hi question about my sub

asian010 · 03-07-2011, 12:09 AM

so i have the base 2010 e90 audio on my car. the subwoofer under the driver seat makes a crackling/farting noise at times when the base hits on a song. if i turn it up enough i can hear it on the passenger side too. ive took it to bmw to get it checked out but tehy said they couldnt replicate it so no luck there. i was just wondering if anyone had a idea whats wrong with the subwoofer. is it blown or something? i dont know much about car audio.

bmw325i · 03-07-2011, 02:11 AM

What are you using to play music (an iPod, mp3 CDs, etc.)

sneaks · 03-07-2011, 03:10 AM

What a lot of times sounds like a failing speaker is actually an amplifier reaching its maximum potential and clipping occurs.
There is a protection circuit in factory stereos to prevent this by catching a peak in the preamp phase and attenuating the signal.
Certain types of music are able to sneak by the preamp logic and you get the crackling you describe.
It is also evident as distortion in tweeters when the amplifier uses the majority of power to replicate a strong bass note. This would be more prone to happen on the base stereo because the frequency ranges aren't discrete (no seperate amp for subwoofer channel)

smooth rnb and hiphop is easier for your unit to play at max volume then trance or euro... usually
rock is heavy in the midrange which is why it seems like those songs can play louder, but those are usually easier for an amplifier to reproduce. system of a down and tool would be exceptions. those artists sound terrible on a poor stereo

in your case asian, i would try listening to a store bought audio cd in your car and then one at the dealer if they let you. make sure the eq settings are the same in both vehicles. If it is only happening in your car, I would look at replacing the amplifier first.
i doubt your problem lies in the speakers, but if you can demonstrate a problem for them, then they have something to diagnose.

redwinger · 06-03-2011, 10:15 AM

funny, i have a 2008 e90 w/ logic 7 and my passenger sub makes a cracking/farting noise at times. sometimes at lower volumes, sometimes at higher volumes. totally random. BMW couldn't replicate the issue as well. happens w/ all music sources.

I can't figure it out, and BMW tested all the speakers and the amp and found no issues. drives me nuts.

VP Electricity · 06-03-2011, 11:02 AM

@OP:

base 2010 e90 systems use a tiny amp IC in the head unit, and the signal going into it is HUGELY boosted in the bass and is also heavily boosted in the treble. They don't have subwoofers under the seat. They have 6" round speakers that look like crap when you see them. We don't usually even call the HiFi and Top HiFi speakers under the seat subwoofers, since they play up to 200 or so, they are just woofers, and they really don't play the 50-and-down sub-bass much.

If you are playing music with a lot of processed bass content, and you have the bass control up (a common situation, since the 6" speakers don't play bass for squat), this happens.

@redwinger:
Your problem would be different. Sounds like some complaints I've heard of a bad l7 amp.

sanchezj14 · 06-10-2011, 02:18 PM

I have an 08 335xi with the Logic 7 system. I had a post about this a while back but no adequate answers. I play a lot of different types of music but when I play Rnb, Hip-hop or songs with deep bass I get the crackle/fart noise at both low and higher volumes. Ive tried lowering the bass on the equalizer nothing works. Hopefully someone can figure our what that it is since BMW can't

03-07-2011, 12:09 AM	#1
asian010 Brigadier General 120 Rep 3,236 Posts Drives: 335i Join Date: Feb 2008 Location: bay area iTrader: (6)	hi question about my sub so i have the base 2010 e90 audio on my car. the subwoofer under the driver seat makes a crackling/farting noise at times when the base hits on a song. if i turn it up enough i can hear it on the passenger side too. ive took it to bmw to get it checked out but tehy said they couldnt replicate it so no luck there. i was just wondering if anyone had a idea whats wrong with the subwoofer. is it blown or something? i dont know much about car audio.
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03-07-2011, 02:11 AM	#2
bmw325i Major General 223 Rep 5,120 Posts Drives: 2006 BMW 325i Join Date: Oct 2010 Location: United States iTrader: (8)	What are you using to play music (an iPod, mp3 CDs, etc.)
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03-07-2011, 03:10 AM	#3
sneaks Lieutenant 17 Rep 431 Posts Drives: '08 335xi Join Date: Apr 2008 Location: 24 Sussex iTrader: (1) Garage List 2008 335xi [0.00]	What a lot of times sounds like a failing speaker is actually an amplifier reaching its maximum potential and clipping occurs. There is a protection circuit in factory stereos to prevent this by catching a peak in the preamp phase and attenuating the signal. Certain types of music are able to sneak by the preamp logic and you get the crackling you describe. It is also evident as distortion in tweeters when the amplifier uses the majority of power to replicate a strong bass note. This would be more prone to happen on the base stereo because the frequency ranges aren't discrete (no seperate amp for subwoofer channel) smooth rnb and hiphop is easier for your unit to play at max volume then trance or euro... usually rock is heavy in the midrange which is why it seems like those songs can play louder, but those are usually easier for an amplifier to reproduce. system of a down and tool would be exceptions. those artists sound terrible on a poor stereo in your case asian, i would try listening to a store bought audio cd in your car and then one at the dealer if they let you. make sure the eq settings are the same in both vehicles. If it is only happening in your car, I would look at replacing the amplifier first. i doubt your problem lies in the speakers, but if you can demonstrate a problem for them, then they have something to diagnose.
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06-03-2011, 10:15 AM	#4
redwinger Private 4 Rep 58 Posts Drives: 2014 X1 Join Date: Apr 2008 Location: Newburyport, MA iTrader: (0)	funny, i have a 2008 e90 w/ logic 7 and my passenger sub makes a cracking/farting noise at times. sometimes at lower volumes, sometimes at higher volumes. totally random. BMW couldn't replicate the issue as well. happens w/ all music sources. I can't figure it out, and BMW tested all the speakers and the amp and found no issues. drives me nuts.
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06-03-2011, 11:02 AM	#5
VP Electricity Brigadier General 291 Rep 3,201 Posts Drives: F34 xDrive Join Date: Jan 2008 Location: portland oregon iTrader: (3)	@OP: base 2010 e90 systems use a tiny amp IC in the head unit, and the signal going into it is HUGELY boosted in the bass and is also heavily boosted in the treble. They don't have subwoofers under the seat. They have 6" round speakers that look like crap when you see them. We don't usually even call the HiFi and Top HiFi speakers under the seat subwoofers, since they play up to 200 or so, they are just woofers, and they really don't play the 50-and-down sub-bass much. If you are playing music with a lot of processed bass content, and you have the bass control up (a common situation, since the 6" speakers don't play bass for squat), this happens. @redwinger: Your problem would be different. Sounds like some complaints I've heard of a bad l7 amp.
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06-10-2011, 02:18 PM	#6
sanchezj14 New Member 1 Rep 18 Posts Drives: 2008 BMW 335XI Join Date: Aug 2010 Location: new york iTrader: (0)	logic 7 sub I have an 08 335xi with the Logic 7 system. I had a post about this a while back but no adequate answers. I play a lot of different types of music but when I play Rnb, Hip-hop or songs with deep bass I get the crackle/fart noise at both low and higher volumes. Ive tried lowering the bass on the equalizer nothing works. Hopefully someone can figure our what that it is since BMW can't __________________ 2008 BMW 335xi black sapphire metallic/ terra interior dark poplar, sports package, premium package, navigation, cold weather package, paddle shifters, comfort access, Logic 7.
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