Why speaker wire gauge matters
Speaker cable is a resistor in series with your speaker. The thinner and longer the cable, the more of the amplifier's power is lost as heat before it reaches the drivers. A small amount of resistance is inaudible, but too much reduces volume, changes the tonal balance of speakers whose impedance varies with frequency, and lowers the amplifier's control over the woofer (the damping factor). CopperRun keeps the round-trip cable resistance below a set percentage of the speaker's impedance – 5 % is a widely used guideline that keeps losses around 0.4 dB.
Cable resistance = 2 × length × resistance per foot · Keep it ≤ 5 % of speaker impedance
AWG explained
American Wire Gauge numbers run backwards: the smaller the number, the thicker the wire. Each step of three gauges halves the resistance. 16 AWG is fine for short runs to 8 Ω speakers, 14 AWG is the all-round choice for most homes, and 12 or 10 AWG is used for long runs, 4 Ω speakers and subwoofers.
Maximum length by gauge (5 % rule)
| Gauge | mm² | 8 Ω speaker | 4 Ω speaker |
|---|
| 18 AWG | 0.82 | 31 ft (9 m) | 16 ft (5 m) |
| 16 AWG | 1.31 | 50 ft (15 m) | 25 ft (8 m) |
| 14 AWG | 2.08 | 79 ft (24 m) | 40 ft (12 m) |
| 12 AWG | 3.31 | 126 ft (38 m) | 63 ft (19 m) |
| 10 AWG | 5.26 | 200 ft (61 m) | 100 ft (30 m) |
Choosing the right cable type
- Conductor: pure copper (OFC) is the standard. Copper-clad aluminium (CCA) is cheaper but has much higher resistance – use one or two gauges thicker if you must use it.
- In-wall: fire-rated CL2 or CL3 jacket is required by electrical codes in most of North America; plenum-rated (CMP/CL3P) above suspended ceilings used for air return.
- Outdoor: UV-resistant, direct-burial cable for garden and pool speakers.
- Multi-conductor (4-conductor): 14/4 cable lets you run a stereo pair or a bi-wired speaker through one jacket.
- Terminations: banana plugs or spade lugs make reliable connections and prevent stray strands shorting the amplifier.
Do expensive cables sound better?
At audio frequencies the properties that matter are resistance, and to a much smaller extent inductance and capacitance. A correctly sized copper cable with sound connections performs as well as audiophile cables costing many times more in blind tests. Spend the money on speakers, room treatment or a better amplifier instead.
Long runs and commercial installs
For very long runs – whole-house audio, restaurants and offices – installers use 70 V or 100 V distributed speaker systems, which carry the signal at high voltage and low current, so thin cable can run hundreds of feet. Ordinary 8 Ω home speakers can't be connected to these lines without transformers.
Frequently asked questions
What gauge speaker wire should I use?
For most home setups with runs under about 50 ft to 8 Ω speakers, 16 AWG is enough; 14 AWG is the safe all-round choice; use 12 AWG for long runs or 4 Ω speakers.
Is 16 or 14 gauge speaker wire better?
14 AWG is thicker with about 37 % less resistance. It matters for long runs and low-impedance speakers; for short runs to 8 Ω speakers you won't hear a difference.
How long can speaker wire be?
With 14 AWG you can run about 80 ft (24 m) to an 8 Ω speaker before losses exceed the recommended 5 % of the speaker impedance.
Can I use regular speaker wire in walls?
Use cable with a CL2 or CL3 fire rating printed on the jacket for in-wall runs, as most building codes require.
Does speaker wire length need to be equal?
No. Small differences in length have no audible effect, as long as both runs use an adequate gauge.
About CopperRun
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