4 1508's, wierd box tuning, box too big?

[adas Pro Seller]

Hey guys so I had a great box for 3 DD 1508s in my car, got my 4th yesterday and made a box with 1 6" aero, not exact on the cu.ft, but I belive right around 3.5(wierd shape), aero tuned to 38hz or so.

Put it in my car, facing forward sealed from rest of the trunk....it sounds incredible but the peak is really strange. it's tuned to 38hz....higher notes don't hit as well as my old box,i'm talking between 55-70. Between 40-45 it's fairly loud, 45-55 is **** loud, but 32-40hz is MONSTER. Sounds like 15's tuned to 32hz.(not complaining though Now, it doesn't make too much sense to me why i'm peaking at, or right below tuning and then louder again in high 40's.

Is the box too big? The cones are controlled very well in the 34-42hz region, bass kicks and higher notes actually seem to excurt more. I was thinking maybe too much port but it seems the perfect amount.

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[Immacomputer 10+ year member]

Your tuning is probably lower than you "calculated". Run various tones from 25-45hz at moderate volume and look for the frequency where the cones move the least. This will be your actual tuning frequency.