depends on the design but size always matters some.
open back creates a "dipole" effect, the sound comes out in two directions but will travel around the baffle and will cancel each other out, the lower the frequency the more cancellation, the bigger/deaper the cab the lower the frequency cut off point is, ie. more bass. the rolloff is slow and the overall tone is more natural sounding do to little loading of the speakers and cab
sealed creates an "infinite baffle" so the lowend cutoff is based on other parameters, if designed right sealed will always have more bass than open back. the air in the box becomes a damper to the cone and along with the spyder and surround is a part of what suspends the cone. the box becomes a part of the resonant system and will have a large impact on the sound especially if it is too small. if the box is too small you get a spike in the response just before the rolloff and the rolloff is higher in frequency, you get a resonance that can be overbearing and a lack of bass below that. in a guitar application bigger is generally better, a perfect size will give the best bass but guitar speakers are suitable for free air mounting and this type of tuning may cause them to get hot do to a more reactive load drawing more amps from the amp, hot windings are more likely to blow and color the sound in negative ways.
ported can give the most bass and highest efficiencies :headbang1:
but can color the sound the most, are harder to design, the speakers must be suitable for such a cab, require more work, well that's enough negatives for now. there are generalizations that say sealed is tighter and ported is looser sounding, well there are loose sounding sealed cabs and tight sounding ported ones. the speaker moves the air in the cab and that moves the air in the port, at some frequencies the port does very little, at some the air in the cab must compress or expand before the air in the port moves, at the right frequency the air in the port moves in phase with the speaker cone creating greater amounts of compression to the air. the speaker does more work and the port puts out a lot of sound.
the box size, the port diameter, the speaker, the port length, the port shape, the box shape, baffle stiffness, stuffing in the box, air density and air pressure, turbulence in the port, will all have some effect on the sound. this is the easiest to mess up, don't try unless you are easy to please or you have a lot of time to try things to get it right, design software exists for the dimension of the box but might not be right for an instrument. the math is really for stereo speakers or subwoofers and drivers designed for ported application. using the same formulas on free air speakers might give a box that is impractically large or small, ports that are impossibly long or short or just plain sound bad.
ccasion14:
