Go Ahead and Laugh...

Power a subwoofer with the head unit? Oh yes I did!

But more on that later.

It all started with trying to find a way to "open up" the sound stage of the stock system. I started a thread asking about adding midranges, but this project took a life of its own so I started a new one.

Rather than focus on why the soundfield seemed so narrow, I turned to the other issue: The annoying, ever-present bass-bump. I bench tested the head unit and found that sure enough, there is a boost in the low frequencies that peaks at about 125Hz, with a sharp drop at 250Hz.

The other issue is the rear speakers. They just sound muddy in general, and that right-rear speaker is the one that is heard louder than all the rest. This had me adjusting the fader mostly toward the front. So I figured I'd go ahead and try crossing over the rear speakers @ 125Hz, and adding a -3db L-pad to the RR.

It turns out the case for the XM radio unit makes a nice project box for the components!




Holy crap what a world of difference! Much smoother bass! And now with the fader centered, it turns out the (corrected) rear-fill is what was needed to enhance the front image.

One small issue still remained though, another bump in bass from the front door speakers at around 40Hz. So in went a harness I made with a couple 500uF caps, crossing over the door speakers at 80Hz, as to lower the 40Hz bump by 6db.



But thinking the overall bass might end up a little anemic, I figured I'd add provisions for a passive subwoofer by deriving a single, mono channel using the front left ch. positive and the right ch. negative. Well that didn't work, I ended up with a weird dc offset. No matter, I just tapped into the L ch. +/-. Then I grabbed the portable sub-box-in-an-action-packer from my other truck, and wired it in with an 8mH coil I had from the system in my other-other truck and BAM! It worked!



Pretty funny, right? No, it's not permanent, but hey, it was a fun project for a rainy Saturday. It actually sounds really good though for what it is, even if it doesn't get real loud. The important thing is I learned where the trouble spots are so someday, as I upgrade, setup will be a snap.

Thanks for reading.

 

That's awesome stuff man