Vehicles

sonett - installing car stereo amplifier

I am sure somewhere out there someone reading this is throwing up in their mouth thinking about a system getting installed in a Sonett.

Well, this Sonett had a radio installed long before I bought it. It consists of an AudioVox tape deck and a single speaker. That speaker is badly blown. It sounds so terrible it is much better to just leave it off. I am all for enjoying the sounds of the engine but this is going to be my daily driver. I need some entertainment.

My plan for the stereo is as follows.

 

  • Install a pair of speakers in the kick panels
  • Install a 8" sub in a small enclosure in the trunk
  • Install a 4 channel amp to power it all
I am not planning on dynamatting anything or installing much of any sound deadening material. My primary concern is keeping the weight down as much as possible while still having a decent stereo.
I already have the amplifier, I kept it from one of my prior car stereo installs in hope I would be able to reuse it someday. That day is here. It is a US Amps 4300x.  It puts out 75 watts x 4 channels at 4 ohms. I plan to use the front channels for the front speakers. I will bridge the rear channels to provide 180 watts at 4 ohms for a small subwoofer. These are the specs right out of the owners manual.
I plan to go with as 8" sub in as light weight of an enclosure as I can find. The JL 8" W3v3 sub in their CP180LG is looking good but I have not committed to it yet. That sub does sound great in the store. The sub and enclosure only weights 17.5 lbs which is pretty damn light. The amp weights 8 lbs. Say the total weight is 36 lbs, not bad at all.
I had originally planned to make a custom sub enclosure, most likely out of fiberglass, but after seeing that CP108LG enclosure and taking some measurements, I couldn't do better myself. The sub will perfectly fit along the back wall of the trunk next to the amp. I couldn't make much lighter of an enclosure. I would however like to ditch the black carpeting on the box and instead wrap it in brown vinyl so it matches better, but that is project for later.
I am getting ahead of myself. Step 1 is finding a home for the amp. This is problematic in the Sonett. I tried many possible locations.
  1. Under passenger seat - amp is too tall.
  2. Behind passenger seat - the seat could never be put all the way back. This would limit leg room. No go.
  3. In place of spare tire - It would fit great down there but I like having a spare tire.
  4. In the trunk, on the back of the fuel tank support - This could work. The problem is that there is no support there, just the gas tank. You would have to craft your own support bars.
  5. In the trunk, on the side walls - There are simply no supports. The interior panels are vinyle wrapped balsa wood (exhageration). 
  6. In the trunk, behind a side wall - No support. There is the vinyl wrapped interior panel, then fiberglass installation, then the fiberglass car exterior. I don't want the weight of the amp supported by the fiberglass body in any way.
  7. In the trunk on the back wall - This is the only workable solution. The problem is simply finding support.
The back wall is really thin wood wrapped in vinyl just like all the other walls. Keep in mind everything, the trunk floor is metal but EVERYTHING above that is fiberglass. There is a metal strip that extends from the metal floor up to the trunk glass latch. I think it attaches to the fiberglass boby, but really the weight is bourne by the metal floor. I decided to use this as my primary amp support. 
I crafted a second support beam out of an L aluminum piece which I bolted to the metal floor. I then ran two aluminum L bars between the factory steel support and my new aluminum support. The amp is screwed to these two aluminum bars. The result is that the weight of the amp is bourne by the metal floor, though it is slightly wobbly on the left side of the amp since the vertical aluminum bar is only attached at the floor, nothing at the top. Still, the entire package feels very secure and I don't think I will ever have any problems. Best of all, all the fiberglass body work was left untouched.

 

Pictures

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The amp will be installed on the back wall
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There is simply no suitable support on the trunk side walls
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all the trunk walls are like this, super thin partical borad wrapped in vinyl. Not strong at all
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panel removed, factory fiberglass insulation visible, for sound deadening
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this will get bolted to the trunk floor. Wood spacer means I dont have to cut the trunk
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trunk floor not cut so no structure issues. Just two bolt holes
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first of 2 cross beams
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joins factory vertical steel support to the new aluminum support beam
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some washer in back get the depth right
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both horizontal supports in place. The amp will be screwed to the horizontal supports
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insullation reinstalled
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panel reinstalled, ready to drill holes and screw in amp
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amp attached to aluminum supports behind the vinyl panel, pretty sturdy
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I am getting cheap. Amp power connectors are expensive. Made my own by cutting down ring connectors
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wiring roughly in position
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speaker wire for two front speakers and coiled up wire for sub in the trunk
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don't have the crimp on battery terminals or fuse block yet. Also haven't run turn-on wire yet
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installation looks pretty clean. The amp is mounted level. The trunk floor is severly bowed

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