How To Find Impedance When Wiring: Break Down

Wiring, the not so fun part of a project. Aside from the cost.

A lot of us are either car audio illiterate or just dibble and dabble but need a little help. We all know the dangers of wiring something completely wrong, so I’m here to help. Slightly.

There are two ways to wire a speaker/subwoofer to an amp – either parallel or in series. Then it spins off to series-parallel or parallel-series, but for the sake of today, we’ll keep it pretty basic.

1. Wiring in parallel is a straight shot, positive [+] to positive [+] then negative [-] to negative [-]

The equation to find the final impedance is fairly simple –

Speaker impedance / # of speakers = final impedance: I.E: 4ohm SVC / 2 speakers = 2ohm

For 3 speakers, things get a little tricky.

4ohm / 3 speakers = 1.3ohm, which there’s no amp with that impedance.

We do advise choosing a 1ohm amp in which there will be power loss, but choosing a stronger amp gives you some wattage leeway.

• If a coil is blown during a parallel connection, the impedance will not be recognized.

I.E: If you have 4 speakers rated at 4ohm, playing at 1ohm, and one of those speakers blow, then you’d be following the equation above – 4/3=1.3, and in this case, you’ll experience power loss.

2. Wiring in series is just a bit different – positive [+] to negative [-] on opposite speakers / then the remaining positive [+] and negative [-] terminal to the amp.

The equation is as follows –

OHM x # of Speakers = final impedance: I.E 2ohm SVC x 2 speakers = 4ohm

• If a coil blows in this sequence, both speakers will stop. Just 1 burned speaker stops the connection of the other speaker.