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steveg · Joined: 28 Mar 2001 Posts: 47 Location: Bristow, VA, USA

What I want to do is a bit far fetched, but not really impossible. On the back of the stock radio is the wire harness + the datalink cable. I have recently gotten an xm radio with an FM Modulator. What I want to do is tap into the datalink cable and feed in to the radio with the xm radio line out.
The datalink cable is 8 conductors, there should be 3 or 4 wires for the audio portion of the signal. Using some switches I should be able to flip between XM and CD signals. Anyone ever messed around with the changer wires?

gigel · Joined: 12 Sep 2002 Posts: 1533 Location: Dallas/TX

Not a lot of help from me, but I'll tell you what I know: the audio portion of it might be easy to do, and while I can't say which pin is what, I remember that you can find out if you open up the head unit. The PCB has inscriptions on it with each pin, and if I remember right, there were L and R on that connector.
The controlling part, now that's a lot harder. I was looking into it, but I gave up. Let us know if you make it work.

steveg · Joined: 28 Mar 2001 Posts: 47 Location: Bristow, VA, USA

thanks for the reply.
i found on ebay the bmw to pioneer changer wire for only a buck pluc $6.50 shipping. I am going to cut it apart and see if I can figure it out.

I thought about opening up the radio, but I was concerned I would have to get through the tape mechanism first to see the inputs. Although if I can open up the bottom may not be so bad.

Maybe I can get from mouser the 10 pin block connector and make the switch right near the front.

n2red · Joined: 13 Jun 2002 Posts: 184 Location: North Carolina

Steve,

I hope you have success on your wiring project.

I have XM, (And I do like it a lot, especially because I'm in a mountainous, rural area..)and I know you know this, but, even though XM is digital, it is NOT CD quality digital. Yes, the programmers are using tracks from CD masters, it loses a lot in it's transmission to the subscriber.

Where I'm going in this distribe is.... don't expect a lot of improvement in audio quality by going with hot leads directly to the head, as opposed to using the FM modulator. Someday the quality of audio that the subscriber actually gets will improve, but no time soon.

If you set your EQ for the way you like your CD's to sound, XM will sound a bit thin. You'll have to boost both ends to make it sound anywhere like your CD's.

Dan

steveg · Joined: 28 Mar 2001 Posts: 47 Location: Bristow, VA, USA

I suppose I notice things with the fm modulator xm that I used to notice when I had another car and an FM Modulator CD Player. Like for instance when ever someone says something with an S in it, it is always staticky sounding.

gigel · Joined: 12 Sep 2002 Posts: 1533 Location: Dallas/TX

Dan, I thought the XM radio has CD quality... What's your setup? They claim to be CD quality in their commercials, aren't they? And it can't just be the source, because every AM station is probably using CDs now, and they don't say anything about CD quality (was AM maxed out at 4.5 kHz?). I am puzzled

n2red · Joined: 13 Jun 2002 Posts: 184 Location: North Carolina

Christian,

XM isn't CD quality, never has been. I have HK in my '97, with an FM modulated XM system. Has the very same "traits" as my co-workers new Expidition with it "built in."

The only "digital" thing about it is that it's transmitted from the satellite transponder in the digital format.

I've seen several XM installations and as of yet, I haven't seen an installation that is as accurate as a CD of the same song played in the unit.

Here's the closest thing I can find from the XM website itself.. (I copied and pasted it so the words aren't my own..)

"Why don't the website audio streams have the same high sound quality as heard on an XM Radio?"

"We stream our audio samples on the Web using Windows Media at an encoded 32kbps. Although this low bit rate may sacrifice detail and quality of sound on the web, it ensures that all web users, from dial-up to T3, will be able to easily listen to a sampling of XM programming. The sound quality of the XM Radio service in cars and homes is notably higher. You won't be able to tell the difference between XM and a CD playing."

Notice anything in those last two lines that claim to have "CD quality?" The term "notably higher" doesn't mean "16 bit resolution"

For more info.....
http://www.xmradio.com/corporate_info/fast_facts_sound.html

[ 07-30-2004: Message edited by: PianoDan ]

[ 07-30-2004: Message edited by: PianoDan ]