Stereo Systems for your Fiero by David Kopielski

Section 1: Upgrading the stock system

Many of us enjoy driving our Fiero's. But due to the age of the car, the stock stereo seems dull. Usually the stock cassette player wears out and the paper-coned speakers deteriorate. There are many options these days to upgrade the stock system. The problem is the Fiero has a small interior and placement of extra equipment is limited. To achieve a nice sounding stereo system in the Fiero is not impossible. This article is a basic guide for what's available. To start with, the radio (or head unit as they are called) can be changed out easily. The options of upgrading the head unit are varied. You can start by just upgrading it to a newer GM radio. There are harness adapters made to simply plug-in the newer units.

Some of the newer units have CD players. A few have CD and cassette players. These just plug in and use the existing set-up. The appearance looks factory installed and provides an easy upgrade. Although depending on where you purchase the unit either on-line or at a local junkyard the cost can rise quickly. This brings us to the aftermarket side. Many companies make stereos. For the most part, there are industry standard sizes. The size is called DIN. GM, Ford, and Chrysler use a size called DIN and a . Due to the size of the opening in the dash, many aftermarket stereos require an adapter plate to mount the DIN sized units. Some folks do not like the appearance of the adapters. Some adapters even cause the unit to stick out up to inch. Pioneer and Jensen make units that are the larger DIN and a for the vehicles. The look is almost factory and the units available have many features and generally more power. There are adapter harnesses for these also. It takes less than 10 minutes to swap out the stereos. Upgrading the head unit is the easiest way to get a better sounding stereo. Next is the speakers. The stock speaker cones are made from paper. Over time with temperature and humidity, the paper deteriorates and tears. This causes "buzzing" or distortion from the speaker. Most aftermarket speakers have cones made of a poly plastic or plastic coated cloth. These will generally out-last the paper cones by many years. Also many aftermarket speakers are "coaxial". This means the speaker is really two speakers. One section (called the woofer) supplies the lower frequencies and another (usually mounted on top called the tweeter) supplies the higher frequencies. This set-up provides a cleaner sound and helps the stereo imaging (the left and right channels of sound are more distinct).

The 1984 and 1985 Fiero's came with seat speakers and dash speakers. The seat speakers are 3 " speakers. Replacing the seat speakers requires the seat upholstery to be removed. There are a few companies still making this size. The 1986 thru 1988 Fieros removed the seat speakers and added 4" X 6" speakers in the sail panels. There are two ways to go in replacing these. You can buy a 4 X 6 replacement speaker or many make a plate speaker. The 4 X 6 plates are actually a 3 " speaker with a separate 1" tweeter mounted on a plate the fits the 4 X 6 hole. These plates sound better acoustically, but you lose some of the lower frequency music like drums and bass guitars due to the small cone size.

The dash speakers on all Fiero's are a 4" X 10" speaker. The 4 X 10 speakers are starting to become extinct. Many companies are no longer making them. There are a few left, but word is that in a couple of years they'll be gone too. No car manufacturer has used the 4 X 10 speaker size in the past 10 years. From 1986 to 1988 there was a "Performance Sound" option for Fiero's. This option installed a 5" subwoofer in a plastic ported housing under the passenger side dash. The level control was mounted with a slide switch on the overhead light panel. A 20 watt mono amplifier was also mounted on the passenger side of the console. This increased the lower frequencies (drums and bass guitars). Rodney Dickman sells a replacement speaker for this. The only problem with the factory sub is depending on the newer GM stereo or aftermarket stereo, you may have a hard time wiring the sub in. Some aftermarket stereos won't even allow you to use it.

Just replacing the stereo with a new GM model or aftermarket and replacing the speakers with new aftermarket ones will instantly give the car a better sound. Most options we will discuss here will allow you to get the entire system upgraded for less than $300.00.

Section 2: More Power

Some folks like to install stereo systems to make the car sound like they are at a live concert. These systems can get very loud and cost thousands of dollars. Even so, many folks just want to increase the sound quality and power without waking up the neighbors.

The first step is amplification. With an amplifier installed, the music will be clearer and less distorted even while driving down the highway with the windows down. There are many amplifiers available. They have features like multiple channels and built-in crossovers (crossovers are explained later). Due to the smaller size of the speakers in a Fiero and small size of the interior, you don't need to buy a large, high wattage, expensive amplifier. For less than $200 you can find a good 4-channel amp with average power (a good amp rating is usually between 35 and 50 watts per channel). Mounting the amplifier is another challenge. The most popular place is behind the seats. Some have mounted them under the spare tire in the front trunk or in the rear trunk. Wherever you mount the amp, you need to provide airflow past it. The amplifiers will get hot if not properly vented. Once they get too hot they will turn themselves off. Wiring the amp is usually done straight from the battery. There is a control line that goes to the stereo that only turns the amp on when the stereo is on. You also will need to run wires to the speakers since the stock wires cannot be used without cutting and splicing. The amplifiers are connected to the stereo thru a set (or sets) of shielded RCA type cables. The signal in these cables coming out of the stereo is virtually distortion free.

Section 3: Changing Speaker Sizes

The speakers in the Fiero are oval in shape. Although they are fine, round speakers are better acoustically. As mentioned previously the seat speakers are already round and for the sail panels there are plates with round speakers mounted on them. The dash speakers can be changed to a round speaker. It requires a plate to be made and depending on the size, it may require some cutting. A 4" round speaker is easy to install and requires no cutting of the dash. The speakers you select can be coaxial or component types. The coaxial is basically two speakers in one just like the aftermarket replacement speakers mentioned in section 1. The component speakers are two separate speakers. One is the 4" woofer for producing the low frequencies and the other is a 1" tweeter for the high frequencies. To separate the frequencies, a crossover (supplied with the speakers) is required. The speaker wires are hooked from the stereo (or amp) to the crossover and the outputs of the crossover are wired to the individual speakers. The component speakers will make the car sound more like your home stereo system. This will increase the clarity of the music. The sail panel speakers can also be changed to a 4" speaker. Going to separate speakers in the sail panels will require you to find a location for the tweeter. Usually a hole is cut in the plastic panel or the tweeter is mounted on top of the panel.

The only choices for the sail panels are the 4 X 6 oval replacements, the 4 X 6 plates, or the 4" round speakers due to the frame of the car and design of the sail panel. A larger speaker would require extensive cutting and/or modification. The dash can be set up to use a 5 " speaker, but minor cutting of the dash and the grill cover is required. Some folks have installed even larger speakers such as a 6" X 9" speaker. Usually the dash is removed and the speakers are mounted from the bottom. If you decide to do this, you need to watch the overall height of the speaker for the driver's side dash. The dashboard wiring harness is there and limits the space available.

Section 4: The Subwoofer

The subwoofer is the speaker that produces the very low frequencies. These are the speakers that can "rattle the neighborhood with the boom, boom, boom sound". Like home stereo's, the low bass frequencies reproduce the drums and bass guitar sounds. The stock subwoofer cannot handle an increase in power. If you add an amp to the rest of the speakers, the stock sub will hardly even be heard. The size limitations of the Fiero make this the most difficult part of the system. The subwoofer also usually requires another amplifier and a crossover for the sub frequencies. Many new amps have a crossover installed so you just flip a switch and use the amp for the sub.

Now for location; there have been many idea's tried. The basic rule is the larger the speaker the lower the frequencies it can produce. The stock unit is only 5". The easiest way to increase the subwoofer would be to increase the size. Once you determine what size the speaker is, you will need to either make or buy a box for it. The subwoofers require a box to function correctly without distortion. Usually when limited space is available, a sealed box it used. By sealed, it means that the box with the speaker installed is airtight. Ported boxes have a hole with a tube in them. The tube is a specific size (tuned) to increase the ability of the speaker to produce lower frequencies. If you pull out your stock subwoofer box you'll notice a plastic tube on top. This is the port. Ported boxes require less power to get the lower frequencies, but require larger box sizes. As an example, an 8" speaker in a sealed box would require the box to be .3 cubic feet. But the same speaker in a ported box would require a .6 cubic foot box.

So now comes the point of where to place the subwoofer. The largest size that will fit in the stock location is a 6 " speaker. Many have put in 8" speakers but the box size is usually too small and it degrades the sound of the speaker. The most popular location is behind the seats. Many just move the passenger and/or driver seat up a little and place the subwoofer box behind it. One very easy subwoofer install is to purchase a "Bazooka Tube"; this is the brand name. It is a powered (no amp required) tube that is 6 " or 8" in diameter and about 19" long. You can wire it up and install it in minutes. An 8" sub in a slim box fits fine. A 10" sub usually causes the seat to be moved almost all the way forward. There are ways to decrease how far forward the seat is and still use 10" speakers. This requires cutting and fiberglass. If you remove the carpeting from behind the seat you'll see a seam that looks like a hard caulk or epoxy was used. From that point down the firewall is hollow inside. If you cut the top panel, you will gain 2 " of mounting depth for the speaker. But the box now needs to be built as part of the firewall. The results are near factory look and the seat is only forward a few clicks. Caution: It should also be noted that on the driver side behind the panel is the filler tube for the gas tank. When cutting out the panel be very careful not to cut the pipe. It is 4.0" from the top seam. The easiest way to avoid it is to cut the bottom and sides then bend the panel up so you can see where the pipe is and safely cut the panel off without cutting the tube. I do have pictures, If you plan on doing this, Email me for the pics.

The next location, which is becoming more popular, is the passenger side footwell. This location decreases the legroom on the passenger side, but allows an 8" or 10" sub to be installed easily. Another location is the center console. The glovebox is removed and a speaker is installed in its place. This location is starting to be used more and you can even buy a new console piece that has all the work done for you. Just mount the console and speaker. Finally the last location is the front trunk. A large speaker, usually 12" diameter, is mounted in a box and put into the front trunk coupled with a high power amp so you can hear the bass (and so can any living thing within 100 feet of the car). To aid in getting the sound from the front trunk into the car, some have made a tube that connects to a hole in the floor with a cover over it.

Section 5: The Electronics

Finally, the last step is the electronic items to increase the frequencies and sound of the music. The first is a graphic equalizer. These are units that have 5 to 12 adjustments at individual frequencies and some even have level controls for subwoofers. With the adjustments you can increase or decrease the amount of a specific frequency to suit your taste. These adjustments are compared to the bass and treble tone adjustments on the stereo itself. If you decide to use an aftermarket radio that is the standard DIN size, there are many equalizers that are DIN size. With the proper adapter both the stereo and the equalizer can be installed in the stock stereo location.

Second are the surround sound digital processors; just like the surround sound systems for home entertainment systems. The units control spatial delay giving you the effect of being in a much larger room. Due to the small size of the Fiero interior and the location of the rear speakers, this can help the stereo imaging (front, rear, left, and right sound separation). Usually it is a small box with a small control panel to vary the delay. This can make the music sound like you are in a small hall or a large concert arena.

In conclusion, there are a wide variety of things to do. This is just a basic reference of what is possible. Whether you just want to upgrade the existing system or compete in a professional stereo contest, you have many options available to you. I recommend the best thing for you is to get a system that sounds good to you and is within your budget. If your looking to change your system or have any questions I can be E-mailed at:

Credits and Links: All photos are used with permission from members of Pennock's Fiero Forum.

To buy or research stereo equipment online: (Buy products/research on-line) (Buy products/research on-line) (Sells GM/Delco factory stereos and harnesses) (Stock Subwoofer Replacement Speaker)