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Old 06-17-2018, 04:22 PM   #1
Mwishlist
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Under seat Mid-bass SUCCESS!

OK, so the one thing that sucks about my vert is the sound quality, mainly the lack of any real bass upfront. The stock speaker location sucks; it has holes everywhere, a huge gap for wiring that kills the output from the driver and most aftermarket speakers donít work well there. The goal is a loud, clear system that sounds good even with the top down and it has to look mostly stock. That's the big stickler, it's easy to just cut up the doors and throw in some 6.5's or something but I didn't want to go that route though.

Enter the Earthquake SWS 6.5 shallow subs:
[IMG][/IMG]

I'm not fooling myself that these are actually subs in the traditional sense, I have a JL Audio sub in the trunk for some decent lows. But these drivers are only 1.75 inches deep, go in an enclosure as small as .2 cu ft. and have a tiny bit over a half inch of excursion. For only $100 a pair I figured it was worth a try. If I can get some decent mid-bass sound and impact from the pair under the front seats, then mission accomplished.

I figured out a placement that would let me fit the sub under the seat, even with the seat pushed all the way forward and at its lowest setting. I'm 6'3 so I have the seat all the way down, but I usually drive with it about halfway pushed forward. The only way to get at least .2 cu ft is with a custom fiberglass enclosure, which I've never done before. But fuck it, I never swapped an entire drivetrain in a car until a few years ago either so, how hard could it be?

Spoiler: I mocked up a quick box and it sounds freaking fantastic, way better than I hoped. I'll post pics an info as I get them built.
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Old 06-17-2018, 06:24 PM   #2
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The pic above is the initial sub placement. Notice the enclosure will be a bit forward of the front seat and dip down to cover that area where the wiring sits. I'm going to try to round this out with a poster tube cut to a partial curve.

Under the seat view for clearance with no carpet:


The back of the carpet foam has to be cut away to get close to the same clearance:
[/url]Mid bass

Since I don't know what the hell I am doing and this is mostly a flat area, I bought some modelling wood to frame it out. I am using the wood for the back and sides with poster tube added to the front so it has curve to it. This will give me a form to lay the fiberglass, then I am going to use fleece on the top.

This is a pic of the taped of area with the frame built out:
[/url]

Note: After doing the first one I realized it's basically a square that's 2" high in the back and 3" high in the front. Then it dips down to meet the floor. You could use mdf on the sides and top and just fiberglass the bottom. This would save a ton of time if you can cut wood but it's damn tight trying to get .2 cu ft. in this area and every inch counts. The fiberglass is lighter, thinner and plenty strong, but a lot of work.

First fiberglass coat. I am going to build it up pretty solid, again I am not pumping thousands of watts here, so I'm not too worried about flex:
[/url]

Finished fiberglass box with speaker ring ($7 a pair on Amazon):
[/url]

Checking clearance under the seat again:


This is a pic with the seat all the way back to show how exposed it will be. I'm going to carpet it and try to match it to the floor carpet. If I had a black interior it would be a lot less noticeable:



Covered with fleece:
[url=https://flic.kr/p/26VRUkB]

Next I need to resin and glass the fleece, carpet it and do it all a second time.
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Old 06-17-2018, 11:01 PM   #3
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Nice! Funny enough, newer BMWs build the subs under the front seats just like that - so you arent totally out in left field.
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Old 06-17-2018, 11:44 PM   #4
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Nice looks like your flushing the sub in. So why did you not bring the fleece down to the inner lip with some staples? I’d be afraid that the fleece will lift with the sub pressure. The mdf is known to delaminate.
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Old 06-18-2018, 06:19 AM   #5
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Originally Posted by _Keith_ View Post
Nice looks like your flushing the sub in. So why did you not bring the fleece down to the inner lip with some staples? I’d be afraid that the fleece will lift with the sub pressure. The mdf is known to delaminate.
Great call out, honest answer is; I have no idea what I am doing

So it's funny, I have seen a few people do that on tutorials but no one explained why they did it, I thought it was for cosmetics. But I was concerned about that so I used a resin mix inside the box, turned it upside down and sloshed it around the speaker ring. Then tried to glass the inside a bit around the ring. I would not recommend this, your way would be a much better seal. I'm going to redo my trunk sub into the side panel and when I do that one, I will definitely do it with staples in the middle.

You aren't supposed to leave just the fleece with just resin, but I figured for midbass it would be ok. However once it hardened it still had a little flex to it, so I added a few layers on top and now it's solid as a rock.
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Old 06-20-2018, 09:04 AM   #6
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So not a huge update, but I finished the first one. I suck at carpeting a box with curves but whatever. I bought some material that looked close to the carpet color, but it was really cheap, started shedding immediately and the color was not close enough. So I went with plan a and went with black:


It's not too bad. I actually found some SEM paint for the arm rests and map pockets that is almost perfect when I redid my interior. If I get really bored I may try using bondo to smooth everything out and paint the enclosures. I also have rings to add a grill, i just haven't gotten around to it yet.

Even though I measured and marked multiple times, the box could go deeper under the seat and be taller to make up for the loss of airspace. I am pretty convinced you could do a fully stealth install of these speakers or fit the SWS 8 inch subs in the current size boxes I built. But I am not re-doing these anytime soon. The second box is almost done and I'll get some completed pics and impressions in a day or two.
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Old 06-24-2018, 11:39 AM   #7
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So I finally finished both and I have to say, it's unbelievable what a difference they make. Seriously, best $100 I've spent on this car yet. The fiberglass was a PITA and cost me more than the speakers, but I wanted to build a custom sub box eventually, so it was good practice for that. I learned a lot of what not to do next time. You could do all MDF boxs, flush the sub so the seat doesn't hit it and be a little short on the cubic foot space needed. But I think that would be ok. I may fab up a quick MDF box and see if I can get them totally under the seat at some point.

They are a little intrusive and not nearly as stealth as I wanted, but goddamn they sound great. The fact that they are little subs actually bring a ton more depth to the front stage than I have had with any other system. My old Tacoma had Boston Acoustic Pro 60s mounted in the doors and they sounded amazing but these just have so much more warmth and lower mids than those ever did. It's not going to win any SQ contests, but even top down highway driving these kill. I'm running 100 watts to each component set and 100 watts to each SWS 6.5. Then rounding it out with a sub in the trunk and no rear speakers.

Final install pic:
[/url]
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Old 07-27-2018, 07:33 AM   #8
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This is awesome. I've been trying to figure out a way to get better sound in this car. I have an 89 325is, 10" Lukebox with a Powerbass sub, e34 mids and Dayton tweeters in the front sail panels with the German Audio passive crossovers fed by a JBL GTO 5EZ and the fold down rear seat to make sure the bass comes through clearly. It's OK, but the stock speaker locations leave SO much to be desired in terms of midbass and presence. I'm not a boom guy, so I typically run the sub output from my head unit at about -6db. I find that if I cut the sub out completely, the speakers sound completely lifeless.

I'm wondering if this could be the solution for me as well.

What crossover settings are you running these with?

Last edited by Cephas; 07-27-2018 at 07:40 AM.
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Old 07-29-2018, 03:58 PM   #9
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Iím currently running them from 300 hz and down. I actually need to band pass them to cut the sub bass out and save that for the sub, but Iíve been so happy to finally have some mid bass and bass up front that Iíve just left It for now.

Iím not a boom guy either and these are perfect. I can play just about any thing I my collection and it sounds great. I almost wish I went or the 8 inch subs just for pure volume with the top down. With a coupe I think the 6 inch are more than enough.
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Old 02-22-2019, 07:07 PM   #10
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You making copies of these yet Our 535xiT and X5M run subs in the same location so it'd be cool to put a set under the seats of the our 325 vs the behind the side panels in the backseat.
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Old 02-23-2019, 03:33 PM   #11
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You making copies of these yet Our 535xiT and X5M run subs in the same location so it'd be cool to put a set under the seats of the our 325 vs the behind the side panels in the backseat.
Haha, no these were a PITA to make but they sound sweet. I added a passive crossover to cut out everything under 80 so I could truly turn them up and it's so nice. If you go with the 6's you could seriously make small rectangular boxes and fit them. The fiberglass I made I could have fit the 8's in and been fine. It was good practice for when I make the fiberglass box for the trunk.
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