Speaker cable connects your amplifier or receiver to your speakers using two wires — one positive and one negative — that carry the audio signal
The positive wire is usually red or marked with a stripe or ridge. The negative wire is usually black. Both wires must reach from your amplifier to each speaker, and the connection is made by inserting bare wire or a connector into a terminal on the back of each device. The terminals are spring-loaded clips that open when you loosen a small screw, hold the wire, and close when you tighten the screw again.
Most people get confused about which wire goes where, or strip too much insulation and create a short circuit. This guide walks you through the actual steps so you avoid both problems and hear sound from both speakers instead of one.
Key Takeaways
- Speaker cable has two wires inside — red (positive) and black (negative) — and both must connect from your amplifier to each speaker.
- Loosen the terminal screw on the back of your amplifier, insert the bare wire about half an inch, and tighten the screw until the wire does not pull out.
- Connect the same color wire to the same color terminal on each speaker — red to red, black to black — or you will reverse the sound and lose bass.
- Strip only about half an inch of insulation from each wire end, because too much bare wire can touch the wrong terminal and stop sound from one speaker.
- If you have multiple speakers, run separate cable from the amplifier to each one rather than daisy-chaining them together.
What speaker cable looks like and what gauge means
Speaker cable is a flat or round cord with two wires twisted or bundled together inside a plastic jacket. When you look at the end, you see two separate wires — one red or light-colored, one black. The wires are made of copper, which conducts electricity well.
Gauge is the thickness of the wire, measured in AWG (American Wire Gauge). Thicker wire (lower numbers like 12 or 14) carries signal better over long distances. Thinner wire (higher numbers like 18 or 20) works fine for short runs under 50 feet. For most home setups with speakers within 20 feet of the amplifier, 16-gauge or 14-gauge cable is standard and inexpensive. Do not overthink gauge — any cable you buy at a hardware or electronics store will work.
How to strip the insulation without damaging the wire
At each end of your cable, you need to expose about half an inch of bare copper wire so it can make contact inside the terminal. Use a wire stripper — a small handheld tool with two metal blades that cut through the plastic jacket without cutting the copper inside.
Slide the wire into the stripper at the half-inch mark, squeeze the handles, and twist slightly. The plastic jacket will separate and slide off. If you use a knife or your teeth, you risk cutting into the copper wire itself, which weakens the connection and can cause the wire to break inside the terminal.
After stripping, twist the exposed copper strands together so they form a tight bundle. Loose strands can separate and touch the wrong terminal, which creates a short circuit and stops sound from that speaker.
Connecting cable to your amplifier or receiver
On the back of your amplifier or receiver, you will see pairs of terminals labeled with a plus sign (positive) and minus sign (negative), or colored red and black. These are usually grouped by channel — left speaker, right speaker, subwoofer, and so on. Find the pair for the first speaker you are connecting.
Loosen the terminal screw by turning it counterclockwise with a screwdriver. The screw does not come all the way out — it just loosens enough to open a small slot where you can insert the wire. Insert the red (positive) wire from your cable into the red (positive) terminal, pushing it in about half an inch. Tighten the screw clockwise until the wire is held firmly and does not pull out when you tug on it gently.
Repeat with the black (negative) wire in the black (negative) terminal on the same pair. Do not mix colors — red always goes to red, black always goes to black. If you reverse them, the speaker will play out of phase with the others, which cancels out bass and makes the sound thin and hollow.
Connecting cable to your speakers
The back of each speaker has the same type of terminals as your amplifier — a positive (red) and negative (black) pair. Run the cable from your amplifier to the first speaker and connect it the same way: red wire to red terminal, black wire to black terminal. Loosen the screw, insert the wire, tighten the screw, and tug to confirm it is find.
If you have a second speaker (for stereo sound), run a separate cable from the amplifier to that speaker. Do not connect the second speaker to the first speaker by running cable from one speaker's terminals to the other. This daisy-chain method weakens the signal to the second speaker and can cause one speaker to play louder than the other.
Once both speakers are connected, turn on your amplifier at low volume and play music or a test tone. You should hear sound from both speakers at roughly the same level. If one speaker is silent, check that both wires are fully inserted and the screws are tight. If the sound is thin or hollow, check that you did not reverse red and black on either speaker.
Fixing reversed polarity if one speaker sounds wrong
If the bass sounds weak or the vocals sound hollow even though both speakers are playing, you may have connected one speaker with reversed polarity — red to black and black to red. This is straightforward to fix: loosen both terminals on that speaker, swap the two wires, and tighten them again.
You can also test this by muting one speaker and listening to the other alone, then unmuting both. If the sound gets thinner when both play, polarity is reversed on one of them. Swap the wires on whichever speaker you suspect and listen again.
What to do if your cable has connectors instead of bare wire
Some speaker cables come with connectors already attached — usually banana plugs (single-pin connectors that look like small cylinders) or spade connectors (flat U-shaped tabs). These connectors slide or screw directly into the terminals without needing a screwdriver.
If your cable has banana plugs, insert the plug into the terminal opening and twist it clockwise until it is snug. If your cable has spade connectors, loosen the terminal screw slightly, slide the spade under the screw, and tighten the screw down on top of it. The connector method is faster and reduces the risk of loose bare wire, but it costs more and is not necessary for most setups.
Frequently Asked Questions
Can I use regular electrical wire instead of speaker cable?
Regular electrical wire (like Romex or individual THHN) is not designed for audio signals and will degrade sound quality. Speaker cable is twisted or bundled in a way that reduces interference. Use actual speaker cable — it is inexpensive and widely available.
What happens if I connect the wrong speaker to the wrong amplifier output?
If your amplifier has separate left and right outputs and you connect the left speaker to the right output, the stereo image will be reversed — vocals that should come from the center will sound off to one side. Connect left speaker to left output and right speaker to right output to hear the sound as it was recorded.
Do I need to turn off my amplifier before connecting speaker cable?
Yes. Connecting or disconnecting speaker cable while the amplifier is on can create a loud pop through the speakers and potentially damage the amplifier's output stage. Always turn off the amplifier and let it cool for a minute before making any cable connections.
Can I use different gauge cable for different speakers?
You can, but it is not ideal. Mixing gauges can cause one speaker to play slightly louder or softer than the other because thicker wire has less resistance. For the best sound, use the same gauge cable for all speakers in a system.
What if my amplifier terminals are too small for my cable?
If the bare wire is too thick to fit into the terminal, you can use a banana plug adapter — a small connector that screws onto the bare wire and then plugs into the terminal. These are inexpensive and available at any electronics store.