Subsonic filter

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=54318
Printed Date: April 25, 2024 at 10:17 AM

Topic: Subsonic filter

Posted By: racer427
Subject: Subsonic filter
Date Posted: April 20, 2005 at 9:27 PM

Hey guy's,

I have read that there are several advantages to running a subsonic filter. Any inputs here?

Also, does anyone know of any manufacturer that makes an out board filter, only a filter not a whole crossover unit?

Chris

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Alpine CDA-9833 HU
Diamond Audio M661 Components
MTX Thunder T6.6 Components:rear fill:
Cadence Q400 4 Channel Mains + rears
Thunder 801D Subs
MTX 1004 10's
Dual 4g wire to rear
4g grounds

Replies:

Posted By: Ravendarat
Date Posted: April 20, 2005 at 10:39 PM

Basically what a subsonic filter does is cuts out all the frequencies below the filter setting. So for example if I set the filter to 25 hz then the subs will not play lower than 25 hz. The reason why someone would do this is if they were using a ported box you dont want the subs to be playing lower than the tunning of the ports or else they will loose control and become very sloppy. As for who makes an outboard one, I honestly have no Idea.

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

Posted By: DYohn
Date Posted: April 20, 2005 at 11:17 PM

I usually recomend the Harrison Labs HP-SUB. It's relatively inespensive, does not add noise to the signal and works well. https://www.hlabs.com/products/crossover/ scroll down about 1/2 way.

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Posted By: racer427
Date Posted: April 21, 2005 at 2:41 PM

I have read that they have advantages when using them with a sealed enclosure as well. As I understand it, keeping out the low unheard frequecies can make the amp run more efficiently as well as keeping the speakers from being damaged. Subs are rated for certain frequencies and for the sub to try and reproduce frequencies under its rating can cause damage to the speaker. Is this right?

Chris

Posted By: TruckSystem
Date Posted: April 21, 2005 at 3:30 PM

My D3600.1 has a subsonic filter on it and I am not sure if I should be using or not either. Have it off right now and am running sealed boxes, should I turn it on?

Sorry for the slight thread hijack.

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2003 Chevrolet Silverado Standard Cab ~ Alpine CDA-9851
Diamond Audio D3600.1 ~ 2x Diamond Audio TM310D4
Diamond Audio D3400.4 ~ Diamond Audio Hex S600s
AstroStart RS5204 Remote Start/Alarm

Posted By: racer427
Date Posted: April 21, 2005 at 10:22 PM

I guess that this one fell be the side! HA HA

Posted By: racer427
Date Posted: April 22, 2005 at 5:40 PM

Anyone have any input here at all? Please?

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Alpine CDA-9833 HU
Diamond Audio M661 Components
MTX Thunder T6.6 Components:rear fill:
Cadence Q400 4 Channel Mains + rears
Thunder 801D Subs
MTX 1004 10's
Dual 4g wire to rear
4g grounds

Posted By: stevdart
Date Posted: April 22, 2005 at 10:15 PM

racer, it all will depend on how big the sealed enclosure is. In almost every case of using a sealed box the response curve will decrease fairly quickly well above the 20 Hz point...so that frequencies that low are going to be attenuated anyway at probably a steeper slope than the filter will do it. But there certainly is no harm in using it anyway, you may just be creating a steeper dropoff at the low end which, of course, is fine to do.

TruckSystem, I think it just makes good sense to use it in all situations if it is there and available.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: kfr01
Date Posted: April 23, 2005 at 12:35 AM

racer427 wrote:

Subs are rated for certain frequencies and for the sub to try and reproduce frequencies under its rating can cause damage to the speaker. Is this right?

This really isn't correct. We ask subwoofers to play below their fs all the time. Simply reproducing frequencies below fs will not damage speakers. Speakers break because of use for two reasons, either over-heating or over-excursion.

Most cases of over-heating and over-excursion can be avoided simply by setting the gain correctly and operating the volume knob with a brain.

Do subsonic filters have a place? Sure. Distortion increases rapidly under the tuning frequency in ported enclosures. If your tuning frequency is high, you should always set the subsonic filter.

Other than that situation would I say this is an "always set" situation? No. Why?

(1) Some subsonic filters cut too high or use too wide of a Q. I wouldn't want to kill some of my ~~30hz frequency response unnecessarily, especially if I own a sealed enclosure.

(2) Unless you push your subwoofer to its limits, over-excursion simply isn't an issue; neither are thermal problems.

(3) If tuning frequency is low AND you listen to your subwoofer within its capabilities, there's probably little real audible and power benefit to buying a subsonic filter or making amplifier decisions based on the presence of a subsonic filter. Indeed, there's really very little information below 30hz in most music.

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New Project: 2003 Pathfinder

Posted By: racer427
Date Posted: April 23, 2005 at 1:23 AM

Great, thanks guy's. I am not gonna worry about using one then. I always run sealed enclosures and listen mainly to rock. Thanks again for the information.

Chris