I figured that the speaker was either broken or worn out and
what little reading I had done on the subject seemed to indicate that there was
no easy fix. BMW had used speakers for
which there is no easily available drop-in replacement. Everything that I read talked about having to
modify the speaker enclosure with a hacksaw or Dremel tool; not something I was
anxious to tackle. To make matters
worse, there had been several iterations of the sound system and it wasn’t real
clear exactly what I’d see when I opened things up.
In the beginning the Z3 only had two speakers; one in each
footwell, but by the time my car was manufactured, each side of the car had a
footwell speaker, a fill-in speaker at the top front of the door, and another
speaker on the rear cabin wall which fired directly into the back of the
seat. In addition, there is a subwoofer
in the middle, between the seats, where there used to be a lockable storage
compartment.
I’d seen the speaker grille for the subwoofer, of course,
and I just assumed that if I were to take that off, I’d see the speaker. But as it turns out, the situation is more
complicated than that.
Behind that grille, there is really just a padded, empty
space. The subwoofer actually sits
deeper in the rear wall in a sealed enclosure that can only be accessed by
removing a panel at the top, between the roll bars. And it isn’t even just a single speaker. Instead, there are two 6.25” speakers,
sitting back to back and wired in reverse phase. The rear-facing speaker is a helper that adds
strength to front-facing one. The
enclosure has an oval port that points forward into the cavity behind the
speaker grille and lets the sound out.
But it doesn’t come out directly. Pushed into that port is tuned plastic horn
that looks something like an upside-down “L”.
The sound exits the port, goes into the horn, is directed to the bottom
of the enclosure, and hence, out through the speaker grille.
The problem comes from the way the horn is attached to the
port: it isn’t. It’s just pushed in and
held by friction. And it’s not a very
tight fit. So when the subwoofer cranks
up and starts pushing significant air through the port, the horn moves along
with it, rattling and buzzing against the grille.
The fix, fortunately, is very simple. The grille pops off easily when you pull up
at the bottom on either side. Then the
horn can be taken out, again very easily.
I took mine out and wrapped some closed-cell, self-adhesive
weather stripping around it at the points where if could contact the
enclosure. Then I put the horn back in,
snapped on the grille, and cranked up the bass.
The difference was amazing.
The sound was clean and tight with no annoying buzz. The whole thing took maybe 10 minutes.
I know the Z3 sound system has been criticized as being weak
and underpowered, but, honestly, the only problem I had with it was the
subwoofer buzz. As I’ve said before, the
only time the stereo is on is when we’ve got the top down and are listening to
classic rock that we are very familiar with.
It’s not the reproduction so much as it is the ambience, so I’m
perfectly content with it.
I’d like to thank Jon T and his “Z3 Page O' Fun!” (http://www.ackthud.net/z3/) for sharing
this fix (http://www.ackthud.net/z3/2000/Subwoofer/subwoofer.html).
You can see some good pictures of the solution on his pages.
