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Discussion Starter · #1 ·
Do I imagine this?
I have just started saving music onto SD cards instead of playing from my iPod. The sound quality seems dramatically improved. Does anyone have a logical explanation or is it just my imagination?
 

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Do I imagine this?
I have just started saving music onto SD cards instead of playing from my iPod. The sound quality seems dramatically improved. Does anyone have a logical explanation or is it just my imagination?
Not your imagination at all Dave - I think by default that itunes will compress your music to 128 kbps when it saves it to your ipod were as you may well be saving music to your SD card at a far higher bit rate and the difference in quality is dramatic. I've started to use 320 kbps MP3's all of the time now as the file size is still realistic and the quality is very good.

Kev
 

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If Dave is copying the files from his iTunes folder onto SD cards then the bitrate will be exactly the same (Perhaps Dave will confirm?)

One other possibility is that the Audi MMI hardware is better at decompressing the music files - however given Apples excellent audio performance this would seem unlikely.

Just a final question: -
Which interface are you using Dave for your iPod

i.e. the Audi AMI one or the Auxiliary connection under the armrest
 

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Discussion Starter · #4 ·
Thanks Guys.
I was just 'dragging and dropping' from iTunes onto SDHC card. I use the Interface cable in the Glove box.
My iTunes was still on the default settings but I have now re-configured to use 320kbps mp3's.
Can't wait to give it a blast.
Thank's for the input.
 

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All a bit subjective to be fair. Doesn't have to be mp3 compression but I can certainly tell the difference between 128 and the higher bit rates. VBR worth a try too.

Storage is so inexpensive now that I don't think you have to compromise as much. I rip everything to lossless or download at 320 kbps (from Play generally), then you have the option of doing what you will with it. There's no going back once you compress a track and I use the higher quality tracks when streaming through my domestic gear, which is a lot less forgiving than an ipod ever will be, and I believe that to a certain extent the same is true of the B&O. Horses for courses!

I started out using my ipod Touch in the car but for my money the B&O is far more capable than the ipod - and I would expect that it would be. I now use a couple of SD cards, a pen drive and the Jukebox - well pleased with the results
 

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Thanks Guys.
I was just 'dragging and dropping' from iTunes onto SDHC card. I use the Interface cable in the Glove box.
My iTunes was still on the default settings but I have now re-configured to use 320kbps mp3's.
Can't wait to give it a blast.
Thank's for the input.
Hi,
where are the settings in i-tunes?

Rich
 

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Discussion Starter · #7 ·
All a bit subjective to be fair. Doesn't have to be mp3 compression but I can certainly tell the difference between 128 and the higher bit rates. VBR worth a try too.

Storage is so inexpensive now that I don't think you have to compromise as much. I rip everything to lossless or download at 320 kbps (from Play generally), then you have the option of doing what you will with it. There's no going back once you compress a track and I use the higher quality tracks when streaming through my domestic gear, which is a lot less forgiving than an ipod ever will be, and I believe that to a certain extent the same is true of the B&O. Horses for courses!

I started out using my ipod Touch in the car but for my money the B&O is far more capable than the ipod - and I would expect that it would be. I now use a couple of SD cards, a pen drive and the Jukebox - well pleased with the results
All makes sense to me Kev,
It's no use having a high end music system to decode your music files if you encode them at low quality.
 

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Discussion Starter · #8 ·

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Good point by JW_Q5 about just copying the files from itunes and the bitrate being exactly the same - I keep mine at 128 in itunes so I don't fill the pod up too quickly and use 320 for the car. I did think about having a mess with Apples 256 VBR

Dave - be good to know if you think there is any improvement with higher bit rates?
 

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Hi,

Perhaps I can shed some light on this subject. I am a 24 year audio engineer professional and the first thing I noticed was how dismal the iPod interface sounds on the MMI. You are correct in that the SD files do sound dramatically better. While a higher bit rate is always preferred (I only use 320kbs), this is not the whole reason for the difference in sound you are hearing.

The connector at the bottom of every iPod and iPhone for that matter, passes the signal ANALOG and not DIGITAL as one might assume. The Analog to Digital (A/D) converters inside the iPod are some of the worst made, Apple probably spends a dollar on them and they are truly, truly awful.

When playing a file back an iPod or iPhone takes your digital mp3 file and then very badly coverts it to analog where it is then sent to the MMI which then converts it BACK to digital so it can read the file info (Artist, Song, Time etc.) then coverts it once AGAIN to analog.

All this converting just destroys any sonic integrity your mp3 file may have had to start with, regardless of it's bit rate (128k, 256k, 320k etc.) This is why I originally was going to use a portable USB drive with the USB connector until I learned the MMI limits how many files you can have in TOTAL from any source at 4000 files, which really sucks actually. So I just use one SD slot with 4000 files on it at 320kbs. One file more, say 4001 and the MMI will not read anything above 4000. The 4000 file limit does not apply to iPod's as the iPod is handling the file structure so the MMI has nothing to do with that, so you can have as many files as your iPod will hold. One of the ONLY benefits of using an iPod as far as I can see.

The first thing I did after getting my Q5 three weeks ago was to run a series of sonic tests on each of the sources and this is what I came up with in terms of sound quality. I used the same songs from both cd and 320kbs mp3 versions of the same and played them back through all of the available sources in the MMI. These are in order of best to worst quality:

1. CD Player: This is mostly due to the fact that if you are playing a cd that is uncompressed, no mp3 files on it, basically your average music cd, store bought, then the music on this sounds best as it hasn't been compromised from compression like mp3. Slight but noticeable difference in sound quality above the other sources.

2. Jukebox or SD cards: This is a tie, they both sounded very, very good...almost as good as the cd version of the same song. Difference in quality is attributed again to the sonic difference between compressed and uncompressed audio files.

3. iPod (iPhone): The worst quality of the bunch due to the D/A conversion I mentioned earlier. Only reason to use an iPod would be for the convenience, no 4000 file limit etc. but certainly not for the sound quality. It was extremely evident just how bad the Apple D/A's were when compared simultaneously to the cd, jukebox and sd sources. There is NO comparison, the iPod just destroys sonic quality.

Anyway, just my two cents for what it's worth, hope this helps.

Rob
 

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Excellent guide, Rob!
I was reading a manual yesterday and was unpleasantly surprised by the 4000 files limit per media...
 

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When playing a file back an iPod or iPhone takes your digital mp3 file and then very badly coverts it to analog where it is then sent to the MMI which then converts it BACK to digital so it can read the file info (Artist, Song, Time etc.) then coverts it once AGAIN to analog.
How sure are you about this? I'll happily listen to your opinions on sound engineering, this is more about protocols, file formats and software and I'm very happy in that domain (programmer for 20 years).

I just can't imagine that:

a) the "file info" (IDv3 tags) are encoded in to the analogue stream in any way, so they would have to come from the digital version
Audi would be stupid enough after converting from analogue back to digital to read the tags (if my assertion a. above is incorrect) that they wouldn't then just continue using the buffered original analogue stream
c) the MMI system would force the iDevice to start playing every song on the device just so it could decode the IDv3 tags from the converted analogue stream.

There are certainly USB and Firewire data pins in the original 30 pin connector that normally transfer this information.

While I know it's newer than these posts, the Lightning cable is 100% digital, so it's definitely not doing D > A > D > A conversion there.

Anyway, just read these posts and it struck me as very strange.
 
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