Check your electrical and your batteries.

A friend of mine had a full charge on all his batts recently : he was blown away, after that. He told me he never thought his system could be so loud !!! He has 2 12" Fi bl in a 4 ft3 box @ 32 or 34 Hz.

Maybe you need to charge your batts before any purchase    

New battery and big 3 done a week ago voltage drop is for 13.9 to 13.7 full till that way I bought a 2500.

You have no idea if that is too small for an 18, or any driver for that matter, without modeling for vent velocity with given power drive level.  There is no rule of thumb for port area...

I thought he had his havoc an 18. That's why I said it was too small.

Would a mayhem 18 be at home in a box 6.6@31 hz port area 81 square inchs?

You have no idea if that is too small for an 18, or any driver for that matter, without modeling for vent velocity with given power drive level.  There is no rule of thumb for port area...

I thought he had his havoc an 18. That's why I said it was too small.

Even if it is an 18 you still have no idea if the port is too small, that is the point.  You have to know how much power he has to tell him anything about the port...

You have no idea if that is too small for an 18, or any driver for that matter, without modeling for vent velocity with given power drive level.  There is no rule of thumb for port area...

I thought he had his havoc an 18. That's why I said it was too small.

Even if it is an 18 you still have no idea if the port is too small, that is the point.  You have to know how much power he has to tell him anything about the port...

Pretty sure it's 1500 rms since he wants to run the mayhem on 1500 rms and he currently has the havoc. So with knowing the amount of power, guessing he likes low tuning because of the tuning he asked, size of the sub (even though it was wrong and was a 15), I could tell him that his port area is low IF it was an 18 though. All I would need is the other parameters from the website. Even if the tuning is off by a hz where he wanted it, it wouldn't of made a big difference.

I know what you're saying is right about no rule of thumb for port area. It has to be specific for the sub and install. I just kind of in my head got the information and then posted my thought that it wasn't enough port area with out showing my work.

I run 4 mayhem 18's in a blow through tuned stupid low.right now im running one DD m4a on all four.only cause other amp is in need of repairs.I do compete in physclone can still pull 51 around 25hz.and burp 52.7 at23hz.with low power you will be fine.in time you will hear that the subs want more power.

I just won a sundown 2500d on ebay so that may do the trick.

Would a mayhem 18 be at home in a box 6.6@31 hz port area 81 square inchs?

will this work

You can size the port for cone area, maximum excursion, and tuning frequency. This will ensure your port is large enough if you add more power later.

In other words, if you reduce your port size based on power level, you always run the risk of not having enough port area if you decide to add more power later. Just size it for the maximum case to start with, unless you are really tight on space and it is just not possible.

The mayhem 18 works great with 80-100 sqin of port.

Sure, 80-100 square inches will work OK with any 18" driver at any power level at any excursion.

 

But, without modeling, you have no idea if that is too much (wasted enclosure volume) or too little (compression) vent area.  Every alignment is different, and without modeling you cannot calculate optimum vent dimensions, period...