Help with SPL Box Design for 6 12's in Expedition.

[JCAudio]

Hey guys, Long time lurker finally had something to ask!

Im building a box for someone who has 6 Rockford p3s on around 7 or 8k watts and I have a few questions.

First question.

Should I double layer 3/4 mdf the whole box or use birch?

Or will single layer 3/4 and a layer of fiberglass resin/ dowel rod bracing be enough?

Or maybe 1" mdf?

Will double baffle be strong enough or do I need to triple baffle?

It will be a square port

Im assuming port back towards rear hatch will be louder than port up or forward...

and last but not least, the car resonant hz is 48hz, I plan on tuning the box to around 40 or should I go higher?

Thanks for any help!

[SnowDrifter]

IMO: Removable port, start long - maybe 38hz or so. Burp, pull it out, cut an inch off, burp again. Etc etc until you find a port length that gives you your highest score

[JCAudio]

Ok. What do you think about the wood. Do you think 3/4 with bracing and double baffle would be strong enough for that much power or should I double layer or use birch

[Kyblack76]

for spl?

shoot for around 50hz....

[JCAudio]

50 hz with resonant of 48? I always heard box max is 5-8 hz above tuning. He wants spl and mild mus4 c bumping. The big problem I'm having is wood strength. Idk if 3/4 With bracing and resin and double baffle will be strong enough. Or if I should use 1 inch / dual 3/4 or birch.

[EP95]

I'd double up on the wood just to be safe, if he wants to still play music I'd tune to around 38-40hz.

[Kyblack76]

SPL, means your just burping to me.....

so, ya, tune to 50, and work down.... you meet vehicle res with tune, and you are gonna get loud.....

[JCAudio]

Ok. I think I'm gonna make multiple ports.

I just don't know about box strength. Will single 3/4 be strong enough or should I do double on all sides

[timc31610]

I would double it and brace the baffle between the subs.