Quote:
itzme218 wrote:
 I've also been trying to find out what happens if a sealed box is too big, but I can't find that answer. Would it lessen output, would it hit lower...say in the 25hz... |
Sealed is about isolating the back wave from the front and using a controlled amount of air volume to make it behave a certain way. It can't be too big, as in the case of an IB where essentially there is no box.. For the most part, increasing size will cause total output to be a bit less, but increase output a bit more in the low end. The bigger the box, the flatter the curve [FR]. Increased size makes it more efficient - requires less power. This is why it is important to pay close attention to excursion as box size is increased. The driver can exceed xmax and sustain damage if volume / power combination is too much.
The volume of air [Vb] is a compressible spring. When air is compressed, it creates heat. The smaller the volume, the more heat - can't be dissipated as fast. Stuffing makes the driver think it's in a bigger box and also absorbs, dissipates, regulates heat. You should also know that as box size increases, so does F3 - the -3db point. Sealed has more very low end output than any other alignment, but in the range where most get little benefit - certainly below the range of human hearing and it takes huge amounts of power or multiple drivers to make that felt.
Driver parameters [Fs, Qes, Qts and Vas] also play heavily into size [Vb] - how big is big and how big is too much. For example, in an IB [very large sealed] Qts becomes critical in shaping the FR. Most often, IB specific drives are going to have a Qts in the .6-.7 range...as this becomes the system Q [Qtc]. IB's typically use 4 or more drives to increase output [SPL]. The same can be done with smaller sealed boxes as well. Typically, output will rise by 3db for every driver added in the same location - ie; the same box.
So, bottom line is that system Q [Qtc] - a direct result of the volume. Smaller is tighter, louder, punchier sounding. Larger is deeper, lower, looser and more natural. Control Vb to shape the sound, increase or decrease efficiency and prevent over excursion.