by JeremyC » Sun Aug 29, 2010 9:13 pm
X-overs simplified.
There are 3 aspects you need to know. The x-over point (or freq) the slope and if its high or low pass.
High pass allows higher freqs to pass through, low pass allows lower freqs to pass through.
For example 80 Hertz 24 db LPF (low pass filter)
The x-over point is 80 hertz.
The slope is 24 db an octave. An octave is 1/2 or double the current freq. So an octave down from 80 is 40. An octave above is 160.
Since its a LPF we are concerned with 80 and 160 hertz.
So at 80 hertz you have a cut off of 3 db.
One octave above 80 you will have a cut of 24 db + the 3 db you lost at 80.
So at 160 hertz your music out of that speaker will be 27 db quieter that it was at 79 hertz.
HPF is just the opposite. Your music would be 27 db quieter at 40 hertz that it was at 81.
6, 12, and 18 can be simply be substituted for the 24.
6 db an octave isn't recommended for a tweeter in a high power system because it doesn't roll off sharp enough.
12 db an octave rolls off fast enough that it limits the speakers excursion as it drops in frequency.
Thats why I said you couldn't use it in place of a dedicated x-over for those kicker tweets.
X-overs simplified.
There are 3 aspects you need to know. The x-over point (or freq) the slope and if its high or low pass.
High pass allows higher freqs to pass through, low pass allows lower freqs to pass through.
For example 80 Hertz 24 db LPF (low pass filter)
The x-over point is 80 hertz.
The slope is 24 db an octave. An octave is 1/2 or double the current freq. So an octave down from 80 is 40. An octave above is 160.
Since its a LPF we are concerned with 80 and 160 hertz.
So at 80 hertz you have a cut off of 3 db.
One octave above 80 you will have a cut of 24 db + the 3 db you lost at 80.
So at 160 hertz your music out of that speaker will be 27 db quieter that it was at 79 hertz.
HPF is just the opposite. Your music would be 27 db quieter at 40 hertz that it was at 81.
6, 12, and 18 can be simply be substituted for the 24.
6 db an octave isn't recommended for a tweeter in a high power system because it doesn't roll off sharp enough.
12 db an octave rolls off fast enough that it limits the speakers excursion as it drops in frequency.
Thats why I said you couldn't use it in place of a dedicated x-over for those kicker tweets.