If you want to run an 18, pony up the space for a proper enclosure.
I'm in the middle of building an enclosure for a pair of 18's on 3k and it's going to be roughly 14.5 cubes net tuned at 24hz/28hz/32hz with interchangeable external ports. My port area for the pair varies from 90" up to 170" depending on tuning.
yea I had the tropo in there it sounded pretty bad had to EQ the shit out of it. It was supposed to be temporarilly in the van untill it made it to my home system which woud have worked good 10' tuned to 28hz on a crown ce2000... but it done blowed up in 2 months lol. waiste of money on the tropo would not recomend!
1st off I love 18" subs: View attachment 39408View attachment 39409View attachment 39410
Manufacturers typically have a marketing dept that will usually go to great lengths to sell their products.
70-90in2 of port in around 5.5ft3net- 7ft3net usually makes most 18's happy. Dependent on power.
For example, this 1750watt 18 was overpowered a fair bit... and was in 5.6ft3 net with 77in2 of aeroport for a reason. Recommendations claimed 6-7ft3 for this sub on their website. Designed around the power and installed for the vehicle it did numbers like 153db+ garage and 152.4db usaci for 2 years with only a slight coil tap when hitting the lanes.
I think I was close/at the subs ultimate potential... 3K clamped worked with a 1750rms Fi ferrite sub.
It wasn't a burp box either, it was tuned to my musical tastes it went as low as I needed it to and got loud for what it was. It sure flexed and slapped windshield wipers when I needed it to... View attachment 39406 View attachment 39407
To go with under 5ft3 you'd probably need a stronger motor, that means a beast sub with more output potential and THAT means... $. The capable 18's I've seen cost and need power and port to use in the 5ft3 range.
Space makes bass... especially in lower power setups.
As stated... space makes bass
Food for thought
Thanks for the help guys I ordered a death row 18d2 just because I had a set of lethal injection 15s in my last build that I really liked. And the FI has less motor for the $. Im gonna have to cut some shelving up to make the box bigger but with an external port and some hacking I think I should be able to get 6.5' to fit.