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Car stereos: upgrades and general notes

See our guide to Chrysler/Infinity stereos and speaker repairs

See getting your Infinity IV system to read CD-Rs and tweaking / fixing CD-cassette combination players.

jzaremski wrote: The audio system for Dakota and Durango changed to Alpine for 2006 [Chrysler has been phasing in Alpine]. Infinity (used by Chrysler for many years) is a Harman-Becker brand, but the actual setup and tuning for
both Harman and Alpine systems was done by the audio group at Chrysler.
There are some differences in the bass response, but they don't sound all
that different... The head units [the part you see] are considered a separate entity from the audio system [speakers and such],
and don't necessarily have anything to do with the sound system brand.
Siemens VDO makes most of the current head units, with Alpine handling the
REC navi and RAK 6CD+Cassette. Harman hasn't made any Chrysler head units
in the past, their first is the 2007 RER navi launching in the Nitro,
Sebring, and Wrangler.

Stereo Upgrades

Information sent by Randy and not edited. Last revision 11/14/2005; first posted 1996. This is not a technical guide, but an introduction showing that this is possible. We do not work for and are in no way affiliated with any of the mentioned companies. Neither Randy nor Allpar take any responsibility for any results consequences of the use or misuse of this information.

Many people wish to put a modern stereo in an older or classic car, but they don't want to tear up the dash and they don't want to attach brackets to hang things under the dash. Others have 6 volt systems that make it difficult as well. Even in a modern car, people like to have a system they can transfer to their next car. These things are all possible. Here's are the basic items in one of these systems:

Power amplifier

The best value system that can be installed today is based on a power amplifier. These 12 volt amplifiers put out very clean sound in a small package. They can be hidden in many places; under seats, in the trunk, or even in a door panel in some cars. They are available in a wide range of quality and power, but for most people an amp that is rated at about a total of 100 watts is fine (this would be about 50 per channel, or 20 watts per channel RMS at .5% distortion). Amps with lower power rating are smaller [and tend to generate less heat] and are easier to hide. The amp should have remote turn on and low level inputs (most do).


This is the one area that must be evaluated subjectively. Generally, I like the 6x9 coaxial 3 way speakers. They have a good bass and don't take up a lot of room. In 6 volt applications, don't go for monsters rated at high wattage. These are sometimes not as efficient (they need more power to produce a given decibel level). With the above amp, speakers rated at around 1.5 times the amplifiers power rating or just above that should be O.K.

Sound source

Modern electronics have brought us the personal/portable CD player. This should be your first choice. The S/N (signal to noise) ratio is excellent in the worst units. Many now are equipped with electronic anti-shock and some even have different equalizations built into help match the sound to the vehicle/speaker combination. The second choice would be a personal cassette player. These work well also, but of course, you can't expect the sound quality that a CD player can produce. I have installed three systems with cassette players and they sound just fine! Cheap CD players sound better than cheap cassette players. [iPods were introduced after this article was written; MP3 players and iPods have wildly varying sound quality, with iPods generally coming out on the high end; but they also tend to produce less power than personal CD or cassette players, and need more amplification or a preamplifier.]

6V systems

There are now available small, solid state devices that can change 6 volt negative or positive ground into 12 volt negative ground, and 12 volt positive ground to 12 volt negative ground. In all these cases, the ground is common so isolating the amp or the speakers is unnecessary. The unit is very small (a cube of about 3"), and only has three wires- input, output, and ground. This can be mounted anywhere because of its small size.

Where it all goes


Speakers are the most difficult to place. Later cars may have a place under the package shelf in the trunk set up for speakers- this should be your first choice. Another location is under a seat mounted behind the skirt- this may muffle the sound a bit. I have mounted mine in small, carpeted enclosures commercially available and designed for this purpose. They have quick disconnects so they can be removed from the interior for car shows and security.


This should be in a dry environment where it will not be bumped, and have clear air movement around it to dissipate heat. You will have to decide because it will vary from vehicle to vehicle. Under the package shelf next to the speakers is a good place. Under the front seat is also good because the low level input wire will be shorter and less likely to pick up interference. Under the dash is also a possibility in larger cars.

CD or Casette Player

This goes on the front seat next to the driver. The power wire (if you are not using batteries) and the low level input to the amp go under the carpet and poke up between the seat cushions. This way, when you leave the car and take the CD player with you (or lock it in the trunk), you can tuck the wires into the cushions and no one can tell that the car has a stereo in it. The signal wire plugs into the headphone jack on the sound source and goes to the low level input on the amp.


My car does not presently have a headliner in it, so I was able to run the wires through the roof channels from the trunk (where my amp is) to behind the front right kick panel. The important thing to remember is to run wires where they will not be abraded by foot traffic or caught in moving parts. Be sure that all power leads are fused and that you have a good ground for the amp. Do NOT attach the ground to the amp mounting screws. Use a separate screw that holds the ground only. Solder all connections (do not use crimp connectors). This is particularly important in 6 volt vehicles where every amp and volt counts! If you system is in a 6 volt car use large gauge wires rated for more than your amp. I used a Monster Wire kit designed for 500 watt amp installations. This limits power loss to a minimum.

Where to buy

A local auto sound shop would be the best place to start. There you can listen to different amp/speaker combinations. This is particularly important when it comes to speakers. I used J.C. Whitney and was able to get the amp, speakers, and power inverter on sale.

The power inverter will be the most difficult to find (if you need one). J.C. Whitney only carries the unit that inverts 6 or 12 volt positive ground to 12 volt negative ground. If your car is 6 volt negative ground contact: Antique Automobile Radio Inc. at 1-800-933-4926 for more information (they will send you a catalog). There are two of these units listed in Whitney- get the higher rated unit.

(Vince Spinelli added, which sells stereos based on Kenwood cores, with new casings and, in some cases, adaptations to 6 volt power suppies. However, they appear to modify them to only work with their own brand CD changers, as opposed to stock Kenwood changes.)


I got everything from J.C. Whitney (on sale!- catalog 91JB - prices good through 9/30/96) [prices rounded off]. The Pyramid power amp was $38, the speakers were $38, the 6x9 speaker boxes were $18, the wire kit was $15, and the speaker wire was $7. This was about $116. If you already have a CD player or Cassette player, you are in business with a sound system for just over $100.

The bad news is that if you have a 6 volt system the power inverter will cost another $80 or more depending on where you get it. But even with this, the system will only run about $300 with a CD player, and about $250 if you but a decent cassette player.

How it works

Even with this modestly rated amplifier, there is more than enough sound output to please all but the most high-DB burned-out happy. The sound is very clean and pleasant. I left the speaker wires long enough to be able to place the speakers up on the back seat while on the road, and on the floor when I park.

Additional resources (by Vince Spinelli)

I found this out when looking for a stereo for a 1976 Caddy... ... that's the web address where they are sold... the deck "cores" are all Kenwood. This company bought a bunch of Kenwood decks, and retrofitted them with new casings and, in some cases, electrical adaptation to 6 volt. Normally, that model Kenwood (not sold any more by Kenwood) would take any 6 or 10 disc Kenwood changer (which is say $100)... but these were hack wired so that you can only use one of the Kenwood changers that they have modified and doubled the price on.

Warning (from Jim and Lisa)

Don't use a 12-volt car stereo/amp/equalizer in a 6 volt system. The lack of proper voltage is liable to cause damage either to the radio or anything attached to it. The car stereo market is designed simply to work on 12V-14.4V.

If you have a vehicle that does work on 6V and want a modern stereo in it, update the charging system to 12v and use a voltage limiter inline to protect those circuits in the car that only require 6V.

If you are going to be building a stereo system for your car, the best way to run the wires is to run the power wires down one side of the car and the signal cables (RCA cords) down the other, doing this avoids unwanted noise.

In older Chrysler vehicles there tends to be problem with a "whine" that can be heard at low volume, this is often fixed by a in-line noise filter on the power side of the radio. These filters are often found at Radio Shack.

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