Subwoofer Wiring & Impedance Calculator

When connecting multiple subwoofers to a single amplifier channel, the wiring topology determines the final load impedance the amplifier sees. Getting this wrong is the most common cause of blown amplifiers in car audio systems.

Series wiring stacks subwoofers end-to-end, adding their impedances together: Z_total = Z1 + Z2 + ... + Zn. Two 4 Ohm subs in series present 8 Ohms to the amplifier. This is the safest choice for keeping the load high, ideal when your amplifier is rated for 4 Ohm minimum.

Parallel wiring connects all positive terminals together and all negative terminals together: 1/Z_total = 1/Z1 + 1/Z2 + .... For identical drivers this simplifies to Z / N. Two 4 Ohm subs in parallel yield 2 Ohms. Parallel wiring allows the amplifier to deliver more power, but it reduces the impedance and increases current draw and heat.

Series-Parallel combines both: grouping drivers in series pairs that are then paralleled. With four identical 4 Ohm SVC subs you end up back at 4 Ohms, maximizing driver count without halving the load. It is the most balanced approach when running four subs from a single channel.

Why impedance matching prevents damage: Amplifiers are rated for a minimum stable impedance, commonly 4 Ohm or 2 Ohm, sometimes 1 Ohm for bridged mono. Below this rating, output current exceeds what the transistors can handle safely. Thermal shutdown triggers, and repeated events degrade the output stage permanently. Even a brief excursion below the minimum can cause latent damage that shortens the amplifier lifespan. Always verify your wiring before powering on and use this calculator to confirm the resulting impedance matches your amplifier minimum stable load rating.