B&O crackling noises

So I took my car in today to get the software update. The new version is MHIG_EU_AU_K1539 (any idea what the letter/numbers mean? K seems like a backwards step from P)

Anyway, the bad news is that it's made no difference, and the issue is still there :-( Dealer says they'll send the case back to 'technical' and see what they say!
 
That's frustrating. Sounds like they've still not properly addressed this then. Fair enough if its a codec / decompression issue, but on a £750 option you'd expect them to have it playing at decent quality regardless of what source you're using. Good luck with the dealer going back to "technical", my experience there is that generally nothing happens....
 
I am battling the issue on the other side of the pond. Had my amplifier replaced with a newer revision one and still crackles.
 
Might be worth considering using an iPod to simply bypass the issue?
 
I've had an issue since December that I know of in my front passenger side speaker, once I get to around 20 or so on the volume and something with some bass comes on the crackle and distortion is pretty bad. is it a simple case of a blown speaker and do you think this would be covered on the warranty? I've not gone too crazy with the volume, so I don't think i'd be my fault.
 
Vertigo1 said:
Might be worth considering using an iPod to simply bypass the issue?
Click to expand...

That's not really a valid solution for me. All my music is ripped as FLAC and put on a 128GB SDXC card (with another one soon to follow - FLAC files take up a lot of space!!). As an ipod wont play these, I'd be forced to convert them to something the ipod could play. Not impossible, just annoying. Oh, and I'd have to spend a few hundred on an ipod too!

We'll see what 'technical' come back with, but based on other people still having the issue, along with mjcourtney's experience of 'technical', I'm not holding out much hope!

Out of interest, does anybody know if there's any kind of escalation path to get this info pushed up to the people that support/design this system?
 
audi upgrades
Gazzz said:
That's not really a valid solution for me. All my music is ripped as FLAC and put on a 128GB SDXC card (with another one soon to follow - FLAC files take up a lot of space!!). As an ipod wont play these, I'd be forced to convert them to something the ipod could play. Not impossible, just annoying. Oh, and I'd have to spend a few hundred on an ipod too!

We'll see what 'technical' come back with, but based on other people still having the issue, along with mjcourtney's experience of 'technical', I'm not holding out much hope!

Out of interest, does anybody know if there's any kind of escalation path to get this info pushed up to the people that support/design this system?
Click to expand...

@Scott kicked off and got a iPod for free because of this issue
 
benc98 said:
I've had an issue since December that I know of in my front passenger side speaker, once I get to around 20 or so on the volume and something with some bass comes on the crackle and distortion is pretty bad. is it a simple case of a blown speaker and do you think this would be covered on the warranty? I've not gone too crazy with the volume, so I don't think i'd be my fault.
Click to expand...

That sounds like a blown speaker to me. Should be sorted under warranty - my last car blew the top driver's door speaker and they replaced it under warranty with no questions. Did have to wait a week for the parts to arrive though.
 
The Challinor said:
@Scott kicked off and got a iPod for free because of this issue
Click to expand...

Interesting! Although I'm not sure that'd actually be a solution these days, as it's barely possible to control a new iPod (lightning connector) from the MMI anymore! They'd need to somehow source an old model.

Speaking of the issue of controlling using the lightning AMI cable, I hoped the new firmware might fix that, but having tried it on my drive home tonight, it's just as bad. I actually thought it seemed worse than before, but that could just be my memory, as it isn't a feature I use very often
 
Gazzz said:
Interesting! Although I'm not sure that'd actually be a solution these days, as it's barely possible to control a new iPod (lightning connector) from the MMI anymore! They'd need to somehow source an old model.
Click to expand...

That's why I'm sticking with my trusty third gen iPod Touch using a red collar cable. Works flawlessly :)
 
I don't have any apple devices and I actively avoid using iTunes so an iPod isn't really an acceptable alternative for me. Just a bit miffed that we are three years into the 8V production and the fault still exists.... And for that matter, hasn't really been officially acknowledged by Audi. I wonder what represents the larger user base for music... SD cards or iPods / iphone connection through the AMI?
 
iPod is awful especially with Spotify. I can't skip tracks or do anything. I have to control it by using the iPod, but at least the sound quality is better (the crackling still exists but it's a lot less). So I got the iPod touch for free and £750 refunded. I doubt it'll ever be fixed.
 
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All very poor! If they want the help I'm willing to do whatever I can to work through this issue so they can resolve it, but from what people say it sounds like they're just not interested.

For me it's not so much about the money... I just want it fixed. Although by no means the only factor, the ability to spec a decent audio system was one of the reasons for going down the Audi route.

Out of interest, have we worked out if this is only an issue with B&O? It's obviously not specifically the B&O amp (as we know it works fine from an audio CD, for example), so I wonder if it's actually an issue with all cars, just only spotted by those of us with B&O as we're likely to push the system more
 
It is only B&O, and if you laboriously read back through this thread, it's an issue with multiple cascade compression, conversion and artefacts causing the crackling.

The audio CD is uncompressed audio, thus is least affected.
 
I'm not doubting you, but would you expect to see the issue with my 750Hz constant tone if it was a compression/decompression issue? I know compression will usually remove the top and bottom end of the frequency range, but in my mind a given frequency should be able to be accurately represented... but this is from somebody that doesn't know that much about audio compression, so please tell me if my understanding is wrong :)
 
It's not only compression , but also conversion from one coding to another.

By compression, I don't mean audio dynamic compression, but rather coding compression.

For example the B&O amp is on a MOST bus so there is always that leg that needs coding, even from CD.

The VWVortex/Fortitude thread is quite revealing (Post #102 & #117).
 
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Thanks veeeight (even if you have kinda lost me with audio dynamic compression and coding compression!).

I don't suppose anybody has wiring diagrams about how the various components are connected? I'm guessing from what veeeight says that the main computer (5F) is connected to the B&O amp by MOST (fibre). Also the AMI can be analogue audio or a data connection, depending on what's plugged in - I assume this goes into the 5F unit? What about the DVD/CD player? Is that MOST connected to?

Also, is MOST just an interface, or is it a bus that runs around the car? i.e. would DVD/CD <--MOST--> 5F <--MOST--> B&O amp be how things are connected, or is it a ring of fibre which runs around the car, and any device to read/write onto the bus?
 
In short day to day using dab, iPhone, wifi streaming I literally don't notice it at all. If I noticed it I'd be complaining straight away. Under test conditions via Bluetooth I could get it to do it slightly but phone calls are not affected.
 
Sorry for jumping in. Is this an A3/S3 problem or more widespread?
 
@Gazzz

No this is not a B&O only issue. I have the Audi Sound System and had this problems shortly after getting my A3 delivered last November, it's gotten so bad to the point that the hissing/pop noises have gone away taking both the left and right channel sound with it, leaving audio outputting coming only through the center speaker. It was enough for me to take the car to the dealer. The dealer diagnosed it saying they are going to have to replace my MMI. They said the part is special and have to come from Germany.


Again this is not a B&O only issue, it's an MMI issue, which is why I think it affects everyone! It's just a matter of time before you will start hearing it, if you haven't already heard the popping hissing, eventually you will lose sound.
 
^ That doesn't sound like the same fault.

I have *** and it doesn't do any of that, nor any of the B&O crackles.
 
Yeah maybe it's not the same issue/faults.

But they are very similar in that the first 2 months with my A3 the sound would occasionally get distorted at one the right speaker, sometimes make a loud pop sound whenever I ride over a bump, and the pop would occur different speakers on either side.

It's only degraded in recent weeks to the point that sound just stop coming from both the left and right, and only the center speaker.

But for the longest, I was reading this thread having the exact same issues as others. Which is why I think it IS a MMI defect, not a Bang and Olufsen since I don't have Bang and Olufsen and I'm getting the same symptoms as the rest.
 
I had a call from the dealer today, who had got a message back from Germany (via Audi UK). They said the issue is with files that have a sample rate of 44.1kHz, and the 'solution' is to use a sample rate of 48kHz instead. As a CD is 44.1kHz, that's also what all my FLAC files are ripped at. So I created a couple of FLAC files (both 750Hz tones, one at 44.1kHz and one at 48kHz) and quickly ripped a CD at 48kHz too, and went out for a drive. Much to my surprise, the tone with a 48kHz sample rate doesn't have the issue, and the CD I ripped also sounded just fine (although it's much more difficult to identify in music).

I'm guessing this is what veeeight was referring to. Is MOST using 48kHz, so my files were being resampled up to 48kHz, then maybe back down again by the amp, or something along those lines? I still don't quite understand why playing a CD (44.1kHz) is fine though.

Anyway, although this isn't really a solution (iTunes rips at 44.1kHz for example, and that's probably what most people will use), it does allow me to create files which won't cause the issue. From my perspective, assuming I don't experience issues when I try it on a larger sample of music, I'm reasonably content. If my understanding of the issue is correct, it does sound like something they should be able to fix in software though.
 
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Confirmed that this works for me too. I ripped the 750Hz tone to 48K and no more crackle. /facepalm
 
So is the 44.1/48kHz just for lossless files like WAV/FLAC? What's the deal with compressed formats like MP3?
 
Taken from an Apple Support Document:

"Sample Rate:
The number of times per second that the music waveforms are captured digitally. The higher the sample rate, the higher the quality and the larger the file size. Don’t choose a sample rate higher than the rate used originally to store the music or you’ll waste space. CD quality, for example, is 44.100 kHz, so choosing a higher rate when you’re encoding from a CD is unnecessary. In general, the best choice is Auto, which uses the same rate as the original music."


In a word, bother...

I've used multiple audio ripping tools over the years, so need to check what I've end up with as only some were ripped in iTunes. Really don't fancy re-ripping everything again, although I will if it avoids any crackling when my car arrives.
 
Vertigo1 said:
So is the 44.1/48kHz just for lossless files like WAV/FLAC? What's the deal with compressed formats like MP3?
Click to expand...

Good point! I'll try and check with AAC and MP3 when I get a chance. Maybe they don't suffer the same issue. I suspect that might be wishful thinking though!
 
It does seem a bit of an own goal to have the issue at one of the most common sampling rates around......

At least progress on understanding the issue though.
 
Most of my music is purchased as 320kbps mp3s. I'm guessing if I try to re-sample this from 44.1khz to 48khz I'm going so suffer some quality loss due to recompression?
 
I've created mp3 and aac files which I'll test at lunchtime and report back

I'm not sure if there's any loss from going 44.1->48k. As it's not a multiple, I'm wondering what goes in the extra space? Will be be a duplicate of some data, or will it just be left blank and ignored? It's way beyond my understanding I'm afraid
 
In bad cases of sample rate conversion, it will just speed up or slow down the track!

It all depends on the sampling rate converter. Pros use a hardware based solution, but I suspect most people will resort to a software based solution.
 
veeeight said:
In bad cases of sample rate conversion, it will just speed up or slow down the track!

It all depends on the sampling rate converter. Pros use a hardware based solution, but I suspect most people will resort to a software based solution.
Click to expand...

Interesting, so is that kind of what we're hearing with the crackling noise? When it's being upsampled from 44.1k to 48k, is the 3.9k gap just being left blank, which has the effect of sounding like a crackle/click type noise? Or is far too simplistic?
 
There'll always be some quality loss when resampling, just as with resizing a photo. Whether you can detect it or not is another, subjective, question.

I understand sampling rates and the 44.1/48kHz thing when it comes to formats like WAV or FLAC but I'm trying to work out how this affects compressed formats. When you compress a lossless file at a given sampling frequency into an MP3 or whatever, then when you play it back does it effectively decompress it back to the original source sampling rate on the fly then pipe this through the normal processing that a WAV or FLAC would go through? If so then I guess it could also be affected in the same way.
 
Just been out and done some more testing, and both MP3 and AAC (m4a) have the exact same issue, and are also 'fixed' if they are 48kHz
 
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So basically take a 48kHz original and compress that to MP3/AAC?

As mentioned above, the vast majority of downloaded MP3/AAC files are 44.1kHz, as will be anything ripped from a CD, so the possibility of resampling and subsequent quality loss is a good question. Personally I think this is going to be nigh on impossible with a compressed file as you'll have to decompress it, then resample then compress it again which will lead to significant quality loss.
 
I totally agree, it's not *the* solution, but it is a solution (or a bodge, depending on your viewpoint)

I'm not sure whether the resampling is going to leave us worse off than before. If we make the assumption that the MMI was already doing that (badly) in order to send it over MOST, then the same process is happening, just in a different place. I'm not sure we ever did find out whether it was being resampled to go over MOST though, or whether that's still an assumption. What really needs to happen is it be capable of sending whatever sample rate it needs, without conversion. I'm not sure that's ever going to be possible though, due to the fact it can play Nav directions and parking beeps over the top of the audio. I guess you'd need to resample those in realtime, then mix them with the audio source and then send them over MOST? Or something like that. I'm starting to understand why this isn't the simplest of things to fix
 
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