Subwoofer Wiring Impedance Calculator

Frequently asked questions

How does the wiring impedance calculation work?

Series: R total = R1 + R2 + ... Parallel: 1 / R total = 1/R1 + 1/R2 + .... A dual voice coil driver is named for the impedance of ONE coil. A D2 driver wires to 1 ohm or 4 ohms on its own, never 2. Check what your amplifier is stable to before choosing a configuration, because a load below its rating is how amplifiers die.

Are these figures published or are they rules of thumb?

Both, and the page labels which is which. The Helmholtz port relation, the Thiele/Small alignment equations, cone area geometry, Ohm’s law, conductor resistance and ampacity, and manufacturer specifications are published and are labeled as such. Amplifier efficiency, cabin gain, the farad per thousand watts rule, port area per cubic foot and coverage percentages are conventions with no measurement behind them, and they are labeled as conventions.

Why does this calculator sometimes refuse to give an answer?

Because there genuinely is not one. A port can be too large in area for the box and tuning asked of it, a vented alignment stops describing a useful box outside a Qts range, and a sealed box cannot produce a total Q below the driver’s own. In each case the calculator returns nothing and explains why, rather than extrapolating past the end of a published relation.

Do I still need an installer if I use this?

Many owners do their own 12V work, and these are the figures that work is sized from. What matters is that a car battery delivers hundreds of amps into a short without hesitating, so the main fuse goes within 18 inches of the battery positive terminal and the battery comes off before power wire goes in. If any of that is beyond what you want to take on, a professional installer is money well spent.