Audio

Speaker wire gauge & line loss

Cable run, gauge and load impedance → resistance, power lost, and dB drop at the speaker.

Long low-impedance runs eat amplifier power in the copper. Enter the one-way distance, AWG, and speaker impedance to see round-trip resistance, damping-factor impact, and the level lost at the speaker — and the smallest gauge that keeps loss under your target. Includes a 70 V / 100 V constant-voltage mode.

System

inputs

Length unit

One-way runm

Amp to speaker. Round trip is doubled for you.

Wire gauge

Load impedance

Nominal. Real impedance dips below nominal at some frequencies, so loss is worse there.

Loss target

Level lost at the speaker · 16 AWG

0.82dB

9.0% of amplifier power heats the cable

round-trip cable resistance 0.791 Ω against a 8.0 Ω load

Smallest gauge for ≤ 0.5 dB

12 AWG

3.31 mm² · 0.33 dB on this run

Damping factor at the speaker

9.6

Z ÷ (R_cable + 0.04 Ω amp output). Above ~50 is inaudible; a 1000-spec amp on the datasheet becomes this at the far end.

verdict

▸ Audible on an A/B, and you are handing amp power to the copper. Go one gauge heavier if the run is easy to change.

all gauges · 30 m one-way · 8.0 Ω load

AWG	mm²	Round-trip Ω	Loss dB	Power lost	Damping
10	5.26	0.197	0.21	2.4%	33.8
12	3.31	0.313	0.33	3.8%	22.7
14	2.08	0.497	0.52	5.8%	14.9
16	1.31	0.791	0.82	9.0%	9.6
18	0.823	1.257	1.27	13.6%	6.2
20	0.518	1.998	1.94	20.0%	3.9
22	0.326	3.177	2.90	28.4%	2.5
24	0.205	5.053	4.25	38.7%	1.6

Solid copper at 20 °C. Stranded and warm cable run a few percent higher; copper-clad aluminium (CCA) roughly 1.6× — avoid it for speaker lines.

where the power goes

The cable is a resistor in series with the speaker. Its share of the amplifier's output is the coral slice; the rest reaches the driver.

Need this math wired into a real system? We do that for a living.

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