2008 Silverado Bose subwoofer replacement

[Ahsmo]

I alluded to this project earlier in a thread... and this contains no PG equipment...yet.

I didn't want to take up any usable space in my truck so I have cut the original bose sub out of the bose box and replaced it with a RE audio rex 8".

I didn't know if this project was going to work so I picked up a cheap ebay amplifier just in case. I didn't want to spend a significant amount of money on a PG amp that I might not ever use again.

I used a Boss Audio CX450 which is supposed to do 110w x2 at 4 ohm. It cost me all of $69 and it came with a remote sub volume control! If it doesn't have the balls to keep, I'll swap it out for a PG amp. I think it should do just fine. The heat sink is a huge block of aluminum.

My initial thought on the box was to just cut out a little bit of plastic and put in a piece of ply wood. I got stupid and cut out rings and fiber glassed in the rings. The fiber glass idea was a terrible one. Getting all of the holes sealed up between the glass and the plastic was a challenge.

[Ahsmo]

Here is where I installed the amp. I glued the amp mounting board to the back wall of truck. I cut out a little bit of insulation to fit the amp. I used T-nuts to mount the amp to the board. I think it came out pretty well/standard.

The ground placement is temporary until I get the other seat back in.

[Ahsmo]

Here is where I mounted the fuse holder.

This also shows the box progression. I should have stopped when I had the first board fitted.

Then I got stupid and thought it might be 'fun' to glass in speaker rings. I was very wrong. The glass I bought from westmarine was odd. It did not smell like the stuff I was used to and I never got the ratio of hardener to resin right. Oh well. It was totally un-necessary to use fiberglass in the end.

[Ahsmo]

I need to find the rest of my pin hole leaks in the box and put everything back together!

All of the connections are soldered btw.

Feel free to tell me why I am an idiot for even trying this.

[kg1961]

just like most of us need better than stock
looks good so far but why such thin speaker wire? if the sub is in the front and the amp in the rear I would have gone much thicker

[Ahsmo]

just like most of us need better than stock
looks good so far but why such thin speaker wire? if the sub is in the front and the amp in the rear I would have gone much thicker

I really have no design explanation other than I really don't expect the wire to carry more than 5 amps. I figured 18 gauge would carry that just fine without the insulation breaking down due to excessive heat. But lets walk through it:

18 gauge is (ref. google search) 6.385 ohms per 1000ft. I have exactly 15ft from amp to sub.

6.385 times 15ft / 1000ft = 0.095775 ohms

5amps^2 times .096 ohms = 2.4 watts This is the loss through the wire with 220 at 8 ohms playing at my highest level which the wire will never see because I don't drive my junk very hard unless I am showing off for someone.


Note: 5 amps comes from an output voltage of 20.97 volts at the output terminals (41.95 bridged) and 220watts bridged.

Why do you say you would have used thicker wire? To minimize the voltage drop across the wire or to prevent insulation break down?

[smgreen20]

Well, the only advise I would give is to go ahead and fiberglass the entire inside of the box.

1, you'll find all of your air holes that way, and

2, that abs box is only 1/8" thick and even though it's just an 8", it still has the potential to crack it over time.

Other then that, it looks good. Now you just need to tell us how it sounds when it's done.

[Ahsmo]

I put the truck back together this afternoon. Before I did that I moved my ground to a stud on the floor of the cab that some part of the tire changing system attaches to. I used some 80 grit to get the paint off the floor around the stud before I use a nut to secure the ring terminal. You can see a stud I tried to use but I couldn't find a nut to secure the ground terminal so I used the stud under this black thing.

I also did some trouble shooting on a problem I thought had to do with signal transfer from the Bose amp to the high level inputs of my amp. Turns out the ground connection on the high level inputs does not need to be hooked up to ground. If you do hook it up to ground you get a nice alternator hum.

I also put my remote sub woofer volume control knob in the center console.

I am going to hold off on saying how it sounds for a few days until I get used to listening to it. Thus far I have just been listening for distortion for just a few minutes at a time.(making sure I'm not breaking anything) I would use a dmm to set the gains but it is impossible to disable the full range speakers. I can image a 60hz test tone would do a number on those bose speakers.

I ultimately decided not to glass the inside of the box just to save on time. If it cracks I will probably build my own box to go in that space with a much larger driver. That plastic is pretty sturdy so we'll see how long it lasts.

[Ahsmo]

I drove over to the grocery store with my wife in the truck yesterday and here is what I thought:

The bass certainly is louder. The 8 inch sub will play down pretty low but not at terrifically high levels at lower frequencies(its an 8 go figure). I forgot to put in poly fill before I put the woofer into the box. By the time I realized my mistake I was halfway through installing the console. It is punchy and sounds good with rock and country. When I turn the volume up the bass does not seem to draw down relative to the other speakers. I was listening specifically for this the whole time. I played different types of music to try to detect it. I am overall pleased with how much bass I have now. The volume knob in the center console allows me to turn the sub down when I want it to really blend well with the rest of the speakers or turn it up when I have a song on that I really want some more bass out of.

My reference system was in my old car that had several different woofer setups. My loudest setup hit 137db on the dash with a term lab mic. My best sounding setup was with two Boston Acoustics 10s in a sealed box powered by Phoenix Gold Amps.

Things I would have done differently:

-Not glassed in the speaker rings. The first board I cut was fine.
-Put poly fill in the damn box
-Figure out a better source for a switched 12+ source. The white wire on the Bose amplifier harness works fine but does give a turn on pop. The solution is buy one of these PAC-Universal Trigger Output Module or come up with a circuit that will delay the turn on and turn off. I may correct this by going with the latter of the two for fun. The pop is only present when putting the keys in and turning on the radio then starting the truck. If you just start the truck there is no pop.
-glassed the inside of the box. I am worried the ABS plastic will crack one day but when that happens I'll build a bigger box to fit in that space.

This setup is leaps and bounds better than the Bose setup. so in that way it was a success