Question about what it means for a subwoofer to have more or less air space by recommendation.

[BMS]

So obviously i want the most cone surface area so i can push more air so i wanted 15's but I wanted the soundqubed hdc4 subwoofers the problem is they recommend 3.75-5 cubic feet per sub and i don't think i have that much space, but the new crescendo contralto 15'' subwoofers only recommend 3-4 cubic feet. What does this say about the differences in these subwoofers? I like to feel the bass not hear it so much the more flex the better so i was wondering if i could get some pointers on whether i should build my boxes on the small side of the recommendations or the large side.

[Chris Braun]

Big box = bigger bass

[yurvalentine]

The more flex the better eh?

[reedal]

Big box = bigger bass

Around tuning.

Output will drop more the farther from tuning you go with a larger box. Smaller box gives a flatter response. If you are supplying the HDC4 with rated power (2kW), AMI customs (who is probably the biggest advertiser and knowledgable of SoundQubed via his truck The Black Nasty), recommends a 5 cubic ft box with 18 square inches of port area per cube (per a sub), tuned between 35 and 40hz. I would recommend tuning to 35hz.

[ShadeTreeMechanic]

If its output you are after and your box for 15s is on the small side then they recommend that 12s will be louder. So in essence, 12s in the right sized box will be louder than 15s in the wrong size box.

[Chris Braun]

If its output you are after and your box for 15s is on the small side then they recommend that 12s will be louder. So in essence, 12s in the right sized box will be louder than 15s in the wrong size box.

Ya I'd have to agree. Actually why not get lower end 15's that require a smaller box, get your electrical right and ride the SPL wave!

[BMS]

ok so when it says 3-4 cubic feet 4 is better for a louder response and 3 is better for flatter response. but I am still curious as to what makes the subs require different amounts of air space with the same cone area. I suppose the cone area might be a bit different if one of the subs has a different size surround.

[BMS]

also i suppose the woofers excursion would affect the amount of air space you need if the cone can travel farther.

[ShadeTreeMechanic]

The T/S parameters for a woofer are the characteristics that are used to figure box volume port tuning and response curve. Google T/S parameters and you will find the Wikipedia about how these came about and several online box calculators and port calculators.