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The assumption is made here that displacement is directly proportionate to output.

http://www.caraudiocentral.net/forums/s ... post&t=835

This is not true.

There are *many* factors which dictate output... in a ported box, xmax means very little.

But... lets say even in a sealed box, where displacement would seem to matter more... what would make a sub with less XMAX be louder than one with MORE xmax?

Effeciancy.

One 12 has 12mm xmax, one has 26mm xmax... the 26mm xmax is WAY LOUDER right?

No... not if it takes the 12mm sub 400 watts to reach 12mm, and the 26mm 1000 watts to reach 12mm. Unless you have the pockets to power a high xmax sub in a reasonable size sealed box, its not gonna be worth it.

T/S params, freq response... all that stuff makes a big difference in how a sub will perform in a certain box... going by displacement alone is NOT a good idea!

In that case... how did my strokers EVER do a 151.1 at 48hz? How did they manage a 154.0 at 58hz? Only 1400 watts in a wall that was pushed back far enough so that i might as well have used a CRX... how did that happen with subs that cry after approx 10mm?

A well designed ported box.

THose subs may displace more than a a cheapy 12... but both 15's sealed playing a 30hz tone at full tilt would have been womped by the most modest of setups. WHy? Because they don't work for a shat in sealed boxes... thats how they are. One of my CVR 12's is louder sealed at a 30hz or so than both the strokers.

Of course, it is a public forum... opinions are welcome :)

did you come here to stir up stuff or what? when the "assumption" is made, especially one about the subject you brought up. its in the correct box...etc.. also a CRX is a hatchback.. the vehicle also has alot to do with it... the correct box will make a big difference in just something you throw together, also it will hit different decibles in a different vehicle, even with the same amount of power. i know where you are coming from, but you just joined this place... but if you were to have been here for awhile, alot of "assumptions" arent made without everything being taken into consideration. i mean its just like saying "yeah man you need 2000watts rms to be loud" what?!?! just about everyone here knows that, that is not true.

you guys are hostile... lol. I guess you are your post count here? Maybe I should spam it up so that I can be as smart as everyone else? Excuse me for not agreeing with everyone, and btw, you just said:

"Your right, but that doesn't matter because you don't have enough posts"

ANyway, I posted this here... because if you read that article, it would lead you to believe that displacement is all that matters. That is far from true, and it needs to be appended to allow for this. You can't go around deciding on your next setup by a manufacturers posted xmax rating... if that was the case, we'd all be running treo. THey post BS ratings.. but I suppose it doesnt matter.

And that boss 3kw amp really does 3500 with good voltage....

Just so you guys know, this isn't the most inviting forum.. and you are trying to get people to shell out 10 bux for "all Platinum Member Locations! Plus ability to have Avatars, and custom signatures."

My check is in the mail...

If someone would like to have a civilized discussion, that would be pretty sweet... I'm here to learn/teach... not to say everyone sucks that doesnt have X number of posts.

Good points!

Now to the context of the situation.

Now where does it say in that thread that total displacement is the end all be all figure to go by?
Where does it say its a sure fire method to be the loudest?
Where does it say that your application does not matter?

It simply says "what will have more potential", pure and simple. Its an easy concept to grasp- just like the Bang for Buck/ Super Sub topics. But it seems some people are unable to grasp simple ideas and need to turn everything into a debate- or assume there are underlying objectives.

It is a large deciding factor. So are the other TS specs as you have noted.
Everything is application specific, nobody here will argue against that. For the most part nobody here will argue against what you posted (Except the boss amp?) because it is true.

I just think your not on the same page as the rest of us. This is NOT a cut-throat forum like many others. If we are found to be wrong we admit it and move on. There is no deciet here either. We are up front and honest people. I sugguest you start taking what is said here at face value and stop assuming there is underlying objectives or someone is trying to set you up, as we are not.

The part I like is where you go on to rag on our forum. Remember you signed up here, you come here- we didnt force you. You are also free to leave whenever you want.

Now lets all get on the same page here and squash this beef!

this board is really just like any other boards i have been too, some of us are biased towards certain brands..etc..but once you favor a board like i have this one, all the others just seem... too different i guess, but just like all the boards there will be arguements, ive been in some with a few members, and vice versa.... but its ok, we get over it and start a new thread and what not.... this board is just like a relationship! i dunno, just stick around Speakerman and im sure you will like this place..

It's all in the application. If you're looking for a subwoofer that provides high SPL over a wide bandwidth, such as daily driven sealed box applications, then you'll want a subwoofer that offers high linear displacement and has a suspension designed to operate well in a sealed box. Most subs that fill the bill for that are designed to work well in a variety of enclosures, so you will choose based on what you like more so than what the subwoofer necessitates. If you're going for more extreme ported or bandpass applications (especially competition type enclosures), you'll need to choose based on how well your sub will work in a ported box, such as motor strength, suspension Q, surface area, and many other factors. There is just too many things to weigh out when determining SPL to post an "end all/be all" statement on what to look for in a sub, which is why Ryans tutorial above is very generalized (and he stated that). The majority of people visiting our forum aren't out for big monster SPL machines, they're just wondering what will sound good and get loud on the commute to work every day, in SQ type enclosures.

ok, let's see.
first, don't assume anything. if you want to do a scientific approach to a comparison, use a controlled environment where all factors are equal or at least measured against a control, and vary as few factors as possible when looking at two speakers side by side.

if we're going to ask about displacement, let's understand that both compared subs should be in the same box, or both in ideal volume boxes of the same order at least.
Then we come to environment. same car, same box position, etc.
Power should be the same to both drivers if we're going to compare them, or should be altered based on sensitivity to compare Xmax or displacement.
yes with the same power a 12mm and a 24mm Xmax sub may be about the same volume for output, but that 24mm xmax sub is usually going to have higher power requirements, and thus will reach greater excursion, thus displacing more air and thus resulting in a 'louder sub' in the end.
of course box order or type matters, as does power, sensitivity, motor control, vehicle cabin Fs, and plenty of other factors.
In the end, every variable has an effect on the final outcome, but with proper design, superior specs usually result in a superior sub.
Honestly, the right box and proper power and all of those factors should be assumed ideal if the installer has half a brain. It's when you get people doing installs who don't know what they're doing that you run into the biggest problems.

by the way, what was the point of this thread? are we looking for best SPL? best sound quality? what exactly are our goals? they were never clearly defined, and that's another fault in the approach to this query.
Personally I use a pair of RE XXX 12" subs in an aperiodic rear loaded enclosure in a car that's 17' long and 6' wide and made of pure old school detroit iron. The enclosure is entirely designed for SQ, but with ~1280wRMS to each sub from good class AB amps, it can get plenty loud if I want it to.
I do love the sound of the car's exhaust though.. it's such a shame to drown that out.

"Ever been asked what will be louder?

4- 12" Brand Z subwoofers or 10- 8" Brand D subwoofers?

Well thats take that question and reword it properly:

What will have more POTENTIAL?"

Leads you to believe "potential" = louder

When in fact... more xmax doesn't mean it will be louder.

If you were a noob and read that post, thats what you would assume, more potential = louder. You just need to explain that out better.

And even if a sub IS moving farther... it doesnt mean its louder.

wow im glad this is getting somewhere.

KikiTheCat wrote:if we're going to ask about displacement, let's understand that both compared subs should be in the same box, or both in ideal volume boxes of the same order at least.
Then we come to environment. same car, same box position, etc.
Power should be the same to both drivers if we're going to compare them, or should be altered based on sensitivity to compare Xmax or displacement.

This is where alot of issues happen when doing woofer comparisons... when you are dealing with a set of sealed box woofers, you can simply put them in box that approximate the same Q, and go from there.

But when you have a set of ported woofers... things get hairy. It will vary greatly from woofer to woofer, assuming the specs aren't very similar.

yes with the same power a 12mm and a 24mm Xmax sub may be about the same volume for output, but that 24mm xmax sub is usually going to have higher power requirements, and thus will reach greater excursion, thus displacing more air and thus resulting in a 'louder sub' in the end.

You can make a rule of thumb out of that, but its far from true in real life. Until you get into the very low frequencies... the big displacement woofers just aren't more useful than a more "common" woofer.

of course box order or type matters, as does power, sensitivity, motor control, vehicle cabin Fs, and plenty of other factors.

Yep, this is *all* that matters.

In the end, every variable has an effect on the final outcome, but with proper design, superior specs usually result in a superior sub.

Must not have ever used an H2... .heheheh

It's when you get people doing installs who don't know what they're doing that you run into the biggest problems.

This is why CVR's have such a bad rep... and even the mighty w7 falls into alot of crappy shop I just ripped ure pants off installs.

by the way, what was the point of this thread? are we looking for best SPL? best sound quality? what exactly are our goals? they were never clearly defined, and that's another fault in the approach to this query.

Just adressing the notion that more displacement = louder... this wasn't the only thread that lead in that direction. Seemed to be a misconception on the forum.

More displacement doesn't even mean more POTENTIAL in some cases.

Personally I use a pair of RE XXX 12" subs in an aperiodic rear loaded enclosure in a car that's 17' long and 6' wide and made of pure old school detroit iron. The enclosure is entirely designed for SQ, but with ~1280wRMS to each sub from good class AB amps, it can get plenty loud if I want it to.
I do love the sound of the car's exhaust though.. it's such a shame to drown that out.

with 2500 watts... i'd sure hope it could get loud!

THe real Q here is... are you even using all of the sub? Would another sub that is more effeciant not be louder? You are well within the limits of the XXX with that power, and I'm sure that was the idea.