How to pick the right size enclosure

[CheЯRyMan]

Ive been building HDS312 enclosures lately and the recommended volume is all over the place from

2-4ft^ per sub. According to box analysis software using the Thiele parameters to find the best suitable size and frequency. I compared 5 different sized enclosures using the suggested f3(half power point)

which will give you the flattest curve with the smoothest drop off. Based on the results below 3ft^ per sub will yield the best trade off of size vs frequency drop off at -3db. The bottom graph shows vent velocity's anything under 100ft/sec is considered acceptable but I like my number to be under 75. From the normal amplitude graphs(top) The smaller enclosure suffers only at the f3 of 22hz and a fb tuned to 27hz and has the lowest vent velocity (port noise). The bigger volume boxes vent velocity is growing but the f3 of 18hz (anything under 20hz is hard to hear) is a achieved.

Click to read more...

 

[LosIsATool 5,000+ posts]

Ive been building HDS312 enclosures lately and the recommended volume is all over the place from 2-4ft^ per sub. According to box analysis software using the Thiele parameters to find the best suitable size and frequency. I compared 5 different sized enclosures using the suggested f3(half power point)

which will give you the flattest curve with the smoothest drop off. Based on the results below 3ft^ per sub will yield the best trade off of size vs frequency drop off at -3db. The bottom graph shows vent velocity's anything under 100ft/sec is considered acceptable but I like my number to be under 75. From the normal amplitude graphs(top) The smaller enclosure suffers only at the f3 of 22hz and a fb tuned to 27hz and has the lowest vent velocity (port noise). The bigger volume boxes vent velocity is growing but the f3 of 18hz (anything under 20hz is hard to hear) is a achieved.

2.5 cubes. tuned at 32hz with 35-40sq inches of port. If the car does not have huge cabin gain this will play down to 25 and up to 50 very flat.

 

[CheЯRyMan]

What you say is supported in pic 1 graph labeled 5cuft. My vent is 50sq and the f3 is 22 and fb is 28hz

 

[LosIsATool 5,000+ posts]

I cant see it well but if you start getting over 3 cubes you really lose mechanical power handling

 

[CheЯRyMan]

This is far as the numbers can take us with the limited sub parameters but the setup does show 2 to 3 ft^ is the best trade off for the HDS312. The one I just finished was a 4.2 enclosure(max size for trunk access) for 2-12's.

 

[LosIsATool 5,000+ posts]

They act like the DD 3500 and 95s. I had my pair of 12s in 4 cubes net tuned at 32 with 14 sq per cube. I was 1.5 flat from 26-50. I couldnt go any bigger or I would have went to 5 cubes.