Vented Boxes Restrict Too Much Cone Movement

[WarDrumz 10+ year member]

Man, vented boxes can be GAY!

I have a 1600wrms Crystal CMPx2 15" in a vented box 30"W x 18"D x 17"H tuned to 35hz with a port opening of 4" wide x 15.5" high.

My sub has an xmax of 28mm each way, and there is no freakin way I can make it move that far in that vented box. The sub can only handle 1600wrms thermally, and I have 1500wrms going to via my Brutus 1500D. The dern thing only moves half of it's xmax with 1500wrms!!

I was reading the debate between Below30 and other members. He said that a sealed box puts more restriction on cone movement, and I must say, THAT IS ABSOLUTELY INCORRECT.

I think I can honestly say that if i put my sub in a good sealed box I can get more output than I am getting in this vented box.

The recommended vented box for my sub is 3 cubic feet after all displacements, and I know it has more space than that, and it STILL only moves about 1".

That's not all. Since my box is tuned to 35hz, I turn my SSF to it's max setting which just happens to be 35hz. Well, anything even close to that frequency and my sub does not freakin move more than about .25"

I would risk roasting my sub if I give it more than 1500wrms. So basically I need about another cubic foot of air space to get fully excursion. Thats gay.

Vented box can ****.

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[bigbassman Premium Member]

um...

turn the SSF down to 25hz or so.. way to high.. you don't set it to tuning.. set it below tuning..

I don't understand why you're wanting major excursion..

but if you think that box *****.. try sealed with that sub..

you'll discover pretty excursion isn't going to outperform the ported box...

Loyd L.

 

[WarDrumz 10+ year member]

um...
turn the SSF down to 25hz or so.. way to high.. you don't set it to tuning.. set it below tuning..

I don't understand why you're wanting major excursion..

but if you think that box *****.. try sealed with that sub..

you'll discover pretty excursion isn't going to outperform the ported box...

Loyd L.

You can't understand why I want major excursion?

Bcuz my sub is capable of major excursion.

About the outperforming the vented box....The cone is BARELY moving near tunning, darn near all the output is from the vent. I don't see how the vent can outperform the sub sealed with twice the xcursion.

Plus...I am thinking about using my other matching CMPxw 15" and sealing both of them. To the people who think that one of them vented can equal 2 of them sealed, I don't think so. Definately not on the Low notes. One of them sealed would give me twice the xcursion of what it's moving now vented, and then double that bcuz of the 2nd sub.

I'm starting not to like vented. Also, why would I turn the SSF down that low? I can see maybe 30hz, but 25hz might damage my sub with 1500wrms 10hz under tunning. Plus under tunning it's supposed to be a steep drop off in output.

 

[bigbassman Premium Member]

the wonderful thing about a vented box... the vent contributes greatly to OUTPUT....

thats why its there..

the 3rd order design will not make the woofer have a huge throw above tuning... sorry

just because the woofer has the ability for long stroke.. doesn't mean it has to be throwing at its limits..

also let it be known that a woofer in most circumstances is mechanically safe 1/2 octave below the tuning of the port/vent..

but whatever.. I've only built a couple hundred vented and sealed boxes.. I don't know anything..

Loyd L.

 

[nosaj070 10+ year member]

but whatever.. I've only built a couple hundred vented and sealed boxes.. I don't know anything..

Just to let you know, this guy knows probably more about SPL than any guy on this forum by far. In a little bit simpler terms, the sub/enclosure is most efficient around the tuning frequency, hence the reason for low excursion. Just to let you know, 28 mm is only 1.1 inches, I see no problem with getting 1 when you are only measuring it by eye.

 

[Bill T. 10+ year member]

You questioned the master? Thats wrong...

Anywho, I put my XXX in a sealed box. Yeah, I would say it moved a lot more. But was it louder? Not one bit. Just because the woofer can excurt more doesnt mean it will be louder. If your not happy with the sub now in a vented box, then you picked the wrong woofer.

As for SSF, always lower than your tuning frequency. Slopes, octaves yada yada.. the SSF protects the sub from going below the set frequency. Generally, I would say a 15" should be about 20~25Hz. If its higher than your tuning, then your ripping yourself off. The tuning is where you get a gain (of course it tapers off but thats the peak) setting your SSF above that and the amp will not go below it to your tuning point.

So in essence, if your tuning was 30Hz and you set your SSF to 38Hz, it would sound like a sealed with no low end.

Bill T.

 

[Qckrun 10+ year member]

Just to let you know, this guy knows probably more about SPL than any guy on this forum by far. In a little bit simpler terms, the sub/enclosure is most efficient around the tuning frequency, hence the reason for low excursion. Just to let you know, 28 mm is only 1.1 inches, I see no problem with getting 1 when you are only measuring it by eye.

Well Loyd and Dustin i would say are like almost the same but Loyd is a set up lol, just because of what he's done //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Loyd & Dustin > All

P.S.

Just hit 1k posts //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Yeppie

 

[bigbassman Premium Member]

dustin is my hero.... //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Loyd L.

 

[Qckrun 10+ year member]

dustin is my hero.... //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif
Loyd L.

Dustin > Loyd... haha just kidding

Loyd>ALL

Whoever can get 18 8s wangin off 1800watts is a pure SPL genius, and god. Even when they werent tryin too lol.

LOYD>ALL

 

[Bill T. 10+ year member]

Not only does it wang.. its **** sexy.

Loyd > u and everyone else

Bill T.

 

[nosaj070 10+ year member]

I stand corrected Dustin=Loyd //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Jim Boom 10+ year member]

If you have WinISD Pro you will recongnize that the excursion is the least around the tuned frequincy, because at that frequincy is where the subwoofer does not have to work as hard in a sense. So its not that its ported its that its tuned correctly, if you want excursion put in a 15 hz base test, (you can't hear it, but the mfker moves).Peace

 

[WarDrumz 10+ year member]

the wonderful thing about a vented box... the vent contributes greatly to OUTPUT....
thats why its there..

the 3rd order design will not make the woofer have a huge throw above tuning... sorry

just because the woofer has the ability for long stroke.. doesn't mean it has to be throwing at its limits..

also let it be known that a woofer in most circumstances is mechanically safe 1/2 octave below the tuning of the port/vent..

but whatever.. I've only built a couple hundred vented and sealed boxes.. I don't know anything..

Loyd L.

Man, nobody said you don't know anything. That why I asked the question, Because "I" didn't know, hence the question mark.

But do you agree that if the box were bigger like one cubic foot, that the woofer could achieve more xcursion? If so, that's one of my points. You have to have a HUGE box to make it move as far as the Manufacturer designed it to. HUGE in my case means, bigger than recommended.

Nosaj. 1" is str8? Well, not to me. Not when the sub is capable of moving twice that. Also meaning that I am not getting FULL POTENTIAL from my setup. All because vented boxes need to be HUGE.

Given my circumstances, I believe that the sealed enclosure will give equal output. Twice the excursion will equal the sub at half the xcursion + the vent in my opinion.

PLUS, It will be easier on my amplifier and my electrical system because there is NO WAY I'll need the same 1500wrms in the proper sealed box to reach full xcursion. MAYBE 1000wrms, maybe.

And to the other guy, just bcuz I may want to discontinue use in a vented box doesn't mean I wasted my money. My sub excels in both types of enclosures. And no my SSF was not set over tunning, that's silly.

 

[bigbassman Premium Member]

my pee pee is bigger than dustins..

I win by default? //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

and yes.. a woofers excursion will be lowest, at, and just above the tuning frequency of the port.. however.. due to back emf, there will be an increase of excursion up to around one half to 3/4 octave above tuning.. the woofer will have the most excursion above tuning at that point..

and of course.. below tuning excursion increases until something breaks.. usually 1 octave or more below tuning frequency..

Loyd L.

 

[tat2 10+ year member]

we all love loyd's 8"s.

wow thats sounds real dirty.