If you've ever bought a new pair of bookshelf speakers and stood there wondering what wire to use, you're not alone. Speaker wire seems simple — two conductors carrying an audio signal — but the choices around gauge, length, terminations, and material make a real difference in how your system sounds and how easy it is to install.
Here's a complete guide to speaker wire and the connectors used to terminate it.
What is speaker wire?
Speaker wire is a two-conductor cable that carries amplified audio from your amplifier or receiver to your speakers. Unlike line-level audio (RCA, 3.5mm, XLR), speaker wire carries the high-current signal that actually drives the speaker drivers.
The two conductors are typically labeled:
-
Positive (+) — Usually marked with a red insulator, a stripe, or a printed line on the jacket
-
Negative (−) — Usually marked with a black insulator or no marking
Getting polarity right matters. If you wire one speaker in reverse (positive to negative), you'll hear thin, hollow sound with weak bass — the speakers will be "out of phase." Always match positive to positive and negative to negative across all speakers in your system.
Speaker wire gauge
Gauge (AWG) tells you how thick the conductors are. Lower gauge numbers mean thicker wire.
18 AWG — The thinnest commonly used speaker wire. Fine for short runs (under 25 feet) to bookshelf speakers and surround speakers. Adequate for low-power applications.
16 AWG — The most common consumer speaker wire. Suitable for most home theater installations up to 50 feet. Good balance of cost and performance.
14 AWG — Thicker wire for longer runs (50-100 feet), higher-power systems, or in-wall installations. Required by many building codes for in-wall speaker wire.
12 AWG — Heavy-duty wire for very long runs (100+ feet), commercial installations, professional PA systems, or whole-house audio.
10 AWG and below — Specialty wire for distributed audio systems, 70V commercial PA systems, or very high-power applications.
Why does gauge matter?
Speaker wire has resistance, and that resistance creates voltage drop and power loss between your amplifier and speaker. A thinner wire has more resistance.
Rule of thumb: keep the wire's total resistance under 5% of your speaker's impedance. For an 8-ohm speaker, that's 0.4 ohms maximum round-trip. 16 AWG copper has about 4 ohms per 1000 feet, so a 50-foot run (100 feet total round trip) adds about 0.4 ohms — right at the limit.
For most home installations, 16 AWG is the safe default. Upgrade to 14 AWG for runs over 50 feet or 4-ohm speakers.
Pure copper (OFC) vs Copper-Clad Aluminum (CCA)
This is the single most important speaker wire decision you'll make.
Pure Copper (OFC — Oxygen-Free Copper) — All-copper conductors. Higher cost but lower resistance, better long-term durability, and proper electrical performance. The standard for any quality installation.
Copper-Clad Aluminum (CCA) — Aluminum core with a thin copper coating. Cheaper but has roughly 60% the conductivity of pure copper. CCA wire often advertises a gauge size that, electrically, performs more like wire two sizes thinner. A "12 AWG CCA" cable might perform like 14 AWG copper.
Always buy pure copper speaker wire. The savings from CCA are negligible, but the performance difference is real. CCA wire also corrodes faster at terminations, leading to oxidation buildup that degrades sound quality over time.
How to tell: look at a freshly cut end. Pure copper is shiny orange-pink throughout. CCA has a silver-colored core (aluminum) visible under the copper coating.
Termination options
You have three options for connecting speaker wire to your equipment:
Bare wire
Strip about half an inch of insulation, twist the strands tightly, and insert into your equipment's binding posts or spring clips. Simple and works well if done correctly.
Downsides: bare copper oxidizes over time, increasing resistance. Loose strands can short out and damage your amplifier. Wire fatigue at the connection point can break strands.
Banana plugs
The most common termination for serious audio installations. A banana plug screws or crimps onto your stripped speaker wire and then plugs into the matching socket on the back of your amplifier or speaker.
Pros:
-
Quick to connect/disconnect (helpful when rearranging equipment)
-
Solid mechanical connection — no loose strands
-
Easy to verify polarity (red plugs to red sockets)
-
Protects bare copper from oxidation
Cons:
-
Costs more (typically $1-3 per plug)
-
Requires equipment with banana jacks (most modern receivers have them, but not all)
Spade lugs
Y-shaped or U-shaped metal terminals that you screw down under a binding post. Less common than bananas but provide an excellent connection.
Used primarily in pro audio and high-end home installations. The advantage over bananas is a larger contact surface, but for most home audio the difference is inaudible.
Banana plug types
If you go with banana plugs, you'll see a few variations:
Standard 4mm banana plugs — The most common type. Single spring-loaded or solid-pin design. Compatible with virtually all binding posts.
Dual banana plugs (often called "dual bananas") — Two banana plugs in a single housing, with the standard 3/4-inch spacing of US binding posts. Useful for plugging both positive and negative into a speaker terminal cluster at the same time.
BFA-style (single sleeve) bananas — Slightly different shape, push-on design. Less common.
Locking bananas — Twist to expand the plug inside the binding post, creating a locked connection. Used in pro audio where vibration could loosen standard bananas.
In-wall vs exposed speaker wire
For permanent installations where wire runs inside walls, building codes typically require CL2 or CL3 rated cable. Look for these designations:
CL2 rated — Class 2 cable, approved for in-wall use in most residential installations.
CL3 rated — Higher fire safety rating than CL2, sometimes required by local codes.
CL2P / CL3P (plenum-rated) — For runs through air handling spaces (above drop ceilings, etc.).
FT4 / FT6 — Canadian equivalent ratings.
Don't run cheap zip-cord speaker wire inside walls — it's not rated for the application and creates a fire hazard.
Quality factors
Beyond gauge and material, watch for:
-
OFC (oxygen-free copper) — Less corrosion than standard copper. Worth the modest premium.
-
Conductor count — More individual strands (typically 41 strands or more for 16 AWG) means more flexibility and better fatigue resistance.
-
PVC vs polyethylene jacket — PVC is fine for most uses. Polyethylene resists chemicals and UV better for outdoor use.
-
Clear vs solid jacket — Clear jackets let you see the copper (verify it's pure copper, not CCA). Solid jackets look cleaner.
At Kentek, we carry pure copper speaker wire in 18, 16, 14, and 12 AWG in lengths from 25 to 250 feet, plus quality banana plugs for terminations.