Calculators
Cone area
Uses the guidebook’s size chart. Port area doesn’t count. Mixing sizes? Add a row for each.
Total cone area
226 sq in
Box volume
Outside measurements in inches. Net volume takes off the walls, each sub’s displacement and the port.
Gross inside volume
4.99 cu ft
Net volume
4.39 cu ft
Port tuning
Net box volume and the port’s size and length give the tuning. Or pick a tuning to get the port length. An estimate: real boxes vary a few Hz.
Tuning (port area 28 sq in)
25.9 Hz
Port length for that: 13.3 in
Speaker wiring and ohm load
Subs, voice coils and how they’re wired give the load your amp sees.
Final load
1 Ω
Amp current draw
Total amp power and efficiency give the current the system pulls at full tilt. Class D amps are usually 75 to 85% efficient.
Current needed
926 A
Batteries must cover
606 A
That’s more than one alternator makes: plan on a dual alternator setup and a strong battery bank. For short burps, batteries carry the difference; for long average runs (30 seconds and up), the closer the alternator is to the draw, the better your voltage holds.