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Discussion Starter · #21 · (Edited)
so no increase in SPL/low extension?
I took out one and that solved the flapping/chuffing noise they caused, and i got higher SPL & lower extension.

I'd consider putting some of the flaps back and seeing if that changes anything. don't want to big of a "port" or you can actually lose SPL
This thread has some good analysis regarding car ports and SPL:


I think you're right that there may be a sweet spot. I may have seen a 1-2db drop on my SPL meter after removing that access panel.
 

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This thread has some good analysis regarding car ports and SPL:


I think you're right that there may be a sweet spot. I may have seen a 1-2db drop on my SPL meter after removing that access panel.
great find!
the good news is there's proof that opening these vents up does make a difference 😂. i might be wrong that adding some of your flaps back would be the right idea.
if what they're saying is correct (smaller vehicles benefit from larger "ports"), then it might be better to open them all up 🤷‍♂️
 

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Discussion Starter · #23 ·
great find!
the good news is there's proof that opening these vents up does make a difference 😂. i might be wrong that adding some of your flaps back would be the right idea.
if what they're saying is correct (smaller vehicles benefit from larger "ports"), then it might be better to open them all up 🤷‍♂️
Thanks! That was my thought too. I may try to measure SPL with all 8 flaps on, only 4 on, and all of them off at one point to see if half of them on is indeed my sweet spot. I'd imagine that it would be dependent on the size of your sub and how much air it "wants" to displace.
 

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Thanks! That was my thought too. I may try to measure SPL with all 8 flaps on, only 4 on, and all of them off at one point to see if half of them on is indeed my sweet spot. I'd imagine that it would be dependent on the size of your sub and how much air it "wants" to displace.
i look forward to your results!

personally i'd feel wary of leaving them all open to nature/the elements. might put a mesh screen/carbon pre-filter over the ports after opening them up.
 

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Discussion Starter · #25 ·
i look forward to your results!

personally i'd feel wary of leaving them all open to nature/the elements. might put a mesh screen/carbon pre-filter over the ports after opening them up.
Tested with all 8 removed, and then all 8 covered and sealed with saran wrap (hurray for magnets!). Which was a PITA, I can barely use that stuff in the kitchen.

1db room gain with all 8 open. I'm going to leave them all off. I don't think I can get them back in anyways. Plus I left the car in the pouring rain this morning and both vents were bone dry afterwards.

281977
 

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Discussion Starter · #26 ·
One nice thing is that my gas cap is now almost completely silent, and with all the vents open, there's very little noise on the outside even with my volume cranked to 45. Bike rack doesn't seem bothered any longer. I was starting to insulate my 1UP, lol.
 

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One nice thing is that my gas cap is now almost completely silent, and with all the vents open, there's very little noise on the outside even with my volume cranked to 45. Bike rack doesn't seem bothered any longer. I was starting to insulate my 1UP, lol.
how do you suppose opening ports reduced all the rattle? I wonder if if reduced SPL at the resonant frequency of your bike rack 😂
 

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Discussion Starter · #28 · (Edited)
how do you suppose opening ports reduced all the rattle? I wonder if if reduced SPL at the resonant frequency of your bike rack 😂
I think the gas lid and pressure flaps were both causing component parts to vibrate. Like a cascading ripple all the way to the bike rack.

I would worry less about SPL, since at best it's only a couple of decibels, and make sure that when you blare some bass heavy music to 85% volume, nothing in particular is buzzing audibly. Take a close listen to the gas lid in particular.

ETA: Upon further reflection, I think that could make sense about the resonant frequency of the rack. Ultimately I think the relationship between music and pressure is such that you want to reach that sweet spot with max-ish SPL but the least amount of vibrations from components achievable.

Also ETA: Some of the rattle was reduced by dampening inside the lid mount. Damn thing still buzzes though. I'd say it might qualify as a design defect since I think the Bose sub can make it buzz like crazy on a stock 2021 sedan. It's low-key funny that a car with such advanced tech manages to F up the gas lid in so many new and creative ways.
 
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