2002 Monte Carlo - Sealing off the trunk question
#1
02-09-2011 | 04:58 PM
Thread Starter
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Joined: Jan 2011
Posts: 74
From: Atlanta, GA
2002 Monte Carlo - Sealing off the trunk question
Has anyone sealed off their trunk space from the cabin?
Im thinking about sealing off my trunk from the cabin so I can negate that sound wave issue in cars with trunks, so I was wondering if anyone has done this and if so, what dimensions did you make the sheet of MDF and what did you seal it with?
Im thinking about sealing off my trunk from the cabin so I can negate that sound wave issue in cars with trunks, so I was wondering if anyone has done this and if so, what dimensions did you make the sheet of MDF and what did you seal it with?
#3
02-10-2011 | 05:16 AM
Thread Starter
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Joined: Jan 2011
Posts: 74
From: Atlanta, GA
yeah i just wanna check my measurements against ones that have already been made. thanks for the attempt at help though.
#5
02-10-2011 | 03:28 PM
Joined: Oct 2010
Posts: 654
Theres no one set of measurements that will work for all applications since whats needed is determined by the size of ur sub box. You dont simply seal off the trunk from the cabin, you set ur box in place with the subs and port aiming forward and seal all around the box to ensure the air doesnt make its way back into the trunk, including sealing off the rear deck really good as well. So each application is unique, theres no right or wrong measurements. I mean, you could seal off the whole trunk from the cabin if you wanted to but that wouldnt be a good idea at all.
#6
02-10-2011 | 07:06 PM
Joined: Dec 2010
Posts: 697
i'm not sure where this logic is coming from but why would one SEAL a trunk off from the cabin? the cons would out weight he benefits. might have less baffeling, but your lows from your sub (assuming you have one) will be coming through the rear seat very poorly.
#7
02-10-2011 | 09:07 PM
Joined: Oct 2010
Posts: 654
i'm not sure where this logic is coming from but why would one SEAL a trunk off from the cabin? the cons would out weight he benefits. might have less baffeling, but your lows from your sub (assuming you have one) will be coming through the rear seat very poorly.
A.) Going to run his sub(s) in IB alignment
B.) Going to build a 4th order and port it through the rear deck or ski pass opening.
or
C.) Going to run his sub(s) and port forward with that wall being used as the baffle of the box.
If he's not planning on doing either of the above, sealing off the trunk is a bad idea.
The whole purpose to sealing off the trunk is to eliminate the issue of cancellation due to the front and rear sound waves being out of phase with each other. How do you know if you have cancellation? Easy. Sit in your car and listen to a song you're familiar with, while you're listening to the song have a buddy open the trunk, if the bass gets louder then you indeed are having cancellation issues. How can the bass get louder with the trunk open? Makes no sense huh?
In this picture the vertical line is the back of the trunk and the black box is the subwoofer box which is facing towards the cabin. When the sub hits, the sound goes foward into the cabin (red wave) but also reflects off the back of the trunk to become the reflected wave. When those two waves are way out of alignment as shown in the picture there will be major cancellation. Simply opening the trunk will cause that reflected wave to "disappear" and not reflect back in the trunk and not cause cancellation in the process.
In this picture the sub is aimed at the trunk and the result is that the waves aren't nearly as out of phase as the first picture, resulting in much better bass response but still not as good as it can be.
In this picture the sub box is moved so it's closer to the back of the trunk with the sub firing towards the trunk resulting in the waves nearly being in phase with each other resulting in the best bass response.
Firing the subs/port into the cabin with the baffle of the box sealed off from the trunk results in a wave patter much the same as the last picture, directs all the sound/air into the cabin area and nearly eliminates that horrendous trunk rattle on high powered systems too.
#8
02-11-2011 | 07:39 AM
Thread Starter
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Joined: Jan 2011
Posts: 74
From: Atlanta, GA
Either i'm misunderstanding what he's trying to do or he's misunderstanding what he's trying to do and when/why it should be done. Judging from the posts he's made it sounded to me like he wanted to completely seal off the trunk from the cabin to "negate that sound wave issue in cars with trunks" (cancellation). But he never made any mention of firing his sub(s) into the cabin, furthermore he was asking "what dimensions did you make the sheet of MDF", until he chimes in to clear the air I can only assume his plan is to simply put up a wall directly behind his back seat to seal his trunk from the cabin. The only way that would work well is if he is:
A.) Going to run his sub(s) in IB alignment
B.) Going to build a 4th order and port it through the rear deck or ski pass opening.
or
C.) Going to run his sub(s) and port forward with that wall being used as the baffle of the box.
If he's not planning on doing either of the above, sealing off the trunk is a bad idea.
The whole purpose to sealing off the trunk is to eliminate the issue of cancellation due to the front and rear sound waves being out of phase with each other. How do you know if you have cancellation? Easy. Sit in your car and listen to a song you're familiar with, while you're listening to the song have a buddy open the trunk, if the bass gets louder then you indeed are having cancellation issues. How can the bass get louder with the trunk open? Makes no sense huh?
In this picture the vertical line is the back of the trunk and the black box is the subwoofer box which is facing towards the cabin. When the sub hits, the sound goes foward into the cabin (red wave) but also reflects off the back of the trunk to become the reflected wave. When those two waves are way out of alignment as shown in the picture there will be major cancellation. Simply opening the trunk will cause that reflected wave to "disappear" and not reflect back in the trunk and not cause cancellation in the process.
In this picture the sub is aimed at the trunk and the result is that the waves aren't nearly as out of phase as the first picture, resulting in much better bass response but still not as good as it can be.
In this picture the sub box is moved so it's closer to the back of the trunk with the sub firing towards the trunk resulting in the waves nearly being in phase with each other resulting in the best bass response.
Firing the subs/port into the cabin with the baffle of the box sealed off from the trunk results in a wave patter much the same as the last picture, directs all the sound/air into the cabin area and nearly eliminates that horrendous trunk rattle on high powered systems too.
A.) Going to run his sub(s) in IB alignment
B.) Going to build a 4th order and port it through the rear deck or ski pass opening.
or
C.) Going to run his sub(s) and port forward with that wall being used as the baffle of the box.
If he's not planning on doing either of the above, sealing off the trunk is a bad idea.
The whole purpose to sealing off the trunk is to eliminate the issue of cancellation due to the front and rear sound waves being out of phase with each other. How do you know if you have cancellation? Easy. Sit in your car and listen to a song you're familiar with, while you're listening to the song have a buddy open the trunk, if the bass gets louder then you indeed are having cancellation issues. How can the bass get louder with the trunk open? Makes no sense huh?
In this picture the vertical line is the back of the trunk and the black box is the subwoofer box which is facing towards the cabin. When the sub hits, the sound goes foward into the cabin (red wave) but also reflects off the back of the trunk to become the reflected wave. When those two waves are way out of alignment as shown in the picture there will be major cancellation. Simply opening the trunk will cause that reflected wave to "disappear" and not reflect back in the trunk and not cause cancellation in the process.
In this picture the sub is aimed at the trunk and the result is that the waves aren't nearly as out of phase as the first picture, resulting in much better bass response but still not as good as it can be.
In this picture the sub box is moved so it's closer to the back of the trunk with the sub firing towards the trunk resulting in the waves nearly being in phase with each other resulting in the best bass response.
Firing the subs/port into the cabin with the baffle of the box sealed off from the trunk results in a wave patter much the same as the last picture, directs all the sound/air into the cabin area and nearly eliminates that horrendous trunk rattle on high powered systems too.
#9
02-11-2011 | 09:13 AM
Thread Starter
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Joined: Jan 2011
Posts: 74
From: Atlanta, GA
i'm not sure where this logic is coming from but why would one SEAL a trunk off from the cabin? the cons would out weight he benefits. might have less baffeling, but your lows from your sub (assuming you have one) will be coming through the rear seat very poorly.
there would be more baffling if you just had a box in the trunk, due to it firing through the seat and the mdf.
in any case, im going to port through the rear deck.
#10
02-11-2011 | 09:14 AM
Thread Starter
|
Joined: Jan 2011
Posts: 74
From: Atlanta, GA
Theres no one set of measurements that will work for all applications since whats needed is determined by the size of ur sub box. You dont simply seal off the trunk from the cabin, you set ur box in place with the subs and port aiming forward and seal all around the box to ensure the air doesnt make its way back into the trunk, including sealing off the rear deck really good as well. So each application is unique, theres no right or wrong measurements. I mean, you could seal off the whole trunk from the cabin if you wanted to but that wouldnt be a good idea at all.