# Infinite Baffle without destroying the car



## ryan s (Dec 19, 2006)

Since I really don't want to take up a ton of trunk space for a box, I'm having a hard time coming up with a way of fitting a 15" sub. I know...making a lot of threads recently, especially since bass is bass :blush: I want to mount my amps a certain way and I don't want to make a lot of weird chambers and stuff to come up with air space. Also sticking with only 400 watts at the moment.

Thinking IB. I know sqshoestring has 4x of the GTO-clone Infinitys...2x of those 12s would fit my budget and power capabilities in IB mode, with more cone area than a 15. 

How do people make IB baffles without welding, extensive cutting, and cans and cans of Great Stuff? In other words...how do you guys make IB installs presentable and removable if necessary?

Butyl rope to seal the baffle (and 6x9 baffles...maybe...I might shift the sub baffle back towards the trunk) with a layer of blue tape on the sheetmetal, sound deadening for the little holes...what about things like the center seatbelt and seat back latch and other things on the rear deck?


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## falkenbd (Aug 16, 2008)

I used a double baffle for my IB.

Its wedged in and angle brackets are screwed to the baffle and to the sheet metal that is a support on each side.



Another thing you could do it build a baffle that fires through the rear deck holes, and mount the subs hanging down into the trunk. 

You are gunna put screw holes in a few places no matter what you do, but you don't have to destroy anything.


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## ryan s (Dec 19, 2006)

I've thought about the rear deck mounting but my car has the trunk torsion bars under it, and no real way of converting to struts 

There's a couple screw holes where my current box is mounted and the carpet covers the lower ones :laugh:

How did you seal the baffle to the car? I've never used a separate gasket for my subs so I wonder if just carpet plus weather stripping would be enough...?


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## el_chupo_ (May 27, 2007)

What kind of car?
Is rear deck open to trunk?
Do your back seats fold down?
Any existing holes to the cabin?


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## ryan s (Dec 19, 2006)

el_chupo_ said:


> What kind of car?
> Is rear deck open to trunk?
> Do your back seats fold down?
> Any existing holes to the cabin?


1998 Accord sedan
Yes
Yes, in one piece
6x9 holes (obscured by trunk bars), ski pass-thru (plastic, lockable, behind fold down armrest)


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## el_chupo_ (May 27, 2007)

I am not familiar with the various generations of Accords, but there are several IB installs in Accords on the forum:

http://www.diymobileaudio.com/forum/diyma-build-logs/66357-2001-honda-accord-diy-sq.html
http://www.diymobileaudio.com/forum...-2000-honda-accord-coupe-diy-install-bay.html
http://www.diymobileaudio.com/forum...e-ib15-4ohm-car-version-idmax-comparison.html
http://www.diymobileaudio.com/forum...ccord-build-log-alpine-zapco-tc-sounds-2.html

Along with a ton of civics (check out bikinpunk's - he has 2 15's IB in his civic). It looks like there is a "lip" around the edge of the split between the cabin and the seat. If you can make a baffle that goes all the way around that you should be able to cover the by-nine holes, and others, and be good to go, a la this:


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## ryan s (Dec 19, 2006)

I've seen those build threads at one time or another but I'll look through them all again 

Here are some terrible pics of what the trunk sort of looks like. The current box hides lots of OEM pieces :laugh:

There are 2 issues I'm wondering if there are good solutions to. One is the plastic/carpet trunk liner that's one piece:










It doesn't sit flush with the metal:









Rear deck is pretty off limits, but the stock holes to mount the 6x9s will make it easy to baffle:









The pass-thru:









The backside. A "vent-thru IB" has crossed my mind but I don't want to mutilate the pass-thru:









I forgot to picture them...but right above the rear struts on each side is a big hole:











In the last pic, you can see the "lip" on the rear deck since I took out the trim piece years ago...half broken.

How do I contend with the trunk liner and larger holes above the struts? 

Thanks for the help!


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## el_chupo_ (May 27, 2007)

smaller holes = CLD on top and bottom.

Bigger ones screw on a thin piece of mdf/plywood/bracing and CLD over it.


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## ryan s (Dec 19, 2006)

Not sure I can reach anything back by the strut towers, although I'd have to take out the liner to have a closer look. It's a really tight spot...


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## el_chupo_ (May 27, 2007)

You wont be the first one laying down in your trunk trying to figure out how to climb out the back when you cant reach the trunk opening to pull...


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## ryan s (Dec 19, 2006)

I hate getting stuck!!!!!! :laugh:


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## BMWturbo (Apr 11, 2008)

I used some closed cell foam blocks to wedge in between the strut tower tops and the rear shelf to seal them from the cabin, perhaps you can do something similar?


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## ryan s (Dec 19, 2006)

ooooo now that's a nifty idea! Did you use any kind of tape of deadener to keep them in? Just a pressure fit?


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## BMWturbo (Apr 11, 2008)

I probably went a bit further then you are willing to. I used MDF panels over any hole larger then about 30mm dia and used dynamat over any hole smaller then this I could get to.

The closed cell blocks were cut into a 'C' shape so as to be able to be forced into the gap and create an airtight seal around as much of the strut/parcel shelf union as I could gain access to.

I also used caulk to seal all joins and paths I could find between the cabin and the boot.

I found that often holes that seemed to lead to nowhere had a path back between the boot and cabin, so these paths were sealed with an open cell style foam, that could easily be pushed into the gaps and enough was used so that I was comfortable that air couldn't easily pass through.

My Baffle was bolted (using 6 bolts) to the rear seat back and sealed via a neoprene ring directly to the skiport inner lip. This took some time to get right and required fibrglassing etc to get it to match neatly enough to be able to use a 2mm thick gasket.

You'll know you have it about sealed when you shut the car doors and they don't close as easily due to the air not being being able to move between the cabin and the boot (to the vents). You'll also see the sub move when you close the doors.


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## ryan s (Dec 19, 2006)

Haha, yeah...that's a little more involved than I wanted to do :laugh:

I should be able to tear the trunk apart on Monday or Tuesday or hopefully before the end of next week and assess what all's going to happen with it and the methods I'll need to use.

Some AWESOME ideas in here...glad I asked, even if it is in the Dumb Questions forum :laugh:


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## sqshoestring (Jun 19, 2007)

Different car but mine I built a frame that had gussets all the way up, wider at the top. I made a frame that went around these steps at top of seat, then back maybe 8" or something into the rear deck. It was just enough to cover the factory speaker holes. Mounted that to car, then the actual baffle goes on the frame and gussets go down one each side one center to floor. Went inside and laid around 4" wide wood down sides to edge of seat hole (no fold downs). Antother down top and bottom to fully seal. If I had gone wider I would have hit the wheel wells. The gussets were needed to lean the baffle back some, to fit quad 12s. So the top 12s are set back and nearly to the deck in height...a few inches above the top of the seat hole (where I would have folddowns if I had them.


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## ryan s (Dec 19, 2006)

Finally got the trunk stripped out, an IB15 on the way, and now reluctant to put any effort into it due to all the rust and moisture in it. REALLY don't want to put my "nice" amps in right now.

But on the other hand, this will be good practice since I really don't care what gets f'ed up as long as some trim/carpet covers it and doesn't affect resale value 

With regards to this pic...I took some others of what is behind the trim pieces. The build log doesn't mention what happened (if anything) with the gaps.










Notice the supports on both sides









See the gap? It's hidden by the carpeted plastic










Now, I'm sitting on the back seat looking backwards. The left is the tire well and shock tower. *Where/how would I attach a baffle to the outside of these gaps? *









Do I need to seal these up?


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## amir12 (May 10, 2010)

Regarding sealing the rear deck, would it be okay to keep rear fill in this case? Would the bass "leak through" the 6x9s?

Is it really necessary to remove rear fill (6x9's) and seal them up?

I understand the rest of the rear deck needs to be sealed but I'm just worried about the rear fill.


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## ryan s (Dec 19, 2006)

I would be inclined to say they should come out. It's a little different than versus a regular box...since with IB...the trunk IS the box and would be sharing airspace.

Mine are now sealed off :laugh:


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## sqshoestring (Jun 19, 2007)

It depends on if you have VBA or not  Seriously, you can run say a pair of 10s IB maybe 12s and its no problem to run 6x9. But if you step up and really start pounding the sub with big xmax or 15s, then you start creating a lot of pressure in the trunk and you can start moving the 6x9s via pressure. At that point you need to box off the 6x9. I've listened intently many times and before they move I can't hear any canceling or anything. If you have open holes like speaker holes, they must be plugged. If you have some leaks here or there do what you can but tiny holes (say a limited number smaller than a finger) don't make a difference. Carpet/foam (like weatherstrip) can work great to seal IB and be removable when the time comes. I only use spray foam in cavities when I must, its too messy and often there are other ways. If the leak has a contorted path, it will work like a port and most are tuned very low. You can also rate leaks by air flow playing low tones.

6x9 tend to be pretty stiff they will hold up to some sound pressure. IMO if they don't move that much with the subs dialed up good, I don't care anyway because the sound difference at high output is likely not noticeable, at least I could never hear it. On the other hand you could experiment with venting to the outside but not sure that would take much pressure away.


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## ryan s (Dec 19, 2006)

sydmonster did IB in the spare tire well, I believe...


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## sqshoestring (Jun 19, 2007)

You can do it to the outside, but I never had any problem with it working in the seat or deck.


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## RaVeNMonStar (Sep 12, 2015)

Hi, quick question. 
How much airspace is a rule of thumb for IB? 
I've read on a few fourms that say 25 times the vas of the sub/s
Other sites say 10 times the vas. Lastly, another site says 4 times the vas is acceptable.


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## sqshoestring (Jun 19, 2007)

I now have pair of pyle 15s IB, the trunk is about 1.5X Vas of the pair. I lose 1db at 20hz on the model, and that seems correct I can barely detect a difference when I open the trunk doing tones and sweeps. It really depends on the sub but its so easy to model in winisd I just do that. You can slide the box volume down (use a sealed model) and when you see the curve start to hump up, then you are going out of IB. IB just means you are not changing the FR from what it is in a 1000cf box...more or less. And really if you change it a small amount you can EQ it back, but you get up to 3db loss at say 30hz and you will notice it. I like it pretty flat 30-80 that is where I need it, but hard to do with smaller subs. You will find low qts subs have less output down low, but they care a lot less what size box they are in. Some of the HT IB subs have massive Vas and those kick the lows out but you can get in trouble in a trunk as a small box will trash their response at low Hz, or if you use multiple subs. Just model it and get the response you want. Generally you want higher qts .5-.7 unless you have a small volume available for each sub, and you usually want a low Fs 20-30Hz unless you like tighter boomy bass and don't want the subs to dig low. My 15s are Fs 20 and Qts .7 and work great for my use, they will play near flat to under 30hz, they sound pretty nice even with no EQ and LP at 200hz.

I run 500rms on these. I had the quad 12s and they had a higher tuning I didn't like plus that was a lot of sub in a smaller trunk. I had to run a PEQ on them. They did have a little more output due to more cone area, but my biggest complaint is the sub board loaded was so heavy I could hardly get it in/out of the car, it made the car drive differently lol. The 15s are much lighter and dig deeper.


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