# Is trying to "Seal" Doors a fool's errand?



## Gilroy (Mar 31, 2007)

What are we really trying to achieve with door mounted midrange/midbass drivers? 

Are we trying to seal up the door in attempts to create a pressurizable chamber, like a speaker box? Seems unattainable but from what I can see, alot of people think they are doing this. 

Are we trying to increase the natural frequency of the various panels? Therefore mass load or stiffen, so that we get the frequency up and/or the amplitude down of the resonance and it's harmonics high enough to be out of the audible range?

Do foam rings around the driver really "direct" the sound, or are they just dissipating the energy that would otherwise go into the inner door skin or panel?

What does decoupling of the various spaces really achieve? Keeping the backwave from transmitting energy to the door panel so that you don't have to increase the door panel's natural frequency? 

For reference, I have a BSME, I took a class in EM, circuits, and digital logic so I can try to follow as far technically as someone wants to go but I deal mostly with refinery process piping and equipment on a day to day basis so I understand forcing frequency, natural frequency, and harmonics decently enough. 

I'm asking because I just installed 2 of the NVX 6.5's in my doors, the midbass is not great, and in a previous life I spent lots of money and time putting sticky aluminum stuff all over my doors and trying to seal holes and dampen vibrations. I'm trying to be more efficient in my old age now.


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## SkizeR (Apr 19, 2011)

what your trying to do is prevent the rear wave from interacting with the front wave, which will end up causing destructive interference.


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## Gilroy (Mar 31, 2007)

SkizeR said:


> what your trying to do is prevent the rear wave from interacting with the front wave, which will end up causing destructive interference.


So let's dive into this, define "interact". 

They are naturally isolated, for the most part, by the door panel. The front wave should go right through the speaker grill, and if not "sealed" well, the back wave would just reflect off the outer door skin into the inner door panel, where it will dissipate through vibration for the most part of the panel, but the backwave entering the cab or interacting with the front wave seems minimal.


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## dcfis (Sep 9, 2016)

The nvx has some decently impressive midbass. Well mine does but my doors are deadened, sealed off and isolated


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## SkizeR (Apr 19, 2011)

Gilroy said:


> So let's dive into this, define "interact".
> 
> They are naturally isolated, for the most part, by the door panel. The front wave should go right through the speaker grill, and if not "sealed" well, the back wave would just reflect off the outer door skin into the inner door panel, where it will dissipate through vibration for the most part of the panel, but the backwave entering the cab or interacting with the front wave seems minimal.


unless your mounting the speaker to the door panel itself.. no, its not. i guess unless you did a ridiculously good job at sealing the driver to the door panel fast rings style


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## Truthunter (Jun 15, 2015)

So call me a fool if you want but all I can say is that with two different vehicles there was a noticeable difference in output and quality (transient decay or whatever you want to call it) after sealing up the doors as best as possible. I don't go crazy with the "sticky aluminum stuff" aka CLD, just 25 - 40% coverage and use it to cover the smaller openings. Butyl rope between crash bars and outer skin. Cover and seal large openings with galv sheet-metal and closed cell foam. Layer of ccf/mlv under door panel and some more CLD on large unsupported areas of door panel.

As far as what each product does I refer to: https://www.sounddeadenershowdown.com/


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## Gilroy (Mar 31, 2007)

SkizeR said:


> unless your mounting the speaker to the door panel itself.. no, its not. i guess unless you did a ridiculously good job at sealing the driver to the door panel fast rings style


Well, let's think about that for a minute. 

Most doors have large openings that would allow air flow between the door panel and the door chamber (between inner and out skins), granted. But, the distance between my moving woofer cone and the door panel grill is 1/4" down to almost nothing at high volumes/excursion, whereas the rear waves have to travel back to the door outer skin, reflect forward to the inner skin, then reflect off the door panel where they would be somewhat absorbed. Assuming there is enough energy left to make it to that 1/4" air space around the front of my woofer with any sort of amplitude, the woofer is on a different part of the music. So I'm not sure that there would be any sort of real cancellation happening in this case.


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## SkizeR (Apr 19, 2011)

Gilroy said:


> Well, let's think about that for a minute.
> 
> Most doors have large openings that would allow air flow between the door panel and the door chamber (between inner and out skins), granted. But, the distance between my moving woofer cone and the door panel grill is 1/4" down to almost nothing at high volumes/excursion, whereas the rear waves have to travel back to the door outer skin, reflect forward to the inner skin, then reflect off the door panel where they would be somewhat absorbed. Assuming there is enough energy left to make it to that 1/4" air space around the front of my woofer with any sort of amplitude, the woofer is on a different part of the music. So I'm not sure that there would be any sort of real cancellation happening in this case.


then dont seal your doors. idk what to tell you lol


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## Gilroy (Mar 31, 2007)

Truthunter said:


> So call me a fool if you want but all I can say is that with two different vehicles there was a noticeable difference in output and quality (transient decay or whatever you want to call it) after sealing up the doors as best as possible. I don't go crazy with the "sticky aluminum stuff" aka CLD, just 25 - 40% coverage and use it to cover the smaller openings. Butyl rope between crash bars and outer skin. Cover and seal large openings with galv sheet-metal and closed cell foam. Layer of ccf/mlv under door panel and some more CLD on large unsupported areas of door panel.
> 
> As far as what each product does I refer to: https://www.sounddeadenershowdown.com/


Please don't take this the wrong way, I'm in no way claiming what we've all done to our doors doesn't improve things. I'm trying to dial in exactly what works and why.


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## Gilroy (Mar 31, 2007)

SkizeR said:


> then dont seal your doors. idk what to tell you lol


I was under the impression this was a forum for technical discussions, I'm not here to challenge or dispute anyone's beliefs. I'm trying to flesh out the technical reasons behind what works or doesn't work.


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## Truthunter (Jun 15, 2015)

Gilroy said:


> the back wave would just reflect off the outer door skin into the inner door panel, where it will dissipate through vibration for the most part of the panel,


The vibrating inner door panel (skin) will also vibrate your door trim panel (which it's connected to) creating it's own audible output; some out of phase with the output from the front of the speaker cone; and all of it contributing energy not included in the original source signal.


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## SkizeR (Apr 19, 2011)

Gilroy said:


> I was under the impression this was a forum for technical discussions, I'm not here to challenge or dispute anyone's beliefs. I'm trying to flesh out the technical reasons behind what works or doesn't work.







SkizeR said:


> what your trying to do is prevent the rear wave from interacting with the front wave, which will end up causing destructive interference.





Truthunter said:


> The vibrating inner door panel (skin) will also vibrate your door trim panel (which it's connected to) creating it's own audible output; some out of phase with the output from the front of the speaker cone; and all of it contributing energy not included in the original source signal.


there ya go


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## Gilroy (Mar 31, 2007)

Truthunter said:


> The vibrating inner door panel (skin) will also vibrate your door trim panel (which it's connected to) creating it's own audible output; some out of phase with the output from the front of the speaker cone; and all of it contributing energy not included in the original source signal.


I'd buy that the inner skin could vibrate the panel, but the chances of those having the same resonate frequency seem pretty low given the different materials used to construct them. But that at least seems to drive someone to increase the stiffness of the inner skin through bracing?


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## MB2008LTZ (Oct 13, 2012)

Gilroy said:


> I was under the impression this was a forum for technical discussions, I'm not here to challenge or dispute anyone's beliefs. I'm trying to flesh out the technical reasons behind what works or doesn't work.


It is exactly what you think, open minds, looking for the best in car audio sound quality, and the folks that know, will tell you why or why it doesn't work. That being said, I, personally can tell you that sound deadening, even in it's most basic form can and will improve the acoustics of an automotive interior. In my limited knowledge and experience, I can honestly say that there in no education like the real world, to find your own specific application, goals, and quality of sound one is looking for. What you are trying to achieve, or answer, when it comes to automotive interiors is endless. Go out to shows, listen to various vehicles, talk to members, listen to their advice, educate yourself, and enjoy it. Then draw your own conclusions to what will work best for your specific build. This is exactly what I did and I could not be more grateful for the info and friends I have acquired from this site! Happy Holidays!


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## Truthunter (Jun 15, 2015)

Gilroy said:


> I'd buy that the inner skin could vibrate the panel, but the chances of those having the same resonate frequency seem pretty low given the different materials used to construct them. But that at least seems to drive someone to increase the stiffness of the inner skin through bracing?


Resonant frequencies very likely different for the two but vibrations non the less are contributing audibly. Increasing stiffness of the inner skin with bracing would be beneficial and I believe that is one of the functions of constrained layer dampener.


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## GEM592 (Jun 19, 2015)

In my opinion, for most midbass installations in the standard front door location, the primary goal isn't to provide a sealed chamber behind the drivers. Indeed, there are subwoofer applications that don't even require such a thing, and there are high quality door installs some have done that incorporate vents.

One way or the other, the goal is to control the backwave. You either remove it, or carefully control it. The most popular approach is to simply try to remove it, by deadening the surfaces it will tend to reflect from, or be transmitted through. It turns out that, due to a variety or factors, you are better off simply trying to reduce the ability of these surfaces to transmit or reflect sound, and a perfectly air-tight chamber behind the driver is of negligible importance. You only really need to worry about "sealing" construction surfaces near the driver itself, including of course where the driver seats,


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## Marky (Nov 15, 2011)

You can be subjective to the input that your being given but a few of them I know they have more experience then you could imagine. Take it or leave it but there is nobody here because of monetary gains. But Audiophiles who are attempting to help you achieve better end result with your systems performance.

I am going to toss in my 2 cents of coarse. 

The sheet metal construction of car doors is as bad of a enclosure as one can imagine for a driver enclosure, which is why you never see a sheet metal enclosure for home stereo speakers.
The sheet metal doors shake and rattle with vibrations very easily from the drivers cone and it produces its own distortion. The CLD on the inside of door "outer door skin" helps to make the panels firmer so thats reduced. Plus it reduces outside noises from entering the door and interior.
Then closing access holes in doors with sheet metal followed again by CLD will help do the same with inner door panel.
Then a CCF over the CLD inside door is for reducing backwave inside the door itself. Some bag fiberglass to do the same and have seen lots of raves from it. 
On inner panel a CCF and a layer of MLV is done to again stop resonance and distortion from driver as well as blocking any of the noises from entering the interior.


If you spend the time and money to dampen or soundproof your doors the stereo system is going to have a better sound quality. Because the sounds from back of the cone are not bouncing around inside the door like it would have. Then its not rattling like it would as plain open sheet metal plus road noise is not going to be heard from inside the interior of vehicle.
There is no loosing here if for no other reason do it for the simple function of reducing tire and road noise plus what the engine and exhaust would do.

I put two layers of CLD on my outer door skins then a 1" layer of CCF over that. Also two layers of CLD on inner door with 1/4" CCF and 1/4" of MLV all under door panels.
Yes it works and I go down the highway at 70-75mph with no road or engine noise in the cab. 

The speakers don't have to work nearly as hard because they don't have to cancel out the road noises any longer if its already been eliminated.
You can pick apart any particular product used or split hairs about how much one thing does or does not affect the end result. But it does help with the stereo systems sound quality, what you need to decide is how far do you want to take it. Can do none of it or install 400+ lbs of sound deadening materials into your vehicle.

Because its not going to be installed by any of us. Like a sign I saw in a machine shop:

Speed Costs Money...........How Fast do you want to go ??


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## MikeS (May 23, 2015)

The most effective increase in midbass for me was sealing the gap around speaker that contacts the door trim panel so the driver does not leak under the trim. 
Pack of D shaped rubber seal cost few euro.. For large gaps there is some compressing foam type stuff too.

~30-40% coverage of cld (few patches to trim panel too) and solid mounting rings (with seals under them and driver) goes a long way.


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## Patrick Bateman (Sep 11, 2006)

There's a couple of reasons that I haven't put speakers in stock locations in over a decade now:

1) When you chop up your doors, you reduce the resale value of your car by thousands of dollars. I had a 2001 Accord that I literally couldn't give to the Goodwill because it was so heavily modified, in the pursuit of car audio nirvana.

2) I've found that a small speaker in a perfectly sealed box can frequently outperform a larger speaker mounted in a door. For instance, a 4" woofer in a perfectly sealed box can often produce more output than a 6" woofer in a door. The key here, IMHO, is that a speaker mounted in a door basically behaves like a speaker in an open baffle.

To put some color on how this works:

If you put a 4" woofer in a perfectly sealed box, the box itself will control the excursion. That allows a very small woofer to play very loud. To put this in perspective, JBL uses 2" drivers in their prosound arrays. A 6" woofer mounted in a door (or an infinite baflle) has no excursion control below the point that the woofer unloads. That frequency is pretty high, because a car door isn't very large.


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## claydo (Oct 1, 2012)

The main benifits of a properly treated door are very simple, to reduce the level of backwave influence on the audible response of the speaker, and to minimize the energy transfer through the various parts of the door in an effort to quell resonance.


Boom shocka locka.


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## Jeffdachefz (Sep 14, 2016)

Have you ever achieved extremely powerful midbass yet? Literally you can make your shorts fly and it pierces your lungs, keeps up with 150+db of sub stage? Needless to say that kind of midbass level causes extreme rattle if you dont dampen vibrations and decouple, there is zero chance of you enjoying your music.

What's been said about the rear wave has already been said however i'd like to add that if you dont seal the big gaps in the door, you are trying to use the door panel as part of the enclosure and plastic leaks sound and is way weaker than deadened sheet metal. The midbass you try to achieve will never amount to squat when you rely on plastic door panels as the enclosure vs a solid deadened door or a fiberglassed speaker pod.

Best you'll get with that approach is, "oh your midbass? it's there i hear it" vs a real hard thump you get from a live drum that is extremely viceral and powerful aka the "holy sh*T that midbass" reaction.


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## Locomotive Tech (May 23, 2016)

OP I was once on the fence when it came to deadening doors. I was told this should be the first thing to accomplish before installing mids in the doors. My scepticism was further fueled by the cost of the materials and the labor involved. After researching I did decide to take on the cost and time. 

My approach was a little more involved, I have a Civic, a very noisy car to say the least. I had the premium factory system with a small sub in the rear deck. I decided to deaden the doors and see the result with the factory system. The results were undeniable!

If you are skeptical, you could always experiment yourself. Try doing one door and see if you can tell a difference.


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## Holmz (Jul 12, 2017)

SkizeR said:


> then dont seal your doors. idk what to tell you lol


Gilroy's question is actually a very good one.
(Knowing that it works is way different than knowing how it works.)

I am leaning towards not even putting woofers in the doors, but will load up the skins to try and remove noise from entering the cabin.


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## Westye (Dec 6, 2017)

Patrick Bateman said:


> There's a couple of reasons that I haven't put speakers in stock locations in over a decade now:
> 
> 1) When you chop up your doors, you reduce the resale value of your car by thousands of dollars. I had a 2001 Accord that I literally couldn't give to the Goodwill because it was so heavily modified, in the pursuit of car audio nirvana.
> 
> ...


If you don't mount the speakers on the doors....where then? And how? 
Sealed box? Asking for curiosity, not saying that you are wrong or that is not the norm.


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## Niebur3 (Jul 11, 2008)

Kick Panels.


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## nadams5755 (Jun 8, 2012)

Fully sealing your doors could be bad for the rain drops collecting inside the bottom of your door. The results could be good but it will be a lot of effort.

You could consider boxing your doors instead, which leaves the rest of the door alone. “Back to stock” usually involves just getting some replacement door panels. 

Or like niebur suggested: kick panels.


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## claydo (Oct 1, 2012)

Fully sealed is not the objective of door treatments, with the window channels at the top, there is really no such thing. Anyone who treats near the bottom of the door risks interfering with any factory designed drip channels, and is truly asking for a prematurely rotting door. Luckily seams are strong enough to avoid the resonance measures we are all taking. Kick panels are cool and all, but are not possible in every car, and just like most doors may quickly become a limiting factor in what equipment you can use. In my manual equipped ride, with me being an avid dead pedal user, my tiny kicks are out of the equation. I'd be lucky to get 5" driver down there, and even that would eliminate my dead pedal. My doors however will hold 10s, with some work. Are resonance issues a royal *****? Hell yes they are, but a worthwhile pursuit for my personal satisfaction with my system.. A lot of folks automatically default to kicks being superior, but I can't deny my favorite demo of all time came from a car with door mounted midbass, one that absolutely dominated the modex class in meca for years.......


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## Holmz (Jul 12, 2017)

Westye said:


> If you don't mount the speakers on the doors....where then? And how?
> Sealed box? Asking for curiosity, not saying that you are wrong or that is not the norm.


Or dashboard.
If one does not have kick panels then it makes it easier to go for the dash.


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## Sine Swept (Sep 3, 2010)

Biggest challenge with doors are locking mechanisms and metal rods into plastic connectors. I've found reasonable measures to deal with the many other issues, ie shimming back window tracks for a few more mm of clearance, but those damn locking mechanisms are a *****. I have been back inside for exploratory surgery more than I can count. My speakers are T-nutted in there for a reason - I'm the reason.


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## Marky (Nov 15, 2011)

^^^^ YUP

Agreed on the drains along the bottoms of the car doors have to be left clear of any foams and any thing except water itself. I bought a 2006 F250 with a diesel engine that was noisy as a school bus. I put Dyna-Mat and a 1" polyurethane foam rubber on the outer door skins for the purpose of sound reduction. Left both 2" up from bottom of the doors.
Then closed all access holes with 16ga aluminum sheeting then Dyna-Mat over that.
After I heard the difference that made in the front doors the interior was stripped down to nothing but bare sheet metal. Proceeded to go overboard with sound deadening the truck after installing just under 500lbs of CLD CCF MLV in the thing. Even put a 1" aluminized MLV CCF under the entire cab and firewall.
End result is a diesel truck with 4" open exhaust and 38" tires @ 75mph has zero engine/turbo noise in the cab. Quiet as a Prius Its absolutely worth the battle.









The in cab sound level at 65-70mph is 60-62 dB and was only possible because of the sound proofing materials available today.

Just do it one door at a time and if the difference isn't to your satisfaction then shut it down. But as you have seen from the ones that have installed it and has first hand knowledge know EXACTLY how well it does work.


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## Patrick Bateman (Sep 11, 2006)

Westye said:


> If you don't mount the speakers on the doors....where then? And how?
> Sealed box? Asking for curiosity, not saying that you are wrong or that is not the norm.












I put this sealed box under the brake pedal and that worked ok

But I had better results later on. For instance, putting the same woofer into a bandpass enclosure allowed me to widen the stage. This is because the apparent source of the speaker can be placed at the edges of the car.

I tend to use arrays though also, and in those situations, I just use a number of smaller speakers in sealed boxes. This is a lot more practical if you can 3D print them. Back when I made them out of wood it would take FOREVER because it's basically like building a little subwoofer box and it takes a long time, AND you have to build 4-8 of them. Exhausting!

I'm not a huge fan of putting speakers in stock locations because I don't like cutting up my car, but there's nothing stopping you from putting a sealed box in the stock location.

https://www.madisoundspeakerstore.com/approx-5-woofers/sb-acoustics-sb15nrxc30-4-5-woofer/

Here's an example. If you stick one of these in an enclosure that measures 5"x5"x5" that will get you an F3 of 105Hz. Admittedly, most people want an F3 around 80Hz. But there's a few things to consider:

1) All the measurements I've seen indicate that cabin gain begins around 160Hz, so you'll definitely see some gain in the low end of this sealed box

2) 5" x 5" x 5" isn't very big. You could use a bigger box to get a lower F3, or even use a bigger driver. I used a 5" driver to basically show a starting point.

3) A sealed box has a really shallow rolloff, so it's going to produce more bass than you might expect from something with an F3 of 105Hz, particularly when you factor in cabin gain.


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## claydo (Oct 1, 2012)

Patrick is a bit of a theory man more so than application .......when ya find a small sealed box that can hold a candle to a higher qts designed large woofer on a baffle.....well, I'm gonna have to see it integrated into an interior to believe it. No matter the suspension travel restrictions an air spring imposes on a smaller cone, in a bass situation, you know displacement rules......


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## Truthunter (Jun 15, 2015)

claydo said:


> integrated into an interior


LOL, I just thought that phrase funny coming from you oke: :tongue3:


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## Patrick Bateman (Sep 11, 2006)

claydo said:


> Patrick is a bit of a theory man more so than application .......when ya find a small sealed box that can hold a candle to a higher qts designed large woofer on a baffle.....well, I'm gonna have to see it integrated into an interior to believe it. No matter the suspension travel restrictions an air spring imposes on a smaller cone, in a bass situation, you know displacement rules......


For me, the main thing is just that I don't want to **** up the car. I literally had a car I couldn't give away. 2001 Honda Accord. I tried to give it to a charity and they wouldn't take it. Ran perfectly fine, interior was completely ****ed.

I'd done all the crazy **** that people do to get great midbass. Sound deadening, reinforcing the doors, fitting speakers that were larger than stock, etc.

B&C 8NDL51 in a sealed box worked the best. Same woofer in a bandpass in my Mazda worked even better. 

Haven't considered putting a speaker in a door since then.


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## SkizeR (Apr 19, 2011)

Patrick Bateman said:


> For me, the main thing is just that I don't want to **** up the car. I literally had a car I couldn't give away. 2001 Honda Accord. I tried to give it to a charity and they wouldn't take it. Ran perfectly fine, interior was completely ****ed.


then dont hack it in a way thats non-reversible


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## claydo (Oct 1, 2012)

Truthunter said:


> LOL, I just thought that phrase funny coming from you oke: :tongue3:


Lmao.....hey, I might finish my doors one of these days......maybe.


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## claydo (Oct 1, 2012)

I get where you're coming from on the destruction of an interior Patrick.....lol, I can relate to that. I tend to drive vehicles until there repair costs surpass the cars value before replacement. That's the only way I can justify the costs of new vehicles, not to mention the cash I sink into the stereo instal......I must enjoy them for years to justify the costs (both monetary and time investments)....... it is a lil funny you were turned down by a charity tho.....


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## Arete (Oct 6, 2013)

Jeffdachefz said:


> Have you ever achieved extremely powerful midbass yet? Literally you can make your shorts fly and it pierces your lungs, keeps up with 150+db of sub stage? Needless to say that kind of midbass level causes extreme rattle if you dont dampen vibrations and decouple, there is zero chance of you enjoying your music.
> 
> What's been said about the rear wave has already been said however i'd like to add that if you dont seal the big gaps in the door, you are trying to use the door panel as part of the enclosure and plastic leaks sound and is way weaker than deadened sheet metal. The midbass you try to achieve will never amount to squat when you rely on plastic door panels as the enclosure vs a solid deadened door or a fiberglassed speaker pod.
> 
> Best you'll get with that approach is, "oh your midbass? it's there i hear it" vs a real hard thump you get from a live drum that is extremely viceral and powerful aka the "holy sh*T that midbass" reaction.


This is EXACTLY the reason I've had to go the extra mile with Closed Cell Foam and Tesa Tape for clips. I sealed off the holes in the metal which produced GREAT midbass but the rattles were insane. I'm still working on it actually. It's one of those jobs that for me seem unending but TOTALLY worth it if the goal is good sound.


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## Patrick Bateman (Sep 11, 2006)

SkizeR said:


> then dont hack it in a way thats non-reversible


but the VOICES IN MY HEAD tell me to


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## Babs (Jul 6, 2007)

*Is trying to &quot;Seal&quot; Doors a fool's errand?*

I’m a huge fan of treatment with the end goals of minimizing interaction of backwaves into the cabin, which is all we’re doing here.. However I do still ponder an enclosure. There’s always options. 

Examples from Speakertechnics.com
Those Europeans take their builds seriously. 


































An example of my door...


















Sent from my iPad using Tapatalk Pro


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## claydo (Oct 1, 2012)

I'd love to fabricate full enclosure like that.....but damn at the work....lmao, I'm a bit lazy. I love those ported illuminators....wow!


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## Babs (Jul 6, 2007)

*Is trying to &quot;Seal&quot; Doors a fool's errand?*



claydo said:


> I'd love to fabricate full enclosure like that.....but damn at the work....lmao, I'm a bit lazy. I love those ported illuminators....wow!



Ya know.. I think to me, it’d actually be easier and more feasible than kicks. 

Agreed.. If I knew anything about a ported enclosure that’d be big fun! Been looking at some lower Qts high end stuff lately.. Morel Ti, Dyn, Scans, etc. Wonder what freq you’d want to port such a thing? I imagine it’d all be determined on about how much volume you can squeeze out of it. Let’s discuss while looking at my doors at NCSQ.. I’m seriously contemplating it. 


Sent from my iPad using Tapatalk Pro


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## claydo (Oct 1, 2012)

I'll certainly be up for a discussion about it, I've spent a lot of time thinking about it myself....


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## SkizeR (Apr 19, 2011)

*Re: Is trying to &quot;Seal&quot; Doors a fool's errand?*



Babs said:


> Ya know.. I think to me, it’d actually be easier and more feasible than kicks.
> 
> Agreed.. If I knew anything about a ported enclosure that’d be big fun! Been looking at some lower Qts high end stuff lately.. Morel Ti, Dyn, Scans, etc. Wonder what freq you’d want to port such a thing? I imagine it’d all be determined on about how much volume you can squeeze out of it. Let’s discuss while looking at my doors at NCSQ.. I’m seriously contemplating it.
> 
> ...


You mean "let's look at the final product that I finish in time for the NCSQ" 

Sent from my SM-G950U1 using Tapatalk


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## claydo (Oct 1, 2012)

*Re: Is trying to &quot;Seal&quot; Doors a fool's errand?*



SkizeR said:


> You mean "let's look at the final product that I finish in time for the NCSQ"
> 
> Sent from my SM-G950U1 using Tapatalk



Lmao......motivation! Excellent!


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## Babs (Jul 6, 2007)

*Re: Is trying to &quot;Seal&quot; Doors a fool's errand?*



claydo said:


> Lmao......motivation! Excellent!






SkizeR said:


> You mean "let's look at the final product that I finish in time for the NCSQ"
> 
> Sent from my SM-G950U1 using Tapatalk



Ha! Y’all should know me better than that by now. LOL!!! How long did that 3-way and IB build take!? 

Sorry for the derail. 

Yes in short, solid full coverage between door and card with CLD, filling holes, CCF and MLV is NOT a foolish task if you’re installing drivers in doors. Though not truly sealed, it makes a difference, along with several other items for best midbass performance in doors. Word! Drops mic. Goes to the bar. 


Sent from my iPhone using Tapatalk Pro


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## jowens500 (Sep 5, 2008)




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## jackk (Dec 27, 2010)

I have a feeling a lot of responses in this thread failed to enable the discussion OP is trying to engage - white paper style kind of discussions on the technical reasons why sealing the door would help - so that he can invent/consider/come up? w/ a more efficient way of improving mid-bass response? 

If what I read is correct - sorry to tell u OP I learned that there is no other ways around that ever since I’ve done it once. 

Cheers!


Sent from my iPhone using Tapatalk


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## JH1973 (Apr 21, 2017)

You can talk about technical reasons and theory about why sealing a door improves performance but in the end lets be real,what really matters is how something improves driver performance audibly to the listener.How it affects imaging and direction.

The 2 things that took my system to the next level were CLDing the door heavily and getting the time alignment in a respectable configuration.The first improved driver performance audibly hands down and the second improved the imaging drastically.
I went back and sealed the big hole with sheet metal on the driver side door and it did absolutely nothing to improve the sound.I will never waste my time trying to seal the holes again.Next time I'll use that energy to install MLV and CCF.At least I might eliminate some road noise that way.


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## Gilroy (Mar 31, 2007)

JH1973 said:


> You can talk about technical reasons and theory about why sealing a door improves performance but in the end lets be real,what really matters is how something improves driver performance audibly to the listener.How it affects imaging and direction.
> 
> The 2 things that took my system to the next level were CLDing the door heavily and getting the time alignment in a respectable configuration.The first improved driver performance audibly hands down and the second improved the imaging drastically.
> I went back and sealed the big hole with sheet metal on the driver side door and it did absolutely nothing to improve the sound.I will never waste my time trying to seal the holes again.Next time I'll use that energy to install MLV and CCF.At least I might eliminate some road noise that way.



The second part of your post is exactly why the first part matters to me. No one wants to waste time and money doing things that aren't effective. It just seems like with all the experience and knowledge on this board, we could have improving midbass down to an efficient formula that should work for almost anyone's doors. It seems like we aren't quite there yet, as a community. A whole lot of "spray and pray" approaches, with some things helping, some not, some being marginal, etc.


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## therapture (Jan 31, 2013)

As the OP has no doubt realized, sealing up and deadening a door is one of the BIGGEST performance gains to be had as far as good midbass is concerned, not even counting vocal performance which also realizes big benefits when the door card/skin/plastic doesn't resonate and buzz which "colors" the output at best and cancels out some frequencies entirely at worst.

Add some TA and good EQ work to that, and you have a tremendous performance gain.

With ****ty door work, all that TA and EQ is only half as effective.


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## JH1973 (Apr 21, 2017)

Very easy for people(me included)to "hear" a sonic difference in the sound after they've spent hours working on it.....or not.Best thing people can do is treat one door with whatever idea that it is and then sit and compare the sound from treated side to untreated side.Be honest with yourself,does it sound better?Very easy to hypnotize yourself into thinking it sounds better because of the hard work you put into it.

As a side note I will say that Richard Vedvik's idea with installing fiberglass sheet boards on the outer skins of doors looks very interesting and I may try that someday.


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## BrainMach1 (Jun 19, 2014)

JH1973 said:


> Very easy for people(me included)to "hear" a sonic difference in the sound after they've spent hours working on it.....or not.Best thing people can do is treat one door with whatever idea that it is and then sit and compare the sound from treated side to untreated side.Be honest with yourself,does it sound better?Very easy to hypnotize yourself into thinking it sounds better because of the hard work you put into it.


I am current treating a door on one of my trucks but have not started the other. I might just take,those measurements so I can see for myself. 

I did take general noise measurements before starting to compare my 500+ hp truck to my plain work truck to my Navigator. 

Sent from my SM-G955U using Tapatalk


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## Holmz (Jul 12, 2017)

​


therapture said:


> ...
> With ****ty door work, all that TA and EQ is only half as effective.


Half as effective is -3dB...


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## therapture (Jan 31, 2013)

JH1973 said:


> Very easy for people(me included)to "hear" a sonic difference in the sound after they've spent hours working on it.....or not.


With midbass, there is no doubt what occurred when you actually have midbass thumping in the well sealed door versus almost none at all. Providing the driver itself is capable physically of the excursion needed to play down into the 75-100 range of course.

Listen to a sub enclosure with one side not attached. Now attach it and lsiten again. Same deal.


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## Holmz (Jul 12, 2017)

therapture said:


> With midbass, there is no doubt what occurred when you actually have midbass thumping in the well sealed door versus almost none at all. Providing the driver itself is capable physically of the excursion needed to play down into the 75-100 range of course.
> 
> Listen to a sub enclosure with one side not attached. Now attach it and lsiten again. Same deal.


It is not exactly the same unless there is no door skin on the outside and it is becomes and infinite baffle.

Stiffening the skin and/or adding mass is one aspect. Another is dampening. Then the third aspect is that the road noise also gets lowered with sound deadner of mass loaded products.


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## Gilroy (Mar 31, 2007)

I have some oak wood dowels and a new set of fast rings sitting next to me. What would be the best set of before vs. after measurements to get? I was thinking of playing pink noise and taking screen shots of the frequency response curves to see what, if any, measurable difference the fast rings make (the back wave piece and the front wave piece.) then doing the same adding dowels between the two door skins to stiffen them and brace the woofer. I'll start with that and see what happens.


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## Holmz (Jul 12, 2017)

Gilroy said:


> I have some oak wood dowels and a new set of fast rings sitting next to me. What would be the best set of before vs. after measurements to get? I was thinking of playing pink noise and taking screen shots of the frequency response curves to see what, if any, measurable difference the fast rings make (the back wave piece and the front wave piece.) then doing the same adding dowels between the two door skins to stiffen them and brace the woofer. I'll start with that and see what happens.


Impulse response.


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## Gilroy (Mar 31, 2007)

Holmz said:


> Impulse response.


Thanks, just bought an $8 app on my Pixel 2 that seems to calibrate for the phones mic. I"ll see what I get out of it.


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## SkizeR (Apr 19, 2011)

Holmz said:


> Impulse response.


waterfall. not impulse




Gilroy said:


> Thanks, just bought an $8 app on my Pixel 2 that seems to calibrate for the phones mic. I"ll see what I get out of it.


nothing useful


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## Holmz (Jul 12, 2017)

SkizeR said:


> waterfall. not impulse
> ...


Maybe you are right. Waterfall is frequency domain and impulse is time domain.
Resonances are better in freq, I'll defer as to whether damping shows up in time domain or not.


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## Gilroy (Mar 31, 2007)

I took and recorded lots of RTA measurements but then settled on something easy, playing from 60hz to 180 hz in 10hz increments, and listened for resonance. One door received (1), 1" diameter oak wooden dowel on the weak side of the door panel behind the 6.5" driver, and the front and back fast rings. The other door remained as is. The treated door's natural frequency was driven up high enough from that one dowel and whatever help the front ring gave me (some panel isolation in theory) to not hear any resonance from 60hz to 140hz, at 150hz very minor buzzing started. The other door sounds like absolute hell (buzzing, clanging, etc) from 60hz, especially bad at 90hz, all the way to 150hz. 

I'll add more dowels as time allows and see how far that gets me.


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## thornygravy (May 28, 2016)

Even if it didn't do anything for the door speakers.. it'd still do it for the sweet sound your doors make when they close, aka (the cadillac effect).


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## Babs (Jul 6, 2007)

*Is trying to &quot;Seal&quot; Doors a fool's errand?*



SkizeR said:


> waterfall. not impulse



Also a good way to measure improvement from treatment before/after would be by Transfer Function in an app like Smaart or Systune or AudioTools Transfer Function on the cheap. 

The phase plots along with magnitude plots would likely change significantly to denote the improvement, but the plot I’m thinking of is referred to as a “coherence plot”. Coherence simply shows a percentage for seeing deviation between electrical and acoustic response by frequency. So things like reflection and backwave bled “distortion” shows up very easily. A straight line across the top 100% is the impossible ideal. At various spots throughout the frequency range, the line will fall for a particular driver, meaning that it is deviating from electrical signal for some reason. Possibly the crossover applied, reflections taking over or in our discussion here, backwave energy mixing and corrupting the front wave of the driver along with mechanical resonance. Comb filtering or modal cancellation as well. Etc etc. 

Which is the sole singular reason for door treatment for SQ, beyond just soundproofing for road noise. Eliminating the sound generated from behind the driver from messing up what we want to hear.. The sound wave from the front side of the cone. 

Coherence plot in Transfer Function is actually very cool. It’s an extremely useful tool for visually seeing where acoustic issues are interfering with the driver’s ability of simply delivering the signal its sent. I can actually see this on an iPad in AudioTools, though Smaart would be a hugely more powerful and accurate tool of course. 



Sent from my iPhone using Tapatalk Pro


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## therapture (Jan 31, 2013)

Holmz said:


> It is not exactly the same unless there is no door skin on the outside and it is becomes and infinite baffle.
> 
> Stiffening the skin and/or adding mass is one aspect. Another is dampening. Then the third aspect is that the road noise also gets lowered with sound deadner of mass loaded products.


Yes, but still the back wave needs to be stopped from interfering with the front wave. A door is still IB in practice since it vents via the weatherstrips and what not.

My Acura TL, a notable quiet car, is very noticeably even quieter inside after treating the doors.


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