RetroSound® radios are high-powered and are designed to work with 4 ohm speakers.

Be sure to check or replace your existing speakers if they are not 4 ohm.

Your RetroSound® radio’s speaker output wire CANNOT be wired to a common ground system.

Common grounding: when speakers in the vehicle use a chassis ground or a common grounding point for the negative side of the speakers. To use a RetroSound® radio you will need to either purchase an adapter or rewire your vehicle’s speakers.

Your RetroSound radio’s speaker wires CANNOT be bridged.

Bridged: connecting two speaker wire outputs together in an effort to increase power. This will NOT work!

Any unused speaker wires MUST be capped off individually.

Unused speaker wires must not touch each other or “short out” by touching the vehicle’s chassis; this will cause the radio to not work.

From your RetroSound® radio speaker connector


With the factory radio or radio harness still in the car with speakers:

Remove the factory radio (if still in place) to access the wiring behind the factory radio, or go to where the old radio was located. There is usually a plug or harness coming from the rear of your factory radio (or in the original location of the factory radio).

After determining which wires carry voltage (see wiring a radio), next we will locate the speaker wires. In most vehicles there will normally be two wires per speaker* (one positive and one negative).

4 speakers should have eight wires (one positive and one negative per speaker).

2 speakers should have four wires (one positive and one negative per speaker).

The easiest way to determine speaker location and polarity of each speaker is with a common household battery (either AA or AAA – nothing larger). First, make sure that the speaker wires you are going to check do not carry voltage.

Speakers and speaker wires have a positive (+) and a negative (-) polarity, as do batteries. Hold the speaker wire you believe to be positive to the positive battery terminal (+). Gently tap, in a brushing motion, the other wire to the negative battery terminal (-). If the speaker is working and the wires are connected, you should hear static or a popping sound from the speaker each time the wire touches the terminal. If you do not hear static or popping, go directly to the speaker and test it.

Listen for which speaker the sound is coming from and watch that speaker for movement as you test. If the speaker “pops out”, then polarity is correct. If speaker “pops in” then polarity is incorrect, and your speaker wires need to be reversed.

Once you have determined the speaker location and polarity connect those wires to the corresponding output wires on the RetroSound® radio.

*Note: If you have a common grounded system or factory amplified system, this testing may not work. It may be necessary to purchase an adapter or rewire your vehicle. For further options please contact technical support by email ( or by phone (

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No speakers or factory radio:

Follow the instructions in wiring a radio . Then simply run new wires to each speaker location in your vehicle, making sure to avoid sharp edges or moving parts .