.feet?

I believe 1.25'cu is a fairly safe option, although I guess it depends on what you're looking for. I know that JL 12w3's can perform well in enclosures around that size, and I think that Alpine Type R's would do nicely as well. It's kind of a "not too big not too small" volume: made to be versatile. And you can always decrease the volume of the box (just add material to the inside of each chamber), you just can't increase it. So when it comes right down to it, you would be able to accomodate any sub that requires 1.25'cu or less in a sealed enclosure. There should be quite a few to choose from in the low to mid-priced sub range.

On a side note -- though a lot of people don't feel the need to take this into consideration -- it helps to factor in the volume of the sub as well, because that will be taking up a portion of the box space. The bigger the sub's basket and components, the greater the effect it will have on the dynamics of the box.

5/8" MDF isn't exactly ideal, but if the box is built right it should hold up. But, the box in the picture isn't MDF. It's particle board. Maybe the one you get will be MDF, but not if you're getting what's pictured.