Anything you can breath through will work, and won't add an aperiodic loading effect. Metal grill material backed with a layer of open cell foam and sprayed with some water repellent should work just fine. You might ask Orion525, as he's doing something similar in his build log here (look at the last few pages for the trunk build):

http://www.diymobileaudio.com/forum...gs-project-install-gallery/146448-e34-three-way-kicks-cement-board-baffles.html

 

screen door mesh works good.

 

Why not replace the 8" IB subwoofer on the rear deck with something larger? Modify the rear deck. You are making it too complicated.

 

Really do you even know anything about my car? Can you tell me whats in my trunk and what my systems consists of? Oh why dont you list all my equipment and tell me what color my car is? Wanna tell me what else to do with my car seeing as you think I'm making things to complicated?

 

I am familiar with the LS430 in its stock form. That is all.

 

WOW... That escalated quickly... . Just wondering why venting to the outside??? I'm very familiar with IB setups, but thought you need the truck somewhat sealed??? I'm guessing needing a little more breathing room to get lower frequency???
Thanks

 

The trunk is not going to be the enclosure as most IB set ups are. Basically in an IB configuration all you're trying to do is isolate the rear waves from the front.

Jesus Hilo, pissy much? For the record his suggestion is simpler and also doesn't cut a hole in the bottom of a Lexus in Hawaiian air.

No not pissy but it does irritate me when someone is telling me what I should do without any knowledge of whats at hand. Also I am not cutting any holes in my car I am using an already existing opening.

In all fairness, it does depend on what other equipment is in the trunk. Air ride tank, nitrous system, computer equipment, amp rack? Sorry, I should not have made assumptions on the design goal. We are all a little crazy on ideas. I err in assuming everyone wants reasonable volume levels and flat frequency response.

The LS430 has a rear HVAC system behind the seats which can pose some challenges. Rear deck probably will fit a single 10 or 12" without significant modification.

If high output is the main goal, it would be possible to build an IB enclosure to house a driver as large as 18". Leave the top of the enclosure open, seal it to the top to the rear deck, and open the rear deck up to the cabin. The rear wave would be open to the trunk. The trunk VAS (or air space) should be enough for a single 18" driver.

What are the design goals?

You are correct certain versions of the LS430 have the rear AC system mine being one. Because of the rear AC system and its ducting there is no practical way to mount a larger driver in the rear deck. So I am using the sub opening as a passage for sound to enter the cabin.

so, the "existing trunk vent holes" aren't sufficiently critter proof? Existing trunk vents holes are sealed with a little flap. For what I want done these will be removed as the flap will not allow an IB configuration. It would basically seal off the rear wave creating a somewhat sealed enclosure.

and are these vent holes, actually pressure relief structures for when you close the trunk, or the doors, so there's no compression and subsequent difficulty in getting the door to latch? Car has auto closing doors and trunk lid. I can partially closed the doors and the auto close feature will pull the doors to completely closed and sealed. Also there are other vents besides the one's I'm considering using.

I'm afraid if you do build your baffles to isolate the existing trunk vent holes, you're removing the pressure relief portion of them, or their main purpose.

Also, if this is to be done because you want to keep the middle of the trunk large enough to fit suitcases and what not, the issue of even being able to sufficiently seal the baffles, and the reality that the trunk itself is going to act like a big compartment muting the output into the cabin, and the fact that IB subs are not going to move air in a pliable container, like a band pass enclosure will, and you're setting yourself up for a less capable system by design.

It's possible that your implementation of this design will surpass my expectations but we're already talking about making bass in the trunk of a Lexus, which is acoustically isolated already and would require significant modification to get the bass to enter the cabin efficiently, and compounding it with a secondary compartment using infinite baffle loading schemes, that further reduces the output available in the cabin from parasitic losses by the trunk lid's flexure and the acoustic filtering of the Lexus standard, sound control.

I'd look into a piping scheme, where I glassed in the enclosures to either side, and used a duct to port into the cabin where there is room. You'd have to accept the compromises of a fourth-order band pass config, though.

then if that's not working, possibly doing a raised deck with shallow mount subs, to get the speakers into the cabin.

If you must have the IB response, you can do the raised deck with aperiodic venting to the trunk, and get your transient perfect detail that way without needing anything drastic in the trunk.

There are shallow mount subs out that require very little depth, and having them in the cabin directly coupled to the air, may give you what you need for far less work overall.

and who's going to care if your deck is 2.5 inches higher than before? Who's going to care only the most important person ME

So, is venting the backside to atmosphere to save space while keeping Qtc and efficiency reasonable? I think that's a better idea than the typical sealed enclosure sitting in the trunk.

I don't know what the best choice is for getting bass into the cabin in your particular car. I would think removing the stock 8" to allow bass to pass through with a pair of 12s in the trunk would have far better output and sound quality than an 8" in the stock location. I don't know what you're capable of fitting in the deck. If you can do a single high excursion 12", that might be the way to go. I know most of us use lots of cone area in IB but a single 12 sealed and the same sealed 12 IB will have the same output potential and people get away with single sealed 12s all the time. I ran a single 12W6 and it was awesome. Output was fine for SQ and would get decently loud with very little power. It got very low very easily but I ended up using a 30hz subsonic to keep excursion under control which is far better than using a box to kill efficiency to control excursion. On top of that, sealed enclosures reduce cone control and it gets worse the smaller the enclosure gets. For that reason alone I like the idea of a couple subs in the corners vented to atmosphere since most corner boxes are undersized.

This is basically what I'm looking at doing. A pair of 12's on either side of the trunk vented to atmosphere and the stock sub location to allow sound into the cabin. I'm sure I will have some oddities due to a pseudo bandpass configuration.

No one knows any details of my vehicle or my system configuration or goals so all of your assumptions are unfounded.

There are already a few compromises made in order to keep the aesthetics I am going for. Unfortunately sound is second to aesthetics in this vehicle as it's strictly a show car and not something I drive or even sit in much.

 

Jesus Hilo, pissy much? For the record his suggestion is simpler and also doesn't cut a hole in the bottom of a Lexus in Hawaiian air.

 

In all fairness, it does depend on what other equipment is in the trunk. Air ride tank, nitrous system, computer equipment, amp rack? Sorry, I should not have made assumptions on the design goal. We are all a little crazy on ideas. I err in assuming everyone wants reasonable volume levels and flat frequency response.

The LS430 has a rear HVAC system behind the seats which can pose some challenges. Rear deck probably will fit a single 10 or 12" without significant modification.

If high output is the main goal, it would be possible to build an IB enclosure to house a driver as large as 18". Leave the top of the enclosure open, seal it to the top to the rear deck, and open the rear deck up to the cabin. The rear wave would be open to the trunk. The trunk VAS (or air space) should be enough for a single 18" driver.

What are the design goals?

 

so, the "existing trunk vent holes" aren't sufficiently critter proof?

and are these vent holes, actually pressure relief structures for when you close the trunk, or the doors, so there's no compression and subsequent difficulty in getting the door to latch?

I'm afraid if you do build your baffles to isolate the existing trunk vent holes, you're removing the pressure relief portion of them, or their main purpose.

Also, if this is to be done because you want to keep the middle of the trunk large enough to fit suitcases and what not, the issue of even being able to sufficiently seal the baffles, and the reality that the trunk itself is going to act like a big compartment muting the output into the cabin, and the fact that IB subs are not going to move air in a pliable container, like a band pass enclosure will, and you're setting yourself up for a less capable system by design.

It's possible that your implementation of this design will surpass my expectations but we're already talking about making bass in the trunk of a Lexus, which is acoustically isolated already and would require significant modification to get the bass to enter the cabin efficiently, and compounding it with a secondary compartment using infinite baffle loading schemes, that further reduces the output available in the cabin from parasitic losses by the trunk lid's flexure and the acoustic filtering of the Lexus standard, sound control.

I'd look into a piping scheme, where I glassed in the enclosures to either side, and used a duct to port into the cabin where there is room. You'd have to accept the compromises of a fourth-order band pass config, though.

then if that's not working, possibly doing a raised deck with shallow mount subs, to get the speakers into the cabin.

If you must have the IB response, you can do the raised deck with aperiodic venting to the trunk, and get your transient perfect detail that way without needing anything drastic in the trunk.

There are shallow mount subs out that require very little depth, and having them in the cabin directly coupled to the air, may give you what you need for far less work overall.

and who's going to care if your deck is 2.5 inches higher than before?

 

So, is venting the backside to atmosphere to save space while keeping Qtc and efficiency reasonable? I think that's a better idea than the typical sealed enclosure sitting in the trunk.

I don't know what the best choice is for getting bass into the cabin in your particular car. I would think removing the stock 8" to allow bass to pass through with a pair of 12s in the trunk would have far better output and sound quality than an 8" in the stock location. I don't know what you're capable of fitting in the deck. If you can do a single high excursion 12", that might be the way to go. I know most of us use lots of cone area in IB but a single 12 sealed and the same sealed 12 IB will have the same output potential and people get away with single sealed 12s all the time. I ran a single 12W6 and it was awesome. Output was fine for SQ and would get decently loud with very little power. It got very low very easily but I ended up using a 30hz subsonic to keep excursion under control which is far better than using a box to kill efficiency to control excursion. On top of that, sealed enclosures reduce cone control and it gets worse the smaller the enclosure gets. For that reason alone I like the idea of a couple subs in the corners vented to atmosphere since most corner boxes are undersized.

 

I would just seal them in the same places.

Using those vents is a bad idea IMO. Not enough vent air for the sub. And don't those vents only open one way- to let the air out when the trunk closes?