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How to add extra car speakers

Choosing speakers
Whether you are fitting four new speakers, or just adding an extra pair to your existing system, the choice is vast. Below are some old speakers and fader controls from Pioneer. A TS-VX700 is a surface-mounted wedge-type rear speaker. B TS-R800 mounts into the rear parcel shelf. C TS-X30 is a surface-mounted rear speaker. D TS-1612 flush-mounted speaker for use in front or rear locations. E AD-940 fader control. F UD-780A fader control.

The standard twin-speaker car stereo system has one obvious drawback. If you mount the speakers on the rear shelf, to hear the sound clearly you often have to turn up the volume to a level that is too loud for the rear seat passengers.

Conversely, if the speakers are fitted at the front of the car - and they are usually low down in the door panels - the sound in the back can be muffled by the seats.

All-round sound

The solution to this problem is to fit a four-speaker system, with two speakers mounted in the front and two in the rear.

For the front of the car you will probably find that the door panels are the best, if not the only, location available, though some cars have speaker positions built into each side of the dash.

In the rear of the car you can again mount the speakers in the doors (or the side panels on a two-door car), or on or under the parcel shelf.

Choosing speakers

There is a huge variety of speakers to choose from - in general you should buy the best quality speakers you can afford.

Make sure that the speakers you buy are capable of handling the power output of your radio-cassette or graphic equalizer - if you have a 30 watts per channel unit, the speakers must be capable of handling at least that amount and preferably a little more. But don't put 100 watt speakers on a 10 watt radio-cassette - the amplifier won't have the power to drive the speakers cleanly, and the sound will be muffled and distorted.

Fader control

Finally, if your radio-cassette or graphic equalizer isn't specially designed to run four speakers, you will need to fit a front-to-rear fader control.

This unit allows you to control the balance between the front and rear pairs of speakers.

Installing car speakers

1. Front speakers
The usual position for the front speakers is in the front door panels and you may find a built-in mounting for the speakers behind the panels. You can sometimes also fit them to the kick panels situated in the footwells although they are at more risk of getting wet or knocked in this position.
2. Rear speakers
In saloon cars the rear speakers are best fitted to the rear parcel shelf. With hatchbacks and estates you could fit them to the rear side panels or small side shelves often found in the rear compartment, but make sure they can't get knocked by any luggage. Again, the panels may have built-in mountings.
3. Fit speakers
Choose a fitting position where the speakers won't obstruct any other components. Mark and cut out the trim from the panels or parcel shelf. Drill any securing holes and fit in the speakers. Secure the speakers and fit the wiring to them at this stage (see Projects 5).
4. Fader control
Position the fader control so you can easily reach it from the driver's seat and mark the screw hole positions. Drill the holes and secure the switch using self-tapping screws.
5. Wiring to fader
Disconnect the battery to avoid any short circuits. Find the speaker wires where they emerge from the radio/ cassette unit. Identify the input terminals on the fader switch and then join the wires from the left- and right-hand channels of the cassette unit to their respective terminals on the fader switch.
6. Fader to speakers
Run the four pairs of positive and negative wires — one pair from each speaker—to the fader switch. Check with the switch fitting instructions and find the output terminals on the switch. Connect each speaker wire to its respective output switch terminal. Reconnect the battery and test the system.
Wiring a car speaker system
This is a typical wiring diagram for a four-speaker system. The four speaker wires from the radio/cassette unit, which are used for the normal two-speaker arrangement, are first connected to the fader switch input terminals. From the switch output terminals a pair of wires, one positive and one negative, are connected to each speaker. If a graphic equalizer is fitted to the system you should connect the fader unit between the equalizer and the speakers.
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