Rear speaker (2-door) housing improvement?


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So I've done a lot of searching and couldn't find anything on this really.

Setting: I'm replacing all stock "component" speakers with Polk db6501 components. They get great reviews and have a low 35hz range. I already have a decent Pioneer headunit with an 8 band equalizer (40hz to 10khz). I will be powering the speakers off a Rockford Fosgate punch amp and using the crossovers that come with the Polks. I am NOT planning on adding a sub unless I absolutely have to. I hope to have enough mid-bass out of this setup to not need it. I don't need a huge thump and don't want to spend the money or lose space, so please skip that advice.

Question: what is behind the speaker panel in this picture? Is it well sealed? I've circled the area in yellow and I'm wondering if it would help to close it off from the rest using dynamat or even spray foam. To create a small closed speaker box, if you will. Has anyone done this? Can anyone give me an idea of how close that plastic panel is to the exterior?

I'm just hoping someone else can tell me what to expect so I can go in with a plan. If not, then I'll tear into it to see what's up and determine if it makes sense to go that route or not.


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Go Kart Champion
That's the way I'm leaning now. It would make such a small enclosed area it would likely make the speaker suffer. I've found some formulas online for calculating box size but can't find the necessary specs from the speaker to calculate its required volume.


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Sub. Ive got the eonon headunit and a rockford sub with built in amp. Next process would be to change the speakers. Some say theyre good enough ? I wish they could sound crisper. My wife has the fendr audio system in her jetta. Im envious.

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Ready to race!
I just put a full set of Clarion 6.5's in. There isn't much behind that panel but a bunch of foam and sound suppression material. You could easily put a larger speaker in there, but you'd have a hard time getting it to fit in the panel itself.