X-Max Factor-Which would move more air?

[Triticum Agricolam]

If you are looking for an easy way to compare subs, there isn't one. That doesn't mean you can't make informed decisions though. I'm on my phone right now but I can expand on this more later. 

[ShadeTreeMechanic]

In order to know what would be louder in a vehicle, you would have to be able to take into account the size of the vehicles cabin. And the configuration of the subs in the box will be different. Too many variables. I would bet that they won't sound the same tuning wise. I would bet the lower x max 12s would have a higher F's and the output curve would peak at a higher frequency. This may compliment the cabin gain better. Or it may not.

[Chase Wallace]

Ok, I'm following both of you so far I believe. I've seen a video showing how a sub acts at the port frequency vs how it acts in a sealed box. I think the video was even slowed down to show the excursion better and it demonstrated what Trit said. I also understand that different vehicles will respond differently. I've noticed some vehicles get a lot louder with a lot less. What I don't really understand is how to guess which would be louder in which vehicle. I went through a few systems in my 2001 Camaro SS back a long time ago and all of them seemed much louder reflecting off the back hatch than similar systems or even the same after I sold it to a friend and installed it in his truck. From my perspective that vehicle just got louder with everything so I don't really understand how that would help me choose a particular sub.

36 minutes ago, Triticum Agricolam said:

If you are looking for an easy way to compare subs, there isn't one. That doesn't mean you can't make informed decisions though. I'm on my phone right now but I can expand on this more later. 

Thanks man, I would highly appreciate the insight when you get a chance. I'm not trying to build an all out SPL setup and I'm trying to figure out what would work best for my truck which I should be able to fit two 15's or four 12's in. I should have around 4500 RMS to put to either combination. Really though I would like to understand why one setup should be better than the other instead of just being told what should be louder. I mean I want to know but I also want to understand why and be able to make informed decisions in the future. I used to install car audio for a small shop when I was a teen and would like to get back into it with my own small little shop one day so I really want to be able to make the best informed decisions as you say.

[Chase Wallace]

Please come back and share your knowledge with me =(

[Triticum Agricolam]

On 1/16/2017 at 7:10 PM, Chase Wallace said:

Please come back and share your knowledge with me =(

Sorry, I intended to get back to you but I'm forgetful and easily distracted.

So the first thing to keep in mind when comparing subwoofers is most subwoofers are more alike than they are different.  Assuming you are using the same box specs and input power two different subwoofers are more likely that not going to perform very similarly.  You may see a 1 db difference in output between two subs, but that's inaudible and unless you are completing, its irrelevant.   Similar performance between similar subs is usually the case, there are always exceptions though, using box simulation software (such as WinISD, BassBoxPro, etc) can help you identify when that may happen.  

 

[Chase Wallace]

1 hour ago, Triticum Agricolam said:

Sorry, I intended to get back to you but I'm forgetful and easily distracted.

So the first thing to keep in mind when comparing subwoofers is most subwoofers are more alike than they are different.  Assuming you are using the same box specs and input power two different subwoofers are more likely that not going to perform very similarly.  You may see a 1 db difference in output between two subs, but that's inaudible and unless you are completing, its irrelevant.   Similar performance between similar subs is usually the case, there are always exceptions though, using box simulation software (such as WinISD, BassBoxPro, etc) can help you identify when that may happen.  

 

It's no problem, I figured life happened and you would eventually come back. I'm just very excited about get obsessive about trying to learn things.

Similarly built subs performing similar given all else is the same sounds logical but I suppose the frustrating thing for me is that I don't know enough about T/S parameters to really say two subs are very similar. The examples I gave were comparing mid range 12's to two higher end 15's on the same power. Maybe it was a bad idea to try to compare the two before having a better understanding of everything. I've read a lot more about T/S parameters since I made this post but there are still things I'm just unsure about. I've been modeling different setup's using WinISD beta and I'm probably over looking it but to me it seems to show the gain and slope of two different setup's from a baseline that is useful when designing a box and changing how it sounds but without knowing the baseline I'm not seeing how I can know which setup should be louder. For example the four 12's vs two 15's comparison had both setup's gaining about the same amount at peak but the four 12's did not roll off that peak as fast on either side. The four 12's looked like the clear winner yet the two 15's have the ability to move the most air when Xmax is factored and had a significantly lower Fs. I'm wanting to get as loud as possible on music and love super deep lows so the much higher Xmax, higher displacement, lower Fs 15's seemed like the better choice. Conflicting conclusions really frustrate me!

[Triticum Agricolam]

Exactly which two subs are you comparing?  I'd be more than happy to help you interpret the WinISD results, I just need to know what you are working with. 

Sounds like you are still caught up on Xmax.  Unless you are going to be pushing the subs to their mechanical limit, the greater Xmax of one sub over the other means nothing, NOTHING!!  With ported subs "moving air" isn't a function of cone excursion.  It has a LOT more to do with box size, tuning, and input power.  

[Chase Wallace]

9 hours ago, Triticum Agricolam said:

Exactly which two subs are you comparing?  I'd be more than happy to help you interpret the WinISD results, I just need to know what you are working with. 

Sounds like you are still caught up on Xmax.  Unless you are going to be pushing the subs to their mechanical limit, the greater Xmax of one sub over the other means nothing, NOTHING!!  With ported subs "moving air" isn't a function of cone excursion.  It has a LOT more to do with box size, tuning, and input power.  

I'm not really still caught up on Xmax. I was saying from what I understand the higher Xmax, lower Fs, and lower box tuning would all be factors that would allow the two 15's to play louder down lower. The subs I was comparing were Sundown SA-12 v3's to Sundown X v2 15's. The four SA-12's and two X-15's have the same overall power handling and nearly the exact same box size requirements. I had ordered a Sound Magus 3.5k but it was back ordered so I canceled and picked up a Twisted Sounds 3.5k so I should have around 4500rms to play with now. My sub plans however I think might have changed as I want to try to model four DC lvl 3 18's in a blow through because I'm trying to keep a rear seat in an 2000 Chevy extended cab 1500. I had box/seat design that would have given over 12 cf but to get the port area needed the port would have had to be too long and skinny so I'm basically tossing that idea and planning to see if I can mock up four 18's in a clamshell like blow through around 25cf with a big slot port built into the bottom of the seat or a couple huge aeroports if the length isn't too long like I imagine it will be.

I made this thread to try to better understand and compare different drivers. That's why I thought it might be best to have separate post. I didn't want the discussion to just result in "well this combo will surely be loulder" without an explanation of why. I want to build a better understanding that I can apply in the future and not just to my specific goals in one build.

Here is the link to the other thread where I tried to mock up everything in WinISD beta :