Upgrade The Bose Stereo System in C4 Corvettes

Corvette Specialist Has The Cure For A Sorry-Sounding System

Andy Bolig Apr 1, 2001 0 Comment(s)

Step By Step

This is the hardest step. As mentioned, each meager-size speaker and amplifier is contained in a box to give the appropriate sound. To properly work on the system, remove the interior doorskin and metal plate that’s bolted to the inside of the door. This is the only way to remove the entire speaker-box assembly.

Once the box is removed, separate the two halves of the box to reveal the amplifier. Note that there is some filler material inside the box; this is an important part of the system. Because of the space requirements, GM could not install a larger box and speaker. This filler material makes it sound like it’s bigger.

Each speaker has an amplifier—this is typically the problem with the system. Some symptoms that may indicate the amplifier is bad include a hissing noise or a sound out of the speaker that’s barely discernable. These amplifiers can be rebuilt, but Corvette Specialist provides all-new amplifiers to its customers.

One of the situations that shortens the life of the amplifiers is a capacitor that starts to leak. The fluid eats away at the other surrounding components.

You can test each speaker by removing it from the speaker box .

Use a short jumper wire to power the speaker with a double-A battery. If you see the speaker move when you put power to it, the speaker is working properly. If there is no movement, the speaker should be replaced. It is recommended that you replace speakers and amplifiers in sets. All of the speakers are the same age as the one that quit, so it’s just a matter of time before the others quit, too.

There are differences between the boxes used for the rear speakers. The coupes had boxes that slid into the side of the rear hatch area.

The convertibles used boxes along with a flat panel that became part of the floor area immediately behind the seats.

Once you remove the flat plate from the convertible style of rear speakers, you can access the amplifiers just like the other boxes.

Corvette Specialist can also repair other components of the Delco-Bose system. We had a head unit from a ’95 Corvette that has white lettering, and we wanted to match the orange lettering of the rest of the dash in our ’90 Corvette. Corvette Specialist rebuilt our unit and installed the older-style faceplate. The newer head units were slightly better, so Corvette Specialist provided us with a matching faceplate and an upgraded radio.

There were changes made to the receivers during the time they were used in C4 Corvettes. One of the more obvious is that, while the ’84-’89 units were contained in one unit in the dash, the ’90-’96 systems consisted of a head unit in the dash and a receiver unit under the dash on the passenger side of the car. For obvious reasons, they will not interchange.

The receiver units from the ’90-’96 systems differed between the Bose and the non-Bose models. The Bose model has no fins on the heat sink located on the back of the unit, while the non-Bose receiver has fins on the heat sink. They cannot be interchanged.

A problem with the head units we hear about quite often is that a CD installed in the unit will not eject. There is a small rubber bumper inside the unit that rests on the CD when it’s not in use. If the CD is left in the unit for more than a day and not played, the rubber bumper can become fused with the CD due to heat in warmer climates. Sometimes the CD can be ejected once the system cools down, but many times you’ll have to disassemble the unit to break the rubber bumper loose from the CD. Chris at Corvette Clinic says it’s best to simply remove the CD when you won’t be listening to it for a while.

The Delco-Bose stereo system in the C4 Corvette has changed over the years, due to improvements in materials and technology. This is good news to the owners of later-model C4s, but it spells trouble for those who have the earlier-model Delco-Bose system still residing in their dash, waiting for the perfect time to lash out with hissing, scratching--and possibly even silence.

The Delco-Bose system is different from other stereo systems. It relies on smaller speakers contained in their own boxes, each powered by a small amplifier rather than a larger speaker powered simply by the head unit. These systems will put out plenty of sound when they're working, but it's only a matter of time before they start to exhibit signs of wear. Often, the first signs are a scratching noise or hearing an engine noise through the speakers. Every once in a while, the speaker will simply cease making sound altogether.

Many have gone the way of removing the entire system, not understanding the symptoms and how easily problems can be corrected. With the help of Corvette Specialist and the Corvette Clinic, we were able to see firsthand how you can have your Bose and hear it too.

Armed with this information, and the knowledge that Corvette Specialist is able to cure any of the ailments your Delco-Bose stereo system could experience, we hope to ease your concerns about the complexity of these systems. Maybe it will even improve the sound of the music you get from your radio—making your Corvette even more enjoyable to drive.

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