Stereo upgrades and installation

Written by Randy at FRCN. Originally posted at allpar.com; adapted and used by permission. We do not work for and are in no way affiliated with any of the above mentioned companies. We cannot take any responsibility for any results consequences of the use or misuse of this information. This page is rather dated and may not be valid in cars made past 2000 or so; updated in 2018.

While Toyotas are top-of-class in many aspects, stereos generally are not one of them. Indeed, the main advantage of the Chevy Prizm over the similar Toyota Corolla is its superior Delco stereo system!

While many people wish to upgrade their stereo or put a modern stereo in a classic car, they don't want to tear up the dash and they don't want to attach brackets to hang things under the dash. 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 sound system today is based on a 12-volt power amplifier; these put out clean sound in a small package, and can be hidden in many places; under seats, in the trunk, or even in a door panel. 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 easier to hide, and generate less heat (an issue in small spaces, since heat can damage surrounding trim). The amp should have remote turn-on and low level inputs.

Speakers

Generally, I like the 6x9 coaxial 3 way speakers. They have a good bass and don't take up a lot of room. Monsters rated at high wattage are sometimes not as efficient (they need more power to produce a given decibel level). With the 12-volt amp, speakers rated at around 1.5 times the amplifiers power rating or just above that should be okay.

[Corolland additions] Speakers are fairly easy to install in the doors - once you get the doors apart. However, you must be sure to get shallow enough speakers to fit. Do not get cheap with speakers, they are probably the most important part of the sound system. You can pay $50 for a pair of “name brand” speakers and get something that doesn't work as well as the stock cones.

Sound source

[This section was written by Corolland due to changing times] While portable CD players were once a good option, today the ideal is to get an amplifier with USB and card inputs. The USB input can be connected up to an iPod or other music player, or even to a cellphone with music. An outdated (unsafe due to old operating systems) Android phone or iPhone with no SIM card can make a cheap replacement for an iPod, or you can find a used iPod Touch; there are now adapter kits to convert real iPods from hard drives to flash cards with up to 256 GB of storage. The ideal would be an amp that accepts memory cards, but that leaves the problem of where the controls and display are going to be.

Where it all goes

Speakers are the most difficult to place; most Toyotas have a place under the package shelf in the trunk set up for speakers, which should be your first choice. Under a seat, mounted behind the skirt, is another good spot. I have mounted mine in small, carpeted enclosures designed for this purpose, with quick disconnects so they can be removed from the interior for car shows and security. [You can add these enclosures to stock speakers. Depending on your car, replacing the speakers on the deck lid can be incredibly easy or surprisingly hard. Get into the trunk when you do it, and by all means wear goggles! Stuff falls down.] Inside the door panels is the best spot for good stereo sound; manufacturers put tweeters into the ends of the dashboard for that reason. Bass can be anywhere, but for treble, location really matters.

Applifiers should be in a dry environment where they will not be bumped, and have clear air movement around it to dissipate heat — in short, though you can put them into the doors, you should not do that (especially since any leak could result in a dangerous short). 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 often possible.  

The control unit can be stored on a cushion in the glove compartment, with the wires going through a small hole in the glove compartment lining (you can remove the light and use that hole to avoid damage).

Wires can go through the roof channels; often, there are wire channels under the door sills. 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). I used a Monster Wire kit designed for 500 watt amp installations to limit power loss to a minimum.

Where to buy

A local auto sound shop lets you listen to different amp/speaker combinations. This is particularly important when it comes to speakers. Or you can use J.C. Whitney or RockAuto and get the amp, wire, and speakers on sale. The price for everything can be $120-$200. Even with this modestly rated amplifier, there is more than enough sound output to please all but the most high-decibel burned-out folks. 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.