Subsonic Filter.
05-10-2004, 10:48 AM
#1
0 Watt CAFz'r
Thread Starter
Join Date: May 2004
Posts: 26
Hello everyone. My name is - GunMetal TeG - and I am about to take this forum by storm, remember my name or not, your going to see me around here alot from now on.
So this is my question.
I have 2 12" rf hx2 in a sealed fiberglass setup. I would like to put the subs in a ported box for SPL competitions. The problem is I have a jbl bp1200.1 and it does not have a subsonic filter. Or at least that is what I am told.
1. How does my amp not push the same power to the subs regardless of ported or sealed?
2. Where can I get a subsonic filter or should I not bother and sell the amp and buy a new one?
3. Thank you for your time.
So this is my question.
I have 2 12" rf hx2 in a sealed fiberglass setup. I would like to put the subs in a ported box for SPL competitions. The problem is I have a jbl bp1200.1 and it does not have a subsonic filter. Or at least that is what I am told.
1. How does my amp not push the same power to the subs regardless of ported or sealed?
2. Where can I get a subsonic filter or should I not bother and sell the amp and buy a new one?
3. Thank you for your time.
05-10-2004, 11:13 AM
#2
Guest
Posts: n/a
he amp puts out the same power no matetr what, box design has really no effext on it other than maybe the impedence spike, but that is nothing to really worry about since you don't have much control over it.
I wouldn't worry about a subsonic filter unless you have a really high tuned box for competition then use the same boxx for daily driving, in which case you will get bad sound and shouldn't be done anyway.
I wouldn't worry about a subsonic filter unless you have a really high tuned box for competition then use the same boxx for daily driving, in which case you will get bad sound and shouldn't be done anyway.
05-10-2004, 11:47 AM
#3
Add an outboard croosover like the Audio Control 2xs, it will give you an 18db slope on the crossover and a subsonic filter. The idea behind it is to limit the low frequency extension of the subs. Eliminate the wasted power and the potential damaging frequencies that are beyond the tuning capabilities of the box.
Dereck is pretty much bang on with his recommendations about the amp power, the amp will power the same no matter what type of box it is presented with. The ported box will play louder, no doubt as you are now reinforcing the front pressure wave with the back pressure wave and quite possibly (for SPL purposes) tuning the box to the loudest resonant frequency. In this case Dereck is right, the subsonic will probably not do much as the tuning frequency would probably be around 70hz, give or take a c hair. Thus a full octave below is 35 hz and another full octave below is now at 17.5 hz (this is where the subsonic would come in). In the case of an SPL tuning the crossover in the amp (not sure what it is but I'll guess 12db) will roll off the frequencies at a rate of 12db per octave, thus by the time a usable frequency is being reproduced in the lower region, say like two octaves down, it will be down in output by 24 db, maybe more depending on the slope of the crossover. (If you use the Audio Control it would be down by 36 db). A subsonic filter is a good idea no matter what. If you are doing a purely SPL system it may have little effect like Dereck says, if you are after a system that has more output and a lower tuning frequency, then a subsonic filter may definitely be of use.
Dereck is pretty much bang on with his recommendations about the amp power, the amp will power the same no matter what type of box it is presented with. The ported box will play louder, no doubt as you are now reinforcing the front pressure wave with the back pressure wave and quite possibly (for SPL purposes) tuning the box to the loudest resonant frequency. In this case Dereck is right, the subsonic will probably not do much as the tuning frequency would probably be around 70hz, give or take a c hair. Thus a full octave below is 35 hz and another full octave below is now at 17.5 hz (this is where the subsonic would come in). In the case of an SPL tuning the crossover in the amp (not sure what it is but I'll guess 12db) will roll off the frequencies at a rate of 12db per octave, thus by the time a usable frequency is being reproduced in the lower region, say like two octaves down, it will be down in output by 24 db, maybe more depending on the slope of the crossover. (If you use the Audio Control it would be down by 36 db). A subsonic filter is a good idea no matter what. If you are doing a purely SPL system it may have little effect like Dereck says, if you are after a system that has more output and a lower tuning frequency, then a subsonic filter may definitely be of use.
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