Quote:
Originally Posted by godbreath /img/forum/go_quote.gif
so then you have the audioengines playing the whole spectrum including the bass,, and then the subwoofer is just playing the low frequencies? i thought it was bad if you have your main speakers and your sub playing the same frequencies, so thats why i wanted to put in a filter before it gets into the audioengines.
|
you are correct.
you dont want your speakers working harder than they should because you can get more detail out of the speaker when it isnt being over-worked.
moving on,
one solid difference between front firing subs and down firing subs depends on whether the down firing sub has a plate at the bottom.
some have plates to prevent the sub from firing directly into carpet, which helps disperse details in the sound.
another reason down firing subs are made is to help flatten their frequency response.
you can choose a speaker and then build a box at a specific size for half of the frequency range.. then adjust the height of the sub box from the floor to achieve the other half of the frequency range at the same decibel level.
this is essentially exactly what a bandpass box is supposed to be designed to do.. the port just blasts out both frequency responses and they are perceived as one long, solid 'loudness' despite which note you play.
they say bass frequencies are non-directional and that isnt entirely true.
in an open space - the further away from a speaker you are, the harder it is to hear the speaker.
that is a fact that cannot be altered.
a 'trick' or 'method' that is used to produce more 'loudness' from farther away is to place the speaker cone down towards the floor (with a hard surface) so the sound spreads out equally in all directions..... then you put the speaker box kinda close to a wall so the soundwaves bounce off the wall - which creates a 'double' or 'amplification' affect that helps your ears hear the bass from far away.
in general though, you will lose details in the clarity of the subwoofer when you bounce the soundwaves off a wall.
such a situation requires a DSP processor to manipulate the soundwaves to compensate for bouncing off of a wall or hard surface.
and that is the only real reason to purchase a down firing subwoofer.
you also want to avoid purchasing a front firing subwoofer with a port that is going to be blasting air directly into a wall.
subwoofers in this type of situation always sound extremely boomy and because the soundwaves are bouncing off the wall, the result is muddy sound instead of clear detailed pronunciation (unless your sub has a DSP processor to compensate sound reflections)
you also want to avoid a front firing subwoofer that has front ports that are releasing air in opposite phase of the speaker cone, because the result is two soundwaves that cancel eachother out and therefore the audible output is going to be very weak.
in your exact situation,
i would suggest a front firing / rear ported subwoofer that has a variable phase adjustment.
dont confuse variable phase adjustment with a 0 / 180 degree switch.
you can simply reverse the wires if you want to change the phase like that.
what you want is a variable phase switch that allows you to select any degree of phase between 0 and 180 degrees of offset.
then put the sub under the desk and face the speaker cone towards a hard surface, such as a wall of the desk or a wall of the room.
then you need to adjust the variable phase until you can hear the most details from the sub while it is playing.
chances are, the results will go from loud / boomy / obnoxious to a lite and more detailed sound OR the sound will go from lite and hard to hear the details because the soundwaves are too busy canceling eachother out, to a rich loud and detailed 'shout'
usually the box the speaker is in will have a substantial meaning as to which way the difference will swing.
but dont be afraid to flip the speaker wires around and try again because you might be able to change the 'lite with details' to a 'shout with details'
and the reason this is possible is because the speaker in the specific size box automatically puts the soundwaves at a degree of phase.
say for example you buy a sub and the phase of the speaker in the box is 40 degrees.
when you adjust the variable phase knob.. at zero, the results are 40 degrees.
and then you start adjusting the phase towards 180, but you have to constantly add the original 40 degrees.
finally, if your sub would sound best at 20 degrees, you need to flip the speaker wires around (put the positive wire on negative terminal) and then put the knob at 0 which equals -40 degrees.
then you simply adjust the variable phase knob to 60 degrees because -40 + 60 = 20
variable phase knobs are used in situations described above.
you are supposed to turn the knob until you get the most details out of the subwoofer at the listening position.