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Discussion Starter · #1 ·
Hello,

I have a sq car I have competed with the last couple of years. It is a 1998 Pontiac Firebird (which is a challenge itself). I have 7" Midbass in the doors, 4" midrange and 1" tweets off the a-pillar and a 10" sub in the rear. My question is about putting a 8" sub in the dash or moving the midbass up to the dash firing against the windshield. Is this possible in the huge dash of that car (I can remove the dash pad but not sure what is underneath the metal part of the dash itself...seems like it may be a cavity)? If it is possible, will it improve sound quality and/or bringing the bass upfront. I notice many many european cars doing the midbass in the dash...any advantage or disadvantage?
 

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Discussion Starter · #2 ·
Does anyone have an opinion on this?? I would really appreciate the advice.
 

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Discussion Starter · #4 ·
I attached some pics to show what I mean. I would do this with just the midbass and the midrange/tweeter would be on axis on the dash off the a-pillar.
 

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I attached some pics to show what I mean. I would do this with just the midbass and the midrange/tweeter would be on axis on the dash off the a-pillar.
I think it will rattle the hell out of your dash. If it's strong enough to withstand the beating I think you'll get some very impressive results.
 

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Discussion Starter · #6 ·
Rattles are definitely something to consider. The dash pad is attached via velcro from the factory. As far a phasing...do you think it would be better than having the midbass all the way in the doors?
 

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Rattles are definitely something to consider. The dash pad is attached via velcro from the factory. As far a phasing...do you think it would be better than having the midbass all the way in the doors?
I would think that having the speakers in front of you close together would be a good thing.
 

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Discussion Starter · #8 ·
Have you ever heard a setup like this or known anyone to do this? It seems like 1/2 the guys on the DLS Team in Europe do this and are very very successful with it.
 

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WTF?
 

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The Treo guys in town did this several years ago with a Firehawk. They put a 10" sub in the center of the dash firing straight up. I was very new to car audio at the time but I remember it sounding quite good.
 

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Unless you are a skilled installer/mechanic, don't do it. Getting into the dash on 4th gens are a pain without removing the glass. There are a few spaces, but nothing worth doing.
 

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Sorry for the repost of this link, I just happened to have it near by.

My Trans Am

Doing a sub on the dash will be very difficult but you may be able to get rid of the central AC/Defrost vent to some effect.

In this car, I did a dash install with Illusion 5 1/4 mids (with 1.5" mounting depth) way back on the dash and still had major clearance issues.

Even with the Illusions we had to shave the windshield wiper control arms way down (almost to the point of being useless), btw: that's what is underneath your dash.

Also, you need to be VERY careful with that windshield. When I was working with that car they were pretty expensive ($600) and I broke two of them accessing my mids.

Good luck!

Edit: Just realized this thread was from March!
 

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Discussion Starter · #15 ·
Sorry for the repost of this link, I just happened to have it near by.

My Trans Am

Doing a sub on the dash will be very difficult but you may be able to get rid of the central AC/Defrost vent to some effect.

In this car, I did a dash install with Illusion 5 1/4 mids (with 1.5" mounting depth) way back on the dash and still had major clearance issues.

Even with the Illusions we had to shave the windshield wiper control arms way down (almost to the point of being useless), btw: that's what is underneath your dash.

Also, you need to be VERY careful with that windshield. When I was working with that car they were pretty expensive ($600) and I broke two of them accessing my mids.

Good luck!
So, I have pulled out the dash pad and the metal portion of the dash just has the wiper control arms and vents? Is there room in the dash for a large woofer in the center? How far does the firewall protrude (if any) into the dash area? Is there lots of open space under there? I can't seem to find anyone that know on this car. Thanks for the help!
 

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Have you ever heard a setup like this or known anyone to do this? It seems like 1/2 the guys on the DLS Team in Europe do this and are very very successful with it.
Up from the dead!

Hey, have you seem the build threads from some of these installs? Many of these guys are pretty much rebuilding the dash to make it stronger, more uniform or shaped, and for better firing angles.

As far the cultural differences? I think the judging is different? At a show in the States the majority of the top 10 will have kick panel installs. Overseas, the majority will have dash installs. I think some of these dash installs might work out very nice in some cars but not so good in others.

I would think some small cars may not work out as well? But one never knows what is possible with such heavy modification to the car. I remember I was blown away with an old school backseat driver install in a Ford Fiesta.

I would love to listen to some of these dash installs.
 

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So, I have pulled out the dash pad and the metal portion of the dash just has the wiper control arms and vents? Is there room in the dash for a large woofer in the center? How far does the firewall protrude (if any) into the dash area? Is there lots of open space under there? I can't seem to find anyone that know on this car. Thanks for the help!
It's been 10 years (at least) so I'll have to sift through the mind-fog a bit.

If I recall, there was no easy space under the dash perid. This being said, we only removed the dash cover (and front windshield of course). There may be some sort of usable space where the defrost vents to the glass, but you'd have to do some dissassembly to find out how usable.

As for the firewall, I don't remeber the exact clearance but it does go back under the glass quite a bit. Remember this is a "cab-forward" design and you have to drop the entire front suspension and engine out of the bottom of the car to do any real engine work. Your best bet is to pop the hood and do a visual inspection. You should be able to see the firewall pretty easy.

As an aside, one thing we were considering, if we were going to go to the next level was to build enclosures for the mid/tweet past the firewall and into the engine bay (more far field/on axis this to get passed the window reflection. This would have required a complete re-fabrication of the entire dash areas, cutting through the firewall, as well rebuilding/designing the entire wiper assembly but if I recall it was "technically" doable.

Doing some sort of dash mounted sub is something that we considered for awhile but ultimately walked away from due to the expense and difficulty associated with it. I ultimately went with heavily fabricated door solution but felt at the end of the day it could have sounded better. Those frameless windows never ceased to rattle with all of the mid bass in the front of the car. I ended up tuning the entire front stage around the door's threashhold for midbass and not the limitations of the mid drivers. Keep in mind this is after almost 7 months of fabrication (working nights) and countless hundreds of hours tuning.

If I were in your shoes, I'd probably stay away from this one unless you're willing to go all the way. This will not be a trivial task by any stretch.
 

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I agree with Michaelsil1. The dash is notorius for rattles and also bass is none directional. I would think subs in the rear, mid bass could go up front (doors?) I've found the best sound stage is achieved with mids in the dash (center) with highs. This puts the sound stage in front of you on the hood of the car. Just my thoughts.
 
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