kevinkar

Hi all,

I bought a used 2005 in 10/13 with the stock Bose nav unit and XM. While I'm one of the owners who think the stock unit and sound is pretty weak, it's not horrible and is at least 10 years old so I'm cutting it some slack. It does take some tweaking to get it to sound right though; more than I'd like to spend. However, I noticed an oddity for which I was looking for some helpful input.

If I turn on the radio and it's already on XM, there is no bass. No matter how much I slide bass to the right or raise the volume, nothing. Pretty tinny. If I then switch to FM, it also has little to no bass. If I turn the volume really high though, the bass comes through. Sometimes if I start off in FM, same thing but I don't have to switch to XM, I simply up the volume and the bass is active again.

So it appears I have what acts like an active amp for bass (my home system has a sub that's passive/active, only "turning on" when additional power is requested by the source material otherwise it works but is passive and not powered) and I have to have the volume past some threshold to activate it. I know there's no aftermarket amp in the car and I'm sure the stock radio does not have an active amp so it must be a fault in the system. Amp? HU? Loose wire? Bad door speakers?

Any thoughts on what might be causing this and where I need to look to troubleshoot? It's repeatable and always turns bass on if I up the volume but that's obviously an annoyance every time I get in the car!

Thanks,

Kevin

markcz

XM barely has any bass in the signal

What happens with a store bought CD?

kevinkar

Same thing. I have a CD in now and sometimes when I start the car the CD starts playing but with no bass. Cranking up the volume high and back down real quick seems to enable bass.

So the lack of bass seems to be both intermittent (it does work fine some times) and on all sources. Only oddity is that it seems to not be enabled with a volume crank up on XM and I have to switch to FM or CD to get that trick to work.

And yeah, a CD sounds great in the car making the Bose stereo seem to be pretty good. FM, not as good and there's a lot of bass/treble/midrange I have to fiddle with to get each station to sound decent. Of course we all know XM is what it is.

If the bass worked 1st time every time, no real issues. It's just sometimes it's not there and the only way to enable it is the volume crank up trick. It's not that big a deal but it should work and I'm just trying to figure out what it might be.

markcz

C6 prints are HERE

Look at print 3/10. The amp that powers the small speakers is powered and triggered by the same wires as the door subs. Power comes thru AMP fuse on red/black wire, trigger to turn them on comes direct from radio on white wire at pin B3. One of those wires could be loose or broken, but that wouldn't make much sense for how you get it to work. If you have a meter you could verify that you have B+ power and the trigger at the speakers (when it isn't working).

The amp is also the crossover for separating the door sub signal in C6 bose. I suppose it's possible the crossover portion of the amp could be going bad, but that would be harder to troubleshoot. If you can find another C6 amp to try that would be the easiest IMO.

And it could be the radio itself

kevinkar

Thanks. I have a multimeter so I'll see what I can discover. It's intermittent so I'm sure it's going to fail when I don't have time to check and will work on the weekends when I have loads of time to test!

As for it possibly being the radio, that's not too bad a deal since I was considering swapping it out eventually for a more modern one, likely one of the current Kenwood units. Of course I believe that's another can of worms but might not be so bad in the long run.

If I'm able to test any time soon, I'll let you know what the results are.

Thanks again,

Kevin

kevinkar

Been a while and this is kind of an old thread but I wanted to update it.

Replaced the door panels with new ones (going from cashmere to ebony) and they seemed to have solved the no-bass issue. For a time. Now it's doing it again but there's a twist.

When I notice a lack of bass, I no longer turn the volume way up to get it to appear as that's annoying and my wife does not like it. I discovered that now all I have to do is to click the window up button for a second (the windows are usually down) and the bass magically appears!

What???? I'm pretty sure the window switch merely sends a signal to the computer letting it know I want to raise/lower the windows and it sends a signal back to the window motor. So this may be one of the many electronic control units not sending a signal to the amp?

This always happens on the road and I don't have a multimeter in the car so I never seem to be in the garage to check the circuitry as noted in the previous reply so I have not been able to do that yet.

But it sure is interesting that it still does it and the window switch affects it.

Odd.

markcz

The window circuits are completely separate from the sub circuit. The only possible link would be that maybe the window glass is rubbing on one of the sub supply wires inside the door. It's possible you could have unknowingly adjusted that wire away from the glass when you replaced the door skins, but it has now worked it's way back.

kevinkar

Yeah, I guess that's possible. I guess the door cards are not too much of a pain to take off again. I'll see what I can see.