After box rise and voltage drop.
You have never measured any of this so this is pure conjecture.
If u can follow the cut design you should have a nice box.
That's where this whole thing started. He bought (what we assume should be) a decent design from somebody and half arsed everything along the way from too few layers to not sealing properly.
Just a thought........sell the one that is having issues and use whatever you can get for it for a real box plan by a designer and get some real wood and stop cheating out on the box. You should be doing 150+ all day but seem down right determined to make this hard as possible on your self and keep redoing it. Slow down and do it right and be done. Two 18s will be just as loud if not louder than what you have now if in a properly designed box. If you would've ate the few $ and payed someone to design a wall in the first place you would've been done 50 pages ago. Also I've never heard of somewhere or metering because it's Brazilian or because they don't think it's worthy. Sounds to me as if either a) you just don't want to take it to the shop and see or b) you've irritated them. Shop around here as long as you give them a few $ they will meter xpolds on a boss amp for all they care. Just slow down and do it right. Stop wasting your time and money.
I was saying 2 18's from the get go, but read my previous reply (or the entire thread if you can stomach it). His initial fiasco was his attempt to build a design someone else sold him and was half arsed all around. Craig Butler could hand him a design and he won't get loud if he doesn't build it solid and airtight and take time to properly seal it off from the rear.
coil get louder then 4" coils most likely
All things equal this is typically true. The extra power the 4" coil can take is pretty much what you need to overcome the inefficiency of the larger coil. All things being equal 3" coil should edge out, that's why Warden DD-Z and similar still use them for their SPL subs. That said, who knows what quality steel, magnet, parts, and design CT uses? A sub that looks beefy could always be poorly designed or use inferior materials and be utter crap. Though in this case, I don't think the subs are the weak link here.
It's had to get over a 150db. I only got a 7k amp right now wired down to .33ohm
Hopefully this means you sorted out your financial issues without having to give up all your audioz. That hurts even to think about.
god dammn!....yeah I'm definitely doing something wrong for sure. mrj what are you running? And door open on the dash. Ok so I'm going to listen to you guys and I'm going to try running just two of them and be very conservative on the gain. What do you guys recommend for cubic feet? My dimensions are 42x35x28.....with those dimensions I can make a simple box with no weird angles. That puts me at 18 cubes, I was going to put them at the bottom and have a huge port going across the top. I need some opinions and idea's please
Back to square one? OK. Plan for port on the driver's side, use as much airspace as you can (keeping all right angles), and as much port area as you can. Do all sides 3 layers, baffle 6 layers and TAKE YOUR TIME making sure everything is rigid, airtight (not with foam, with straight cuts, glue, and fasteners), and then take your time COMPLETELY sealing off the front from the rear.
You can very easily shrink the box or port as needed after everything is solid and upgrade to some chunkier 18s down the road if you like.
This guy got great results with some SoundQubed hdc3s which are about as power limited as your subs. The black you see around the port is an insert for music which he takes in and out for burps or playing music. His build log is on SMD forum somewhere and should be instructive.
The ONLY reason you should consider top port would be if you want to compete in an org that meters at the kick.
