Help with my enclosure

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
hello guys, I need urgent help with my enclosure.

now to begin with, the first problem is my car's layout. the trunk is completely sealed from the cabin, so only a port can enter the cabin (see pictures)

the box is 70liter, recomended for 1x MTX 15 not for 2, I can obviously quit one if I see that one is making more output than 2 that's not the point.

I made some tests, and the box is almost well tuned, the bass kicks in at 40hz (although I tried to tune it at 30hz) but its okay.

the problem is that once I close the trunk, I get almost no db in the cabin. otherwise with open trunk, it sounds "well".

how can I solve this?? do I need a 4th order? something else? is the trunk acting like wave cancelation?

thanks guys

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shredder2

CarAudio.com Elite
Nov 19, 2017
2,197
197
Az
the box is 70liter, recomended for 1x MTX 15 not for 2.

the box is almost well tuned, the bass kicks in at 40hz (although I tried to tune it at 30hz) but its okay.
The last time you posted on this forum about your theories and did not listen to anyone... so you got what you have there.

Look at the unbraced baffle between the mounting holes, configuration and volume... I almost did not respond due to your not listening last time.

Looks like a TOTAL fail to me... if you are well tuned or almost why post asking to fix that abortion?

 

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
The last time you posted on this forum about your theories and did not listen to anyone... so you got what you have there.

Look at the unbraced baffle between the mounting holes, configuration and volume... I almost did not respond due to your not listening last time.

Looks like a TOTAL fail to me... if you are well tuned or almost why post asking to fix that abortion?
Sorry I don't have that much experience. Unbraced baffle what does it mean?? do I have to make the box stronger? volume is good for 1x 15", it matches exactly the rated 70liters. what else do I have to change??

 

fithwheel

Member
Dec 8, 2017
872
184
indiana
A prefab sealed box with a pvc pipe added to it. How could you go wrong with that lol.

I like the amp just laying there too.  Seems like the trunk is the least of your troubles. Time to start over maybe? 

 
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shredder2

CarAudio.com Elite
Nov 19, 2017
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197
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Idk... maybe put a prefab (your building skills look questionable) built for a single 15, or dual 15's in there (whatever you need to load the amp correctly) and remove the rear deck speakers... just quit trying to make a 10lb turd into a gold nugget. 

 
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XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
guys I made yesterday some further tests. now listen. I opened the trunk, and seems like I gained 10db. with open trunk, I'm happy with the results, so that's the most important part. seems like some noise cancellation is going on there. how can I fix that?? which layout do you usually use for a sedane that has the trunk isolated from the cabin?? My plans are to start over and build a proper enclosure, but first I have to find the right layout for the purpose. That's why I'm making tests with the actual box.

To make it short: Open trunk, I only get one side of the waves that come out of the port, the rest gets lost outside the trunk, maybe similar to a sealed box.

Closed trunk, the waves seems to bounce back, but instead of adding, they make some sort of cancellation. I need to understand why

 
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Jeffdachef

Gunz That Turn on Nunz
Feb 5, 2013
17,261
252
South Coast Metro, CA
Sorry I don't have that much experience. Unbraced baffle what does it mean?? do I have to make the box stronger? volume is good for 1x 15", it matches exactly the rated 70liters. what else do I have to change??
1 15 needs 100-120 liters. two 15s need 200-240 liters of airspace AFTER subtracting the space the subwoofer and port takes up. No whatever you state or read is not true especially when doing ported and your port is way too fking small and firing the wrong direction. They need to fire the same direction as the subs in a trunk setup thats why you are louder with the trunk open. You are in cancellation hell, 15s need airspace and you are literally choking the fk out of those subs, i feel sorry for them being in such a horrible home with a horrible owner that has no idea how to take care of them.   Also you cant have the port and subwoofers facing different directions like that. You fked up the phasing completely. This is a complete and total hack job.  Either you listen to people on this forum who knows what they are doing or you can do your own sh*t and completely fail over and over and over and over again. I think you prefer the 2nd choice though. 

Roasting the fk out of you aside, you can fix this output problem by flipping the box around have the subs face towards the cabin with the port 4 inches away from the trunk with the port firing towards the trunk..

 
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Jeffdachef

Gunz That Turn on Nunz
Feb 5, 2013
17,261
252
South Coast Metro, CA
start over and do two 12s in a proper box firing towards the rear and you'll be a lot louder than what you have right now.     The 4th order blowthrough with two 8s  might work but you'll have to completely seal off the rear deck. Make sure no pressure, sound or air goes back into the trunk.  Seal off the seat opening completely, you cannot have  any kind of sound wave or pressure come back into the trunk or else you'll lose all output.

If I were you, I'd take the whole system design and enclosure building aspect completely out of your hand and let other people decide on your build and have them design your enclosure. All you do is just build the box to spec.  You have proven that you yourself cannot be trusted to design any sound system that works well.

 
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XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
I understand, I'll probably end with 1x 15".

MTX oficial suggested box is 70liters for ported enclosure. I could probably get up to 140liters by designing a new enclosure.

but first I have to understand the cancellation. Its useless to put effort in a whole new box, and end up like now. I can't do much with my given space, because I only have a tiny hole that connects the trunk with the cabin, and there's only space for a port.

why does it cancel with closed trunk and not with opened trunk????

 
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fithwheel

Member
Dec 8, 2017
872
184
indiana
I understand, I'll probably end with 1x 15".

MTX oficial suggested box is 70liters for ported enclosure. I could probably get up to 140liters by designing a new enclosure.

but first I have to understand the cancellation. Its useless to put effort in a whole new box, and end up like now. I can't do much with my given space, because I only have a tiny hole that connects the trunk with the cabin, and there's only space for a port.

why does it cancel with closed trunk and not with opened trunk????
I swear I've read this whole thread and the question as to why it is responding the way it is with trunk opened and closed has already been answered. It was also mentioned how you should design a new enclosure.
Please build a new enclosure with the port on the baffle and with the proper amount of air space/liters. You could start a new thread and ask for a enclosure design if you're not confident as to how to design it or what size round port you should use and how long. Please clean up your wiring and mount the amp. Last but not least please carefully read each response to future questions and take it all in and please try and not ask the same questions over and over again that have already been answered. Thank you and good luck with your system.

 

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
I swear I've read this whole thread and the question as to why it is responding the way it is with trunk opened and closed has already been answered. It was also mentioned how you should design a new enclosure.
Please build a new enclosure with the port on the baffle and with the proper amount of air space/liters. You could start a new thread and ask for a enclosure design if you're not confident as to how to design it or what size round port you should use and how long. Please clean up your wiring and mount the amp. Last but not least please carefully read each response to future questions and take it all in and please try and not ask the same questions over and over again that have already been answered. Thank you and good luck with your system.
yes, sorry, maybe its my bad english. could you please explain again what happens to the trunk?? a Little more detailled for me to understand. thanks!!

 

fithwheel

Member
Dec 8, 2017
872
184
indiana
yes, sorry, maybe its my bad english. could you please explain again what happens to the trunk?? a Little more detailled for me to understand. thanks!!
Enclosure too small = weak output 

Port too small = weak output

wrong orientation = weak output 

You basically have done just about everything you wouldn't want to do. 

 

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
guys, I understand that everything is wrong with my layout, but I need first to understand how cancellation Works in my case, otherwise I'll do same shit again

 

shredder2

CarAudio.com Elite
Nov 19, 2017
2,197
197
Az
I'm curious Op... what exact vehicle are you working with?

You might have stated in one of your previous threads but it's easier to ask.

 

fithwheel

Member
Dec 8, 2017
872
184
indiana
Not sure how someone can explain it in a way you'd understand? Anyone that would continue to do things that don't work just because said person doesn't understand something but is being told a better way but continues to do it all wrong?Not sure why you would do that but ok.

Idk maybe think about how air pressure/sound waves and trunk and cabin can affect things. 

Seems to me having the back wave firing into the cabin while the front wave is firing into the rear of the trunk is a problem but idk I've never tried it. Seems like a bad idea to me anyway 

 

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
hi Brahs!!! so Little update!!

I took out the sub from the trunk to test it and surprise, it was leaking everywhere!!! basically, they used the outer carpet as sealant, and nailed the cheap "MDF"

there where gaps up to 1cm!!!!!

I sealed everything with some Wood-silicone, and everything changed radically.

still bending everywhere, but at least, its sealed, and all the air exits from the port. the sound is nothing special, sounds.

hair is moving fairly, if i volume up, so good sign, i'll put a video on YouTube soon

next step, stuff some wool, maybe it helps with the bending and bad quality MDF. its not even MDF, its pressed carton.