BoxwrightTwo rules
In series the impedances add: two 4 Ω coils make 8 Ω. In parallel they divide: two 4 Ω coils make 2 Ω, and in general 1/Z = 1/Z1 + 1/Z2 + … A dual voice coil sub is two coils on one cone. Wire them in series or parallel to each other first, then wire the subs.
Dual voice coil subs
“–” means that layout does not apply to one sub.
| Subs | Coils series, subs parallel | Coils parallel, subs parallel | Coils series, subs series | Coils parallel, subs series |
|---|---|---|---|---|
| 1 × DVC 1 Ω | 2 Ω | 0.5 Ω | – | – |
| 2 × DVC 1 Ω | 1 Ω | 0.25 Ω | 4 Ω | 1 Ω |
| 3 × DVC 1 Ω | 0.67 Ω | 0.17 Ω | 6 Ω | 1.5 Ω |
| 4 × DVC 1 Ω | 0.5 Ω | 0.13 Ω | 8 Ω | 2 Ω |
| 1 × DVC 2 Ω | 4 Ω | 1 Ω | – | – |
| 2 × DVC 2 Ω | 2 Ω | 0.5 Ω | 8 Ω | 2 Ω |
| 3 × DVC 2 Ω | 1.33 Ω | 0.33 Ω | 12 Ω | 3 Ω |
| 4 × DVC 2 Ω | 1 Ω | 0.25 Ω | 16 Ω | 4 Ω |
| 1 × DVC 4 Ω | 8 Ω | 2 Ω | – | – |
| 2 × DVC 4 Ω | 4 Ω | 1 Ω | 16 Ω | 4 Ω |
| 3 × DVC 4 Ω | 2.67 Ω | 0.67 Ω | 24 Ω | 6 Ω |
| 4 × DVC 4 Ω | 2 Ω | 0.5 Ω | 32 Ω | 8 Ω |
Series or parallel, the coils give the same motor strength (Bl²/Re), so the box design does not change. Leave one coil unconnected and the motor strength halves: Qes doubles and the sub plays looser in a box sized for both coils. Use both.
Single voice coil subs
| Subs | Parallel | Series |
|---|---|---|
| 1 × SVC 2 Ω | 2 Ω | – |
| 2 × SVC 2 Ω | 1 Ω | 4 Ω |
| 3 × SVC 2 Ω | 0.67 Ω | 6 Ω |
| 4 × SVC 2 Ω | 0.5 Ω | 8 Ω |
| 1 × SVC 4 Ω | 4 Ω | – |
| 2 × SVC 4 Ω | 2 Ω | 8 Ω |
| 3 × SVC 4 Ω | 1.33 Ω | 12 Ω |
| 4 × SVC 4 Ω | 1 Ω | 16 Ω |
| 1 × SVC 8 Ω | 8 Ω | – |
| 2 × SVC 8 Ω | 4 Ω | 16 Ω |
| 3 × SVC 8 Ω | 2.67 Ω | 24 Ω |
| 4 × SVC 8 Ω | 2 Ω | 32 Ω |
Match the amplifier
Every amp has a minimum stable load: “stable to 1 Ω”, “2 Ω stable”. Pick a layout at or above it. Most class D mono amps make their most power at their lowest stable load, which is why 1 Ω and 2 Ω layouts are popular. Going below it makes the amp run hot and shut down, or fail.
Identical subs share the power equally in any of these layouts. Mixing different subs on one channel does not share evenly, so keep a bank to one model.
What a meter reads
A multimeter shows the coil’s DC resistance Re, not the nominal impedance. A 4 Ω coil reads around 3.2 to 3.6 Ω (the JL Audio 12W3v3-4 prints Re = 3.56 Ω). A 2 Ω final load reads around 1.6 to 1.8 Ω. That is normal. A reading near 0 Ω is a short.
Sources
Results are design estimates. Check the driver’s datasheet and your amplifier’s minimum load before you build.
Checked against the sources: October 27, 2026