thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Collaboration, Voice & AV · Foundational

Loudspeaker Impedance

The nominal AC resistance of a loudspeaker, such as 4 or 8 ohms, which determines the load presented to an amplifier.

Definition

Wiring identical loudspeakers in series adds impedance (two 8-ohm speakers equal 16 ohms), while parallel wiring divides it (two 8-ohm speakers equal 4 ohms). An amplifier must be rated for the total load; loads below its minimum rating can cause overheating or shutdown. Constant-voltage systems use transformers to avoid impedance calculations.

Example

Four 8-ohm speakers in parallel present a 2-ohm load, which a 4-ohm-minimum amplifier cannot drive safely.

Exam tip

Equal speakers in parallel: Z divided by the number of speakers. In series: Z times the number.

Related terms