Ported or sealed Sub Enclosure

Maddbuck · Post by **Maddbuck** » March 25th, 2002, 10:46 pm

Just bought 2 12" MTX subs and need to decide on whether to build a ported or sealed box.I'm leaning towards ported but it requires more space.so basically tell me which most of you prefer or which is better in your opinion. thanx

loudsubz · Post by **loudsubz** » March 25th, 2002, 11:09 pm

Sealed -More power able to go to subs -Smaller Box -More low end -Easier to buildPorted -More output with less power -Larger -Harder to build

-=deathtrap-mx3=- · Post by **-=deathtrap-mx3=-** » March 25th, 2002, 11:10 pm

well do you want SQ or SPL? ported boxes will give ya hella SPL, but kiss SQ outta the window. i prefer sealed b/c i enjoy Sq over SPL, but a sealed box should be able to keep ya content with the SPL it produces at the same time.

loudsubz · Post by **loudsubz** » March 25th, 2002, 11:14 pm

<BLOCKQUOTE>quote:<HR>Originally posted by -=deathtrap-mx3=-: well do you want SQ or SPL? ported boxes will give ya hella SPL, but kiss SQ outta the window. i prefer sealed b/c i enjoy Sq over SPL, but a sealed box should be able to keep ya content with the SPL it produces at the same time.<HR></BLOCKQUOTE>If you tune the box low enough, say 20 hz or something, then the SQ is still very good on Ported boxes.Some even prefer the ported over sealed for SQ.

jamik_69 · Post by **jamik_69** » March 25th, 2002, 11:18 pm

it all depends on how much bass you want and sound. i have a sealed box now with 2 rockford he2 12" it buts deep bass but my ported box sounded cleaner. if you go with a sealed box you need a lot of watts powering your subs at least r.m.s i reccomend a ported box besause it has a cleaner sound the only down side is you wont be able to put any thing in your trunk. if you need a little trunk space go with sealed :p

Maddbuck · Post by **Maddbuck** » March 26th, 2002, 2:06 pm

I'd like more bass than my current twin 8" subs give out. The ported box will only take up 2" more room than the sealed box design I have going. I got specs from mtx website and the ported requires 2 cu ft with a port of 4" x 9.25 tuned for 39Hz.Don't think my amp will be powerful enough. it is 2ch 300w with 75w rms per channel. So I need th most I can get out of this amp, it will be bridged this time around.

VizualXTC · Post by **VizualXTC** » March 27th, 2002, 6:23 am

<BLOCKQUOTE>quote:<HR>Originally posted by Maddbuck: I'd like more bass than my current twin 8" subs give out. The ported box will only take up 2" more room than the sealed box design I have going. I got specs from mtx website and the ported requires 2 cu ft with a port of 4" x 9.25 tuned for 39Hz.Don't think my amp will be powerful enough. it is 2ch 300w with 75w rms per channel. So I need th most I can get out of this amp, it will be bridged this time around.

<HR></BLOCKQUOTE>What subs do you have? You mentioned MTX 12" but is it the 3000, 4000, 6000, 8000, Road Thunder, etc. If you are only losing 2" with ported and are loking for SPL over SQ then ported is the way to go. If you have aome extra money, go with some aeroports. They give you a +3dB response (equivalent to doubling input power) over regular port tubes. The only prob is these can be up to $35 each ( <A HREF="http://www.partsexpress.com" TARGET=_blank>www.partsexpress.com</A> has them for pretty cheap) so if you decide to go with the regular ports, make sure you lengthen them correctly. Also, if I were you, I would definatly get a better amplifier. It is easier to blow a sub by giving it too little power than giving it too much power. If you are running 2 8000 DVC's then you will want at least 400W to each sub. If you are running 6000 then about 250-300 to each sub. 75 watts per channel is not even close to enough power. I would go with a nice d-class MTX amp, or maybe the Kenwook eXcelon 401 amp. Those should give you the power you need to get kick a-- bass.[ March 28, 2002: Message edited by: VizualXTC ]

Maddbuck · Post by **Maddbuck** » March 27th, 2002, 3:18 pm

they are MTX thunder4000 subs. I am thinking of bridging my amp for now. Can't afford a new amp just yet. if I do get a new Amp I would like it to run my four speakers and the the 2 subs or is it better to have one amp for the speakers and one amp for the subs? how would I go about running power to 2 amps?thanx

EvilSnot · Post by **EvilSnot** » March 27th, 2002, 5:41 pm

<BLOCKQUOTE>quote:<HR>Originally posted by VizualXTC: What subs do you have? You mentioned MTX 12" but is it the 3000, 4000, 6000, 8000, Road Thunder, etc. If you are only losing 2" with ported and are loking for SPL over SQ then ported is the way to go. If you have aome extra money, go with some aeroports. They give you a +3dB response (equivalent to doubling input power) over regular port tubes. The only prob is these can be up to $35 each (http://www.partsplus.com has them for pretty cheap) so if you decide to go with the regular ports, make sure you lengthen them correctly. Also, if I were you, I would definatly get a better amplifier. It is easier to blow a sub by giving it too little power than giving it too much power. If you are running 2 8000 DVC's then you will want at least 400W to each sub. If you are running 6000 then about 250-300 to each sub. 75 watts per channel is not even close to enough power. I would go with a nice d-class MTX amp, or maybe the Kenwook eXcelon 401 amp. Those should give you the power you need to get kick a-- bass.<HR></BLOCKQUOTE>You CANNNOT blow a sub by giving it too little power, ohms law dosent bend to the whims of common misconceptions. A woofer is basically a resister with a thermal power rateing, disrtortion (ala clipping) isnt a magical form of super power, it's just power reguardless of wave form or whatever the local mecp guy says, lol

(I don't mean to sound like a d---, but this is a very common misconception.

) If you trully want more bass for your buck, a ported box is the way to go. Aeroports are snazzy and all, but quite franky a +3db is a bit of strech...I personally perfer a standard slot port w/as much surface area as I can afford to spend, lol! Don't believe the hype that port boxes sound "slopy" (well...some do...hehe), I've heard an OZ matrix in tunned box +-3db @ 28hz, and I'll tell you i've yet to hear it's equal, ungodly brutal and beautifully responsive! If your handy, or at least feeling like a project, a well made 4th order bandpass would probably give you around the maxium output possible with your current equipement, if your intrested, shoot an email with your what equipment you have (all i need is a model number) and how much room you have to work with (if it's an mx3, i already got you covered, lol!) and i'll fire up some measurements that you'd need for maxium output for music listening (which i'm assuming you want!, lol!) Good Luck!

Spetznaz · Post by **Spetznaz** » March 28th, 2002, 1:40 am

Right on, somebody else running MTX. I've got two 12" Thunder 6000's running in a sealed box. I've got them bridged off a (I think, without looking at the amp) MTX 4405 amp (5 channel), so only about 300 watts to the subs, no rear fill. With that box, I still have room for my army stuff in the back part of the trunk thats left. I've also hit about 141 Db with no tuning. Lots of punch, and some drawn out bass, although not like a ported box.

VizualXTC · Post by **VizualXTC** » March 28th, 2002, 3:38 am

<BLOCKQUOTE>quote:<HR>Originally posted by Maddbuck: they are MTX thunder4000 subs. I am thinking of bridging my amp for now. Can't afford a new amp just yet. if I do get a new Amp I would like it to run my four speakers and the the 2 subs or is it better to have one amp for the speakers and one amp for the subs? how would I go about running power to 2 amps?thanx

<HR></BLOCKQUOTE>The best thing is to have 2 seperate amps. One 4 channel and one 2 or 1 channel to run your subs. If you have a deck with 3 sets of RCA preouts, then there should be one specifically for your subs. If you only have 2 then one is rear and one is front. If you only have 1 then it uses both front and rear. Here is the aeroport site. It's $17.50 each for the 4" and it describes them on the link. <A HREF="http://www.partsexpress.com/pe/showdetl ... 7122&DID=7" TARGET=_blank>www.partsexpress.com</A> And EvilSnot, it IS possible and even more likely to blow a sub running too little power. Tested and proven. I'd love to know where you get your info kid.[ March 28, 2002: Message edited by: VizualXTC ]

EvilSnot · Post by **EvilSnot** » March 28th, 2002, 7:11 pm

Here, you can start with these couple threads, and then I posted a bit heavier reading on the bottom. Careful who you call kid, some us actually know what we're talking about and can back it up. <A HREF="http://www.carsound.com/ubb/ultimatebb. ... 2;t=001611" TARGET=_blank>http://www.carsound.com/ubb/ultimatebb. ... =001611</A> : David Novone sums it up here pretty simply <A HREF="http://www.carsound.com/cgi-bi ... 748&p=</A> here's Richard Clark also saying the same thing <A HREF="http://www.carsound.com/ubb/ul ... 002442</A> David Novone once again <A HREF="http://www.carsound.com/ubb/ul ... 012159</A> Post that makes fun of posts like this <A HREF="http://www.carsound.com/ubb/ul ... 009576</A> And this one here is basically required reading Here's a couple sites you should visit if your still intrested: <A HREF="http://www.rane.com/pdf/note128.pdf" TARGET=_blank>http://www.rane.com/pdf/note128.pdf</A> : mostly on issues of compression <A HREF="http://ohmslaw.com/" TARGET=_blank>http://ohmslaw.com/</A> : POWER IS POWER!!!!!! Termpro.com (sorry I can't remember the exact thread, but theres a great one by wayne harris that goes a bit into the subject too!, that, and this THE site for car audio. None compare to the amount of knowledge that place has.)And to how i got "my information" I was a db drag "kid" back in the day, and spent a good portion of my college enrolled through SVSU's electrical engineering program. Untill I lost intrest in it and switched to computer information systems. Enjoy![ March 28, 2002: Message edited by: EvilSnot ]

Maddbuck · Post by **Maddbuck** » March 28th, 2002, 8:10 pm

thanx for the info decided to go with ported anyways. it will be worth the experience and if it sux I'll revert the the sealed design. basically I figured ported will help with the lack of amp power a little bit. I ordered all the nick nacks for the box now just need to go get MDF and construct it. will let ya'll know how it turned out.

loudsubz · Post by **loudsubz** » March 29th, 2002, 2:06 pm

Too Little Power: As you have probably heard, some people say that too little power can blow speakers. Well... How can I say this... BULL S*** Too little power will only cause the maximum output level to be low. Abuse and the defective 'wing nut' (an idiot) connected to the volume control blow speakers with low powered amplifiers. If driving a speaker with low power would cause them to fail, speakers would fail every time you lower the volume on the head unit. I will try to explain what happens when speakers are driven with clipped signals but remember... you get what you pay for.

Damaging Woofers: When a woofer is driven with a high powered amplifier to high levels, there will be a significant amount of current flowing through the voice coil. Since the voice coil has resistance, there is a voltage drop across the speaker's voice coil (which the amplifier appreciates greatly

. This means that there may be a great amount of power being dissipated (in the form of heat) in the voice coil. When a speaker is driven with lots of clean power, the cone moves a great deal (in proportion to the output voltage from the amplifier). For speakers with vented pole pieces, this movement forces a lot of air to flow in the magnetic gap (area where the voice coil rides). When the woofer moves out of the basket, the chamber that's under the dust cap and around the voice coil expands which pulls cool air into the magnetic gap. When the woofer moves the other direction, the chamber size is reduced and the hot air is forced out of the vent in the pole piece. This air flow cools the voice coil. If a relatively low powered amplifier is driven into clipping (to a full square wave for a lot of people), a relatively large portion of the time, the voltage delivered to the voice coil no longer resembles a sine wave as it would with an unclipped signal. While the amplifier's output is clipped, this voltage may be considered to be DC. No matter what you call the clipped part of the waveform (DC, not DC...), the voice coil is not being motivated to move as far as it should for the power that's being delivered to it and therefore is likely not being cooled sufficiently (since the speaker is driven by a linear motor, the voltage applied to the voice coil determines how far the voice coil moves from its point of rest). At points a, b, d, e, f and h the voltage is changing causing the voice coil to move in the gap and therefore pull in fresh cool air. At points c and g, the voice coil may still be moving a little due to momentum but may not be moving enough to cool properly. Remember that during the clipped portion of the waveform current is still flowing through the voice coil. Since the displacement of the voice coil (and therefore the airflow around the voice coil) is no longer proportional to the heat being generated, the voice coil can overheat. This excess heat may cause the voice coil former to be physically distorted or melt the insulation off of the voice coil wire (especially if the speaker is rated to handle no more than the power that the amp can produce cleanly).taken from : <A HREF="http://www.eatel.net/~amptech/elecdisc/2ltlpwr.htm" TARGET=_blank>http://www.eatel.net/~amptech/elecdisc/ ... .htm</A>[ March 28, 2002: Message edited by: loudsubz ]

EvilSnot · Post by **EvilSnot** » March 30th, 2002, 6:50 pm

<A HREF="http://www.eatel.net/~amptech/elecdisc/" TARGET=_blank>http://www.eatel.net/~amptech/elecdisc/</A> Is a very informative site, thanks for the reminder of it's location. Fatal flaw though in that entire argument (not sure if your agreeming with me or disagreeing, lol) is that when a amp is driven into clipping, your spl always increases. If the cone movement slow, so too whould the displacement, and hence no gain. There's a reason for his disclaimer (you get what you pay for). Read the threads I posted above, they arent just written by "some guy" with alot of info. [ March 30, 2002: Message edited by: EvilSnot ][ March 30, 2002: Message edited by: EvilSnot ]

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Ported or sealed Sub Enclosure

Ported or sealed Sub Enclosure

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