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Discussion Starter #1 (Edited)
My car has very big opening in door panels. Like nothing on inner side. I covered them with big sheets Dynamat. I feel the bass is muddy and not much tight. How to improve it?

https://reflectology.co.uk/wp-content/uploads/2015/01/20140723_165851.jpg
(not my door but same model.)
Equipment:
Head unit OE
Helix P Six MKII (Helix DSP2 and Zapco 6ch AP are going in.)
Sinfoni T25T
Scanspeak 10F
Sinfoni T165W
ARC Black 12" IB (Zapco ST-500XMII 300watt)
 

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Just make a template of that giant hole, cut it out on a piece of 1/8” expanded pvc, damp the inside with some RESONIX cld squares,screw it to the door and try to use that bar in the middle as a support also then damp the outside and cover that up with RESONIX 1/2” ultra soft ccf. Next you have to make your own fast ring from 3/4” hard ccf, then finally damp the door panels with cld, wrap all clips with tesa tape at the base where the panel meets the door, put the panels back on and enjoy some super dead doors. Its very time consuming but is totally worth it.
 

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Despite the size of that hole, it does look fairly straight forward to cover. Mullings is on the right track, find something rigid, but reasonably flexible, cut a template from cardboard, transfer the template to some aluminum flashing, or pvc, carefully determine where you can screw/bolt the material to the door without obstructing the door panel, or any of the window components, cover with more deadening material making sure to seal up all of the edges around your newly installed cover.

It's a bit of work, but it should help a lot. You're not so much trying to create a sealed enclosure (that just isn't possible in a car door), you're trying to prevent the sound waves from the back of the speaker from reflecting off the door and canceling out the front wave of the speaker.
 

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Discussion Starter #4 (Edited)
Due to the size of that access hole, fabricate 3-5 liters fiberglass seal enclosure behind woofer might be possible. Or is it too small for Sinfoni 6.5" to breath? Would it sound better? Currently system has ok bass amount, I just feel it has no impact like chest punch.
 

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Due to the size of that access hole, fabricate 3-5 liters fiberglass seal enclosure behind woofer might be possible. Or is it too small for Sinfoni 6.5" to breath? Would it sound better? Currently system has ok bass amount, I just feel it has no impact like chest punch.
If you're expecting to be punched in the chest by a 6.5" speaker, you're expecting too much. The subwoofer should be used for the majority of the bass, the midbass reinforces the upper bass. When they are tuned together well, the midbass will anchor the subbass in the front of the car, so it will feel like the midbass speakers are doing most of the work, when if fact the sub is.
 

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Discussion Starter #7
Just make a template of that giant hole, cut it out on a piece of 1/8” expanded pvc, damp the inside with some RESONIX cld squares.
here is a little guide that you can follow that we did that follows exactly what Mullings is saying

https://resonixsoundsolutions.com/vehicle-database/2018-honda-accord-door/
Thanks guys. I think to go with fiberglass. Would 2 layer of fiberglass + some grids of dowel attached would be enough?
Cloth or Chopmat is better option?
https://www.amazon.com/Fantasycart-Fiberglass-Cloth-Plain-Weave/dp/B00M188N2G/ref=sr_1_5?crid=1U82P5SP6CJYP&keywords=fiberglass+cloth&qid=1559354819&s=gateway&sprefix=fiberglass,aps,170&sr=8-5

https://www.amazon.com/Nordstrand-Fiberglass-Chopped-Strand-glass/dp/B01EVYEST4/ref=sr_1_2_sspa?crid=1U82P5SP6CJYP&keywords=fiberglass+cloth&qid=1559354819&s=gateway&sprefix=fiberglass,aps,170&sr=8-2-spons&psc=1
 

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Tbh, while fiberglass may be best, it's an ABSURD amount if work vs using plastic. I would use abs or thicker expanded PVC (like 3/16).

Sent from my SM-G975U using Tapatalk
 

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Discussion Starter #9 (Edited)
If you're expecting to be punched in the chest by a 6.5" speaker, you're expecting too much. The subwoofer should be used for the majority of the bass, the midbass reinforces the upper bass. When they are tuned together well, the midbass will anchor the subbass in the front of the car, so it will feel like the midbass speakers are doing most of the work, when if fact the sub is.
My rear subwoofer is 12" IB. May be the problem? It has good volume. I put cutoff fq at 80hz. (when I put no crossover, the curve still drops sharply at 75-80 by itself.) I read somewhere said punch chest mid bass is upper bass region like 100-200hz. How to improve?
 

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Discussion Starter #10
Tbh, while fiberglass may be best, it's an ABSURD amount if work vs using plastic. I would use abs or thicker expanded PVC (like 3/16).

Sent from my SM-G975U using Tapatalk
I am worried if I have to do job twice with fiberglass later.
Since I already have dynamat cover that hole, I plan to use it as base for fiberglass work. Mask surrounding and paint dynamat with fiberglass release agent. Lay and coat 2-3 layers. Take fiberglass out and trim it.
Remove dynamat. Mount this Panel.
Does it sound about right?
 

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I am worried if I have to do job twice with fiberglass later.

Since I already have dynamat cover that hole, I plan to use it as base for fiberglass work. Mask surrounding and paint dynamat with fiberglass release agent. Lay and coat 2-3 layers. Take fiberglass out and trim it.

Remove dynamat. Mount this Panel.

Does it sound about right?
Ive done exactly what you're thinking on a door that looks almost exactly like yours.

Its not worth it. A lot of fiberglass and $$$ to get it perfect.

Instead, get some 1/4in abs sheets. Parts express sells them. Put it against your door metal. Put one screw in to hold it to the metal and then take a heatgun and heat up the abs in sections. It'll turn Almost gooey but not quite. Almost the consistency of CLD if you put it in the freezer. Moves but holds its shape when u stop moving it. It'll form to exactly the shape of whatever you push it against.

If you roll down the window(for a flat spot in the large empty areas) and then do the process above. You'll have an abs insert thats easily taken on/off with a few screws thats Exactly the shape of your door.

This pic is a flat piece of abs that was heated up and then vacuum molded. But you can see exactly how many curves you can get with abs and some heat. Vacuum molding is just forming over a template. The door is your template. The forming is your hand pressure.


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If you're expecting to be punched in the chest by a 6.5" speaker, you're expecting too much. The subwoofer should be used for the majority of the bass, the midbass reinforces the upper bass. When they are tuned together well, the midbass will anchor the subbass in the front of the car, so it will feel like the midbass speakers are doing most of the work, when if fact the sub is.

Truth! OP - these guys are sending you in the right direction. My 6x9’s can do pretty snappy midbass. But turn the sub off and the impact drops a lot. When you get the sub matched at the crossover point and time aligned properly it makes you think the 6x9’s are doing a lot more because as gijoe said, all the bass appears to be in the front center of the vehicle. Sealing and deadening up the doors properly gives that drivers response the ability to play to the sub as well as stop nasty resonances that drag the image away and muddy it up.

In my opinion fixing the doors for proper midbass is just as important to the subbass quality as the sub is! So many people try to add more power or more subs, when they are really looking for better midbass
 

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Well, we have to stop vibration... we know this. It seems to me the most efficient way to do that is cross bracing if all else fails. A physical restraint.

Once in a panel van, we took pieces of metal and welded them so as to connect the outside akin with the inside frame, instead of allowing the curve in the sheet metal to provide all the strength. It just COULDNT flex. Worked out well.

Don’t weld it, as a coworker discovered. Use epoxy and do it in bare metal. Make sure the windows can move freely.

Lastly, curves are stronger than flat surfaces. On a different scale.... crush a crap ton of toothpicks or really thin dowel rods, mix them up into fiberglass resin, and smear them on a non-visible side of a door skin.... it’ll never flex again. Each toothpick is a curve, and distributes the load. Try on some scrap if you don’t believe.
 

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Discussion Starter #17
Tbh, while fiberglass may be best, it's an ABSURD amount if work vs using plastic. I would use abs or thicker expanded PVC (like 3/16).
ABS (what thickness?) or Expanded PVC 3/16" would be better choice in sound quality and easier of installation?
 

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Despite the size of that hole, it does look fairly straight forward to cover. Mullings is on the right track, find something rigid, but reasonably flexible, cut a template from cardboard, transfer the template to some aluminum flashing, or pvc, carefully determine where you can screw/bolt the material to the door without obstructing the door panel, or any of the window components, cover with more deadening material making sure to seal up all of the edges around your newly installed cover.

It's a bit of work, but it should help a lot. You're not so much trying to create a sealed enclosure (that just isn't possible in a car door), you're trying to prevent the sound waves from the back of the speaker from reflecting off the door and canceling out the front wave of the speaker.
IMHO that is the right way to go.
If you are not able to build a proper volume enclosure for your driver be it sealed or ported it is a waste of time and money.... with really good install the punch in the chest from 6,5 driver is possible...been there done that. My ported doorpanels are just one of them, but that is probably not too common type of install in car audio:rolleyes::cool::surprised:
 
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