Questionso does the subsonic filter prevent the subs from producing any note under the setting? what exactly does it do?
and thanks a bunch. i totally understand how to tune the bad boy now. you've been an awesome help!
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Actually, I google a test tone generator and found quite a few that work really well, in fact i just made a cd with the following tracks
1. 100hz-90hz
2. 90hz-80hz
3. 80hz-70hz
4. 70hz-60hz
5. 60hz-50hz
6. 50hz-45hz
7. 44hz
8. 43hz
all the way down to about 30hz I think
all the tracks are like 3 seconds long
I checked with the guy who made the box for me and he said the port frequency would be right around 37hz as you said it probably would
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I guess if you want, you could send me a private message on this site with your personal email address, then I could email you attachments of mp3 files that you could burn to a cd if you know how to do that. you'd just have to make sure they all go on the cd in order.
wanna try that?
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NICE!!! ok so what you're going to do with this is when you get this system all hooked up, put the cd you made in, and start working your way down in tracks. it may be useful to write down a list of what track is what frequency and have a friend at the controls changing tracks while you look at your sub and see how far it's strokin.
so if you think your box is ported at 37, start around 60 and work your way down without changing the volume. if you have the sub cranked up pretty good, basically right around 52 hz you should see the sub moving about 8 millimeters back and forth. keep going down in freqencies, one at a time, and the sub should stroke back and forth less and less after 50-52. if your friend built it as he is saying, (tuned at 37hz) then at 37 hz the sub should only be moving about 1 mm back and forth. the track where it moves the least is your tuning frequency. as you go to tracks that are deeper than this freqency the sub will start to move more and more again. the idea is that if you have the subsonic filter set just right, the sub will not move more than when it moved the most (as I predicted up around 50-52 hz) in these lower freqencies.
if it moves less and less and less and continues this way in a linear kindof fassion from 60-20hz then you have your filter set too high.
basically as you lowwer the freqencies, it should have a bump where it strokes more and more from 60-50 ish, then less and less from 50-37 ish, then more and more again from 37 to about 27 ish. then stroke less and less again. and the distance the sub strokes at 50 should be about the same as 27. if it strokes more at 27 then turn up the filter, if it strokes less at 27 then turn down the filter.
man its hard to explain this!!!!!
hope this all is helping!!!
Answeryou're very welcome! give yourself some credit too because this is one of the more complicated parts of audio for most people to understand.
the subsonic filter will make the notes lower than where the setting is quieter. technically the number of the setting should be 3 db quieter and get progressivly quieter the deeper the notes from there are. so if you set the subsonic filter to 30 hz, then 30 hz should be 3 db quiter and I believe this filer is 18 db per octave after that. one ocative is 1/2 the freqency so 1/2 of 30hz is 15 hz. so by 15 hz you're 18 db quieter than at 30. every 3 db less is 1/2 the previous volume. so if 40 hz is your refrence, where the filter hasnt kicked in yet, and 30 hz is the -3db point of the filter, then 30 hz is 1/2 as loud as 40 hz, then down at 15 hz you'r -18 db of that, so if we say your refrence volume before the filter kicks in is 140 DB, it will equate to this:
100hz - 40hz = 140 db
30hz = 137 db
15hz = 119 db
so the system is puting less effort into making the notes below the tuning freq. it doesnt look like much in DB but remember that every 3 db is 1/2 the previous volume so 18 db quieter is 1/2 , then 1/2 that, then 1/2 that again, then 1/2 that again, then 1/2 that again, then 1/2 that again!!!! so as far as volume and wattage the difference with the filter on from 40 hz to 15 hz is the difference between 100% and 0.78125 percent!!!
so without the filter, lets say your amp is 600 watts, its going to push 600 watts at all freqencies, even at 15 hz which would damage the sub, but with the filter set to 30 hz, it will push 600 watts from 100-40hz, and 300 watts at 30hz and about 5 watts at 15hz. this keeps the sub from stroking out of control at 15 hz.
