I need something for the rear of the car, to cut out the exhaust noise from the ls in my '49, I've got Dynamat all over the rest of the car, just need something in the trunk and or behind the back seat . I can hear the exhaust plenty out the window, but I'd like be able to hear the back stereo speakers better.... any real world experience/advice appreciated.
I used Dynamat in my 65 GTO clone. I can't comment on the sound level because I prefer the exhaust note over the radio. It did help with the heat from the exhaust a good bit. Can you fade the audio balance to the rear some. That is what I have done in some of my other cars.
I put dynamat type insulation in the trunk, as well as all the panels in the cabin. I use DEI products. It definitely helps.
I'd attack it 2 ways. Consider it a big boom box. Dampen the inside of the box so it is a dead sound chamber. Put the mat on the floor, the sides and make sure the trunk lid is not just reflecting. Then I'd isolate it from the interior. If your rear speakers are on the package tray, they are going to need a chamber between them and the trunk so trunk noise isn't just working the cone.
Dynamat is primarily to kill resonance by adding m*** to panels. Cover it with Dynapad for sound absorption. Chris
If you go have a look at the car audio sites you’ll find some article talking about this. I’m not suggesting you buy the stuff, just pick up a little info. Crutchfield would be a start for enclosures like RodStRace mentions. Plywood and particle board are common materials, cheap and easy.
Yep, you just want to keep any thump or rumble in the trunk from acting on the back of the speakers. There is all sorts of math to sizing this to the speakers, you can get pretty involved. Just looking at the stuff for sale should give you enough info to build yourself. https://www.crutchfield.com/m_500/Car-Subwoofers-Boxes.html
The Jalopy Journal
