determining best port size

[Triticum Agricolam]

26 minutes ago, joshuaV said:

PLA2678 sorry, 4000W. 

Thanks.

Unfortunately Pyle has a very consistent reputation for completely lying about their products.  That amp probably puts out about 800 watts at best.  

So the two 8" ports will tune you to about 30 Hz, the two 4" ports would tune you very low, to about 20 Hz.  In addition to tuning you exceptionally low, the two 4" ports are way too small and will significantly degrade output.  The two 8" ports should give pretty decent performance, however there is a significant issue with your box size.  Those subs only have a 8mm xmax, on 800 watts you are greatly exceeded that and will likely destroy your subs before too long.  To bring cone excursion back down to safe levels you need to reduce the size of your box, a LOT.  Pyle recommends 2.1 cu ft per sub and that's an reasonable place to be.  With a 4.2 cu ft net volume box you could use one of your 8" ports, which should tune you to about 35 Hz and will provide enough port area for that size box and power level.  You could probably get away with using as large as a 6 cu ft box along with the single 8" port.  This would tune you to around 30 hz.   The downside to reducing your box size, in either case, is it is going to reduce low frequency output quite a bit, but its either that or destroy your subs with your current box.  

 

[joshuaV]

Thanks for the info guys, i am looking at upgrading the subs and amp, i am looking at sundown, X V.2 15's. with their 4k amp.

Would they be better with this box? 

[Triticum Agricolam]

Just now, joshuaV said:

Thanks for the info guys, i am looking at upgrading the subs and amp, i am looking at sundown, X V.2 15's. with their 4k amp.

Would they be better with this box? 

That box is too big for a pair of just about any 15".  For example, Sundown recommends 4.25 cu per sub for the X-15.