BOSE Subwoofer Vibration

[fastboydave]

Hi all.

I've had a look through the 996 forum and havent found anything about the problem i am experiencing. I have the BOSE system installed on my 996 TT and the subwoofer 'vibrates' at certain bass frequencies. It appears to be the 'casing', as when i put presure on it (push down) or push a screwdriver between it and the carpet underneath the 'vibration' goes away. I experienced similar on my previous Boxster S with the BOSE optional extra and it did my head in!

Has anyone else experienced this? Can anyone recommend anything? At the end of the day, this is supposed to be a decent system and it appears that there is (in my opinion only) a design flaw if it cannot handle the bass it is designed to handle. The bass is set to neutral on the head unit and loudness off, so i am not even 'pushing it'.

Any suggestions will be very much appreciated.

Thanks,

Dave.

[Scouser]

.... the subwoofer 'vibrates' at certain bass frequencies.

Yes I think that's it's purpose ;)

Seriously though. Sounds like either s fitting is loose or the woofer coil is on it's way out because it's been overdriven.

[fastboydave]

.... the subwoofer 'vibrates' at certain bass frequencies.

Yes I think that's it's purpose ;)

Seriously though. Sounds like either s fitting is loose or the woofer coil is on it's way out because it's been overdriven.

Thanks Scouser for those words of wisdom! :-)

Have been in contact with Bose actually and they assure me (ofcourse!) that they have not seen any problems with their system such as described. Dont think its the colis as when i hold the box it stops, if it were, wouldnt it continue?? Dont know? As you have suggested (and Bose) it could be surrounding trim (possibly panel underneath?) and at the weekend i will have a good look...... maybe Dynamat time????

[eben]

Just have mine out and reinstalled it today to get at the tops of the springs. It is held on with 2 screws accessable through a space after the Bose bezels are removed. If these screws aren't tight I could see that causing a buzz. There is thick foam under it and below that there are 2 aluminum panels that hold circuit boards ( maybe the main computer ?). If those panels aren't tight maybe one of those could buzz. Of course it could be the speaker box itself. If you remove it partially and them try the song that makes it buzz you may be able to tell if it is the speaker or something near it.

Good luck

[fastboydave]

Just have mine out and reinstalled it today to get at the tops of the springs. It is held on with 2 screws accessable through a space after the Bose bezels are removed. If these screws aren't tight I could see that causing a buzz. There is thick foam under it and below that there are 2 aluminum panels that hold circuit boards ( maybe the main computer ?). If those panels aren't tight maybe one of those could buzz. Of course it could be the speaker box itself. If you remove it partially and them try the song that makes it buzz you may be able to tell if it is the speaker or something near it.

Good luck

Well over Christmas i had a good look at this.

Firstly i removed the subwoofer from the home position and held it in my hands while some bass was on. As i suspected the subwoofer continued to vibrate/distort so it was not the surrounding panels. The next step was to dismantle the box to see if the cones of the speakers or the parts in the box were making the noise. This was done after removing many many security screws around the edge of the enclosure and lifting it off. I subsequently took the speaker side back into the car and put the same CD track back on to see if the vibration/noise remained. This time the sound was clear, with no disctortion. So once again, my suspicions were panning out. To clarify what was going on, i had to put the enclosure back together and hit/thump the outside to simulate the vibrations of the speakers. You could clearly hear an unwanted vibration located within the enclosure which appeared very similar to the unwanted noise within the car. Therefore it was taken apart again and hit with the box open to see what was moving.

Anyway, to cut a long story short. After seeing what parts moved/vibrated inside and repeatedly taking the enclosure apart and putting back together, there were a few key points. There are prongs that hold down the cable inside and it were these that vibrate, just like a tuning fork. Also, one of the ports (tube) for the speaker was very close the the side of the main box and could easily vibrate onto it. To sort all this out i put rubber/foam tape on the end of these prongs and where the port could hit the side. After a few more constructions/deconstructions of the subwoofer enclosure i managed to get a good quality bass reproduction at all frequencies and volumes. Thank god! Something BOSE should look at i think........

[DiscobayJoe]

I haven't yanked the factory sub to look at it yet. I have some Damplifier on the way (Dynamat-like material) and plan on performing a little surgury.

Hopefully those of you who have opened yours up can help me with a few questions:

What size is the actual driver (subwoofer)?

The factory amp appears to use two sets of cables for the sub. Is it a dual voice-coil driver?

Is there anything inside the sub cabinet other than the port and the speaker (passive crossover,etc)?

Any pictures?

Thanks,

-Joe

[fastboydave]

I haven't yanked the factory sub to look at it yet. I have some Damplifier on the way (Dynamat-like material) and plan on performing a little surgury.

Hopefully those of you who have opened yours up can help me with a few questions:

What size is the actual driver (subwoofer)?

The factory amp appears to use two sets of cables for the sub. Is it a dual voice-coil driver?

Is there anything inside the sub cabinet other than the port and the speaker (passive crossover,etc)?

Any pictures?

Thanks,

-Joe

Hi. From memory (and i've had a New Year and a few Saturday nights since then!) there are TWO speakers within the enclosure, each spaced equal distant from the centre. They are approx 6" diameter.

The port tubes (rectangular pipes) go right up to the rear of the cone and then to the front of the enclosure on both far left and right sides.

There are only positive and negative wires going to each speaker (two sets) and nothing else, well apart from the pronges that only serve to give unwanted vibrations rather than actually holding the cables down!

Havent got photos unfortunately, but really not needed. The most difficult part is unscrewing what seems like 100 torx screews to open it. Everything else is easy.

Oh, be carful when you pop off the Bose surrounds of the ports to get to the torx screws holding the enclosure ot the car. You can easily damage the 'clips' that hold them in. Lever it a bit at a time all round and you should be ok. You actually damage them getting them back in too, so make sure they are located properly before going fully home, else you'll bend them off.

Good luck, Dave.