# How many use subsonic filters?



## LaserSVT (Feb 1, 2009)

I was just curious. I like to have all the musical information there and have tried my system both ways. There is a more live feel without it on but with it on I can push the subs much harder with bass heavy music before they distort. I just dont like the thought of not having it all there.
I now have mine set at 15hz as for 99% of my music there is no information below that anyway and as I said it really allows me to get crazy with the output when a favorite song comes on.

So I wanted to know who runs them with what kind of sub/enclosure setup and at what freequency and if you really can hear any difference.


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## legend94 (Mar 15, 2006)

I'm using the one built into my amp. Current setting is 15hz with 24db slope in a sealed box.


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## Hillbilly SQ (Jan 26, 2007)

I've used a subsonic but that was with an 8" sub tuned low 30's. It's quite a bit easier to make a single 8" cry than it is a pair of 10's tuned mid 30's


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## boricua69 (Oct 14, 2009)

Sir, subsonic or infrasonic filter was desing for ported box, not sealed. But other people use it in IB or Freeair sub or midlow woofer. Years ago when bazooka was popular most instaler didn't have the knowledge of the subsonic and burns and damage a lot of bazooka subs. In those days many use class ab 2 channel amp in mono for sub and those amps doesn't has subsonic. But others add active crossover and use it.


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## hurrication (Dec 19, 2011)

I actually use one for a low power 12 in a sealed box, but for a reason. The sub is a big motor/big mms sub and has a very soft suspension with a fs of 16hz. The goal was for huge low end with moderate/high qtc on small power in small enclosure space and it works great, but the thing beats the guts out of itself with subsonic information. IIRC mine's internal to the amp and at around "25hz" according to the silk screening around the pot @ whatever db slope the amp uses.


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## 1996blackmax (Aug 29, 2007)

Mine is set at 20Hz 12db/octave. Lowest my amp will go.


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## LaserSVT (Feb 1, 2009)

Kinda figured it would be all over the place. The Quart I just yanked out of the shop car was stuck at 15hz subsonic and when I installed the JL amp I turned it off and the car played deeper. I set it to 15hz and noticed no difference. Granted 500 watts is not even tickling his SPG555 subs. On my truck though it just allowed me to use more of my power when it came to bass heavy songs. Since I listen to different music I just turned it off again this morning. I cant really seem to tell a change save for a couple bass specific songs which I only play for my bass head friends.
Guess the Quart had a 15hz subsonic but didn't matter as it seemed the amp couldn't play that low anyway. LOL

BTW, it was a 2 year old Onyx POS. LOL


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## nstaln (Feb 11, 2009)

Subsonic filters should be used primarily to control/stop the subwoofer from unloading below the tuning frequency of a ported box...I always consider the subsonic filter freq and slope when designing ported boxes...the right subsonic filter can really add quite a bit of really low end to a sub/enclosure system...I've used Harris Labs FMods for years with great results...a steeper slope isn't always better...you're really just controlling excursion below the tuning freq,sometimes a 12db per/oct can allow a sub to dig a bit deeper and still not push it past it's linear x-max.

It also depends on power...if you have slightly less power you can get away with a more shallow slope and dig a little lower than if running higher power and needing a steeper roll-off to control excursion.


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## subterFUSE (Sep 21, 2009)

I recently stopped using a high pass filter on my subs and I do prefer how they sound that way. They don't appear to be pushed anywhere near XMax so I think I'm going to leave them that way from now on.


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## nstaln (Feb 11, 2009)

This pic shows the difference in cone excursion for an 8w7 when used without a ss filter(red), when used with JL's recommended [email protected] filter(orange), and with [email protected] filter(yellow). The enclosure is 1cube tuned at 32hz with 500rms applied.

As you can see the unfiltered ported box(red) make the sub reach it's linear xmax limit of 19mm at 26.61hz...playing anything below this will possibly cause damage to your sub in this system.

JL's recommended ssf of [email protected](orange) sure does keep the cone well within xmax limits...but it sure does leave quite a bit of unused usable excursion.

The [email protected](yellow) is a balance between the two...lets the sub dig deeper, yet keeps the sub from over-excurting below tuning freq.










This pic show the difference in SPL between the (3) systems.

The red is indeed playing louder/lower...but your sub may be destroyed.
The orange is OK but is giving up a lot of low end extension.
Yellow is the compromise...sub is protected yet boasts 87.8db vs 79.9db @20hz over the recommended [email protected]'s a difference of 7.9db at 20hz!


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## LaserSVT (Feb 1, 2009)

Thank you sir. That is the exact kind of info I needed.


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## gijoe (Mar 25, 2008)

I use one at 20Hz, I personally don't see the point in having my subwoofers play frequencies that I can't hear. Below 20Hz there is some tactile perception, but it takes a lot of power and leads to high frequency noise from buzzing panels. I'd rather have the power available for frequencies I can hear.


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## sqnut (Dec 24, 2009)

The music I listen to doesn't have much content below ~50hz. Never used a HP on the sub.


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## cajunner (Apr 13, 2007)

I think that there is room for a narrow band boost at tuning, and a steep SS filter just below it, because it allows a small box to sound bigger.

and we love small boxes.


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## wisnulie (May 24, 2015)

nice information
thanks all


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## therapture (Jan 31, 2013)

Mine is at 15hz on my V9. If I Set it at 25hz, I can tell a big difference. Lower than 15, hardly any, if any at all difference.


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## gregerst22 (Dec 18, 2012)

therapture said:


> Mine is at 15hz on my V9. If I Set it at 25hz, I can tell a big difference. Lower than 15, hardly any, if any at all difference.


I have an IB setup an my alpine V9 is set at 15hz also. It's basically there to help protect the subs from me doing something stupid like to playing a 10hz test tone at full volume.


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## legend94 (Mar 15, 2006)

legend94 said:


> I'm using the one built into my amp. Current setting is 15hz with 24db slope in a sealed box.





therapture said:


> Mine is at 15hz on my V9. If I Set it at 25hz, I can tell a big difference. Lower than 15, hardly any, if any at all difference.





gregerst22 said:


> I have an IB setup an my alpine V9 is set at 15hz also. It's basically there to help protect the subs from me doing something stupid like to playing a 10hz test tone at full volume.



There seems to be a consensus which is rare on here 

This has been my favorite amp in over a decade. So much power and very clean.


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## BuickGN (May 29, 2009)

cajunner said:


> I think that there is room for a narrow band boost at tuning, and a steep SS filter just below it, because it allows a small box to sound bigger.
> 
> and we love small boxes.


Boxes? What are boxes?



gregerst22 said:


> I have an IB setup an my alpine V9 is set at 15hz also. It's basically there to help protect the subs from me doing something stupid like to playing a 10hz test tone at full volume.


Same here. I have mine set to 15hz because it won't go any lower abs I can't turn it off that I know of. I learned the hard way that when burning a test tone Cd, start with the high frequencies as track #1. 16hz at full output with 1,000w total on my IB15s. Luckily nothing was damaged. 

I'm one of the few that prefer a very low SS filter and obviously mine is infinite baffle with a pair of IDMax15s. 10hz is where I like it. It sounds petty but there is the rare piece that extends below 20hz, usually something with a pipe organ in it that will tickle the 16hz area. You can't hear it but you can feel it and sense the energy in the air. It gives you a sense of power; it's hard to explain. This is the one thing that sways me toward the Max15s over the AV15s. Just sheer displacement and obviously they sound really good though probably not as good as the AVs I'm sure. Oh, started leaving the spare tire well open and I swear they sound better that way. I modeled them with a few extra cubes and it puts me in the .59 Qtc area which seems to be a great compromise. 

Back on topic.... I like a subsonic at 10hz because I swear there is a difference even if it's too low to hear and I have the displacement to play it at full output without hurting the subs and being IB and with lots of displacement it plays everything with authority, material that I didn't know existed on my old sealed setup is not there and it's loud. I want a filter even though most would say why have a filter if it's at 10hz because there is the rare recording that has a rumble to it that I would guess to be 10hz or less and not only does it use up excursion quickly, you may not realize it's there unless it rattles the car. 

I think a subsonic is under appreciated for sealed boxes. If you've got your sub in a small box with a .9 Qtc and 60hz Fsc (which isn't that uncommon after modeling lots of popular subs in the recommended enclosures), why not cut the 30hz and below material that will never be heard anyway. Reduce the amount of useless power going into the sub so you have more headroom at a given volume.


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## kyheng (Jan 31, 2007)

Depending on the sub used, enclosure. Some amps are only with fixed value of subsonic, it is useless basically.


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## hone1er (Feb 17, 2015)

Makes me want to change amps. Mine only has on/off @ 30hz 24db/octave. Definitely holds back some of the lows. I could really use an extra 7 db at 20hz.


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## subterFUSE (Sep 21, 2009)

I found that putting the SSF at 20 or 25Hz @ 24dB caused a major drop in SPL at those frequencies, plus slightly above.

If I use 36dB slope the SPL doesn't get attenuated as much above the crossing freq.

But, ultimately, I have found that my subs seem perfectly happy without the SSF. I can play as loudly as I can stand to have them playing, and they handle it well.


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## BuickGN (May 29, 2009)

subterFUSE said:


> I found that putting the SSF at 20 or 25Hz @ 24dB caused a major drop in SPL at those frequencies, plus slightly above.
> 
> If I use 36dB slope the SPL doesn't get attenuated as much above the crossing freq.
> 
> But, ultimately, I have found that my subs seem perfectly happy without the SSF. I can play as loudly as I can stand to have them playing, and they handle it well.


Are your subs sealed or IB? I've also noticed that a 20hz SS filter hurts frequencies slightly above 20hz. Modeling all of my speakers in WinISD with filters on both ends was an eye opener for me. I started doing that back when I thought the frequency the crossover was set to did not begin to drop until right at that frequency. At least it made sense of what I was hearing. 

I still toss around the idea of 3 Esotars in an IB setup in my car. They're small enough to where I can fit them pretty easily but that's the problem too. I need three of them to get the output that I like and that gets really expensive.


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## subterFUSE (Sep 21, 2009)

Mine are IB. Running them with a Sinfoni Grave bridged mono. Should be 925W to them. Sound quality is fantastic. I've just always wondered why the cones look like they don't move. I'm used to seeing subs that visibly show their excursion.


Sent from my iPhone using Tapatalk


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## Weigel21 (Sep 8, 2014)

Eh, I've used the SSF in every amplifier I've used that had one. Majority of my setups have been sealed and the use of the SSF had little to no effect on the sound I heard, so I figured why not use it, can't hurt. Then there's ported setups I've ran and set the SSF at 5Hz below the tuning frequency, though I think the rule is that it needs to be set at half an octave below the tuning and with a sharp slope.


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## sqnut (Dec 24, 2009)

subterFUSE said:


> I've just always wondered why the cones look like they don't move. I'm used to seeing subs that visibly show their excursion.
> 
> 
> Sent from my iPhone using Tapatalk


Visible excursion depends on the amount of low end in the content you're hearing. Put on some electronic or dubstep, you'll probably see them move much more.


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## LaserSVT (Feb 1, 2009)

cajunner said:


> I think that there is room for a narrow band boost at tuning, and a steep SS filter just below it, because it allows a small box to sound bigger.
> 
> *and we love small boxes*.


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## 1996blackmax (Aug 29, 2007)

LaserSVT said:


>


Ha!


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## 1996blackmax (Aug 29, 2007)

sqnut said:


> Visible excursion depends on the amount of low end in the content you're hearing. Put on some electronic or dubstep, you'll probably see them move much more.


Yup, you sure will!


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## LaserSVT (Feb 1, 2009)

Suprising how much people agree on all this here and that nobody is trying to kill anyone else. Kudos guys!

Great info and was really just more of a curiosity I had. Since my system is sealed and I generally listen to rock or classic rock or 80/70's stuff I plan on just turning it off. Just have to remember its off when someone asks me to play some bass music and not go too wild with the volume.

I am overly proud of my stereo and used to enjoy showing it off but everyone just seems to judge a system on how much bass it makes and what it can vibrate. I will throw in something that should be impressive and will show the clarity and detail and stage and when I look over the person just has a glazed look and you can see the thought of "I thought he had a system? And why am I listening to an acoustic guitar?".
So I sigh, turn up the bass knob and throw on some "Bass I Love You" or some other mindless hip hop song and then they get all giddy.


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## subterFUSE (Sep 21, 2009)

sqnut said:


> Visible excursion depends on the amount of low end in the content you're hearing. Put on some electronic or dubstep, you'll probably see them move much more.



I listen to 95% underground house music. ?


I think maybe it's just the Dyn subs don't move very much? Don't get me wrong they sound great. Just been craving more punch.


Sent from my iPhone using Tapatalk


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## BuickGN (May 29, 2009)

Sealed and IB output is solely determined by displacement. So if you have two subs with the same cone area, the one that moves the most is going to have the most output. If you need more punch and they're not moving much, it's not a sub problem. I'm assuming you've already looked at the highpass filter lol. 900w is a lot for a pair of 12s IB but are you sure there's not something that's preventing them from getting full power? That much power should have those Dyns near their mechanical limits at the lower frequencies. For example, the 12W6 will be near xmech with only 260w from my experience and xmax is achieved with far less. It pretty much has to be a power/wiring/signal/filter problem if the subs aren't moving much in IB. I bet you'll find that punch without changing equipment.


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## sqnut (Dec 24, 2009)

subterFUSE said:


> Don't get me wrong they sound great. Just been craving more punch.
> 
> 
> Sent from my iPhone using Tapatalk


Punch comes from midbass more than sub. The punch is in the 60-100hz region.


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## legend94 (Mar 15, 2006)

sqnut said:


> Punch comes from midbass more than sub. The punch is in the 60-100hz region.


Could the right sub not play those frequencies as well as maybe roll off to blend them together?

When I turn my sub off I don't get quite the midbass punch. Still there just not enough.


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## Lycancatt (Apr 11, 2010)

I don't usually use them in car audio but I have for ported setups where I knew the owner was going to drive the subs really hard.

In pro audio I use one at like 31 hz most of the time, sometimes higher for crappy small subwoofers. Lowend extension isn't important to most ravers, they want that punch so not using up power down low is really helpful.


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## Beckerson1 (Jul 3, 2012)

sqnut said:


> Punch comes from midbass more than sub. The punch is in the 60-100hz region.


Midbass region but as to if it comes more from the mids or sub I would say that depends on your crossovers for one, drivers used (a 6.5,8,10 inch driver). 

This is kinda why I say the sub helps reinforce the mids in this range as if you turn the sub off completely you should notice a difference in this range. 


My case with 6.5" mids the sub adds a lot. If I turn the sub off the low end ( and I'm talking 70-100hz becomes very anemic)

One of many reasons why I'm going to 8's for the front midbass in the future here. 

Hope is to use the sub to more or less handle just the subsonics 20-50hz and the 8" drivers to handle 50hz to 250 or so then I'm going tweeterless (with the option to add tweeters if needed) but with the orientation I'm willing to do I should have no issues without tweeters


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## BuickGN (May 29, 2009)

sqnut said:


> Punch comes from midbass more than sub. The punch is in the 60-100hz region.


This is repeated a lot around here but I remember a thread talking about punch and some people's idea was 50hz, some was 250hz. 

It's safe to say that many of us consider the sub to add a ton of punch to the system. Anyway you want to describe it, the subs do the majority of it and that's coming from someone with 9" midbasses. A door mounted midbass will never come close to a pair of 15s for punching you in the chest.

Hell, recently I drove for a day without the front stage working and played the subs for a few minutes on the way home and even with a 24db/45hz LP with just the subs playing, there was still plenty punch/kick/whatever you want to call it. You can't say a sub is not a huge contributor to punch or kick or whatever you want to call it.

I usually run the subs up to a good 65-70hz even with 9" midbasses, there's no reason not to, so especially for people like me, the subs are a huge contributor. With the subs off, there's still punch but the lower end of it's gone.


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## therapture (Jan 31, 2013)

While I agree the sub(s) add some - most of us don't have ib 15's as a contributor hahah.

The snap and attack definitely come from the front stage, or should in most cases - in my own opinion.

I have considered going with a better midbass driver than my HAT imagines just because I desire so muh upfront bass and midbass. I drive them pretty hard but I think my door work may not be up to par to handle a heavy hitter in there.


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## legend94 (Mar 15, 2006)

therapture said:


> While I agree the sub(s) add some - most of us don't have ib 15's as a contributor hahah.
> 
> The snap and attack definitely come from the front stage, or should in most cases - in my own opinion.
> 
> I have considered going with a better midbass driver than my HAT imagines just because I desire so muh upfront bass and midbass. I drive them pretty hard but I think my door work may not be up to par to handle a heavy hitter in there.


I think you should consider adding another sub like the one you have. It made a significant difference for me when going from 1 arc 12 to a pair.


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## BuickGN (May 29, 2009)

I need to update my sig. I have a pair of IDMax 15s IB now. They somehow play well into the midbass realm easily and sound ok doing it. I didn't expect a sub like this to be capable of playing the range it does. 

Anyway, maybe we need to define "punch". Maybe this is why no one can ever agree. If it's the kick, the beat, the punch you in the chest, make your rear view mirror fall off kind of punch, that's what I'm talking about. It's there even with my front stage off. Maybe we're talking about something different. 

I listened to people and I eventually gave up my Esotar midbass for the 9" midbass with considerably more excursion and with the same 300w each on them. I realized what I was after was higher up than the 50-60hz range I thought I needed more of. It was kind of depressing the realize the midbass I thought I needed turned out to be a tuning issue that the 6.5s could have easily handled. 

Even so, the subs play the 60-100hz range with much more authority and much more efficiently. I have the displacement and power for great midbass snap but they will never be as good as the subs. I still run my 9s at the same 70hz crossover point as my 6.5s. The 9s will handle pretty much anything you throw at them and sound great doing it but there's no need with the subs there. 

If I cross them lower, no higher than 50hz, they take over some of the punch that the subs normally handle and sometimes I run them down to 35hz when I get tired of the subs. 

What frequency range do you guys consider the punch to be at? What I call punch is between 60-100hz but I also like a strong 250-400hz which a 6.5" won't have issues with and that's what I was looking for when I went with the 9s but didn't realize it.


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## sqnut (Dec 24, 2009)

.....and we're off to the races. Ok, let's start at the top. The 30hz PN track at 100db will feel loud. It's tactile and chances are it is shaking a few things. It will feel louder than what you're really hearing it as. The 100hz at 100 db will sound louder than 30 but less tactile. The punch I'm talking about is partly tactile but partly heard. 

For a minute let's say we do 20-70 from the sub and 70 and above from the midbass. Any decent 6.5-7" driver should be able to play the 70-100 range with authority. So when you switch off the sub, what you're losing is the 20-60 hz range. I'd say that is about 25% of the low end. Again this depends on what you're listening to. With say classic rock the loss may be 15% with something like dub it may be 40%. 

Any decent 6.5-7" well installed should do the 70-100 just fine. There's enough tactile input at 70-80hz, for you to feel the bass. Bigger drivers have more cone area and they would do even better. If 8-9" drivers sound anemic in the door, its 100% a tuning issue. Electronic slopes on subs in a car are often different from the actual acoustic slopes and most often I have to use 6-8th order slopes on the sub to get where I want. Like with so many other things, it eventually comes down to the tune.


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## sqnut (Dec 24, 2009)

BuickGN said:


> I also like a strong 250-400hz which a 6.5" won't have issues with and that's what I was looking for when I went with the 9s but didn't realize it.


Be careful with the 200-400 zone. It's often louder than it should be in a car. 200-250 adds bloat and kills the really tight and focused low end. I'm not going to say snappy midbass because the snap is in your midrange. But an over cooked 160-250 range will give you a fatter low end as opposed to a tight lower end.


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