Best Subs for this Amp

Here is the page for the power series amps: http://www.poweracoustik.com/powerseries.html I'm sorry to say but they look to be peices of crap. If you still want to keep it I would reccomend a sub that dosn't take much power to get moving like a JL 15 W0 or some Adire Audio shivas. I think two of the JL woofers in a large ported box would sound pretty good for an SPL setup. The Shivas would work also, but you wouldn't be pushing them to their full extent so watch the gain setting. This amp is overrated for sure and I'm sure that was just a typo from Power Acoustik above (you should see the manual for a Power Acoustik amp I have...).

Yea, I figured the amp isn't that great, I bought it over 2 years ago online and it was only $120...so I get what I paid for.  I have used several different set-ups with this amp...I've borrowed friends subs and used them and they aways sounded decent...I have no clue what the power was of those but they always hit pretty hard.  I have been considering using a slot box with the ones I have now but can definitely reconsider if I get new subs that call for something else.  Also my brother wanted to build a fiberglass enclosure for any subs I have, so I'm also considering that...but I definitely need to research all that and what options I have. 

I don't have a big budget and I don't even know if I will get new subs soon, but IF I do, I just wanted to know what to look for.

From what I gather so far, if I keep this amp, I need to have 2 4ohm subs with a 90dB sensitivity.  Sub brands to look for are infinity, kappa and memphis...though I've never heard of the last two.

Kappa is an Infinity line. You can get Infinity Reference or Infinity Kappa.

As for 90dB, I just recommend 90dB or more. You don't HAVE to listen to that. The Infinitys have more, and I am not sure about Memphis.

alright, sounds good.  if i should happen to do a fiberglass enclosure, are there any sub brands i should avoid?

cause as far as i know its not TOO hard to do a sealed fiberglass enclousre, but is it possible to port it just incase the subs sound better ported?

Most drivers can be run in a sealed or ported box, but will have different optimal dimensions for each. Ported boxes make sloppier but louder bass, while sealed boxes make tighter bass. I prefer sealed, but you'll have to decide which you want to use on your own.

Here are some sub brands to avoid, there are more but I can never think of them all at once (no specific order): Pyramid, Pyle, Legacy, Jensen, Road Gear, Power Acoustik ;), Volfenhag, Visonik, Sony, Boss, Pioneer, anything on Ebay that doesn't actually list a brand name, Audiobahn... Like I said, there are more to avoid, but that's about all I can think of at the moment.

You should take care in selecting the sub for the box design you plan on using.  Download WinISD pro to help you.  It is a real mistake to shoe-horn a sub into an enclosure design if the sub is not right for the box! 

What are your goals for the subwoofer?  SPL, SQ, both?  How much space (volume) do you have to use?

These things will effect the subs you should be looking at.

I partially disagree. On the contrary, this specification is important to look at and consider relative to your goals and other system components. 

However, don't place too much emphasis on it to the exclusion of losing the picture of the overall subwoofer.  What dragonrage was doing either, "90db or more," I disagree with.  I'd argue a 88db woofer with that best fits the enclosure he plans to make would be better than a poorly fit 90+db subwoofer.  Also, realize that not all marketers are completely honest (cough audiobahn cough).

Having said that, along with some good enclosure modeling software, sensitivity can help determine if a subwoofer will be a good match for your system components and your amplifier power.  A couple of db difference won't matter much... but once you get 3db off, assuming otherwise similar characteristics, you'd need TWICE the amplifier power to achieve the same volume.

To sum up:  Sensitivity is one useful rating.  It should not be overstressed.  It should not be disregarded.  Evaluate the overall sub based on your needs and goals. 

Why are you still not doing this?  Do you really love this amplifier that much?