shumi_9

I consider myself a bit of an audiophile. Over the course of 20 years I have built a compromised system that functions quite well as HT and two channel system in a dedicated room. Here is my music's room frequency response (see first picture).
I took some time to sweep the 991 equipped with a Bose system placing the microphone at the driver's listening position (see second picture).
As you can see, the frequency response is bass heavy (as expected for a car system I think). I then decided to sample individual frequencies in the bass region due to rattling issues I have been fighting since delivery of the car. As I suspected, the test shows that between 40 and 100 Hz, other frequencies are excitied likely due to rattling of the inside panels. The rattling appears to be a non issue above 100 Hz. I will bring the car back to the dealer to see what they can do about this (see third picture)

chuckbdc

991 door panels have a history of rattles that sound like speaker noise. Mine has had it fixed by tighening fasteners and it just recurred- a panel is on order from the factory now.

shumi_9

They are replacing the entire panel? Did they tell you what is wrong with the old one? Is it from the driver's side?

chuckbdc

Drivers side door- had it the week I got the car - March 2012. Very obvious in colder temps. Radio on or off made no difference.

Someone on this site described rolling up a doller bill and inserting it in the front edge where the plastic part - air bag cover- touched the door frame. I did that and it worked. So I took it to the dealer and they removed the panel "tightened the fasteners" and placed a bit of insulation tape at the spot where the dollar bill had been. All fixed. PS I had the same thing on a Boxter S a few years ago and that did the trick there too.

Last week is started again. Off to the dealer (also for changeover valve campaign). They advised that they hear the sound in the door and have ordered a new door panel. Surprises me- but it is their call so long as they make it right.

hlee1169

shumi, how come you didn't get the Burmester sound system?

shumi_9

Excellent question my friend...bought my car from dealer's floor for my birthday

shumi_9

Ok...so how can you quickly find out if your panels are prone to rattlening, and best of all, how can you convince your service manager that you have a problem?

Purchase or download this disk and play TRACK 1 loud. You will know instantly if you have a problem in the low frequency regions.
Ask the service manager to work on the problem until this track plays clear of any distortion/rattling.

http://www.stereophile.com/features/338/

chuckbdc

I had a simpler test. I had the tech drive the car with the radio on and off. Same noise. Your mileage may, as they say, vary.

chuck911

The audiophile solution here is to replace the panel with one made of carbon fiber. Or fiberglass. Only composites are strong enough to control and damp the sharp transient vibrations of good speakers. Then rework the entire panel mounting, bonding it to the door frame with sealant. Liberally apply sound deadening material in every available location while you're in there. Rejoice at the resulting improved visceral impact and stunning clarity.

Of course (almost) nobody does this. But it gives you some idea what really needs to be done in order to correctly eliminate these kinds of problems.

Would I do it? Not bloody likely! I would just have the dealer get a roll of carpet tape and go to town until the rattles are gone.

991Dreamer

The dollar bill thing worked? I'm surprised. I thought it would take at least a fifty.

holminator

Wonder if it will take a check.

chuckbdc

No it is not that bad. A 20 will do. Depending on your options, you can also leather wrap it.

holminator

Fine. This car. Geesh. I might as well "put a ring on it."


Beyonce sounds like a chipmunk, but I digress for you.

hlee1169

Nice, need to give this a try.

DrJay

all highs and lows, must be Bose...