How to Wire a 4×12 Guitar Cabinet
The 4×12 cabinet is the backbone of rock guitar tone. Whether you're building a cab from scratch, replacing blown speakers, or rewiring an old cab with new drivers, you need to get the internal wiring right. Get it wrong and you risk damaging your amp. Get it right and your rig runs at its best.
This guide walks you through the standard wiring method used by Marshall, Orange, Mesa, and virtually every other 4×12 manufacturer: series-parallel wiring.
What You Need
Four matched speakers — same impedance rating (typically 8Ω or 16Ω). Mixing impedances distributes power unevenly. Stick with matched speakers for a standard 4×12.
Speaker wire — 16 AWG or heavier. Don't use instrument cable — it's too thin and can overheat under load.
A ¼" mono jack socket — this is the input on the back of the cab where your speaker cable plugs in.
A soldering iron and solder — or push-on spade connectors if your speakers have spade terminals.
Understanding the Wiring
A 4×12 cab uses series-parallel wiring. Here's the concept:
Two pairs in series. Both pairs connected in parallel.
Speakers 1 and 2 are wired in series — the negative terminal of Speaker 1 connects to the positive terminal of Speaker 2. This doubles their combined impedance.
Speakers 3 and 4 are wired the same way — another series pair.
Then the two pairs are wired in parallel — both pairs connect to the jack socket. This halves the combined impedance back down.
The result: four 16Ω speakers give you a 16Ω cab. Four 8Ω speakers give you an 8Ω cab.
The Maths
| Speakers | Each | Series Pair | Pairs in Parallel | Cab Total |
|---|---|---|---|---|
| 4 × 16Ω | 16Ω | 16 + 16 = 32Ω | 32 ∥ 32 | 16Ω |
| 4 × 8Ω | 8Ω | 8 + 8 = 16Ω | 16 ∥ 16 | 8Ω |
| 4 × 4Ω | 4Ω | 4 + 4 = 8Ω | 8 ∥ 8 | 4Ω |
With series-parallel wiring and four identical speakers, the cab impedance equals the speaker impedance. Four 16Ω speakers = 16Ω cab.
Step-by-Step Wiring
Wire Pair 1 in Series
Connect the negative (−) terminal of Speaker 1 to the positive (+) terminal of Speaker 2 with a length of speaker wire. This is the series link — it chains the two speakers end-to-end.
You now have two free terminals: Speaker 1's positive and Speaker 2's negative.
Wire Pair 2 in Series
Same thing. Connect the negative (−) terminal of Speaker 3 to the positive (+) terminal of Speaker 4.
Free terminals: Speaker 3's positive and Speaker 4's negative.
Connect Both Pairs to the Jack Socket
Jack tip (+): Connect Speaker 1's positive and Speaker 3's positive. Both wires go to the tip terminal on the jack.
Jack sleeve (−): Connect Speaker 2's negative and Speaker 4's negative. Both wires go to the sleeve terminal.
This is the parallel connection — both series pairs share the same signal from the amp.
Check Before You Plug In
Double-check every connection. Make sure no bare wire touches the cab chassis or another terminal. Verify:
✓ Each series pair: negative of one speaker → positive of the next
✓ Both free positive terminals → jack tip
✓ Both free negative terminals → jack sleeve
Wiring Diagram
The jack socket on the left is the input on the back of your cab. Amber lines are positive (+), dashed grey lines are negative (−), yellow lines are the series links between speakers.
Matching Your Cab to Your Amp
Once your cab is wired, check the back of your amp head for the impedance selector or output jacks — most tube amps have 4Ω, 8Ω, and 16Ω options.
| Cab Speakers | Cab Impedance | Amp Output |
|---|---|---|
| 4 × 16Ω | 16Ω | Use the 16Ω output |
| 4 × 8Ω | 8Ω | Use the 8Ω output |
| 4 × 4Ω | 4Ω | Use the 4Ω output |
Why Not All Four in Parallel?
You could wire all four speakers in parallel, but the impedance drops dramatically. Four 16Ω speakers in parallel = 4Ω. Four 8Ω speakers in parallel = 2Ω. Most tube amps can't safely drive a 2Ω load — you'd risk destroying the output transformer.
Series-parallel keeps the impedance in a range that works with common amp outputs while distributing power evenly across all four speakers.
Mixing Speaker Impedances
If you're using speakers with different impedance ratings, the maths gets more complex and power distribution becomes uneven. For a standard 4×12 build, stick with four matched speakers. If you need to calculate a mixed setup, the calculator handles it.
Calculate the exact impedance for any speaker configuration — including mixed impedances, power per speaker, and amp matching advice.
Use the Calculator →Troubleshooting
Cab sounds thin or hollow
One speaker is probably wired out of phase — its polarity is reversed. Check that within each series pair, the negative of one speaker connects to the positive of the next, not the other way around.
No sound from one or more speakers
A broken solder joint or loose connector in the series chain silences both speakers in that pair. In a series circuit, if one connection fails, the whole pair goes silent. Check continuity through each pair.
Amp shuts down or crackles
Possible short circuit — bare wire touching the cab chassis or another terminal. Disconnect immediately and inspect all connections. Also check the jack socket isn't shorting tip to sleeve when the cable is inserted.
Volume lower than expected
Check you're using the correct amp output impedance. A 16Ω cab plugged into a 4Ω output gets significantly less power. Match the impedance as closely as possible.