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2001 325Ci
10 Posts
Discussion Starter #1
My 2001 325Ci still has its original equipment headunit (the Blaupunkt CD43) and (non-HK) speakers. It had gotten to a point where it really wasn't usable anymore. Any low tones just buzzed. The only way I could listen to the radio or a CD was to turn the bass down all the way. So, I began to explore how I could get the sound system back to usability. Ultimately, I decided I would also add the Bluebus unit to the factory system to give it the functionality that I wanted rather than replacing the headunit or going with one of the other bluetooth options. Others may have different wants, but, I decided, this would work for me. At least it would if I could figure out how to fix the terrible buzzing that came out of my speakers. I looked at the speaker upgrade options, but let's face it, I am a cheapskate and I was already splurging on the Bluebus, so I decided to take a look and find out if I could fix my current system, (especially if I could do it without spending too much). Only fellow-cheapskates should read on - you have been warned.

So, I pulled the door cards off my car and took a look at the speakers. This is what I found:

The foam surround was disintegrating. This was the case on all four of the bass speakers. The midrange and treble speakers were okay. So, when bass tones were being projected, the magnet would push the voice coil and cone out, but because the surround was not in place to keep the cone centered, it would wobble and vibrate against the sides of the coil causing a buzz.

After doing some research, I learned that the surround could be replaced and how that could be done. I found a source for replacement surrounds that were close to the original size:
(2) Two 6.2"(157.48 mm) Foam For 6" Speaker Surrounds 647356203046 | eBay

They were $9.99 per pair, so I could get replacements for all four bass speakers for less than $20. Other sources were twice that price. That ticked the cheap box for me. The new foam surrounds were slightly too large in outside diameter at 6.2 inches, and I had to cut about 1/8-3/16" from the outside diameter so it would fit inside the plastic speaker basket.

The next step was to remove the old foam and clean up speakers in preparation for installing the new surrounds. This meant I had to remove the foam both from the paper cone of the speaker and from the plastic speaker basket. I used a razor knife and wood chisel to mechanically remove the foam and the old glue. The glue was very tacky and difficult to remove. Solvent (i.e., lighter fluid) didn't have much impact, and I was hesitant to put much on the paper cone as it might delaminate. But a little elbow grease and patience is all it really takes.

To remove the foam from the cone/diaphram, I first used the edge of the razor knife held at a shallow angle to the cone:

Then I went back with the edge held at 90 degrees to scrape away most of the remaining adhesive:

Don't let the knife dig in to the paper or you'll cut right through.

A similar method was used to scrape the gummy, tacky adhesive from the speaker basket. I used the knife to cut the adhesive loose from the edges of the basket.

Then I followed with the chisel, held perpendicular to the frame to scrape up the old glue:

It took several passes to get as much adhesive removed as I could. Once I had the bulk removed, I used a solvent to clean up the surround mating surface. When it was done, this is how it looked:

The next issue that I had to decide was how to ensure that I was gluing the surround in place while keeping the cone centered in the voice coil. For two of the speakers, I cut the dust cap loose from the paper cone (very carefully) and inserted paper shims between the cone and the magnet:


Once the surround is glued down, the shims are removed, and the dust cap is glued back in place. The shims ensured that when I glued the surround in place, the cone would be centered in the voice coil and would not vibrate against the sides. The trouble with this method is that it was difficult to cut the cap loose without damaging the paper cone, and it was fiddley and took a bit longer.

So, for the other two speakers, I used the "feel" method to center the cone. In that method, when I was gluing the surround in place, I tilted the cone from one side to the other at 12 and 6 o'clock and at 9 and 3 o'clock to its limits and then guesstimated the center. Here is a YouTube video that demonstrates the feel method at about the 13:00 minute mark.
Both methods gave good results.

Gluing the surrounds in place was pretty straightforward. Apply glue, press into place (while keeping the cone centered in the case of the "feel" method speakers). For both methods, I made sure the cone was at a goldilocks position in the voice coil - not too high and not too low when I was gluing it in place.

I used Devcon WeldIt All Purpose Household Cement to glue the surround to the paper cone and to the plastic speaker basket. There is special, rubber-based surround glue that you can buy from audio shops, but it costs more, you have to buy way more than you will ever need, and I would have had to wait for it. Did I mention that I am impatient?

I would suggest applying glue to both the inner and outer circles of the surround at the same time, and installing it all at once. I found it just too messy to try to apply the glue under the foam after it was already partially attached as shown in the video. I also used the Devcon to glue the dust caps back in place - a little glue, lightly press them back into place, and wait for it to cure. You should give the glue a good 12 hours to cure before reconnecting the speakers if you can wait. I couldn't.

The result is that my sound system is usable again. No more buzz from the bass notes. If I were an audiophile, I guess I would want to upgrade everything, but this works for me. The system is functional. I can't wait to get my Bluebus so I can add that functionality.

Total cost: less than $30.00
Surrounds: $21.63; Devcon glue: ~$4.00 (more than you will need)

2001 325Ci
10 Posts
Discussion Starter #3
Why does anyone do any of this?
Here are three reasons off the top of my head.
First, because no replacement speaker could be had for this price.
Second, because I don’t like throwing away an otherwise perfectly good speaker that can be repaired.
Third, for the pleasure of doing the work.

'04 325i, '02 325iT
894 Posts
I appreciate your meticulous work, but that is a lot of effort vs replacing the speaker with one from a salvage car for $5. The junk yards are packed with E46s right now that are ripe for the picking.
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