I upgraded my Bose system with a Kicker zx350.4 4 channel amplifier installed in the factory Bose location. I am running Infinity Kappa 60.9CS components on the front doors. I removed the rear side speakers since that location is worthless for mounting speakers (the OEM speakers are mounted in free air). I replaced the Bose rear deck 6x9's with Kicker CompVT 08CVT652 6.5" subs mounted on 1/4" MDF adapter plates. All speakers are 2 ohm.

The result? The fronts sound amazing. However, the rear subs plain suck. Whenever the bass hits, the entire rear deck just buzzes. The buzz is louder than the actual bass. From what I can tell, replacing a 5 once factory speaker with a 3-4 lb sub is just too much for the rear deck to handle. I have zero interest in reinforcing the steel rear deck. Sound dampening might help but rear deck is really just too flimsy. Infiniti installs a "roll" bar over the rear passenger section for crash bracing. That suggests to me that the rear unibody is not terrible strong in back. Any thoughts?

I will likely just remove the Kicker subs and run a sub box in the trunk. However, I was hoping to avoid losing precious trunk space to stereo equipment.

I suppose that I could install a matching set of Infinity Kappa 6x9's on the rear deck but I wouldn't expect a lot of bass from them.

 

I tried putting 6.5" subs in the rear speaker spots in my RSX, but I had the same outcome. I had the entire panel deadened and used polyfill to cut down on the volume, but that didn't solve the problem. I ended up removing those and just used a front stage and four 8"s in a box in the trunk. Although I wanted to incorporate the 6.5"s, I was very pleased with how it ended up.

 

Are you sure those speakers are for free air applications? if not the suspension will not be stiff enough and will just flop around. Also, 1/4" is much to thin for an adapter plate should use 3/4" MDF.

 

Yes the Kickers can be used in free air applications. They can be used in door panels, etc, according to Kicker. 1/4" MDF is thin but 3/4" will be too thick for the rear deck panel to go fit.

I tore apart the rear interior again (I'm pretty good at it now). Removed the Kicker subs. Left the 6x9 holes empty. My amp now powers a 10" JL Audio sub in a mini box. Sounds awesome now!

 

this is good info to know about the rear deck.. So anything besides free air flow speakers in the rear will make the rear deck vibrate?

 

I ended up installing a set of Infinity Kappa 6x9's. Sound great with great mid bass. I also run a small JL sub box.

 

i have hertz components up front polk coaxials and then i removed the 6x9s for my sub in the trunk. you mentioned that the coaxials are horrible due to the free standing but are the 6x9s in a similar setting? i wrapped that whole rear deck with suede to cover the holes.

 

The rear deck handles a set of full range 6x9 perfectly. I run a JL amp and sound quality is amazing. Plenty of mid bass without any rattles. I definitely prefer having some rear fill versus just front components and a sub.

 

The vibrating problem isn't that the rear deck can't handle it, it's that the trim panel (the piece that holds a 3rd brake light if you have one, and the 6x9 speaker covers) doesn't sit flush against much of anything. You need to pack as much deadening material between it and the metal deck as you can to create a pressure fit so that it doesn't vibrate - and by deadening material in this case I mean thick acoustic foam and/or expanding spray foam rather than sheet after sheet of Dynamat type ish stacked on top of each other.

It's doable, but you'll need to get a little creative, otherwise all but 4 small points on that deck are flapping all over the place anytime there's a chance to.

 

Sound dampen the deck lid

 

Any further progress on this with actually using the correct treatment (closed cell foam)? Has anyone ever bolted enclosures up to the existing spots in the deck lid?

 

Do you think if you kept the stock amp you would have still gotten this excess vibration? Maybe your new amp was just too juiced? I am replacing my stock rear decks and was thinking about the similar kicker free air sub 6x9, but now am scared. I am not changing the stock amp.

 

The stock amp is garbage, u are better off replacing it all..

 

The stock amp will do a terrible job driving aftermarket subs. It is only rated 225 watts peak. That is like 35-40 watts per channel peak or 17-20 watts RMS.

 

Based on the gauge of wire going to the factory amp, I'd say that's being optimistic. I'd guess about 10w/channel RMS.