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Old 10-01-2009, 01:05 AM   #1
CarAudioNut1

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4 12" subs or 2 15"

I know about that the box size makes difference and everything makes a difference but if the recomended sizes were correct what would be better on a 1500rms at 2ohm amp? 4 12" subs ported or 2 15" subs ported to the same specs and all that.

Alot of people say surface area is best. But then again the 12"s wont have the excursion that the 15"s will have due to it going to 4 12"s over 2 15"s

Idk ive been sub shopping for the past full week everyday when I get home from work. I get put down by type Rs , thinking about diamond audio subs or kicker squares (owned the l7s before but had bad sq)..

Hows 2 15" L5 kickers sound with a big ported box?

I have $400.00 for subs and just wanted to know whats the most pound for my buck.


Ive even found these valor 12" 500 watt subs for $25.00 each which means I could pound out 16 of those suckers.But worry about 16 subs all the time working %100 would be hard. I bet that 3 of them would not work out of the box But tell me that wouldnt be a show suv. Would that be louder than 2 15's? lol im so lostttt
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Old 10-01-2009, 05:03 AM   #2
Rare177

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how speakers work is simple physics, they move air at certain speeds which results in a frequency being created, 50hz = 50 strokes per second.

now the larger those strokes the more air that is moved, this results in more output.

so while choosing subs for output, you want ones that displace more air than the other sub.

there's a few ways to work this out, first look at the SD of the driver, this is the surface area..

a 12" has an SD of about 500cm2, and a 15" has about 800cm2

now, 2 12s are going to have 1000cm2, 2 15s 1600cm2, simple maths yeah??

there's more to it than this though, you need to calculate the distance the sub will stroke from a given power, this is tricky..people supply us with a spec called xmax, this is the linear distance the sub will stroke in mm.

so one could calculate total displacement by xmax * sd, who ever comes out on top displaces more air, but there's another problem here, xmax can be measured in many different ways, some measure it at a 70% change to the subs magnetic force, some measure it as the total distance the sub can move, and some measure it based on the size of the top plate and the coil..

also, if you look at SPL subs, they tend to not have alot of Xmax, this is because they rely more on a higher magnetic force (BL), as usually frequencies used to burp SPL are that high the distance of a stroke doesnt matter, for example..an 80hz tone will move very little compared to a 30hz stroke, so in this case an SPL sub with 12mm xmax is still going to be plenty loud from say 50hz and up..

some monster SQ or what some call SQL subs can have an xmax of 30mm+, they are designed to play lower frequencies well and get loud doing so, but most times they lack BL to get very loud on the higher freqs.

lets take a look at a sub i recently bought, the critical mass UL12, it's an SQ sub that can take alot of power.

now, xmax for the driver where BL changes 70% is about 36-38mm, this is ALOT, but xmax based on the top plate and voice coil is only about 32mm xmax...

also, this sub has very low BL, i think the BL is about 11, lower the number the less motor force the sub has, alot of SPL subs have a BL up around 30 or so..

now due to so much xmax this sub will be very loud on lower frequencies, but due to its lack of motor force it relys on alot of power to the voice coil to make it move well up high or any where for that matter..

we could probably take a 12" SPL sub, burp it at 80hz with 1000 watts and it will be louder than this with 2000 watts at 80hz.

play some lower freqs say 30hz, the ul12 will do much better than the SPL sub, so really its hard to say whats going to be louder here, i say the UL12 over a wider range in the substage frequencies..

so here if we go sd * xmax, this ul12 is obviously going to displace alot more air than most SPL subs, but does this mean it will be louder? depends on your listening range.

some programs like winisd, will tell you how far the sub will stroke from a given amount of power, this may be a better guide to help rather than looking at xmax, as alot of subs wont hit xmax..

for example the RE XXX, it has 54mm xmax but it will probably wont see even half of that from the RMS power.

its really hard to say whats going to be louder, but simply put 4 12s have more cone area than 2 15s, depending on a few things the 15s can be louder, they may be more efficient from a given power, meaning yes they can be louder, but once again this is hard to tell by just comparing "4 12s to 2 15s" when we dont even know whats being compared.

and as far as how will 2 L5s sound, about as bad as your L7s, stay away from kicker if any form of clarity at high outputs is your goal, any sub can sound nice on moderate levels, but seeing as you didnt like the L7s thats a big no to the L5s from me.

now that i've covered a few things off about subs, ill try explaining a more important factor, the box + install.

a box for a sub has 2 purposes, to keep the sound from the back of the sub away from the front of the sub, they both are out of phase with each other and will cancel each other out, or in case of a vented box, it uses the back sound with the front sound to give more output, box's are more than that though, they also dampen the driver so it does not bottom out, a smaller box is going to dampen a driver more, a larger box less, its simple really, the air from the back which ends up in the box paddens the sub when it moves back in..

now if you have a small box, you obviously have alot more air compressed inside the box, meaning when the sub strokes back in, its not going to stroke in as far due to the restricted airspace, this can restrict the subs excursion and distance it strokes, this is why a larger box is louder as a rule, it has less damping and the sub can stroke inwards more, meaning more outward movement, so keep in mind your box is just as important as the drivers, if not more important.

the next thing is your cars cabin gain, i've had 4 12s in a sedan and it was not as loud as a single 15" i had on my back seat, reason for this is because the 12s were in the trunk, and alot of pressure was escaping through the trunk lid, aswell as there being more airspace for the sound to move through than when i had the 15" on the back seat.

this is one reason why little cars like hatchbacks are so loud, they're small..

the science to it is also quite simple, when a sound wave has to move in an area less than the length of the wave itself (yes sound waves have a length) it gets a boost, this is called the cabin gain, this is also why sub bass frequencies are louder compared to the highs that come from your tweeter, tweeters play very high freqs that arent long.

now sometimes putting in more subs can effect cabin gain, 4 12s in a sedan did, the sound couldnt freely get into the cars front cabin and the box was far too huge for the space it was in..

so dont be fooled by more subs always being louder, its not..

in terms of SPL competitions, people tend to use small cars due to the smaller cabin, this gives more cabin gain and in term makes your sub bass louder, this is the most important part of getting loud, the average cabin gain is a good 10-20db ontop of what the sub would be in an open enviroment, thats ALOT.

another thing that can cut down output is flex, flex allows air to escape the car, the more pressure build up in the car the more output.

look at the world record car that did 180db with 1 sub, sure it was a great sub used with alot of power but the car played a bigger part, very small car, cemented inside to stop flex, reinforced windows that didnt flex, and the doors were all braced in so they didnt flex out, he did a very good job at making sure all the pressure stayed in the car..

any way i was bored while writing this and forgot half the things i said while writing it, hope it makes sense and hope it clears things up for alot of people, seeing as whats louder is always a big topic.

feel free to question anything i said, as stated i rushed this and forgot half of what i said while writing, so i expect there to be some mistakes etc, or things ive missed.
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Old 10-01-2009, 05:33 AM   #3
CarAudioNut1

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Wow thats a ton of information that has been cleared up for people. I do know that the l7s were loud as hell in spl but sq was garbageee.

Thanks so much for taking the time to write all that good info. No one cares about the spelling and grammar , this isnt a school class.

Do you recomend any 15" or 12" subs to buy? I have about $400.00
Im getting a kicker 1/0 awg wire kit in a few days for $100 on sale. Im doing the big 3 also. Umm and an extra battery.
Like I said I have about a 1550rms amp CEA rated rms.

How do you think this 15" sub would do..

http://www.powermaxelectronics.com/p...92&idcategory=

Or recomend some others around $400
I really do want either 2 good 15" inch subs or 4 decent 12"s

Its also going in a 2 door blazer which is great for a big ported box tuned correctly.

There are sooooooo many combinations of subs I can do I have about 40 saved into my favorites folder and have no damn clue whats the best bang for the buck.

PS: I know what ohm sub to look for and wiring down to 2ohm to get the most out of my mono block amp , just to clear that up

Last edited by CarAudioNut1; 10-01-2009 at 05:39 AM.
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Old 10-01-2009, 05:39 AM   #4
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i wouldn't go with the sub you posted but thats me, i cant give negative feedback on it as i've not used it.

i would go 2 15s.

simply because 2 $200 woofers are more than likely going to sound better than 4 $100 woofers.

now if you can afford an extra $120, i would without a doubt get 2 15" Fi Qs, they have great SQ and 2 15s is going to have nice output, it wont be as loud as the L7s but it will blow them away in sq..

https://ssl.perfora.net/www.ficaraud...iew.shopscript

i can't really think of too many decent output SQ drivers that are 15"s in your price range, the Fi Q is probably your best bet.
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Old 10-01-2009, 05:40 AM   #5
CarAudioNut1

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Im not looking for a sq sub by all means. Im more interested in spl but not as bad as a kicker l7 or l5. Those are about as low as it gets with bad sq.

Cant really afford those subs right now. Plus the rms rating is way too high to be compared to a 1550rms amp its about 500rms off of those and plus I wont be getting 1550 rms out of my amp . Theres some free space within there . Prob a true 1300rms.

I do love those subs though allways have.

Last edited by CarAudioNut1; 10-01-2009 at 05:44 AM.
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Old 10-01-2009, 05:53 AM   #6
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you do not need to feed a sub its RMS power, infact its better to always feed a sub less if the signal is clean and not clipped.

the more power you give a sub the more power compression there is on the coil, this will create more distortion and a rise in resistance, RMS is just a safe level that the sub can play music at before power compression gets too bad, it would do fine from little power..

2 of these would do nice from your amp, is your amp 1ohm stable?http://www.soundsolutionsaudio.com/s...on-Series.html
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Old 10-01-2009, 06:20 AM   #7
CarAudioNut1

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2ohm stable amp. Ive never heard of those subs and there $70 over my limit with shipping. Most sites ship for free. And like you said you dont want to overpower them and they are 600rms each so I would be overpower them for sure at 1200rms.

I like sticking with fi ,re,diamond audio, soundstream,orion,memphis, cerwin vega, hifonics, ect ...

I dont really like risking the new name of a sub when bairly anyone has those to rate them. No offence its just how I buy things. They do look like monster subs but you get what im saying. Thanks for the recomendation though.

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Old 10-01-2009, 06:23 AM   #8
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the guy who makes those subs is one of the best sub designers going around, its just not a mainstream brand, i would take IA subs over anything you listed, all those bands you listed are actually pretty poor, Fi being the only one these days out of those i would recommend, majority of them are made in cheap asian build houses with cheap parts now, no love or care put into them..

you wont find better than the sub i listed in that price, it will get loud and sound nice doing so.
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Old 10-01-2009, 06:46 AM   #9
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Im not new to the game ive been doing systems for the past 9 years but this being my biggest and best one hopefully and I dont want to get a sub that needs 1-2 weeks to be made when ordered , I just dont trust that.

I never got into those underground subwoofers. Idk why I just dont trust them. Its like buying sneakers , would you rather have cozy ugly ones non namebrand or a big sqwoosh nike sign on the side.

Diamond audio and RE are good subs . My buddy has been beating a d315d4 diamond audio sub on 500rms for a year or 2 and It just pounds sooo hard and good sq. His every note crisp. He allways beat my 2 12"s .
I will do some reserch on that namebrand for sure and see if they last and are good. Thanks

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Old 10-01-2009, 06:53 AM   #10
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read what i said on cabin gain, my bet is your buddys car has a much larger cabin gain than yours.

RE subs are decent but i think over priced, diamonds quallity has gone down hill big time in the last year or so, they're now made in asian build houses.

subs are not shoes, compare this.

one of the best sub makers in the market hand building you a sub, or a bunch of asian guys in china building you a sub? what sounds better to you?

the asian guys dont care, they follow the design chart and rush through them, the american guy on the other hand though, he has years of experience, hes designed the driver, and he knows the driver reps his company..

and just for the hell of it, one can argue that the current top SQ and SPL drivers for under $1000 are both made by IA, the Warden for SPL and Flatlyne for SQ.

here's an example, the guy who wont last years word SQ title, has swapped out his $1000+ dyn subs for the $300 IA Flayline subs, thats how good IA products are.
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Old 10-01-2009, 07:27 AM   #11
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CarAudioNut,

You should go to AudioQue's website and read some of the stuff there. In my opinion you couldn't go wrong with an amp and sub combination from them.
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Old 10-01-2009, 07:36 AM   #12
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the only sub AQ really has to offer in that price range is the SDC, im sure it would suit his needs very well in terms of SPL/price ratio, but im not sure if the SQ will suit him.

maybe the L7s were receiving a clipped signal though, and thats why they sounded bad, hard to say but if this were the case im sure the SDCs would do him well with a clean signal.
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Old 10-01-2009, 01:05 PM   #13
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The l7s I had along time ago were underpowered alot. I was running a 1000watt newstyle lanzar amp (lmao) to 2 12" l7s
They bumped but I think they were clipping due to underpowering them. They just sounded like garbage but hit low notes and deep as to the point people refused to get in my car.

Now that I think about it I will have 1500rms going to 2 kicker 15"s L5s (match great) that it might pound pretty dang hard in my 2 door blazer. I think im going to go with those. If they dont do good I can resell them on craigslist for $50.00 less than I bought them for and start over. Im so sick of looking at subs , Its all ive been doing for 10 days now and I just want to get set up and build a box. Ive asked on alot of forums about the l5s and they all say they are the most pound for the buck but there sq just stinks. But if I build a box 3.0 square feet each I think the sq might be decent as that is the minium for a L5 15" ported each.

Unless anyone else can recomend a subwoofer on sale that is better? I so wish I could get those Fi subs that you recomended I know im going to end up buying those so I should just save up some more for awhile. But then again you said the L5s 15" would hit harder. Thats what im looking for.

Idk im going insane here

Id love 4 12" subs for a $100 a pop on sale .
All diff sites,reviews,shipping costs, warrentys, costs, ohms. Is really getting to me lol
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Old 10-01-2009, 01:15 PM   #14
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look into 4 12" Type Rs if you love that idea so much, can get them around $100 on ebay.

you need to get this idea of RMS matching out of your head, in most cases, a sub rated at 1500 watts is going to perform much better with 500 watts than a sub rated at 500 watts.. reason being is theres going to be alot less power compression on the 1500 watt sub, but ofcourse this comes down to how efficient the subs are.

my guess is you were clipping the signal to the L7s, how was the gain set on the amp?

i've heard both the L7 and L5, the L7 sounds better.
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Old 10-01-2009, 02:46 PM   #15
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Caraudionut : look for the SSA Xcon at soundsolutionsaudio.com.
This sub will kill your Kickers.
I had Kickers S15L7 : the 2006 model and after, the 2008 one. They were loud and getting low, but they need a huge sealed box to do so.

The ssa are wonderful woofers : I run a 15" Icon in a ported box, and I looooove it way more than the Kicker. One of my friend had a 2008 S15L7 too, and now he runs a 15" Xcon : it's day and night!!! It's incredible, so accurate, so powerful!!!!!!!!!!!
I tell you : you think the Kickers were playing low? The SSA will outperform them by far.
But Incriminator audio, Fi (the bl for you, not the Q), DC audio, Sundown, they all makes great products that you will like a lot more than the Kickers.

With mainstream sub, you pay all the marketing, and all the re-sellers.
With the brands I listed you buy in the hand of the owners !!! Take a look at the ssa shop / site / forums. (soundsolutionsaudio.com)
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