Optimum Enclosure Size For Mayhem 18

[Knocker]

I'm finalizing my enclosure for my 2015 Mayhem 18 d2. Curious about a few things. I'm hovering between 6.3 and 7 cubic feet and have a choice between either 89 or 103 sq. Inches of port area (depending on how I mount the port wall). Tuned to around 33 hz. Powered by a BC 5500 (turned down of course) in a 4Runner. I've read that increasing enclosure size lowers the system Q for better damping and that decreasing enclosure size improves cone control. I'm a bit confused as to which direction is "better" for SQ and kick drum. Also confused as to whether 12 or 15 sq of port per cube would be better with a good amount of power. I know it will be loud enough either way. Here are my TSPs...

[Joe X]

The smaller box will have better transient response and you want that for a SQ setup, on the port area, better port loading means lesser excursion around tuning and less chances for port noise so larger port area is recommended, lastly yes, for the same power the larger net volume will result in greater excursion, so for higher output (around tuning) on a given power larger box, for sound quality smaller box.

[Knocker]

The smaller box will have better transient response and you want that for a SQ setup, on the port area, better port loading means lesser excursion around tuning and less chances for port noise so larger port area is recommended, lastly yes, for the same power the larger net volume will result in greater excursion, so for higher output (around tuning) on a given power larger box, for sound quality smaller box.

Thanks man. I will shrink the volume down a bit. Curious about something. .. Since AA recommends 5-8 cubes my guess was that 6.5 would be a good compromise, but since SQ is my main concern, just how small can I make this box before decreasing the box volume is no longer a benefit to sound quality?

[Joe X]

So that you can make your mind here are the theoretical plots for the D2 version:

1) orange: 8 cubes net @ 33Hz 97 square inches of port area, 2500W.

2) yellow: 5 cubes net @ 33Hz 97 square inches of port area, 2500W.

Cone excursion, as you can see despite the box size difference con excursion changes very little for the same power:

Vent airspeed, as said everything else being equal, greater box size will result in increased vent airspeed:

Group delay, this relates to sound quality, here the 5 net box shows better behavior:

Frequency response, this is without any cabin effects, probably 2dB gain around tuning for using 8 net vs 5 net, conclusion: larger box slightly stronger low end.

[Miguels]

i had mine on 13 cubes i think or 12.5 and they sounded very good they did get loud too..