want more bass? .... then open your sunroof!

[Notloud00 10+ year member]

thats cool, but i can drive up to about 50 mph and not even notice the roof being open.
sunroof > windows when you care about wind and road noise.

yea but with the sunroof open it sucks. it also changes the freq response of my system which i tuned to be played with two windows down.

 

[tcguy85 10+ year member]

yea but with the sunroof open it sucks. it also changes the freq response of my system which i tuned to be played with two windows down.

for you it does one thing, for me it does another. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[Notloud00 10+ year member]

for you it does one thing, for me it does another. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

lol but opposite door open>all

 

[tcguy85 10+ year member]

lol but opposite door open>all

hard to drive with the door open though //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif.

 

[HTOWNAL 10+ year member]

it doesnt make a difference in my yukon. if i crack the two front windows it does, but with the sunroof open, it sounds same as with everything closed

 

[dragnix 5,000+ posts]

it doesnt make a difference in my yukon. if i crack the two front windows it does, but with the sunroof open, it sounds same as with everything closed

just STFU

 

[bigbangtheory 5,000+ posts]

A lot is vehichle dependent and how you have your install, rather it is hatch, truck this or that.

Usually when I crack the windows I noticed a jump, but not much. I don't have a sunroof either.......anymore.

My one car I had walled off, I had a sunroof and couldn't tell due to it being fawking loud as shit rather it was sealed or open.

 

[Kyle_Keating 10+ year member]

this is just all room response theory. In fact, you REALLY dont want to role a window down or open a sunroof.. what that tells you is that you're mic (listening position) is in a Null and you have standing wave cancellation there. Its of course frequency dependant. Damping can help with a lot of that, but not really practical to put fiberglass all over the car... opening the window or the roof is actually the best form of dampening because its basically like 100% damping for that section of your car because the wave never comes back! Of course if you apply that theory to the entire car, you will have no car and your SPL will be a lot lower! the walls really do increase the SPL a lot so yo know when you're getting rid of the walls and your SPL is increasing..... you have some "room response" issues //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif trust me, every car has this problem.

There is also another phenomena that occurs. This one is a bit more interesting... the car can actually be treated like another box and a big one at that. when you crack a window or a sunroof you inertly creates a filter via resonator (i don't really know what type of transfer function it is, low pass or high pass), but the air in the car is the box and the surface area of the window is the port area of the resonator. the window thickness is the port length (not very thick) but because the air volume of the car is so large, you can still achieve a very low tuning and resonate the air mass in the car. the area of the window effectively becomes the piston for the subwoofer and it can indeed push a lot of air....when you find that resonance you can do something like a hair trick effect..... but when you realize all that is is a simulate port using the car... its much less impressive //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Rich B 5,000+ posts]

I have a very large sunroof.

Its a convertible.

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Not so good when its open though.

//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[dragnix 5,000+ posts]

I have a very large sunroof.
Its a convertible.

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Not so good when its open though.

//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

because when you open it, it's too big of a port

 

[Kyle_Keating 10+ year member]

ya, that pretty much becomes like a half-space room. lots of spl losses.

 

[Kyle_Keating 10+ year member]

in room acustic treatment they actually use things like car windows or sunroofs to filter the response, they are basically ports but they are called "bass traps" that work to filter out frequencies. they are tricky to design

 

[Immacomputer 10+ year member]

thats cool, but i can drive up to about 50 mph and not even notice the roof being open.
sunroof > windows when you care about wind and road noise.

100% agreed. My sunroof open allows no air in while driving no matter what speed unless another window is open (or if I have it cranked)

There is also another phenomena that occurs. This one is a bit more interesting... the car can actually be treated like another box and a big one at that. when you crack a window or a sunroof you inertly creates a filter via resonator (i don't really know what type of transfer function it is, low pass or high pass), but the air in the car is the box and the surface area of the window is the port area of the resonator. the window thickness is the port length (not very thick) but because the air volume of the car is so large, you can still achieve a very low tuning and resonate the air mass in the car. the area of the window effectively becomes the piston for the subwoofer and it can indeed push a lot of air....when you find that resonance you can do something like a hair trick effect..... but when you realize all that is is a simulate port using the car... its much less impressive //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

It's doubtful that it acts like a ported enclosure; do the math and you will find that the tunings aren't very consistent with the theoretical calculation given the area and depth of the sunroof. I think when I did the math on my car, with the sunroof open it should be tuned to about 40hz or something high like that but I'm getting resonance (high amounts of air movement) from 20-30hz. I think it acts more like a mass loaded transmission line does. The cabin of a vehicle is very much like a transmission line enclosure and mass loading the open end of a transmission line by obstructing its mouth with a small port will yield low resonance points and more consistent velocities of air around the two resonance points (line and air mass). I could be way off but it makes more logical sense to me than the ported idea.