Bose Sub Woofer Replacement

Ahsmo · August 16, 2010

On Thursday: The amp is all wired up and I finally got the fuse holder all mounted up. I also got the box all cut up. I also cut out a piece of ply wood...so this is where the box is tonight. I decided this weekend that I don't like it. I am going to cut out some rings tomorrow and glass them into the box.

Ahsmo · August 19, 2010

I glassed in the rings yesterday afternoon. I am having problems getting the resin to set up. I left it over night and this morning it is still a little tacky. I am pretty frustrated. This is not my first time working with fiberglass. The first batch I mixed as per the instructions was way way too hot. The plastic cup ended up melting and smoking. The second batch was still too hot. No smoking but it kicked in just 2 minutes. The last batch I mixed has still not set up. I guess I put too little hardener in it...

I am going to mix up a hot batch in a few hours if it does not get set up anymore.

Ahsmo · August 21, 2010

I got the sub in the box this morning. I found a few holes I missed with the resin. (the hot batch worked!) Once the glue sets up I'll give it a try again. The amp is making the sub move pretty well...

Wingnut · August 21, 2010

Not to rain on your parade here...But I think you're doing a whole lot of work for something that will ultimately disappoint a bit.

See...Bose modulates the signal strength in certain frequency ranges dependent upon certain factors. Like volume. Mainly because their subs can't handle high volumes without sounding like the paper pieces of crap that they are. And the amp that you're replacing doesn't control that. The head unit does. And you're not replacing that.

At least that's my experience with adding subs to a Bose system anyway. I added a really nice amp and two 10" Kicker Comp V/R's to the Bose system in my Trailblazer SS, and it only sounded good at a lower volume level. If I turned it up, it would turn DOWN the bass signal. And all my work was for naught and it sounded like complete ASS if I turned it up. The only way I could make it sound good at higher volumes was to play with the amp gain and range...But then it sounded horrible at normal volumes...And it's not something you adjust on the fly or while driving.

HOWEVER...That truck didn't have a factory Bose sub. Let's hope that it's different for you because your truck actually has a sub. Let's hope that Bose actually sends a decent signal to your amp. But I wouldn't hope that much. I've never had a good experience with adding anything to Bose (or listening to Bose products for that matter).

Or I'm just biased because I can't stand Bose

RayGMC · August 21, 2010

Did you cut out the bose box to add your own sub? How much volume is the bose box?

Ahsmo · August 21, 2010

Not to rain on your parade here...But I think you're doing a whole lot of work for something that will ultimately disappoint a bit.

See...Bose modulates the signal strength in certain frequency ranges dependent upon certain factors. Like volume. Mainly because their subs can't handle high volumes without sounding like the paper pieces of crap that they are. And the amp that you're replacing doesn't control that. The head unit does. And you're not replacing that.

At least that's my experience with adding subs to a Bose system anyway. I added a really nice amp and two 10" Kicker Comp V/R's to the Bose system in my Trailblazer SS, and it only sounded good at a lower volume level. If I turned it up, it would turn DOWN the bass signal. And all my work was for naught and it sounded like complete ASS if I turned it up. The only way I could make it sound good at higher volumes was to play with the amp gain and range...But then it sounded horrible at normal volumes...And it's not something you adjust on the fly or while driving.

HOWEVER...That truck didn't have a factory Bose sub. Let's hope that it's different for you because your truck actually has a sub. Let's hope that Bose actually sends a decent signal to your amp. But I wouldn't hope that much. I've never had a good experience with adding anything to Bose (or listening to Bose products for that matter).

Or I'm just biased because I can't stand Bose

Obviously you know what you are talking about! I will see how this turns out and then evaluate from there. Hopefully if nothing else, all of my work will save someone else all of this trouble in the future.

Did you try to defeat the auto volume adjust?(with as much as you have to say on the subject you must have)

Did you cut out the bose box to add your own sub? How much volume is the bose box?

box internal volume: 7.405L(.261cuft)

port volume is .013cuft

add em up if you plan on not using the port

Wingnut · August 21, 2010

Not to rain on your parade here...But I think you're doing a whole lot of work for something that will ultimately disappoint a bit.

See...Bose modulates the signal strength in certain frequency ranges dependent upon certain factors. Like volume. Mainly because their subs can't handle high volumes without sounding like the paper pieces of crap that they are. And the amp that you're replacing doesn't control that. The head unit does. And you're not replacing that.

At least that's my experience with adding subs to a Bose system anyway. I added a really nice amp and two 10" Kicker Comp V/R's to the Bose system in my Trailblazer SS, and it only sounded good at a lower volume level. If I turned it up, it would turn DOWN the bass signal. And all my work was for naught and it sounded like complete ASS if I turned it up. The only way I could make it sound good at higher volumes was to play with the amp gain and range...But then it sounded horrible at normal volumes...And it's not something you adjust on the fly or while driving.

HOWEVER...That truck didn't have a factory Bose sub. Let's hope that it's different for you because your truck actually has a sub. Let's hope that Bose actually sends a decent signal to your amp. But I wouldn't hope that much. I've never had a good experience with adding anything to Bose (or listening to Bose products for that matter).

Or I'm just biased because I can't stand Bose

Obviously you know what you are talking about! I will see how this turns out and then evaluate from there. Hopefully if nothing else, all of my work will save someone else all of this trouble in the future.

Did you try to defeat the auto volume adjust?(with as much as you have to say on the subject you must have)

Did you cut out the bose box to add your own sub? How much volume is the bose box?

box internal volume: 7.405L(.261cuft)

port volume is .013cuft

add em up if you plan on not using the port

The volume-according-to-speed thing? Yeah. That was turned off. It worked okay with the factory setup, but once you throw an amp in the mix, it makes a mess of stuff!

I hope that the Bose system in your truck is different and this works very well for you. Mainly because I'm not far from buying a new truck, and ALL the trucks I'm looking at have Bose in 'em. So I have a vested interest in your results

Ahsmo · August 21, 2010

The volume-according-to-speed thing? Yeah. That was turned off. It worked okay with the factory setup, but once you throw an amp in the mix, it makes a mess of stuff!

I hope that the Bose system in your truck is different and this works very well for you. Mainly because I'm not far from buying a new truck, and ALL the trucks I'm looking at have Bose in 'em. So I have a vested interest in your results

I just walked outside and tried it without the engine on. It actually sounded pretty good. I turned the volume up and the radio didn't seem to turn the sub volume down. Remember take it for what it is worth, I just hooked it up and had it sitting on the floor.

Can you tell me how the stock head unit seemed to modulate the bass? Did it do it immediately or did it take a while to adjust?

When it finally stops raining I'll take the other one out and put the new one in. The box still has a pin hole leak in it. Fiberglass was not the way to go.

Wingnut · August 21, 2010

It was instant.

But it was a full-on Nav unit...I seem to recall there being a separate control box as well.

I gave up after that though. I didn't want to replace the whole shebang...ANd stereo stuff is heavy anyway, so out it came

I'm sure that each setup they produce is different too. Which gives me hope for your success!

Ahsmo · August 21, 2010

It was instant.

But it was a full-on Nav unit...I seem to recall there being a separate control box as well.

I gave up after that though. I didn't want to replace the whole shebang...ANd stereo stuff is heavy anyway, so out it came

I'm sure that each setup they produce is different too. Which gives me hope for your success!

I'm going to button everything back up after I find all of the pinhole leaks. After a few days I'll report back. Crossing my fingers.

Here is some more box building pictures.

tmoney82 · August 21, 2010

You will need something like a clean sweep or rockford fosgate 3sixty to clean up the signal coming from the stock stereo. The stock stereo has it own eq. One of these signal processers will flaten that eq of the stock radio which will allow the amp to do its on thing. It will act more like an aftermarket radio once you add one of the processers.

Wingnut · August 22, 2010

You will need something like a clean sweep or rockford fosgate 3sixty to clean up the signal coming from the stock stereo. The stock stereo has it own eq. One of these signal processers will flaten that eq of the stock radio which will allow the amp to do its on thing. It will act more like an aftermarket radio once you add one of the processers.

THAT'S what it was called! I was trying to think of it the other day. JL Audio Cleansweep. They were like $400-$500 at the time though...So I gave up.

Ahsmo...You do good work. I can't work with glass to save my life.

tmoney82 · August 22, 2010

You will need something like a clean sweep or rockford fosgate 3sixty to clean up the signal coming from the stock stereo. The stock stereo has it own eq. One of these signal processers will flaten that eq of the stock radio which will allow the amp to do its on thing. It will act more like an aftermarket radio once you add one of the processers.

THAT'S what it was called! I was trying to think of it the other day. JL Audio Cleansweep. They were like $400-$500 at the time though...So I gave up.

Ahsmo...You do good work. I can't work with glass to save my life.

Audiocontrol also make them and I think they are more reasonable.

AKDenali907 · August 22, 2010

I've read that the factory HU provides a line level output to the Bose amp. The bose amp then does the rest. So, you should be able to splice into the line level output from the factory HU (before the bose amp) and run that to your aftermarket amp for a sub.

Is this not true?

If so, I'm planning on just doing the following to replace the bose sub:

- Not really replace it, just turn it off, and run the line level input to a new amp on the back wall

- Running an underseat box with two JL 8W7s

Seems like the easiest solution to me. Don't have to gut the bose, etc.

Thoughts on this approach?

Thanks for the great thread OP, you caused me to register on the forums just to reply.

Ahsmo · August 23, 2010

I've read that the factory HU provides a line level output to the Bose amp. The bose amp then does the rest. So, you should be able to splice into the line level output from the factory HU (before the bose amp) and run that to your aftermarket amp for a sub.

Is this not true?

If so, I'm planning on just doing the following to replace the bose sub:

- Not really replace it, just turn it off, and run the line level input to a new amp on the back wall

- Running an underseat box with two JL 8W7s

Seems like the easiest solution to me. Don't have to gut the bose, etc.

Thoughts on this approach?

Thanks for the great thread OP, you caused me to register on the forums just to reply.

That may or may not be true. I looked, read, and tried to figure out what the deal was with the output from the bose head unit. The only way to figure it out was to ask someone which you are obviously trying to do...and I am not helping or to just try it. The only bad thing about trying it is you have to cut your wiring harness up. I found that thing to be a total piece of garbage. I somehow bent the ground pen just a fraction of an inch and the factory amp kept cutting out every time I looked at the plugs wrong. I bent the ground pin back a fraction of an inch and now it works just fine. So If you are going a little more high end than me(which doesn't take much), I would get a high level converter and install it right at the factory amp and run RCAs back to the amp on the back wall.

Have you found a box for those subs or are you going to build one? There are tons of pre-fab boxes but none that I have seen will fit a 8w7.

If you got 2 8w7s in there I am sure it would be loud and sound good. On the other hand, the my little RE 8 is making stuff in my truck vibrate so you might get trapped in a circle trying to stop all of the rattles.