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Discussion Starter #61
If going with a single 15 mount to the seatback opening. Going with 2 15s mount to the crossmember
Single 15 mount to seatback, double 15 mount to crossmember. Is this because of the weight issue?
 

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Discussion Starter #62
Depends, my current configuration mounted to the rear cross member does have room for amps and processors. When mounting against the seatback you can't. More trunk space mounting against the rear seat. You lose 6 inches mounting to the crossmember.

If going with a single 15 mount to the seatback opening. Going with 2 15s mount to the crossmember
What are your thoughts on placing a smaller sub, 8", in the rear deck? Is this going to cause too much rattle from the rear deck or C pillar?
 

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From the pic, you had to seal off the opening to the trunk with a piece of mdf? Is it nailed or glued against the opening? How does the other side of your trunk look? Do you need to seal off anything else? Like the trunk lid? Or the quarter panel, spare tire area, rear deck area where the rear fill speakers at? If I don't need super low bass, do I need a sub bigger than 12"?

If I put in some 6.5 midbass (subwoofer) in the rear fill speaker location is that considered infinite baffle?
That photo was taken prior to cutting the hole for the subwoofer. I was just showing where you could put the baffle. I'm just running bolts through some holes in that support structure around the ski pass opening.
 

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Single 15 mount to seatback, double 15 mount to crossmember. Is this because of the weight issue?
no, its just the shape of the opening. the baffle is a little short (vertically, rear deck to floor) for two 15s. One 15 can be centered at the tallest point.

I'm doing it a third way and I dont recommend it. More work than it needed to be.
 

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What are your thoughts on placing a smaller sub, 8", in the rear deck? Is this going to cause too much rattle from the rear deck or C pillar?
8 inch IB isn't worth it, you need displacement. Band pass with the port firing through the rear deck is a good option. FG sealed box in one of the side cubbies or pull the spare can be done but IB is waaaay easier. Just two pieces of MDF and some duct seal.
 

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From the pic, you had to seal off the opening to the trunk with a piece of mdf? Is it nailed or glued against the opening? How does the other side of your trunk look? Do you need to seal off anything else? Like the trunk lid? Or the quarter panel, spare tire area, rear deck area where the rear fill speakers at? If I don't need super low bass, do I need a sub bigger than 12"?

If I put in some 6.5 midbass (subwoofer) in the rear fill speaker location is that considered infinite baffle?
So IB is basically a wall off of sorts, you're creating two air spaces (cabin and trunk) where the trunk is leaky to atmosphere. Speakers in the rear deck are effectively infinite baffle and so are door speakers. Think about how large the door cavity is relative to the size of a 6.5 inch woofer. Its also leaky due to drains and so forth.

Directly behind the seat back you mount a baffle w/ a hole for your subwoofer in the ski pass. The baffle above was prior to a hole being cut. You need to account for the thrown of the cone so you mount to the trunk side of the baffle. I'm using 4 3" bolts to hold the baffle in place (mounting to the support).

Subwoofer hole is yellow
red holes are bolts to secure the baffle.

After you install the baffle you need to do the best job you can to separate the cabin air space from the trunk. The trunk is like the enclosure to the subwoofer but its leaking through vents and holes to the atmosphere. So its essentially are really big, leaky box AKA infinite baffle. To do this you want to remove the rear deck speakers, seal and deaden all the holes and stuff in the rear deck as best you can. I use CLD to do this for the most part. Large holes should use some material (wood, plastic, etc) to bridge the gap. If you're going really over the top get the MLV out to create a barrier. Next add CCF to any panel that might vibrate and reinstall all the trim.
 

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What are your thoughts on placing a smaller sub, 8", in the rear deck? Is this going to cause too much rattle from the rear deck or C pillar?
I did that with a great 8". It was barely adequate for medium listening and was for sure the weak link. If you have modest expectations then it could provide a bit of bass.

There isn't enough room across the baffle to mount two 15s using the behind the seat method. You can see from the front side of mine that two can't fit
 

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Discussion Starter #68
I did that with a great 8". It was barely adequate for medium listening and was for sure the weak link. If you have modest expectations then it could provide a bit of bass.

There isn't enough room across the baffle to mount two 15s using the behind the seat method. You can see from the front side of mine that two can't fit
Thanks for the detailed response. My Accord is the LX model so I don't have a ski pass. There is a piece of plastic there normally. I haven't remove the felt cover to see if the plastic is screwed in or glued on. Does this mean you have your arm rest down when you listen to music? You have sealed up the rear deck, so you don't have rear fill speakers or is rear fill speakers not recommended for an infinite baffle application because of leaky holes?
 

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Thanks for the detailed response. My Accord is the LX model so I don't have a ski pass. There is a piece of plastic there normally. I haven't remove the felt cover to see if the plastic is screwed in or glued on. Does this mean you have your arm rest down when you listen to music? You have sealed up the rear deck, so you don't have rear fill speakers or is rear fill speakers not recommended for an infinite baffle application because of leaky holes?
all sedans with fold down rear seats have a ski pass. If you can open up the arm rest to the trunk that would be a great way to vent bass into cabin. Alternatively, you have a split rear seat so one side can be dropped to vent bass while listening to music. Us coupe guys don't have either of these options available we vent through the seat back and hope for the best (luckily there are a ton of holes).

Generally, rear fill requires significant processing to pull off correctly. There are a few active threads on it right now involving a helix dsp. The location of the rear speakers are kinda bad (narrow relative to the drive position and front speakers in the doors) so people typically install a smaller driver in the C pillar. TLDR, skip them and save yourself some money.
 

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all sedans with fold down rear seats have a ski pass.
My '19 Accord Sport did not. There are metal plates on the back of each side of the rear seats. I folded down the armrest and took out the plastic piece and then got out the reciprocating saw with a fine toothed metal cutting blade and cut out a hole to match the size of the armrest.
 

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My '19 Accord Sport did not. There are metal plates on the back of each side of the rear seats. I folded down the armrest and took out the plastic piece and then got out the reciprocating saw with a fine toothed metal cutting blade and cut out a hole to match the size of the armrest.
Oh interesting. Honda must be trying to improve the chassis rigidity or acoustics by sealing off the trunk.
 

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Oh interesting. Honda must be trying to improve the chassis rigidity or acoustics by sealing off the trunk.
Maybe but, they're still installing shi**y factory audio systems. At least they have been since my first wife purchased an Accord 20 years ago. 😟
 

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Maybe but, they're still installing shi**y factory audio systems. At least they have been since my first wife purchased an Accord 20 years ago. 😟
There's probably like one guy who controls speakers implementation at Honda and he's been collecting an easy pay check for 20 years.
 

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7th gen premium system rocks! Still sporting it today for my run around car.

Don't worry with the seatback. At least on the coupe there are over 30 1.25" holes in the metal seatback. I only have to do a tick on the dsp due to the seat being up it down. Might lose a db or so.
 

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hmm, I have 2019 toyota corolla and ive been researching ways to get more bass up front. right now im running with one of my seats folded down... and it sounds great! but i dont want to keep my seat folded down. thinking about running a bandpass or similar with a vent exiting through the rear decks where the factory 6x9's go... this thread has got me thinking about that or an IB setup... intresting...
 
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