Free-Air/IB 6.5" woofers: need help on mounting, sealing, etc. (new to IB setups)

[phenryiv1 10+ year member]

I have 2 Dayton 6.5" woofers that I plan to experiment with in my rear deck. I want to use them in place of a boxed sub. I need my trunk space, and I am in no way a basshead, so for what I paid for them, they are a cheap experiment. They are 8 ohm and will be run off of 200W RMS into a single 4 ohm load (by running them in parallel and bridging my amp).

The car currently has 6.5" coaxials in the rear deck. It also has a 6.5" woofer (Nissan calls it a subwoofer) that has been disconnected. I plan to remove the stock rears and to replace them with the Daytons. I have MDF rings to use to mount these.

Do I mount the speaker on TOP of the rear deck and put the rings BELOW the deck (to make the mounting more secure) or do I put the rings on top of the deck and undermount the drivers?

Also, I plan to remove the stock woofer to give me space to suspend a platform on which to mount my amp (rightside up, of course). Do I need to seal up the gaping hole that I will have in the middle of my rear deck? If so, can I just use caulk and screws to attach wood over the hole?

Lastly, the rear seat is not a fold-down design, but there is open exposed foam. Do I need to use a board or baffle to cover the opening and then seal up around the edges?

Thanks!

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[req 5,000+ posts]

Do I mount the speaker on TOP of the rear deck and put the rings BELOW the deck (to make the mounting more secure) or do I put the rings on top of the deck and undermount the drivers?

well, it depends on how much room there is eaither way. if there are trunk tensioners underneath, you may have to mount the rings above with the speakers above, but if the rear deck cover is shallow, you might have to hang them. it all depends on how much room you have. and we cant tell you that unless you provide pictures. i usually hang mine for ease of installation\removal.

Also, I plan to remove the stock woofer to give me space to suspend a platform on which to mount my amp (rightside up, of course). Do I need to seal up the gaping hole that I will have in the middle of my rear deck? If so, can I just use caulk and screws to attach wood over the hole?

you shouldnt. it really should not matter, there is not enough pressure to need to seal it up. but hell, you could use some cardboard and some silicone if you wanted to do it anyway. as far as the amp goes. ive mounted countless amplifiers from the rear deck upside down. there is absoltutly nothing wrong with it. if it makes life eaiser, mount a piece of 3\4 of 1\2 MDF to the underside of the rear deck. mount your amp to that, and call it a day.

i guarantee it will never ever show any problems mounted this way.

Lastly, the rear seat is not a fold-down design, but there is open exposed foam. Do I need to use a board or baffle to cover the opening and then seal up around the edges?

no. there is not enough pressure for that need. maybe if you were trying to do a pair of 15" IB. but then you would prolly have to mount them where those seats are anyway //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

lol. good luck.

 

[phenryiv1 10+ year member]

^^^^^^^

Thank you. Informative post.

I THINK that I have the room to mount 3/4" MDF rings OVER the deck and still fit them UNDER the covers...is this preferred? If not, I know that I can do the drivers on the deck and the rings under.

I plan to mount the amp rightside up only because I have heard horror stories, but then again, I used to run amps UNDER the flip-up rear seat in my Cherokee with no overheating problems, despite the fact that one ran @ 2 ohms and there was NO ventilation- just an inch overhead and 3-4" on 3 sides.

 

[req 5,000+ posts]

you should eaither mount the baffles above or below, and then mount the speakers to the baffles.

i would mount the baffles below, and then the speakers below those.

for example, this would be mounting the baffle on top of the hole and then the speaker to the baffle

the opposite, the speaker would be 'inverted' firing into the hole. does that make sense?

and i still would run the amp upside down :shrug:

 

[phenryiv1 10+ year member]

mounting it with:

Deck

Ring

Upward-firing driver

makes perfect sense.

 

[Buffalohed 10+ year member]

Good info here.

I'm doing something kind of similar in the future with my rear deck.

Thanks for the info guys.

 

[thesandman 10+ year member]

Good info here.
I'm doing something kind of similar in the future with my rear deck.

Thanks for the info guys.

x2, also does anybody know of some high powered 6x9's subs that i can run IB, or 6.5's that i can use with an adapter of some sort for the rear deck?

 

[strong*I*bumpin 10+ year member]

Here ya go...http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=264-832

 

[audioholic 5,000+ posts]

The only advice I would change is... yes, seal it up. IB relies on the front and rear waves being completely isolated from each other (the 'infinite' part of infinite baffle). If you do not seal up the seperator between the front and rear waves, cancellation will be a problem that will affect freq response and/or output.

In other words, if you are running speakers in the rear deck infinite baffle, the trunk must be sealed up from the passeneger compartment as well as possible. This is rule number 1 in designing an in-car IB setup.

 

[phenryiv1 10+ year member]

The only advice I would change is... yes, seal it up. IB relies on the front and rear waves being completely isolated from each other (the 'infinite' part of infinite baffle). If you do not seal up the seperator between the front and rear waves, cancellation will be a problem that will affect freq response and/or output.
In other words, if you are running speakers in the rear deck infinite baffle, the trunk must be sealed up from the passeneger compartment as well as possible. This is rule number 1 in designing an in-car IB setup.

That is a textbook explaination of what I had always heard- and exactly why I asked. I know that when IB was more common, people used bigger drivers, making it a bigger issue, but I suppose it is the same issue as properly sealing doors to get better midbass out of midranges.

 

[audioholic 5,000+ posts]

That is a textbook explaination of what I had always heard- and exactly why I asked. I know that when IB was more common, people used bigger drivers, making it a bigger issue, but I suppose it is the same issue as properly sealing doors to get better midbass out of midranges.

Exactamundo. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Death By Bass 10+ year member]

if there was a 6.5inch "subwoofer" in the deck stock aswell, why not use three 6.5inch woofers in the shelf? //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[mattmcss 10+ year member]

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-837

I have a pair of those, I might experiment with this summer with an IB rear decklid, underhung to clear the x-max with a 3/4" MDF spacer, I'm going to seal the deck with some sound deadener.

 

[req 5,000+ posts]

you can get some thick cardboard and silicone it over holes. that would work fine. maybe some el-cheapo plastic or even some aluminum sheet from the hobby store.

should take no longer than an hour to seal the rear deck. seriously. id prolly use aluminum and rivets and then sound deaden over it.

thats just me. those 6x9s look cool. so do the 8x12's

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-838

 

[audioholic 5,000+ posts]

req is right, going with such small drivers, the pressure created wont be much. Even cardboard (like he said) will likely do fine. I didn't mean to suggest you needed to build a 3/4" mdf wall or anything. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I assume you will bandpass these like regular subs. Interesting little project, keep us updated.