Just wondering, I'm now at the point to tweak my system, and I have a sealed 13" Focal KX33 sub driving with JL 500/1 amp. The sub can only go down to around 30Hz, should I turn on the infrasonic filter and leave it at 30Hz? I was told in a sealed box, the filter is not necessary.

Your opinion is greatly appreciated.

I would use it.

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FOR SALE: ^^^subs(1.33 ohms) in custom wedged box(1" front MDF) + acoustic wool inside. $450 No offers. Amazing, mint, but too much weight for my lowered car.

i would also use it, and i do use mine. it saves power cuz the amp wont try to output 5 - 30hz at the same volume. if u set it above 30 you'll hear a difference in the music. but i'd just put it at 30 anyways. in this case "30" on the dial is actually 30....so set it there :P

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Thank you, I thought the dial might not be accurate so I set mine to 22Hz right now instead of 30Hz The sub according to the specs, can only go down to 30Hz. I'll change it later on, thank you.

^ The spec actually says "No response below 30hz"?

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Paul Niwranski
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The transfer function of the cars cabin will easily allow for useable response to 20HZ. There is a lot of wasted energy that is consumed trying to reproduce those frequencies. Usually, there is a slope related to the filter however (18db/oct, 24db/oct, etc). This is why you likely see the response that DUKK has given. If it truly has no response at all below 30hz, I would put that amp on a meter and look at the response while adjusting the filter. Never know, it maybe worthwhile....Good luck!

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I try every day to get something done on my system in my car. It is coming one day soon,.....then again, so is the second coming of Christ! Ironically, I do not know the day nor the hour of either!

if ur sub can handle alot of excursion then dont worry about it but if it cant then use it.