Tuning freq for my 12W7

[efm80 10+ year member]

Those subs will not sound that good (my opinion) in a small ported box because there will be a response peak in the 40-50 hz region that coupled with the transfer function of the car will grossly exaggerate those frequencies. On the other hand a sealed box of the same size should couple nicely with the transfer function to play fairly flat all the way down into the single digit frequencies. Larger sealed boxes exercise less influence on the cone and thus the cone moves farther for the same amount of power and in a sealed box cone excursion is directly related to output. This becomes the most apparent at the lower frequencies where the cone must move the most for a given output level. The overall effect is that the larger sealed box is more efficient than a smaller sealed box at the lowest frequencies and thus the system response rolls off more slowly on the bottom end with a larger box. You would get some more output with the ported box but it won't blend with the rest of the system worth a **** and the W7 really are pretty freakin' loud sealed and just sound better set up that way in terms of transient response and tonality.

so basically the ported box would cause the W7's to really peak at around 40hz and sound really unbalanced compared to the sealed box which would play more like the song intended it to with less peak, and more flat from 20-80hz, right??? But I would get more db's from the ported box??? And to get more SQ out of a ported enclosure, you are saying it needs to be a bigger box or am I not following you?? Lastly would the ported box sound and hit deeper than the sealed? Thats always been the experience of mine with the two compared is that the sealed never sounded deep.

eddie

 

[efm80 10+ year member]

I'm with Heliotaxi, sealed is typically what an "audiophile will want (a Qtc of .707)
Here is what it will "probably" do (using my Ouija board!) in a typical vehicle (with the transfer function Heliotaxi was talking about)

Both will work just fine, the vented will be a bit of a "slammer" to it versus the sealed.

I will say that the vented will play 6 dB louder for FREE, or will sound like you have a 4 X more power on it versus the sealed.

Or lets say you have 500 watts on the whole woofer setup, the vented will sound like it has 2,000 on it.

Totally different sounding enclosures. Only you can pick.

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And if you want to play with subwoofer designs (computer simulations) go here:

http://www.linearteam.com (get the Pro version)

Its FREE! And has JL specs already installed. Cool huh!!!

I've modified it a bit to add the transfer function.

PM me if you want to know how to do. Super easy.

Have fun. And remember that we are here to help.

great info caraudioguru! makes sense. so why is it not right to get 6 FREE db's that the ported box would produce?? so basically sealed would just sound more like it is supposed to sound and how the artist intended it to? and if I did have my install guy would would be the exact specifications for the ultimate and ideal enclosure of each 12w7?

thanks

eddie

 

[CarAudioGuru 10+ year member]

There is NO perfect box. Nor is there the "optimum" box. Because of the ambient noise floor inherent in most cars -road noise transmitted thru the tires, into the body into the interior (more expensive cars have better sound dampening).

IF you drive around in a typical vehicle (lets say a Honda Accord, or Toyota Camry) you would see RTA curves with 20-30 dB of boost below 150Hz referenced to 1,000Hz.

I can tell you that because I do that test all the time to show retailers what is going on in vehicles.

And why they seem to have really good tight bass, evenly balanced while DRIVING, and then when you stop the bass is almost over powering the mids and highs.

You just need 20 dB more gain below 150 Hz to make it sound "flat" at least spectrally.

I mean, how many of your friends have 1000 watt 15 inch powered subwoofers at home in their "theater system"???

But how many guys do you know with 1000 watt sub amps for their cars??

Don't you think that is weird?? Not make sense???

Ambient noise field in cars is MUCH higher than at home, therefore we need more power , "gain" at low frequencies to compensate.

So vented tends to be my choice , just because of the free gain. Not totally "audiophile", but in normal systems, with normal guys, PERFECT.

IF you are hard core audiophile, I'd go sealed. .707 Qtc. A little "lean"sounding for most people, I think.

Cars are MUCH tougher to design subwoofer systems for than home. That is for sure.

 

[benchambers80]

There is NO perfect box. Nor is there the "optimum" box. Because of the ambient noise floor inherent in most cars -road noise transmitted thru the tires, into the body into the interior (more expensive cars have better sound dampening).
IF you drive around in a typical vehicle (lets say a Honda Accord, or Toyota Camry) you would see RTA curves with 20-30 dB of boost below 150Hz referenced to 1,000Hz.

I can tell you that because I do that test all the time to show retailers what is going on in vehicles.

And why they seem to have really good tight bass, evenly balanced while DRIVING, and then when you stop the bass is almost over powering the mids and highs.

You just need 20 dB more gain below 150 Hz to make it sound "flat" at least spectrally.

I mean, how many of your friends have 1000 watt 15 inch powered subwoofers at home in their "theater system"???

But how many guys do you know with 1000 watt sub amps for their cars??

Don;t you think that is weird?? Not make sense???

Ambient noise field in cars is MUCH higher than at home, therefore we need more power , "gain" at low frequencies to compensate.

Cars are MUCH tougher to design subwoofer systems for than home. That is for sure.

actually i have 2500 watts at home and 800 in the car...