Beej
NAXJA Forum User
- Location
- The Wet Coast of BC
So if you enter the TS parameters of the comp VT, you get a graph like the following:camarors8992 said:
The yellow line represents an optimum sealed enclosure. As you can see, you get a shallow rolloff starting up at 100Hz and it gets to half the volume (-3dB) at about 40Hz, this is bad, as its giving really poor bass response. The optimum enclosure is way too big for your space too, because its in the neighborhood of 2.5ft^3.
The green line represents your optimum vented enclosure. See how the rolloff doesn't even start until 25Hz? Hello Bass! The downside is, for the 12" CVT, the optimum vented enclosure above is in the area of 4.5ft^3. That's really impractical in your jeep, even though the vents are small, only 2 vents, 2.5" in diameter, running 7.2" in length. This yields a mach of only 0.07 which will give no noise.
So that's optimum, now realistic:
If you are going to put a 12" into an enclosure that will fit your jeep, say around .8 to 1.2 ft^3, you get very different graphs.
Again the yellow is sealed at only 1.2 ft^3 and the green is vented at 1.2ft^3. The vented gives you a boost, but having the smaller size enclosure for the 12" really alters the graphs. To stick with the sealed at this size is preferable, but note how you are going to lose response. The sound volume will be cut in half by 45Hz. For this second one, the vents would have to be 4x 1"diameter vents at 4.51" in length.
So long story short, you can use a 12 in that space, but since it needs more volume for optimum usage, sticking to a 10" in that space is probably the best way to go.
Incidentally, all these calculations were done using WinISP, which is a freeware speaker enclosure program. Thiele-Small parameters (TS) are available from most speaker manufacturer websites, or by calling the manufacturer.
Hope this helps the process!
