InvisibleM

So i got a couple of 12"s for christmas and a 2600 watt amp to power them. plenty of power for sure.

I was planning on building the box myself to save some loot and having a shop install the wiring and maybe some sound deadening material.

the clearance in the back is 15" on the 3GS in the trunk which would make it easy to make a box that height for 12s but I wondered if shaving a couple inches off the top would allow for better airflow back into the cabin for the subs.... if that matters.

I was wondering if anyone else has done a similar setup and what the cost of install on wiring and sound deadening was if they are willing to guestimate.


thanks!

Slammer1

You have to give us some specifics if you expect us to help with your planning. What type of 12s did you get, what is the "2,600" watt amp that you plan to run, and are you planning on running a vented or sealed box for the 12s? Huge difference in the specs for the box. Have you ever built a box before? As for the installation, most shops will charge around $100 to run power from your battery to the trunk. As for the Dynamat, it is expensive itself and the labor is typically quite high as it is a labor intensive install. Are you going to do your doors and cabin, or just the trunk?

InvisibleM

I got some RE Audio RFX 12s rated at 400w peak (190 RMS) and a BOSS ARMOR 2.2600 (yeah its not top of the line but itll work for now)
numbers for the amp: 1300W x 2 Max Power
400W x 2 RMS Power
2600W x 1 Max Bridged Power

and Im gonna put them in a sealed box since a ported would take up too much room. Never built a box but Imma get some 3/4" mdf and build a no frills sealed box. got the specs for the size off the re audio box calculator (http://www.reaudio.com/box.php) so it shouldnt be a problem.

as for the dynamat. Ill probably start with just the trunk and see how that goes. that shouldnt be too expensive to just do that area right?



ah and I forgot to mention i have the Mark Levinson system and need to figure out what to do about that stock sub...

Slammer1

RE's site recommends a .8cf box per 12, which means you are looking for approximately 1.6cf internal volume before the displacement of the drivers. Each 12 has a displacement of .14, so you want to be a minimum of .28 larger than 1.6. Hit your favorite box calculator and shoot for 1.88cf. By the way, the link you attached in your reply is for a ported box, not sealed.

Not sure, but it looks like they only make these subs in a dual 4ohm voice coil configuration? If so, are you wiring these in parallel at 1ohm? Your subs are rated at 190w each which means your total handling is going to be 380w. I know that you say the amp has a maximum output of 2,600w at 1ohm. What is it's rms output at 1ohm? I would honestly guess it to be around 600 or 800....... Either way, it's better to have more power than you need and run less gain. Also of note, you will want more power than the subs are rated when using a sealed box.

I've done Dynamat, but never paid to have it installed so I can't even help with an estimate on the cost there.

As for the factory sub, pretty much everyone that does an aftermarket subwoofer install removes the factory sub. This gives you a "pass through" of sorts so that the bass from your trunk can flow into the cabin.

InvisibleM

Ahh yeah I forgot about the displacement of the subs! nice one
Yeah the calculator is made for L shaped ported boxes but I just made the measurements for the port lengths 0 and then it gives a regular box dimensions.

thanks for the info on the factory sub. didnt even think of it being a pass thru for bass but it makes perfect sense.

Slammer1

30" wide by 15" high by 10" deep (outside dimensions) would give you an inside volume of 1.89cf. That is if you use 3/4" mdf, and would be appropriate to account for the displacement of the subs. If those dimensions don't work for you, move each around a bit and see what you come up with.

Sealed box calculation is quite easy. HxWxD (inside dimensions in inches) and then divide by 1,728 to get the cubic footage.

robertoyou

iTrader: (1)

make sure to take out or disconnect the factory sub as it could cause cross cancelling in sound waves or even possibly blow out the stock sub if you have too much pressure hitting it from the trunk. more likely is the cross cancelling though. also would recommend a different box calculator. the RE audio one has been known to have some flaws with its numbers. might not be too bad on a sealed box though.

swtjlsy

iTrader: (6)

the GS has a small trunk opening no box larger then 14.5 will fit straight in. remember to measure before you build, to make the air space work for you. to dynomat a entire trunk I would say you need a complete box of sheets. you will have to do the rear deck the back seat the trunk floor and the quarter panels along with the spare tire well. around $400 should be about right entire car around 900$.

InvisibleM

wow I better start putting aside money now. I hope that guestimate includes the installation fee!


thanks for the info!

robertoyou

iTrader: (1)

It will definitely not cost you 900 to deaden your car. Not if you do it yourself at least. You can buy pretty cheap deadner. I did all my doors (not 100 % deadened but a very good amount. Probably about 80%. Which if placed in the right places is more than good enough. I also did most of my trunk and trunk door. I only bought one box of dynamat and it was about to 135. If you want the entire car from top to bottom then a few boxes would be needed buy still woud not be 900 dollars. They also sell cheaper but just az good deadner for almost half the price. So that would be even more affirdable

InvisibleM

I was thinking about doing the sound deadening myself but I have zero knowledge of how to take the panels apart and such.

I installed some midranges in my old truck and popped off a panel myself and it never fit back on properly afterward. ever since ive been reticent to do it myself as i dont want to **** up an expensive piece in this car.

anyone know if there are how tos on doing panels in the 3GS?

Slammer1

I've never done a GS but most cars are the same in the fact that they have a couple of concealed screws and then it's a matter of pulling the panel off. On the IS, they are behind the interior door pull and under the power window switch panel. As for the Dynamat, you can get a "bulk pack" on eBay for around $140 shipped. That is 36sf and was more than enough for me to do all four doors as well as the trunk lid. With that said, I had a little bit left over. Fair warning, you will want to wear gloves when you do the Dynamat. It has a metal backing that will cut you when you go to put it in place and roll it out.