Grocery Getter :: 2006 Infiniti fx35 awd
- Thread starter soonster
- Start date
Been following turbocad's advice in focusing on the weaker points when deadening. How to determine a weaker point? I look for the opened/flat/smooth panels where the sound/vibration can resonate the most. If a panel has lots of crimps and stamping, I would cut smaller pieces and cut weight. Certain areas I did use bigger cuts. The weight is always in my mind :smile (2):.
I'm sure Turbocad can explain it better. He should be online to comment :tongue (2):.
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You guys are on slightly different pages. Soon, you are addressing panel resonance specifically, which is probably the best option on the doors because thats where the speakers live. Andy's method is more geared toward sound insulation, which is better in places like the trunk and floor where the sound being blocked is outside the vehicle. Two different branches of the same tree. :balanced:
I'll try not to get too deep but explain a little bit.
the whole idea is to lower the "noise floor" or base background noise IE; road noise, in a vehicle traveling down the road. the noise floor is the level/volume of background "noise" you hear as your car travels down the road. noise comes from many different places. ALL noise originates as vibration, period. this is what "sound" is, vibrations, at many different frequencies.
the noise floor is created from many different sources at the same time, and they all add up to the level of background noise you hear. everything from the engine to the exhaust to the tires rotating on the pavement, and the other cars driving next to you, there engines and exhausts and tires, wind, etc... all a concert of thousands of sounds, thousands of vibrations.
there are 4 main ways to reduce noise in general, absorption, blocking or compartmentalizing, structural dampening and vibration isolation. to stop many of these vibrations/sounds from entering the cabin there are many ways to do it, most efforts in reducing road noise are centered around structural dampening and noise blocking.
many people confuse dampening with blocking. they are 2 different things but they do also kind of overlap in some ways. for example by dampening a panel, it does also make the panel itself a more effective blocker. to understand how dampening reduces noise transmission, one good way to illustrate this is by understanding how vibrations transfer sound.
I'm sure most of you have seen something like 2 soup cans spread far apart with a string stretched between them under tension. you talk softly into one can and someone on the other end can hear whats been said into the first can. what you're hearing is not the actual sound that came out of the persons mouth. it was spoken softly and you would not have been able to hear it directly from the distance between the 2 cans. what you are actually hearing is that sound transfered. the incoming sound vibrates the end of the first can, these vibrations are transferred to the end cap of the second can through the string under tension. what you are actually hearing is not the first persons voice at all, what you are hearing is just the bottom of the second can vibrating. the original sound has been transferred.
in the car most of the road noise you here is transferred sound. sound waves for the most part do not penetrate anywhere near as well as they they transfer. yes a small amount of sound can penetrate openings and vents and even the glass, but the bulk of the noise floor is made up from sound transfer in a closed vehicle. when you are hearing the engine and exhaust for example, assuming the windows are closed your really not so much hearing the direct sound made by the engine and exhaust, you are hearing the vibration of panels and parts of the vehicle. it sounds very much the same and you may think you are actually hearing the engine/exhaust, just as the soup can's bottom panel vibrating sounds very much like the voice input to the first can, but in reality it is not really the engine and exhaust you're hearing as much as it is the sound being transferred. you are hearing some from the glass and the body panels, floor and roof and other materials vibrating from the engine and exhaust. if you reduce some of these vibrations you will eliminate some of the engine and exhaust "sound". at the same time you will be blocking the transfer of sounds from all the other elements too.
to effectively dampen a panel really only takes ~25% area coverage. anything more than this winds up giving progressively diminishing returns... take a big open panel like an outer door skin. a skin like this can in a way act like a big speaker. instead of being driven by a voice coil though it is driven by sound waves imparted on it from all the external elements. just covering 25% of this panel with a good dampener can be ~70% effective in dampening the panel. covering 50% of the panel will increase this to maybe 76% effective, covering it 100% would increase it to maybe 80% effective.... add 2 more full layers on top of that and you may increase it to 88%. the point is that after a while you would wind up adding tons of layers just to be a little more effective. even in just single layer to increase effectiveness by just 10% takes 400% more material and weight. this is why you'll see that most factory panel dampening usually only covers ~25% of the panel. just a square sound dampening pad in the center of the panel does a lot, combined with other effective blocking and absorbing strategies is what gives you the Mercedes and Lexus ride quality.
a relatively heavy dampening pad like what soons using here is very effective at dampening but really isn't the best material to be used as a sound blocker. covering the whole panel 100% makes many think that it's blocking sound better but it's not nearly as effective in blocking sound as a much better suited and much lighter foam material would be. the point is it would be much less effective to cover the outer panel with 2 complete 100% layers of mat like this than it would be to just cover 75-80% as soon has done here, and then use one light weight foam sound blocking sheet between the door and the door panel. not only would the door with 2 full layers not be as effective but it will also be much more added weight. if weight is not a factor then hell, double layer everything and then also add sound blocking foam and really go nuts, but weight is a big factor as a trade off to performance so it becomes a balance of doing enough to be effective without adding too much weight.
another thing I'm not even going to get into too much here but should be mentioned is noise created by resonation. all things have a certain frequency that it will naturally resonate at. this can be most noticed in a car with a big sub as panels buzzing at certain frequencies but many panels and parts of the car can also resonate some just from various sounds imparted on it. dampening can be very effective in eliminating these sounds by lowering the resonating frequency of the panel to the point where it is no longer a problem but this is also a case where going overboard isn't necessary and also can get to the point of diminishing returns.
bottom line, use a dampening product to dampen and then use sound blocking padding to then further block this reduced sound transfer, don't try to use dampening products as sound blockers, after a certain point it is wasteful and inefficient and unnecessary to be effective.
---------- Post added 02-27-2012 at 10:33 AM ---------- Previous post was 02-26-2012 at 11:49 PM ----------
I recieved a good question in a PM and think it would be better for all if I answer it here because it goes with what's already been said:
question:
... I didn't want to "call you out" in the thread, but I remember seeing a picture of your old minivan, interior removed and covered top to bottom with the brown bread insulation. Whassup with that? :p
answer:
yeah, much of that was dual layered, doors were triple in some spots with some reinforcing spots even more and I also added sound blocking and absorbing materials on top of that too... that was an all out effort where weight was not really a concern. after a while I was adding a lot more material just for a little more gain but in the end it was still a gain. it's kind of like performance, it's real easy to get the first 80% out of it, but then gets progressively harder and harder to squeeze out more and more. to get the last 5% out of it can take huge effort and money and precision and testing etc, but when it comes to racing this last bit is what makes all the difference. point is that's the difference between good and competition level. that minivan was built as a competition system, I have 10" midbass drivers in the doors... it was not just adding some dampening for comfort, it was an all out effort to really deaden as much as practical.
if your planning a huge system and SQ is more priority than performance then more dampening and blocking makes sense BUT it also comes down to the weakest link too. in other words it would be way more effective to cover ALL the panels in a vehicle 80% single layer than it would to just cover the easy parts with excess like double layer+ double layer only really starts to make sense once you've already decided to cover everything, roof to floor to firewall etc... and want to really try to maximize your effort, but again, you will get to the point of adding a whole lot more for just a little more gain. also things will start to really get heavy, doors can start to sag and performance will start to suffer.
in the end, like all things, it is a trade off. I'm not really trying to say it's stupid to cover everything 100% and then some, just trying to point out that most efficient gain VS drawback does not require excess and in most cases on an ordinary passenger vehicle it isn't necissary to really go nuts and still get nice gains, the more you do past that becomes less and less gains but more and more weight
the whole idea is to lower the "noise floor" or base background noise IE; road noise, in a vehicle traveling down the road. the noise floor is the level/volume of background "noise" you hear as your car travels down the road. noise comes from many different places. ALL noise originates as vibration, period. this is what "sound" is, vibrations, at many different frequencies.
the noise floor is created from many different sources at the same time, and they all add up to the level of background noise you hear. everything from the engine to the exhaust to the tires rotating on the pavement, and the other cars driving next to you, there engines and exhausts and tires, wind, etc... all a concert of thousands of sounds, thousands of vibrations.
there are 4 main ways to reduce noise in general, absorption, blocking or compartmentalizing, structural dampening and vibration isolation. to stop many of these vibrations/sounds from entering the cabin there are many ways to do it, most efforts in reducing road noise are centered around structural dampening and noise blocking.
many people confuse dampening with blocking. they are 2 different things but they do also kind of overlap in some ways. for example by dampening a panel, it does also make the panel itself a more effective blocker. to understand how dampening reduces noise transmission, one good way to illustrate this is by understanding how vibrations transfer sound.
I'm sure most of you have seen something like 2 soup cans spread far apart with a string stretched between them under tension. you talk softly into one can and someone on the other end can hear whats been said into the first can. what you're hearing is not the actual sound that came out of the persons mouth. it was spoken softly and you would not have been able to hear it directly from the distance between the 2 cans. what you are actually hearing is that sound transfered. the incoming sound vibrates the end of the first can, these vibrations are transferred to the end cap of the second can through the string under tension. what you are actually hearing is not the first persons voice at all, what you are hearing is just the bottom of the second can vibrating. the original sound has been transferred.
in the car most of the road noise you here is transferred sound. sound waves for the most part do not penetrate anywhere near as well as they they transfer. yes a small amount of sound can penetrate openings and vents and even the glass, but the bulk of the noise floor is made up from sound transfer in a closed vehicle. when you are hearing the engine and exhaust for example, assuming the windows are closed your really not so much hearing the direct sound made by the engine and exhaust, you are hearing the vibration of panels and parts of the vehicle. it sounds very much the same and you may think you are actually hearing the engine/exhaust, just as the soup can's bottom panel vibrating sounds very much like the voice input to the first can, but in reality it is not really the engine and exhaust you're hearing as much as it is the sound being transferred. you are hearing some from the glass and the body panels, floor and roof and other materials vibrating from the engine and exhaust. if you reduce some of these vibrations you will eliminate some of the engine and exhaust "sound". at the same time you will be blocking the transfer of sounds from all the other elements too.
to effectively dampen a panel really only takes ~25% area coverage. anything more than this winds up giving progressively diminishing returns... take a big open panel like an outer door skin. a skin like this can in a way act like a big speaker. instead of being driven by a voice coil though it is driven by sound waves imparted on it from all the external elements. just covering 25% of this panel with a good dampener can be ~70% effective in dampening the panel. covering 50% of the panel will increase this to maybe 76% effective, covering it 100% would increase it to maybe 80% effective.... add 2 more full layers on top of that and you may increase it to 88%. the point is that after a while you would wind up adding tons of layers just to be a little more effective. even in just single layer to increase effectiveness by just 10% takes 400% more material and weight. this is why you'll see that most factory panel dampening usually only covers ~25% of the panel. just a square sound dampening pad in the center of the panel does a lot, combined with other effective blocking and absorbing strategies is what gives you the Mercedes and Lexus ride quality.
a relatively heavy dampening pad like what soons using here is very effective at dampening but really isn't the best material to be used as a sound blocker. covering the whole panel 100% makes many think that it's blocking sound better but it's not nearly as effective in blocking sound as a much better suited and much lighter foam material would be. the point is it would be much less effective to cover the outer panel with 2 complete 100% layers of mat like this than it would be to just cover 75-80% as soon has done here, and then use one light weight foam sound blocking sheet between the door and the door panel. not only would the door with 2 full layers not be as effective but it will also be much more added weight. if weight is not a factor then hell, double layer everything and then also add sound blocking foam and really go nuts, but weight is a big factor as a trade off to performance so it becomes a balance of doing enough to be effective without adding too much weight.
another thing I'm not even going to get into too much here but should be mentioned is noise created by resonation. all things have a certain frequency that it will naturally resonate at. this can be most noticed in a car with a big sub as panels buzzing at certain frequencies but many panels and parts of the car can also resonate some just from various sounds imparted on it. dampening can be very effective in eliminating these sounds by lowering the resonating frequency of the panel to the point where it is no longer a problem but this is also a case where going overboard isn't necessary and also can get to the point of diminishing returns.
bottom line, use a dampening product to dampen and then use sound blocking padding to then further block this reduced sound transfer, don't try to use dampening products as sound blockers, after a certain point it is wasteful and inefficient and unnecessary to be effective.
---------- Post added 02-27-2012 at 10:33 AM ---------- Previous post was 02-26-2012 at 11:49 PM ----------
I recieved a good question in a PM and think it would be better for all if I answer it here because it goes with what's already been said:
question:
... I didn't want to "call you out" in the thread, but I remember seeing a picture of your old minivan, interior removed and covered top to bottom with the brown bread insulation. Whassup with that? :p
answer:
yeah, much of that was dual layered, doors were triple in some spots with some reinforcing spots even more and I also added sound blocking and absorbing materials on top of that too... that was an all out effort where weight was not really a concern. after a while I was adding a lot more material just for a little more gain but in the end it was still a gain. it's kind of like performance, it's real easy to get the first 80% out of it, but then gets progressively harder and harder to squeeze out more and more. to get the last 5% out of it can take huge effort and money and precision and testing etc, but when it comes to racing this last bit is what makes all the difference. point is that's the difference between good and competition level. that minivan was built as a competition system, I have 10" midbass drivers in the doors... it was not just adding some dampening for comfort, it was an all out effort to really deaden as much as practical.
if your planning a huge system and SQ is more priority than performance then more dampening and blocking makes sense BUT it also comes down to the weakest link too. in other words it would be way more effective to cover ALL the panels in a vehicle 80% single layer than it would to just cover the easy parts with excess like double layer+ double layer only really starts to make sense once you've already decided to cover everything, roof to floor to firewall etc... and want to really try to maximize your effort, but again, you will get to the point of adding a whole lot more for just a little more gain. also things will start to really get heavy, doors can start to sag and performance will start to suffer.
in the end, like all things, it is a trade off. I'm not really trying to say it's stupid to cover everything 100% and then some, just trying to point out that most efficient gain VS drawback does not require excess and in most cases on an ordinary passenger vehicle it isn't necissary to really go nuts and still get nice gains, the more you do past that becomes less and less gains but more and more weight
once u get it, send it my way too :smile (2):.
thanks john the priceless information/advices.
I'm sorry man, I wish I could get my point across with just a few sentences but me just stating facts without supporting info would just leave more questions than answers. honestly there is so much more that could be added to this but that^^ is me actually trying to be brief :tongue (2):
this guy has some information that supports what I'm explaining here. his extensive sound deadening showdown was considered an industry standard benchmark for years but he now sells his own product so all of his comparisons between the major brands is not on his site anymore. he's the only seller that I've seen admit that more is not better, if you ask most of the other vendors like dynamat fatmat and even b quiet they'll all have you believe that more is better:
http://www.sounddeadenershowdown.com/cgi-bin/index.cgi
he also realizes that the smallest thing that you think can never make a difference in fact does. stuff like wrapping wire harnesses in cloth tape for example... it's amazing how many thousands of tiny noises all add up to the overall background noise you hear
http://www.sounddeadenershowdown.com/cgi-bin/index.cgi
he also realizes that the smallest thing that you think can never make a difference in fact does. stuff like wrapping wire harnesses in cloth tape for example... it's amazing how many thousands of tiny noises all add up to the overall background noise you hear
you need to get on this project like white on rice. :balanced:
Ghesus i wish i had your mileage lol Looks like i'm ripping off my door panels this spring and browning them up. :top: I did the back seat area already. Are you going to do you hatch?
Ahh ok i missed that part of the post. That's gona be tricky taking weight of the hatch. Allot of contact points that hold the trim are in the fiberglass.
