Mazda 3 Trunk Build 153.9 dB 2 DC XL15's

[Jordan Guess]

man thats awesome! good job on saving your amps with that upgrade, no Big 3 pics? or not done yet?

[SCS_Audio]

man thats awesome! good job on saving your amps with that upgrade, no Big 3 pics? or not done yet?

You can sort of see the Big 3 in some of the pictures. In the pics of the alternator you can see the red alternator-battery cable. The brown 1/0 in that picture is the upgraded engine block ground (moved to mounting bolt of the alternator and ran directly to battery bus bar). The OEM one was left intact on the other side (hard to get to). The light silver 1/0 in the battery pictures is the battery-chassis upgrade.

[Njflex]

Thats pretty damn impressive!

[BassHead810]

Thanks Jarred for answering the Big 3 Question. I really dont have any good pics of that its somewhat hard to see.

So we did a test with the fluke..

How much DC current do you think 2 JL1000/1's can pull on a full volume burp through 1 run of 1/0 OFC to the trunk??

I was a little shocked when I saw this number.....

[BassHead810]

I always wanted to know if it would be better to have the 2 subs in one common chamber rather than 2 separate boxes. I didn't think I could get one big box in the car when I started this build so thats why I went with two separate boxes. Now I wanted to cut a large opening between them and bolt them together.

I didnt want to rip the boxes out and ruin my seal-off job and possibly jeopardize the test so I decided I would take the subs out and cut an opening with the jigsaw. I took the subs out and covered the one sub hole with a mdf circle, taped a blanket all along the top edge of the box to keep the dust inside the box and not in my car. I got the shop vac hose inside the box and made my best attempt at cutting an opening between the boxes.

Here's the end result after bolting together and cleanup

I wasn't too concerned with keeping it neat since I was 90% sure I wanted to build a new box anyway.

So anyway, I don't have a termlab picture of the numbers after I cut the opening, but I can say I didn't gain or lose any dB. It was still in the 148.3 range. But the box rise did go down by .4 ohm.

But the other nice thing about joining the 2 boxes together was that it was now easier for me to tune lower which meant I could hopefully get the 17hz note even louder.

So we started testing different ports and tunings and started seeing some pretty insane numbers below 20hz. After a few hours late one night we hit the number shown below at 17hz, meter was at the passenger headrest and driver window was open. This was done with only one 4" aero port, partially internal and partially external.

We were also able to hit 146.4 with the meter at the windshield, but not sealed up, driver window must be down.

Here's some vids

Termlab vid for any nonbelievers

My favorite vid of them all. This one also shows the meter at the windshield score

[quakecitystudio]

What cd material did you do your testing on?

[BassHead810]

I was using either the dB Jams Vol. 14 or the aux in from the iPhone using the "Boom Button" app. Its a quick and easy way to test any frequency.

[BassHead810]

So at this point I had 2 12W7's in two seperate boxes which are now joined as one. With four 4" aeroports and I plug some depending on what tuning I wanted. But I really wanted it to be louder so I decided to build a new box and try some different things.

The new box will be made from 3/4" birch and the inside will be coated with resin. I'm going to get one box for both subs in the car one way or another. Worst case scenario is I have to unbolt the door to get it in, or build part of it inside the car.

Time to go get some lumber

I got 2 sheets of Birch and 1 sheet of 1/2" mdf for other stuff like amp racks, ports etc.

Got all the pieces cut

Look at the layers!

Our new table saw rocks! Porter Cable FTW

Gluing the double-baffle together

More pics to come soon.

[BassHead810]

Ok everybody, here's where the build log starts gettin good Jarred and I spent ALOT of time on this box and I have alot of good pics to share.

Box is starting to take shape

We had some small 45 scraps left over after cutting the angled sides to length so we used them to strengthen a few joints of the box.

I love when a plan comes together. Straight cuts FTW!

Drilling and screwing the 45 pieces together was a little tricky. This is what we came up with to keep the screws perfectly straight.

The step drill won't bend on the 45 and gets the countersink hole started.

Making 2 roundovers for left and right corners of box.

After a few coats of resin.

Thats it for now. Much more to come!

[BassHead810]

Time to make some sub holes. Love the new router and circle jig!

Lookin good so far. I have a nice port planned for that piece on the right.

1st coat

Test fit... I like it

The stretched octo shape for the port will give me around 100sq inches which is about twice the port area of the first setup.

Port pieces cut, stood them up to see how they look.

How precise can we cut with our table saw? How about exactly to my drawings specs!!

Checking the fit of all the pieces... looks good.

We had alot of pieces that needed glued together so we made this 135 degree angle jig to cradle them all.

First batch

Second batch