Upgrading the Audio System
It is very easy to upgrade the SHO's factory stereo system. Discussion of aftermarket stereos and installation procedures could be (and is) a FAQ in itself, so I'll just mention a few of the specifics here. Crutchfield Corporation has an excellent free catalog with lots of information about exactly what will fit; this is not an endorsement, but I personally have had nothing but good service in 7 years of doing business with them.
Radio: DIN chassis size, 6.5-7.5" cavity depth depending on model year
Amplifier: Premium Sound is 20W*4 channels, mounted on the forward wall of the trunk. I still use this for my main channels with a separately amplified subwoofer. The JBL system is biamped with custom equalization for the JBL speakers; it would probably sound kind of weird to swap out either amp or speakers separately in this case.
Speakers: Front doors can mount 5 1/4" or some 6 1/2" units. Some drilling will be required as the factory speakers have an oddly shaped mounting plate. Pre '92 cars also have 3 1/2" cutouts in the dash for tweeters. Rear: 6x8 standard, 6x9 possible with some metalwork
[Stuff on the factory radio and electronics by SGS Thomson as Bill Giovino will happily tell you :-)]
The rear connection is as follows:
_______ L In | 1 4 | R In L Out | 2 5 | R Out Signal Rtn | 3 6 | DAD Status -------
The jumper connector has pins 1 & 2 shorted, and 4 & 5 shorted. Play with the connector jumper shims until you are satisfied that the shim shorting pins 4 & 5 are making good contact. Then put the whole thing back together again. You can use Molex connectors to rig up a connector (package # WMLX-102, containing 3pcs housings # 22-01-2041 and 13pcs terminals # 08-50-0114). A little Dremel-tooling and gluing of two of the 3-connector housings will result in a satisfactory 6-pin connector.
You can hook up an equalizer to your radio/amp system through this connector. L-Out and R-Out go to the equalizer's inputs; L-In and R-In go to the equalizer's outputs. Your radio's fader & balance controls will behave normally.
If you want to hook up a CD player to your radio, you can switch the radio L-Out and R-Out line to the equalizer with the CD-player corresponding left & right outputs, to the input of your equalizer. If you really want to get professional, have your switch pull pin 6 (DAD Status) up to 5 volts when your CD player is on. The radio's display will indicate "CD", and internal equalization of the radio will switch for a CD player's signal. If you are playing a tape at this time, the tape transport mechanism will enter pause mode (tape will stop, pinch roller & head will disengage).
Finally, use shielded audio cables for these low level wires. All shields should be tied together and connected to the "signal rtn" pin.
But my radio doesn't have a "loop plug" or "jumper connector"!
Some premium sound head units do not have a "loop plug" on the back. Instead, the "L and R OUT" are connected permanently to the "L and R IN" by jumpers (actually zero ohm surface mount resistors) on the back of the printed circuit board to which the jack is mounted. These resistors must be removed to "open" the loop so your external switch can do the job.
These "non-CD-ready" heads do not have the internal wiring to support the logic input which switches off the radio and cassette and displays "CD" for your viewing pleasure.
Also, if you have a "non-CD" head unit, you must fabricate a plug to fit the 6 pin socket. One SHOtimes member whittled/expoxied scrap generic Molex jacks to fit.