You're standing there with a pair of old bookshelf speakers and a pile of random cords. Maybe you found an old RCA composite cable—the red, white, and yellow kind—and you’re wondering if you can just snip the ends off and use it to get some sound. It looks like copper inside, right?
Technically, yes. It'll work.
But honestly, just because you can doesn't mean you should. Using rca cable as speaker wire is one of those "emergency only" hacks that usually results in disappointing sound or, in rare cases, a very hot amplifier. There is a massive physical difference between how a line-level signal moves through an RCA cable and how a high-power signal moves to a speaker.
Let's get into the weeds of why this isn't just an audiophile myth.
The Massive Difference in Current
Standard speaker wire is basically a highway for electricity. It’s thick, usually 12 to 16 gauge, designed to carry a lot of current from your receiver to the heavy magnets in your speakers. Think of it like a fire hose.
RCA cables are different. They are designed for "line-level" signals. This is a tiny, delicate voltage—about 2 volts—that carries information between a CD player and a preamp. It’s a garden hose. Actually, it’s more like a straw.
Inside that RCA jacket, the conductor is tiny. We are talking 24 gauge or even 28 gauge. If you try to push 50 watts of power through that tiny strand of copper, you’re going to hit something called resistance. Resistance turns electrical energy into heat. If your wire is too thin, the wire itself starts acting like a lightbulb filament. It gets warm. It chokes the signal.
Your speakers won't just sound quiet; they’ll sound thin. The bass will lose its "oomph" because the low-frequency pulses require the most current, and that tiny RCA wire simply can’t deliver it fast enough.
Shielding vs. Braiding
Here is something most people miss. RCA cables are shielded. They have a center conductor wrapped in an insulator, with a braided or foil shield around the outside. This is meant to block radio frequency interference (RFI) because line-level signals are so weak that a nearby cell phone could ruin the audio.
Speaker wire doesn't need shielding. The signal is so powerful that a little bit of RFI won't touch it.
When you use rca cable as speaker wire, that shielding actually works against you. The physical construction creates something called capacitance. In long runs, high capacitance can actually cause certain amplifiers to become unstable or oscillate. It’s basically like adding a filter to your music that you never asked for, potentially rolling off the high-end frequencies.
Does the Length Matter?
If you are just trying to connect a tiny 5-watt desktop speaker and the run is only three feet? You probably won't notice a thing. It’s fine.
But if you are running ten feet of RCA to a floor-standing speaker? You are asking for trouble. You’ll lose a significant percentage of your power to heat. You're basically paying for electricity that never reaches your ears.
Real-World Risks to Your Gear
I’ve seen people try to use the "yellow" video cable from an RCA set because it feels thicker. Don't do that. Video cables are usually 75-ohm coaxial cables. They are built for high-frequency data, not for pushing raw wattage.
The biggest risk isn't actually fire, though that’s the scary story people tell. The real risk is a "short." Because RCA wires are so thin and the shielding is so close to the core, it’s incredibly easy for a single stray strand of copper to touch the opposite terminal when you're stripping the wire.
One tiny hair-thin strand. That’s all it takes.
If that happens, you short the output of your amplifier. Most modern receivers like those from Denon or Sony have protection circuits that will click off. But an older vintage Marantz or Pioneer? You might just blow a fuse or, worse, fry an output transistor.
What About Subwoofers?
This is where the confusion usually starts. People see an RCA jack on the back of their subwoofer and think, "Hey, that's speaker wire!"
It’s not.
Most home theater subwoofers are active or powered. This means they have their own amplifier built-in. The RCA cable going to your sub is just sending a signal, not the power to move the "woofer" itself. In this specific case, you must use an RCA cable. If you tried to use regular speaker wire here, you wouldn't have the plugs to connect it.
The reverse is also true. If you have a "passive" subwoofer (one without a power cord), you absolutely cannot use an RCA cable. You need thick, heavy-duty speaker wire to move that massive driver.
Breaking Down the "Gauge" Problem
To put it in perspective, let's look at the numbers.
- 12-14 AWG: Standard for long runs or high-end setups. Very low resistance.
- 16 AWG: The "sweet spot" for most home setups.
- 24-28 AWG: The typical size of the internal wire in an RCA cable.
The jump from 16 to 24 gauge isn't just "a little bit thinner." It is a massive reduction in the amount of copper available to move electrons. According to the American Wire Gauge standard, 16 gauge wire has about 4 ohms of resistance per 1000 feet. 24 gauge has over 25 ohms.
That means the RCA wire is over six times more resistant to electricity.
Better Alternatives You Probably Have
If you're in a pinch and don't want to buy a spool of wire, look for an old lamp cord or an extension cord you don't need.
Seriously.
✨ Don't miss: Suspensions on a car: Why your ride feels like a pogo stick (and how to fix it)
A standard "zip cord" from a household lamp is usually 18 gauge. It’s much better at being speaker wire than a fancy-looking RCA cable will ever be. Just snip the plugs off, split the two strands, and you have perfectly functional, high-current speaker wire. It’s not "audiophile grade," but it’s copper, and it’s thick enough to handle the load.
The Verdict on RCA
If you absolutely have to use rca cable as speaker wire to test if a speaker works, go ahead. Keep the volume low. Keep the run short.
But for a permanent setup? It’s a bad move. You’re choking your system’s performance and putting unnecessary stress on your amp.
Your Next Steps
- Check your speaker's impedance. If your speakers are 4-ohm (common in car audio or high-end home gear), avoid RCA cables entirely. Low impedance draws more current, which makes the thin-wire problem even worse.
- Look at the jacket. If you must use a makeshift wire, check the "AWG" rating printed on the side. Anything higher than 20 (meaning the wire is thinner) is going to degrade your sound quality significantly.
- Buy a small spool of 16-gauge oxygen-free copper (OFC) wire. You can get 50 feet for the price of a couple of lattes. It is the single cheapest way to ensure your speakers actually sound the way the manufacturer intended.
- Strip carefully. If you're stuck using the RCA, use a dedicated wire stripper. Using a kitchen knife on those tiny wires usually results in cutting half the copper strands away, making an already thin wire even worse.
Bottom line: Copper is copper, but size matters. Don't send a toddler to do a powerlifter's job.