(3) OA-15v.2 (1) trailblazer

[itsblown 10+ year member]

You guys are nuts doing a build in this cold *** weather!
Looks good though, I can't wait to see the finished product.

Is your buddy shooting for a certain spl number or is it just gonna be a street beater?

Maybe we can set up a Toledo meet and I can get everyone on the SPL LAB sometime

More of a street beater than anything at this moment in time. He is telling me he wants to have adjustable tunning so if he does want to compete once or twice he can. Being that both of us are going to U.T. in engineering its hard finding the time to work on it. Im sure he would be down for a meet up as would I in my own car.

Expect to see some updates over the holiday time

 

[knotdrummer88 10+ year member]

How effective are those insulation bags? And Im going to hear this when its done. I will.

 

[4bannger 10+ year member]

Interested to hear how the insulation bags work. It seems as if the bag itself would case noise.

 

[av83 10+ year member]

[quote name='4bannger']Interested to hear how the insulation bags work. It seems as if the bag itself would case noise.[/QUOTE]
@keep_hope_alive ; swears by them, and that guy knows what he's doing.

 

[keep_hope_alive Premium Member]

I use 1 mil pvc bags. So thin that mids and lows sound passes through. amazing results. Use as much as you can

 

[itsblown 10+ year member]

[quote name='keep_hope_alive']I use 1 mil pvc bags. So thin that mids and lows sound passes through. amazing results. Use as much as you can[/QUOTE]

We are stuffing as much in those doors as possible. Would there be any benefit to putting these bags inside hollow cavities of the car where there is no speakers? In the trailblazer im talking about the sides of the cargo area.

As far as I can tell (with just the front stock bose speakers and both door panels off) the plastic bag doesn't create any noise


Also sorry about the speed of the build but like I said were both super busy college kids, hopefully some progress gets made over break. Installing the aluminum flashing and trying to seal up those massive holes is going to be a nightmare. Also anyone have suggestions for how to mate the speaker bracket with the aluminum flashing?



just showing you how thick the bags are

We used two sided tape on the back of each bag to press it to the door, then we used duct tape to keep the bags pressed up tight against the door and where parts of the window might rub against the bags. If you try out the fiberglass bag method do a test run and roll the windows up and down a few times to make sure it doesnt rip or catch the bags.

Also here are the cross overs we plan on running that were given to us for free by @rctoddjr59 thanks again.

 

[keep_hope_alive Premium Member]

yep, those bags are just what i'm talking about. i have stuffed fiberglass batt and even polyfill in vehicle cavities before and i have noticed a reduction in now long the metal "rings out". hollow cavities are bad, cavities stuffed with fiberglass batt are less bad. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

the plastic isn't audible, sound waves aren't pushing on them like your fingers can - the movement is much, much smaller.

get them doors sealed up and you'll enjoy good, lower midbass and great, smoother midrange. these bags gave me (and others) the most benefit in those to main areas.

 

[knotdrummer88 10+ year member]

yep, those bags are just what i'm talking about. i have stuffed fiberglass batt and even polyfill in vehicle cavities before and i have noticed a reduction in now long the metal "rings out". hollow cavities are bad, cavities stuffed with fiberglass batt are less bad. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
the plastic isn't audible, sound waves aren't pushing on them like your fingers can - the movement is much, much smaller.

get them doors sealed up and you'll enjoy good, lower midbass and great, smoother midrange. these bags gave me (and others) the most benefit in those to main areas.

Im gonna have to try this

 

[keep_hope_alive Premium Member]

Im gonna have to try this

it is worth the effort. even if you've already sealed the doors.

the reason is pretty simple. sound inside the door just reverberates - it builds and builds as music is played. pne easy path out of the door is back through the woofer cone. that's right - woofer/speaker cones can move air but can't do well for blocking sound. so what you hear is a delayed and reverb version of the original back through the cone. the result is a loss of midbass and muddy, peaky midrange. best thing to do? absorb everything you can in that door. as always, you don't want sound from the rear combining with sound from the front.

as you attack building a car audio system the same way a designer builds a homer audio tower speaker - some of my efforts start to make sense.

 

[itsblown 10+ year member]

got some work done will be posting pics after classs

 

[bhsdriller 10+ year member]

have never seen the bag deal used before....will try

 

[gckless 5,000+ posts]

Tuned in. Hoping to pick up a Blazer shortly. Also never seen the bag trick before. You going to seal the doors with wood or metal as well?

 

[itsblown 10+ year member]

For those of you that are interested in using the fiberglass bags in their doors, their is a much easier product to use that has the same acoustical properties as fiberglass called Roxul Safe'n'Sound. Its easier to use because it doesn't retain moisture and there is an adhesive on one side of it, which eliminates the need to make bags and use tape to stick it to the door.

Well we woke up early today to get some work done on this thing after not touching it over the holidays. Its super cold out but thankfully we have a space heater and we just installed some overhead lighting in the garage.

an extra portable light always helps

Building materials have been accumulating in the trunk

We had a couple of bags that were getting rubbed on by the window so we added patches of duct tape in the spots that it rubbed up against. Here is a bag before the patches

we also put tape all around the bag to push air into other areas of the bag that werent as close to being hit as the window came down. the book is to push the air out

Next on the agenda was running the speaker wire into the doors, Unfortunatly GM used a plug to connect the wiring inside the car to the wiring inside the door.

this meant we had to drill a hole of our own

Remember anytime you run wire through a metal hole like that its important to use a rubber grommet, or silicone to prevent the insulation on the wire from being cut. If the insulation gets cut your wire could short out to the body of the car. Even while I was pulling the speaker wire through the hole as carefully as I could I managed to scrape some of the paint off the insulation.

thankfully their wasn't a plug on the actual door for the wiring, it was just a rubber grommet.(sorry for the bad picture, its kind of hard to get a shot of it)

 

[itsblown 10+ year member]

We decided to make a hole in the rubber gromet instead of the door metal to get the speaker wire through.

A small pocket knife does the trick quite nice,

and its through

were going to use aluminum flashing. These doors are a complete pain to seal up because its basically one large gapping hole, and the window motor assembly comes out past the inner metal of the door pannel. Should have pics up soon

 

[itsblown 10+ year member]

More updates! its time to start sealing off the door! GM decided to cheap out, never before have I seen a door that didnt have 2 panes of metal, its litterall just the outside sheeet of metal in the door so creating a seal with an mdf bracket is going to be a *****.

To seal it off we decided to use aluminum flashing. Aluminum flashing can be found at lowes or home depot and is fairly cheap and can be cut with tin snips, which makes it a great product to seal up doors, it just requires a layer of deadener to help stiffen it up afterwords.

I like to use a cardboard cut out to trace out what I need to cut, cardboard is a lot easier to work with and once you make these cardboard templates they can be used on the other door

we used double sided to tape to trace out the edge of the hole that the aluminum is covering, this creates a nice seal between the flashing and door.

here is the first panel of flashing put on. We used Self piercing sheet metal screws to hold it in place, this is probably over kill and the double sided tape would work fine but we dont want to have to go back and re do this stuff. You can see how far the window motor portrudes out in this pic.

the second panel covering the window motor.

We decided to stop there on the aluminum flashing and wait untill we finish making the speaker brackets, that way we can mount the bracket right up to the flashing and hopefully have a perfect seal.