21 Inch Subwoofers

Choosing a 21 inch subwoofer

Every 21″ sub on this page is hand built to order. The lines step up in power, so start with what your amplifier makes (RMS) and how hard you want to push it:

• Mini Team 21: 3,500W RMS. Dual 1 or dual 2 ohm.
• Team 21: 5,000W RMS, for street, SQL and SPL builds. Dual 1 or dual 2 ohm.
• Super Team 21: 8,000W RMS, competition grade. Dual 1 or dual 2 ohm.

A 21″ sub moves a lot of air, so plan for a big enclosure and a strong electrical system before you buy. Our Battery Advisor helps you size the battery bank.

What amplifier do I need?

Match your amplifier’s RMS output to the sub’s RMS rating at the final impedance you wire it to. Our guide to setting amp gain walks through it, and we carry Ruthless Audio amplifiers to power these subs. For 5,000W and up, size your electrical system too with the Battery Advisor.

What box does a 21 inch sub need?

That depends on the sub, your vehicle and whether you are building for SPL or sound quality. Run your numbers through our free subwoofer box calculator, and read sealed vs ported and our ported box tuning guide before you build.

How long does a custom sub take?

Each sub is built after you order it. Custom orders take a minimum of 15 business days to build, and every EM Audio subwoofer carries a 1-year manufacturer warranty. Most models can be ordered with a custom powder-coated frame and dustcap color, carbon fiber cone and dust cap upgrades, and custom dustcap logo text.

Already have one that’s blown?

You may not need a new sub. We sell recone kits and offer a recone service that rebuilds your sub in its own basket.