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Mounting subwoofer box in the trunk

16K views 22 replies 8 participants last post by  the sko  
#1 ·
Anyone have tips on how they secured a 10" or 12" single sub in their trunk? I have a universal box not anything custom so I was just wondering on how others have secured something similar.

Velcro?

Drilled L brackets in the floor?

anything creative?

I am not going to buy/make a custom enclosure.
 
#3 ·
Ls are better than velcro. Be mindful that there's a massive wire bundle, including the main alt run, on the right side of ThreePointShooter43's picture (passenger side) starting at about the edge of that box.
 
#4 ·
I just took a pair of "L" brackets and pounded them flat They each have 4 holes and you use two for the sub box and two for the trunk floor. Screw one end into your sub box the other into your hard trunk floor panel using short pan head sheet metal screws. 4 wood screws for the sub box and 4 sheet metal screws for the floor. Solid install and no sliding around the trunk.
 
#9 ·
If you need a flat L bracket just run down to Home Depot/Lowes and pick up Simpson strong ties. They're usually somewhere around the lumbar. It's basically just plate metal with some holes drilled in it in various places. Find one that's the shape you need and you're good to go.
 
#5 · (Edited)
Remember if you perm mount a bass box be sure to run a string from the trunk latch to the rear fold down seats - in case the battery ever goes bad/dead. Since my box moves was able to finagle my big but back there once to release the trunk lid due to a shorted out battery... didn't have a string in place. If the battery runs down you can always jump it from the fuse box under the hood tho.
 
#6 ·
I Used earthquake straps for a television and bolted one to the back of the box and then used the other one and put the seat bracket bolt through it
 
#8 ·
Yes. I found out the hard way....
 
#12 ·
yeah i might get creative with the L bracketry

i want it easy to remove as well - might try some kind of latch. ill watch the isles of home depot and see what i can come up with.

i guess i might as well show yall the rest of the install

Rainbow components and Kenwood HU
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I have a Kenwood Amp pushing the speakers as well - right now it is sitting where the spare would go but i think ill mount it on the back of the seat - any issues with that?

I mounted the tweeters where the 3.5's were in the dash

I still need to tune it all but it sounds awesome so far
 
#13 ·
Lookin good. Are those 6.5" woofers in the doors? They look a little small.

Back of the seat should be okay. I think I've seen a few folks do that in this car.

Are you amping your components actively, or where are the crossovers?
 
#15 · (Edited)
What model Kenwood amp? Also, what model Rainbows? My first decent set of components were some SLC Kicks. The woofers are sitting in my closet somewhere.

If you've got the tweeters up top, some time alignment would really help you out. I think the newer Kenwood double DINs have some basic TA ability baked into the cake, but I'm not sure on the bandpass crossovers. If the amps can get you the bandpass crossovers and the deck handles TA you can get a lot more out of your setup. I'm happy to help in any way I can over the internet. Feel free to PM. I promise I don't make fun of people for not understanding a 5th order Bessel filter (which I just changed to this evening with excellent results!). You're obviously putting in the effort on the install with the deadener around your baffles. If you've got the equipment you might as well use it.
 
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#16 · (Edited)
Ceri is the man. He can be of great assistance. I too would like to know the rainbows you chose. I had looked at the germaniums for a while but decided against it for the sundown drivers i bought which didn't perform like i wanted and then i ended up with my hybrids. I'd like to try rainbows in the future. Of course, i like the more glitzy vanadiums but yeah, thats quite spendy and i am almost positive that they are and never will be worth the money they charge.

Your install is coming along well! Looking forward to seeing more pictures.

Also, running active is very intimidating at first but i'll tell you this, it is so incredibly easy. For the most part, letting the processor do auto adjustments is great for TA/Volume. I manually tune my X-Overs. You just need to know the capabilities of your drivers. Loose drivers are easy to work with since most have response graphs to work off of. If you can get response graphs, period, that really helps. The hardest part, often times can just be making sure it's wired right and having a good starting place to work from.
 
#18 · (Edited)
Oh definitely. That amp's made for running active. It's got built in DSP even if your deck didn't.

Here's a quick guide on setting up your 2 way +sub system actively. There are more detailed versions on car audio specific forums, but this will get you started.

Put your woofers on channels 3/4 and set the high pass for ~80 Hz to start. Set the low pass to around 2500-3000 Hz. Whatever it gives you for an option around there. Then run your tweeters on channels 1/2 and set the high pass filter for wherever the woofers are low passed. The lower you can get away with crossing your tweeters the higher your stage will seem. I recommended 2500-3000 as a starting point. Go lower if you can, but be careful about distortion. You can go lower if you have steeper crossover slopes (6 dB, 12 dB, 18 dB, 24 dB, etc.). I like steep slopes. It helps with imaging.

Start with a baseline for time alignment. Hop in the car with a tape measure. Sit exactly how you'll normally be listening to the system. If you only listen while driving, put your arms and legs where they'll be. If you spend time in your car just listening, you might want to position your knees and arms in different places. I do all the time. With your head in it's listening position take a tape measure and measure the distance from between your eyes to each component driver. My tendency here is to accidentally lean toward the center of the car more than I normally would and it will make a difference to be off by a few inches. Enter that in for the distance input on the time alignment for each. If your DSP doesn't do distances you can also do specific time delays. Let me know if that's the case and I can give you an equation to follow based on the speed of sound in air. Most these days are already in distance from the listener.

Not done yet. Grab a CD or some other high quality recording of a male vocalist that doesn't have a lot of instrumentation in the background. I've got an IASCA test disc with some excellent tracks on it, but I've also got a Zac Brown Band live album with a few quiet songs I've used before. Turn off subs and woofers. If you can't do that with software then turn the car off completely, no electrical activity, count to 10, and then unplug the RCAs from the amps. If your amps are on you can damage your RCA outputs on the head unit, even if there's no sound. Only plug in the tweeters. Wrap the unused RCAs in paper towels or clean rags. Don't let them touch metal when they're live. Now you're ready to hop back in the car, pop in the male vocalist, close your eyes, and point to where the sound is coming from. Be 100% honest with yourself. You're trying for the nub in the center of the dash where the center channel hole is. If you're left of that, you need to delay the left more. If you're right of that, you should delay the left less. Keep doing this with just the tweeters until you've got a stable image on top of (or behind) that nub. If you can't get it by adjusting the left, reset the left to your baseline measurement and make adjustments to the right. You might have a phase issue. If neither one of them sounds good no matter what you do, swap the positive and negative wires on both tweeters and start again with the baseline TA numbers. This is called flipping the speaker's polarity and causes a 180* phase shift. It won't hurt anything when done to speakers. It's one of the "oldest tricks in the book". It will hurt things with your amp's big power and ground wires, so don't switch those.

So one of those hopefully got you some good results with the tweeters. Now turn the car off completely, give it a 10 count again, unplug the tweeter RCAs and plug in the midbass RCAs. Do the same thing. These may or may not benefit from a polarity flip since they're mounted down in the doors. Sometimes flipping polarity brings the image up higher. Sometimes it just clouds up the image. Definitely try the midbass both ways. My 8" door midbasses are "in phase", but your case might be different. I've got a 3 way front.

After that, power down the car, plug in all RCAs including the sub. Play the male vocalist again and be impressed by the wonders of good time alignment for a few minutes. Then power the car down, flip the polarity on your sub(s), plug everything back in, and see if that got even better on the low end. Sub's polarity is a huge deal so try them both ways and see which one sounds more up front and blends better with your midbass. One will sound natural. The other will sound hollow. My subs are the only thing with reversed polarity in my system. Since you probably don't have TA ability on your sub amp just make sure you've got the phase set right.

So that's how you do basic crossover setup and intermediate polarity/phase and time alignment setup in a nutshell. Equalization is an art. I recommend a calibrated microphone if you're serious about the best results because even the best ears can fool you. If you have independant left/right EQ ability things can get really interesting here with band limited pink noise and fine listening, or full on measurement mic testing.

Damn. I didn't think I wrote that much. I try not to go off like that.

A few last minute pointers on TA. You can temporarily drop the high pass filter on the tweeters if it makes hearing the TA better. Just don't crank up the volume with them set low. Same goes for raising the midbass' low pass. The 1k-2k range is particularly sensitive to directional cues so it can make it easier for tweeters.
 
#19 ·
Thanks Ceri

i will def look into it. My HU has some pretty good filter settings - i used used them to match the sub xover and component xover

i have the comps at 90hz and sub at 120 - i might take that down to 100 not sure yet

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I ended up using "industrial strength" Velcro - i stuck it on the box and screwed it in
 
#20 ·
I have a rattle in the trunk somewhere when it's closed

where are some known areas where i should put some sound deadner? I put some on the flat part of the trunk under that panel but it didnt do much. i have some behind my plate as well so i know it's not that. seems to be near the tails?
 
#22 · (Edited)
I have a rattle in the trunk somewhere when it's closed

where are some known areas where i should put some sound deadner? I put some on the flat part of the trunk under that panel but it didnt do much. i have some behind my plate as well so i know it's not that. seems to be near the tails?
My entire trunk area rattles something fierce!! The poor deck lid shakes like a monster on big bass hits. Like Ceri says check the spoiler and trunk bumpers. Another area is the plate frame. I put a small piece of 2 sided mounting tape on the back side of my plate along the bottom to stop that noise. Some Dynamat under the trunk lid cover should help, I haven't done this yet but it is easily the source of my biggest noise. Sounds like you already thought of those so maybe a little more on the underside of the trunk lid. Check to tightness of the thumb screws on the Tail lights
 
#21 ·
You may need to adjust your trunk's hex head adjustments. They're about 1.5-2" diameter black plastic. If you have the trunk closed press on the corners of the top and see if there's any play. Also, if you've got a spoiler double check that it is tight on the trunk lid. If not, screw it down a little bit.
 
#23 ·
LOL I have the same issue SacTown, I just got done putting in a few rolls of dyno matt in the trunk. Pullout out the carpet and the factory sub box and put it everywhere. Including under the carpet on the trunk lid, seemed to help. Now it is a matter of hunting down the rest of the rattles. Some Dyno matt is always a requirement on the back of the license plate frame.