: Improve MP3 Sound From Factory Bose System



kckranz
03-27-09, 10:56 AM
I have a 2000 Seville STS with factory Bose installed and used to be quite disappointed with the high and low frequency output from that system, especially when listening to mp3 files (via a tape adapter!). If you know or can read up on sound editing basics you will be able to significantly improve mp3 play on your Bose system as I did.

Now, I'm not an audio guru but I do know that when songs are compressed into the mp3 format the high and low end frequencies are "squeezed" out - the flip side of being able to get over 100 songs on one CD. This is the last thing you want since your Bose system is not the best at producing these frequencies anyway. I don't have the money or desire to upgrade the audio hardware so I concentrated my improvements on the mp3 files themselves.

You will need to conduct EQ processing on your mp3 files to optimize them for the Bose system. There are several expensive and some free software applications (Winamp, etc) that can perform this processing for you. I made a backup of my mp3 collection (1500+ files) and used my friend's copy of Sony Sound Forge to batch process my files.

There are several canned EQs that come with sound editors but I made a custom 20-band EQ to enhance the high and low frequencies missing from my Bose system. In short, your EQ will need to resemble a "smile" curve with the mid-range frequencies dipping below or hovering at the 0db gain horizon - you can't just boost the highs and lows without lowering the mids because of peak clipping (which you will hear as clicks, pops, noise, etc). See attachment. Most sound editors have a "normalize" or "volume leveling" process that can be applied to your music and I used this feature of Sound Forge as well - after applying the EQ - so that I did not have to constantly adjust the volume in my car because one song being so much louder or softer than another (very annoying).

It took me a few times to get the end product just right which is why I made the backup of my collection first. As I made adjustments to the EQ I would test them on a 10-song sample of my collection - batch processing 1500+ songs takes several hours.

It took me a week's worth of limited free time to optimize my mp3 collection for play in my Seville but my speakers are now producing full-range CD quality sound (via a cassette adapter) I never thought possible from this system. :yup:

timothyr
03-28-09, 05:49 PM
all i can say is "damn impressive"....when I saw this thread my first thought was another person about to run into the brick wall of bose, then when I heard the route you were taking it clicked that that would actually work. Another thought as far as overall fidelity control, I have seen adaptors that will give you an Aux input in place of the factory changer...in the neighborhood of $50 wholesale, and that would elimiinate lose at the tape head.

iowasevillests
03-29-09, 09:21 PM
Agreed! I wasn't expecting this when I saw the thread title, but nice work. Once I get my right side door pancake sub back in I'm going to have to give this a shot on a CD.


Another thought as far as overall fidelity control, I have seen adaptors that will give you an Aux input in place of the factory changer...in the neighborhood of $50 wholesale, and that would elimiinate lose at the tape head.

I was under the impression though that those adapters only worked if you had factory NAV unit.....or is there something else out there other than cadillacSTS2003's custom harness?

timothyr
03-30-09, 02:07 AM
I will go hunting for it and post a link, but as I recall it would work with any head unit capable of taking a changer.

ballstothewall
03-31-09, 12:20 AM
The best solution to this problem is don't use low bit mp3 encoding, either use 320 and up, or just go with FLAC. You can EQ something to appear back in, but you can't actually make up for what is actually taken away when it gets ripped into mp3. Also, due to the way EQ works, it is best used to reduce a signal, not increase it. But if your happy with it, more power to you.

Disclaimer: slight audio snob

ballstothewall
04-04-09, 01:55 PM
Another post on why mp3 sounds bad...

Here are some screenshots from foobar's spectrum analyzer and it gives a pretty good idea as to what you actually lose when you have .mp3 file formats. The top image is 198k, then 225k, then .flac Loseless as something to compare to. As you can see from the flat line where it stops just how much .mp3 encoding can loose, even more if its been encoded more than once and in different formats. Someone could put it to 64k, then redo it to 128 and it'll say that, but it sure won't be 128k. You can take it down to a lower quality, but you can't bring it back up. The first image is a good example of just how much you can lose through stepping down to .mp3 format...

On crappy factory speakers (yes, I am talking about Bose too) you may not notice much past 128/192, but if you upgrade to real speakers or listen in a home environment it is easily noticeable.

192
http://i28.photobucket.com/albums/c206/balls_to_the_wall/192kspectrum.jpg

225k
http://i28.photobucket.com/albums/c206/balls_to_the_wall/225kspectrum.jpg

.flac
http://i28.photobucket.com/albums/c206/balls_to_the_wall/flacspectrum.jpg

kckranz
04-06-09, 04:12 PM
Well yes the best solution is to either rip using a lossless codec or just play your music from the original CDs, but there's no way my changer and in-dash player will hold 100 CDs. The original post was not as much a discussion of advantages or disadvantages to using one codec or the other, rather a "free" or small $ solution to what the average ears would consider a sound quality "shortcoming".

STSS
04-16-09, 12:32 PM
I was under the impression though that those adapters only worked if you had factory NAV unit.....or is there something else out there other than cadillacSTS2003's custom harness?

I used an automatic audio switcher. It splices in the audio lines of the cd changer. With no MP3 player plugged in, it plays the cd changer. As soon as you plug something in, it cuts into the cd player audio and plays the MP3. Absolutely clear. I think it cost me $50. Sony I think.