port area for two cvr 15s

[imhungnurnot 9]

Hey, im about to build a box for my buddy and i wanna get around 4 cuft. per sub after all displacements. Again they're two cvr 15's. I was thinkin somewhere around 14 inches of port area per sub per cubic foot of volume and im planning on tuning the box around 35-38 hz.

so (14 x 4) + (14 x 4) = 112 inches of port area

I've build a ported box for an Fi Q15 and i had it tuned to 33hz but it sounded like it was tuned very low once it was inside of the truck. And i have read that when the box is intstalled in a vehicle the tuning frequency of the box drops about 5-7hz because of the resonant frequency of the vehcile? So im trying to account for this with this box i'm building now by tuning it higher to being with.

I just want to check and make sure that im going about this the right way. This is the first time i've ported a box for 2 sub's so i'm curious if i calculated my vent area correctly, and if any of you are wondering i'm using WinISD Pro Alpha to calculate my port length once i decide on port area and tuning frequency.

Thanks!

Edited December 5, 2008 by Im Hung N ur Not

[KU40 173]

No, the tuning frequency does not drop once you install it in a vehicle. Not at all. Tuning frequency is a product of box size, port area, and port length. That's it, it doesn't matter at all what vehicle it's in.

40-50 cubic inches per sub would be fine.

[imhungnurnot 9]

No, the tuning frequency does not drop once you install it in a vehicle. Not at all. Tuning frequency is a product of box size, port area, and port length. That's it, it doesn't matter at all what vehicle it's in.

40-50 cubic inches per sub would be fine.

Well I think, repeat "I THINK," that there is some factor that affects the sound. Maybe the area inside of the vehicle?

This guy i know has a tahoe and whatever he throws in it is loud and sounds good. Now i own a single cab and im havin trouble with getting the sound that i like, even with sealed box's. I know you're gonna say thats its because of box volume but i've put bigger boxs across my bench seat and then i put the same exact sub and box into the back of a car and it was louder. So what i wanna know if there is a way that i can optimize how loud a box/sub will be in a certain cab area by tuning the box in accordance to the cab area. I don't know maybe this makes no sense and i'm an idiot ha i've just always wondered about this!!!!!!!!!!!!! Thanks to anyone who can clear this up!!!!!!

[sound=vibration 34]

No, the tuning frequency does not drop once you install it in a vehicle. Not at all. Tuning frequency is a product of box size, port area, and port length. That's it, it doesn't matter at all what vehicle it's in.

40-50 cubic inches per sub would be fine.

Well I think, repeat "I THINK," that there is some factor that affects the sound. Maybe the area inside of the vehicle?

This guy i know has a tahoe and whatever he throws in it is loud and sounds good. Now i own a single cab and im havin trouble with getting the sound that i like, even with sealed box's. I know you're gonna say thats its because of box volume but i've put bigger boxs across my bench seat and then i put the same exact sub and box into the back of a car and it was louder. So what i wanna know if there is a way that i can optimize how loud a box/sub will be in a certain cab area by tuning the box in accordance to the cab area. I don't know maybe this makes no sense and i'm an idiot ha i've just always wondered about this!!!!!!!!!!!!! Thanks to anyone who can clear this up!!!!!!

ok what ur thinking of is cabin gain and frequency response... every car is different even if they are the same exact car.. they will have a different resonate frequency as well... if u are looking for a well all around sound it is best to have someone make a box taking in to effect ur cabin of ur specific car.. for me a nice ported box is fin between 30- 35 hrz for 15in cvr... i have owned some my self.. i think for what u are looking for you will get away with 32 hrz about 8 cubes after displacement and 112 or so sqin of port... should suit u well i think

[imhungnurnot 9]

No, the tuning frequency does not drop once you install it in a vehicle. Not at all. Tuning frequency is a product of box size, port area, and port length. That's it, it doesn't matter at all what vehicle it's in.

40-50 cubic inches per sub would be fine.

Well I think, repeat "I THINK," that there is some factor that affects the sound. Maybe the area inside of the vehicle?

This guy i know has a tahoe and whatever he throws in it is loud and sounds good. Now i own a single cab and im havin trouble with getting the sound that i like, even with sealed box's. I know you're gonna say thats its because of box volume but i've put bigger boxs across my bench seat and then i put the same exact sub and box into the back of a car and it was louder. So what i wanna know if there is a way that i can optimize how loud a box/sub will be in a certain cab area by tuning the box in accordance to the cab area. I don't know maybe this makes no sense and i'm an idiot ha i've just always wondered about this!!!!!!!!!!!!! Thanks to anyone who can clear this up!!!!!!

ok what ur thinking of is cabin gain and frequency response... every car is different even if they are the same exact car.. they will have a different resonate frequency as well... if u are looking for a well all around sound it is best to have someone make a box taking in to effect ur cabin of ur specific car.. for me a nice ported box is fin between 30- 35 hrz for 15in cvr... i have owned some my self.. i think for what u are looking for you will get away with 32 hrz about 8 cubes after displacement and 112 or so sqin of port... should suit u well i think

Ahh i see! I need read up on that! But keep in mind that this box is for a 1997 extended cab chevy 1500 so do you think 32hz will work well?

[sound=vibration 34]

No, the tuning frequency does not drop once you install it in a vehicle. Not at all. Tuning frequency is a product of box size, port area, and port length. That's it, it doesn't matter at all what vehicle it's in.

40-50 cubic inches per sub would be fine.

Well I think, repeat "I THINK," that there is some factor that affects the sound. Maybe the area inside of the vehicle?

This guy i know has a tahoe and whatever he throws in it is loud and sounds good. Now i own a single cab and im havin trouble with getting the sound that i like, even with sealed box's. I know you're gonna say thats its because of box volume but i've put bigger boxs across my bench seat and then i put the same exact sub and box into the back of a car and it was louder. So what i wanna know if there is a way that i can optimize how loud a box/sub will be in a certain cab area by tuning the box in accordance to the cab area. I don't know maybe this makes no sense and i'm an idiot ha i've just always wondered about this!!!!!!!!!!!!! Thanks to anyone who can clear this up!!!!!!

ok what ur thinking of is cabin gain and frequency response... every car is different even if they are the same exact car.. they will have a different resonate frequency as well... if u are looking for a well all around sound it is best to have someone make a box taking in to effect ur cabin of ur specific car.. for me a nice ported box is fin between 30- 35 hrz for 15in cvr... i have owned some my self.. i think for what u are looking for you will get away with 32 hrz about 8 cubes after displacement and 112 or so sqin of port... should suit u well i think

Ahh i see! I need read up on that! But keep in mind that this box is for a 1997 extended cab chevy 1500 so do you think 32hz will work well?

I WOULDNT SEE WHY NOT... NOW THAT DEPENDS ON WHAT UR LOOKING FOR... IF YOU ARE LOOKING FOR A FLAT RESPONSE YOU MIGHT WANT TO GO WITH SOME ONE WHO CAN DESIGN THAT FOR YOU... BUT IF YOUR LOOKING FOR A NICE DAILY BEATER BY ALL MEANS 32 HRZ WILL WORK WELLL... IM NOT SURE WHAT FREQUENCY IT WOULD PEAK AT OR WHERE THE RESPONSE WOULD START TO CLIMB AND ROLL OF BUT IT SHOULD BE FINE... THATS WERE I WOULD TUNE TO IF IT WERE ME

[KU40 173]

Yeah, cabin gain must be what you're thinking of. It generally boosts the lowend, like 30-40 hz. Those are also generally the frequencies that are loudest to the ear. If you want something that will sound loud on the low stuff, tune to 30-32 hz.

[imhungnurnot 9]

I see, well do any of you know of some good tutorials about cabin gain and frequency response that i could look into?

[KU40 173]

I've never seen a tutorial on cabin gain. It's different for every car though, so it would be hard to generalize. What do you want to know about it and frequency response?

[imhungnurnot 9]

Well, how is it calculated? and how is it used to optimize an enclosure for a vehicle?

[KU40 173]

it's not really calculated. Nobody says "Oh, I know I'm going to gain 3.5 db at 32 hz and 2.4 db at 39 hz from cabin gain, so this box is ok like this......" I mean you could measure your box's frequency response curve outside of the vehicle in an environment that won't affect the SPL readings, then put it inside the vehicle and do the same thing and compare the two graphs. But I've never seen anybody actually do that.

Normally it's just used as a generalization, and usually with sealed boxes. People get worried when they see that most sealed boxes have an F3 of 40 hz or so, but cabin gain usually increases the 30-40 hz zone so that the sealed box is fairly level from 30-80 hz or whatever.

You'll have to divulge more on what you mean by "optimize." That could mean a flat response curve to one person, maximum SPL to another person........

In the end, you'll never be able to construct a box that will even out every peak and valley that your vehicle introduces to the response. You'll have to EQ it if you want to do that.