I'm in the process of tuning my system, and this is the first time I have installed a subwoofer.

I have a 10" Alphasonik in a sealed box (thanks darkknight!).

I have read on other forums that if you have a sealed box, you probably don't need to turn the subsonic filter on, but that it's important to turn it on if you have a ported enclosure.

Does anyone feel this is innacurate?

Currently I am using the subsonic filter at 30Hz (24dB per octave slope), the sub is able to go down to 29 Hz according to the manufacturer.

Just wondering if I could maybe turn the subsonic filter off and maybe get a tad more low end sound.

Any guys with boxbuilding experience have an opinion here?

 

ok , subsonic filter is not for how low the sub can go or anything like that. The subsonic filter is designed to have better tuning for the box itself... you can build a box to be 33hz , so you set the sub sonic to 33hz and you'll get the best sound... so only if you know what your box is designed at should you use this... otherwise under high pressure you can have crazy distortion.

 

^^^^^^ ^^^^^^

 

Rhino, your understanding of the filter is correct. It is a high pass filter with a corner frequency of 30Hz with a steep slope such that at one octave below 30 Hz, the signal will be attenuated by 24dB. It's purpose is so that you don't waste power by amplifying very low frequencies and presenting them to your woofer when the output will be minimal. This will just waste amplifier power.

IIRC a ported box will present a very low physical resistance to the woofer below it's tuning frequency and will allow excessive excursion on the woofer possibly damaging it. An acoustic suspension enclosure presents a fairly consistent load regardless of frequency.

I don't remember if the corner frequency is the start of the downward slope of the filter but it may be the -3dB point. If this is the case, you may gain a little bit by setting the frequency a bit lower but I am not sure what settings you have availble. Is the filter on your amp or the head unit? What settings do you have available.

Probably, the setting you have now is close to ideal.

 

I would try 25 Hz if your sub can reach doen to 29 Hz. See how it sounds at different settings.

 

when you say "low end sound" are you talking about audible bass,
or stuff you only feel? turning off the subsonic filter could have the
effect of reducing audible bass because of the power consumption
from reproducing subsonic frequencies.

 

Thanks for the answers, guys.

Basically, I am still tweaking my system tune, and just want to try lots of different things to see if I notice any difference in the sound.

I had read that it was okay to turn off the subsonic filter if you have a sealed box, but never saw anyone on this forum mention that "fact." I just wanted to gather some opinions before trying it myself.

I actually went ahead and turned the SS filter off to try it out. Maybe my mind is playing tricks on me, but I do seem to notice a little more "tactile" bass with the filter off. It doesn't seem to be making the sub clip or anything like that, but I will keep my eye on things for awhile to make sure I'm not getting the impression that I'm damaging anything.

After awhile, I may turn it back on again to see if I can tell any difference without it or if it was just some "placebo" effect. At least I know now that it won't immediately fry your sub or amp if you turn it off ...

Oh, and for SheDrivesIt .. the filter is on the amp it goes from <10 Hz to 57 Hz.