Distorted sound (not rattling)

[teone123]

Hello!

I just bought a 2016 A4 Avant. The other day, with the car parked and engine off, I played some gentle music and noticed a strange distortion coming from the front left woofer. Today, it comes from the right one.
It doesn't sound as a rattling sound (made by a bad driver or vibration). It's more like a distortion generated by some crossover or other electronics.
You can hear it clearly around 100-800Hz. If you increase the volume, the overall sound coming from the system hides that distortion (you can still hear it by paying attention and with some gentle music such as classical), but the distortion doesn't increase that much as the volume...

What could it be?

At first, I though of changing the woofer, then the distortion switched side and I'm not sure it's the drivers anymore :|

Thank you

 

[NHN]

Where are the woofers situated, did you place your hand on the trim, to see if this disappeared, maybe its vibration, 1 to discount anyway.

 

[teone123]

Yes absolutely.
I tried all kind of "mechanical" intervention (such as pressing plastics, grills etc), and I'm 99% sure that this is not the case.

The distortions looks definitely like some DSP (digital signal processing) distortion, which, by the way, it's quite volume-independent.

I'll do a video soon.

Thank you

 

[teone123]

Just tried again to film it: no problems at all.

I tried also a via Bluetooth with an app that generates sinewaves and there was no digital distortion at all, just regulars vibration of door panels... Strange.

I reset the MMI after that, just to be sure.

Don't know what to say. It's definitely a software or DSP problem, but acts randomly...

I'll keep you posted

 

[Garrett 69]

Have you checked that the speaker mounts are secure?

 

[teone123]

Have you checked that the speaker mounts are secure?

How could this generate that kind of volume-independet noise?

 

[Garrett 69]

It could be frequency related rather than volume related

 

[teone123]

Absolutely it is.

Anyway, it has been 5 days without a single problem... Same setting as before.

 

[Garrett 69]

Must be your music taste disagrees with the car then

 

[teone123]

It might be... Lol


Anyway, i tested also with a sine wave generator as input, no problems at all...
Dunno

 

[teone123]

aaaaaand the problem is back.
Yesterday I had a 1000km travel. The last hours the problem came back. Distorted sound... damn

 

[Void20]

Record it on camera?

 

[teone123]

Next time for sure