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Old 29th March 2004, 01:37 PM   #21
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Default high class baby...

well it would appease you all to know that I went ahead and bought some 6" jl audio speakers for the fronts..they are rated for 50Wrms..the clarity is excellent but it doesn't really put out much bass..i suppose alot of that has to do with the fact that it's in a door panel and not a "real" speaker enclosure..but all in all it sounds good..i didn't have time to run the 6x9's off the HU but i'm sure they'll give a nice backfill. Now I just have to go back and fix my buddies mistake of grounding it on a finished surface. He put the ground wire for the amp on the seat bolt but the metal there has paint/clearcoat on it. It worked for about a day but now I'm getting the dreaded engine whine..I'll sand/file it down and squash it back down there and I'm sure everything will be just peachy...

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Old 29th March 2004, 08:36 PM   #22
maylar is offline maylar  United States
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Doors actually make very good enclosures, but there are a few important things to keep in mind.

The speaker should seal really well to the door panel. You'll lose bass response if there's any leaks that allow sound from the back side to cancel the front wave. This is where installation details make all the difference. This may be even worse for your case, since you adapted a non-stock speaker to the mounting.

Using sound deadening material (Dynamat or equivalent) to dampen resonances in the door skins also helps a whole lot with midbass response. Those JL's could sound sweet if the install was better.
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Old 29th March 2004, 09:08 PM   #23
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Default interesting...

well I certainly want to get the best out of the speakers I can..I'm just not sure how to go about doing it...the actual peice the speaker mounts to is plastic..I tried to cover the sides at the front of the speker where the oval flares out but i'm sure i could have done a much better job..also theres a peice of the back thats open...I wonder if I can get a 61/2" peice that would fit in the nissan door panel...i'm afraid thats something that may have to be made ...any suggestions would be much appreciated! I suppose the goal here is to SEAL off everything but the front of the speaker correct?

thanks!
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Old 30th March 2004, 09:01 PM   #24
maylar is offline maylar  United States
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Yes. Seal off the speaker. Stiffen the door panel around the speaker so it doesn't flex. And dampen the snot out of it to eliminate resonances. All of that has a huge effect on bass response.

Some people fabricate home-made baffles with 1/2" or 3/4" mdf to stiffen the speaker mounts. Each car is different though, so you'll have to figure out what works for you.

The goal is no air leaks from back to front of the speaker, and no vibration of the door cavity (sheet metal) that could cause resonances and cancelations.
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Old 30th March 2004, 09:26 PM   #25
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Default awesome

awesome..thanks for your help so far..i'll see if our radio shop has some of that stuff..hopefully its not too expensive! I've only invested about 100 into the project so far and I don't want to end up doubling the cost of it just for that material! oh well we shall see...

Also I'm still having that stupid engine whine problem..I regrounded it on the seat post..i sanded and cleaned the spot where i grounded it..I also printed out another checklist and I'll try it tonight..right now i'm using about a 2' wire thats the same gauge as my power wire (10ga) and i just have the bare wire wrapped around the seat bolt...is that bad? its strange it seems to work fine for a day and then all of a sudden it starts popping and whining..it might go away and then come back..then the next morning it's not there anymore..very confusing..any advice with a good grounding solution would be much appreciated...such as thicket wire..maybe gold contacts??? anything..pleeeze! I know these are awesome speakers and I want to get the most out of them mainly for my wife since it's her car.

thanks so much for your help so far.
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Old 31st March 2004, 02:40 PM   #26
maylar is offline maylar  United States
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Sound deadening material is not cheap. The brand name Dynamat is best known and most commercially available, but it's outrageously expensive. There are alternatives including these:

http://www.b-quiet.com/brownbread.html
http://www.raamaudio.com/
http://www.secondskinaudio.com/secondskin.html

.. and there's a roofing material called Peel&Seal available at some home stores and it works almost as well.

As for alternator whine, the usual cause is slightly different ground potentials between head unit and amp. Just relocating the ground point of one or the other often cures it. Yes, you need crimped lugs and super clean connections (screw the gold tho). I have some whine too... In my case, the HU is grounded through it's case to the dash and I can't change that.

Better quality amps have isolated inputs, which makes them imune to ground loops.

There are special isolated ("directional") RCA cables that can help too. Last resort is a ground loop isolator, which is what I ended up doing.
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Old 31st March 2004, 05:05 PM   #27
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Default thanks again

hey thanks for the links..i actually found out the problem after buying a 4 gauge ground and STILL having the noise..it's my RCA Cables! Apparently there is a tiny fracture right behind the head of one of them and if i bend the rca cable a certain way it all goes away! I went ahead and ordered some 6' double-shielded rca's off e-bay. I'll definitely check out the alternate sound dampening materials. I guess the main problem is they want you to buy like 60 sq. ft. at a time and I don't need nearly that much for just the 2 doors.

thanks again
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Old 31st March 2004, 07:33 PM   #28
maylar is offline maylar  United States
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When you dampen the inside and outer skins of your doors, with a few extra layers directly behind the speaker, you'll use up material. Then when you hear the difference, you'll wanna do your own car too...

Click the image to open in full size.
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Old 31st March 2004, 07:52 PM   #29
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Default sweet...

when you say inside and outer skin are you referring to 2 different surfaces? I assume the picture you showed me was the "inside" part of it .

Is that a rubber gasket around your speaker hole? See my door is a litle different than yours..I've got the regular door and then I have a Plastic bracket that bolts to it...the plastic bracket was originally made to mount a 5x7" speaker in it as well so I had to modify it and well to make a long story short it is NOT isolating the sound coming from the back from the sound coming from the front...so would the following work:

- put the material ALL over the door except for the handle/bolts.
- Place an extra square directly behind where the speaker/mount will go that is a bit larger than the bracket itself..cutting holes for the bolt again of course.

- Mount the speaker bracket and wrap the dampening material all the way around it
- Cut the 6" hole (or whatever the actual hole needs to be out of the top of the bracket and mount the speaker.

does that sound right?

thanks
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Old 1st April 2004, 11:45 PM   #30
maylar is offline maylar  United States
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Quote:
when you say inside and outer skin are you referring to 2 different surfaces? I assume the picture you showed me was the "inside" part of it
Yes. The outer skin is the side behind the speaker, to the outside of the door. It's harder to dampen because you gotta reach inside whatever opennings there are and use small pieces. Be prepared to cut your hands and arms to shreads on sharp sheetmetal edges

Quote:
Is that a rubber gasket around your speaker hole?
XTC foam baffle sold by Crutchfield. Protects the speaker from water.

Your plan sounds OK. Stiffen the speaker mount with as much reinforcement as you can to keep it from resonating. And seal the speaker to the door panel somehow so the backwave can't come around.
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