1998 Caddy Deville Radio Swap

Just bought a 98 Deville with a tape player radio in it.  Want to install a tape/CD Bose unit if possible.  Have a Bose unit from same year which the local dealer says they can unlock (car has the anti-theft feature). The dealer says that I can just interchange the radios but that dosen't sound correct since the Bose system is usually radically different than normal systems.   I know I could second party the radio but I am restoring car for my wife and she would really like it to look "original" as far as possible.

I realize that Bose speakers, in general, depend on an amplifier at each speaker location.  I am assuming this is true of their mobile units also.  Based on my first look at the problem it would seem that I could hook the Bose unit into the car and then put a four channel amplifier between the head unit and the speakers.  

Will this work?  Or has anyone out there done it and have a better idea?    Is the wiring on the connectors the same or different.?  Could someone furnish a wiring diagram of the breakout on the back of the units involved? 

Okie before you read this super long message, lemme first ask you what it is you're trying to achieve?  I got the impression that you only were gonna do the bose swap because she only has a tape player now and you want her to have a cd player as well.  Am I correct?  And does she still want to play cassette tapes or does that not matter as long as she has a cd player?  Finally, using the current system for comparison, how important is sound quality to you?  Is that one of the reasons you want to upgrade to the bose?

If you just want her to be able to play cds then you might want to consider just getting the GM brand cd changer (assuming the dealer sells it).  This will be cheaper but will still keep the stock head unit look. 

speakers that are part of a bose factory system are usually 1-ohm, and if you try to hook up 1-ohm speakers to nearly ALL 4-channel amps you will cause the amp to overheat.  Most class AB 4-channel amps are designed to run a 2-ohm stereo load at most;  usually it ends up getting one speaker per channel though, and seeing as how most automotive speakers are 4-ohm speakers, the amp ends up getting a 4-ohm stereo load.

anyways, another thing you should know is that since bose factory amplifiers are designed to handle a 1 ohm speaker, if you try to run aftermarket speakers to one of these amps they will be VERY quiet.  This is why replacing a single blown bose speaker in vehicles that have a bose system is basically impossible, because you'll end up with one speaker that is about half the volume of each of the other ones.

Not all of the bose systems have amplifiers at each of the speaker locations--for example many nissans use a single bose amplifier mounted on the underside of the rear deck.  The bose system for your particular vehicle, however, does actually use a separate bose amp for each speaker.

Is your main objective to be able to play CDs and yet retain the stock stereo look?  Or do you need the ability to play cassett tapes as well?  If you could find just the bose head unit somewhere on ebay or something then you could put that up in the dash, and get a tiny aftermarket 4-channel amp to hide somewhere behind the dash that would power the current speakers in the vehicle (the bose head unit cannot by itself power speakers--it requires external amplifiers).  They make integration adapters specifically for people looking to keep a bose head unit but replace the speakers and amplifiers with aftermarket equipment, so you'd just use one of those.

Also, I should point out that BestKits recently came out with a Deville dash kit (BKGMK260) and up until now the only way to put an aftermarket head unit in one of these vehicles relied on using crappy kits that made it look real ugly.  The best kits kit though is really slick and that, along with a dark-colored aftermarket stereo, would look pretty good in the vehicle and would certainly cost a lot less and sound a lot better than doing the bose thing.

Sorry somehow I missed the part about you already having the bose head unit, so lemme try and address that issue.

The plugs might even match up, and the dealer can probably unlock it very easily, but when you go to turn the thing on and try to listen to some music, you will hear basically nothing.  You will have to turn it all the way up, just to be able to hear even the faintest amount of sound.  That's because the bose head units do not have amplifiers built in to them, and so they only output a low-level (unamplified) signal.

As I think I may have said in my previous post, you CAN use the bose head unit with your current speakers, provided you give them amplification of some sort.  The cost of a tiny 4-channel aftermarket amplifier, and the proper integration adapter, will still be FAR less than what you'll pay if you get all new bose self-amplified speakers.  Also I think the wiring would have to be changed for them to work properly.  And it will almost always still sound a whole lot better than the bose system too.

Keep in mind though that you will probably not find a 4-channel amp small enough to fit behind the dash, and so it would have to be mounted most likely the back of the rear seat, or somewhere else in the trunk.

Thanks for the response Ethan.

The present speakers, haven't checked the resistance and don't know that a straight DC resistance would tell me that much, but they are the ones that came standard in the car with the "regular" head.  Your last email hit right on the head for what I am attempting to do.  I had planned to try just what you suggested in your last message.  Get the Bose head unlocked and then put an amplifier between it and the speakers.  Your first message also brought up the impedance mismatch that I thought I might have.  I am assuming, based on your last email, that this will not be a problem going directly to an amplifier. 

Could you tell me if the head will have enough output to place the amplifier in the rear of the vehicleeithoug excessive loss and, should I change the plain wires from the head to shielded cable between it and the rear mounted amplifier?  As you mentioned there is not much space in the dash area itself for even a small amplifier, not to mention the heat factor from the ducts in the winter up here in Illinois.

Thanks again for your help.

Dave

Forgot to ask in last answer to Ethan.

Does anybody out there have a wiring/pin out diagram for the 1998 caddy radios so I can make sure I connect things up correctly?

This would also let me know if the wiring is the same for the units.  I am assuming it is because of the need for interchanablity in the manufacturing process.  That being said though, I have done enough restorations of older muscle cars to know it dosen't always work that way.

Your current speakers are 4-ohm speakers, which is what most 4-channel aftermarket amplifiers are designed for.

Here's the wiring info we have for this particular vehicle--I highly recommend you verify these first with a multimeter though just to be sure.

The harness should either be a 32-pin plug or a 21-pin plug.  Regardless of which one it is, the pins should match up with either this diagram or this diagram, respectively.  Don't pay attention to what colors they say the wire is, just go by pin location and wire function and verify with a DMM.

Oh yea I forgot about the VEN4 adapter you need to get.  Here's a quote from the FAQ page of Peripheral Electronics--the company that makes the VEN4 adapter.  It's basically what you're going to be doing with your vehicle: