The stock DeLorean features two 3.5" Craig dashboard-mounted speakers, and two 4"x10" Craig speakers mounted on the rear side walls below the upper seat belt anchors. Many owners upgrade the speakers with new ones, as speaker technology has advanced significantly since 1981. As such, these articles focus more on upgrading the speaker system
The standard DeLorean speakers are located in the dashboard and rear side trim. These can be fairly easily upgrade with new speakers. Upgrading the original Craig speakers with nearly any modern speaker will significantly enhance the sound.
The stock speaker placement and configuration is less than ideal for optimal audio reproduction. For the best sound, you can install speakers in custom enclosures in the footwell and parcel shelf, and install a subwoofer and amplifier for your aftermarket sound system. These are more involved custom installations and may require modifying the car, including modifying the interior or losing space on the parcel shelf to fit the new speakers.
General Sound System Information Edit
There are many sources for information on upgraded the DeLorean's speakers on the internet. Kayo Ong has gone one step further and written an excellent sound system article, now archived on DMCNews, covering sound system design in the DeLorean, with many insights. For example, it discusses how 3.5" front speakers are too small for ideal sound reproduction, how the elliptical 4"x10" rear speakers are not the ideal shape, and how both lack proper enclosures to reproduce lower frequency sounds better. The thin vinyl-covered panel over the rear speakers will vibrate. The cabin itself is poorly shaped and sized for audio reproduction and optimal speaker placement, and by having the rear speakers face each other they can actually cancel or reinforce certain frequencies, resulting in uneven audio reproduction.
When designing a new car sound system, Kayo says that it should be "front dominating" with much of the sound coming from the front speakers. He suggests that the idea speaker placement in the DeLorean are on the left and right ends of the parcel shelf for the rear speakers, and in the footwell area for the front speakers. The article includes information on how to choose speakers, and recommendations for installing a subwoofer aimed at audio quality instead of quantity.
The article is excellent, and is definitely worth a read if you are considering upgrading your sound system.
General Troubleshooting Edit
Intermittent audio from a speaker may simply be a loose connection at the speaker. This is easiest to fix at the front speakers, where you can simply reach under the dash and check the connection at the speaker. It is much harder to check the rear speaker connection due to how they are buried behind the rear side trim. Access to the radio itself is difficult as well, and requires pulling the center console forward, unless you have an after market radio that you can easily remove from the front. The original Craig radio unit can suffer dry joints around the output amplifier IC leading to intermittant loss or poor volume of left, right or both channels.
Other issues may involve problems with the speakers themselves, such as blown cones, a seemingly common cause of rear speaker failure. A blown speaker may simply be very quiet, or may not work at all. The only solution in these cases is to replace the speaker. Bad or damaged wiring can also lead to intermittently functioning or completely silent speakers.