Analogue audio
PLAYER → RCA / JACK → LINE INPUTA low level music signal goes from a CD player, portable player or other source to an amplifier's line input.
A beginner's guide to audio and video connections
Know what goes where.
RCA, Toslink, HDMI, SCART, speaker wire. Cable labels can look like a foreign language when you are building your first system. This visual guide explains what each connection carries, what it plugs into and what to check before you buy.
First, follow the signal
Three jobs, three paths.
Before looking at plugs, decide what the cable must carry. A small audio signal, digital sound or picture, and amplified speaker power each need the right connection.
Digital audio or video
TV / PLAYER → HDMI, OPTICAL OR COAX → RECEIVERThe source sends digital data. The receiver or TV must have a matching input, and support the audio or video format being sent.
Speaker power
AMPLIFIER SPEAKER OUT → TWO CORE WIRE → PASSIVE SPEAKERThe amplifier's speaker outputs send power to passive speakers. This is a different connection from RCA or a headphone jack.
The familiar red and white plugs
RCA carries analogue sound.
Look for red and white or red and black sockets labelled AUDIO OUT, LINE OUT, AUX, CD, TAPE or LINE IN.
A simple stereo connection
One plug for left, one for right.
A standard stereo RCA lead has two separate cables. White, or sometimes black, is the left channel. Red is the right channel. Connect a source's AUDIO OUT to an amplifier's matching LINE IN or AUX IN, then select that input on the amplifier.
RCA carries analogue line-level sound between components. It does not carry speaker power. A turntable usually needs a PHONO input or an external phono preamplifier before its signal can go into a regular AUX input.
The receiver pictured has RCA line outputs labelled for front, rear, centre and subwoofer channels. These send a low-level signal to a separate power amplifier or powered subwoofer. They do not drive passive speakers. Passive speakers use the receiver's separate speaker terminals.
Two RCA audio leads
Usually red and white, two analogue channels for stereo sound.
One digital coax lead
One RCA-style plug carries digital S/PDIF audio when both devices have a COAXIAL DIGITAL socket.
About “coax RCA” versus a simple two-wire cable: RCA describes the plug. Coaxial describes a cable construction with a centre conductor and surrounding shield. Many ordinary red and white RCA interconnects are themselves shielded coaxial cables, one for each channel. A digital coax input is a different signal use, normally one 75-ohm RCA connection. A plain unshielded pair of wires is more exposed to hum and interference, so use a properly made, shielded interconnect for line-level audio.
Two ways to send digital sound
Toslink or digital coax?
Both can send digital audio from a television, CD player or other source to a compatible amplifier. Match the output and input labels at both ends.
Optical digital audio
Toslink, light carries sound.
A Toslink cable sends digital audio as light. It does not carry video and it does not make the amplifier's audio processing automatic. Connect DIGITAL OPTICAL OUT to an optical input, remove the small protective caps and select the matching input.
For a television, PCM stereo is often the simplest setting for a stereo amplifier. Some equipment also supports certain compressed surround formats. The source and receiver must agree. Check both manuals if you hear silence or noise.
Digital S/PDIF audio
Coax, one RCA connection.
A digital coaxial connection usually looks like one RCA socket labelled COAXIAL, COAX or DIGITAL IN. Use one 75-ohm coaxial cable, not the red and white pair used for analogue stereo.
The familiar RCA-shaped plug does not tell you whether the socket carries analogue or digital sound. Read the label at both ends. A compatible digital input can convert the incoming digital signal to sound using its own DAC.
Same plug shape, different signal. Optical and coaxial digital are alternatives for audio only. They do not carry the picture from a DVD or Blu-ray player. Use HDMI, SCART or another video connection for that.
For a television, DVD or Blu-ray player
Picture and sound, one lead or many.
Video connections often carry sound as well. Older analogue equipment and modern digital equipment use different standards, so a plug adapter alone may not convert the signal.
Modern digital audio and video
HDMI connects the picture too.
HDMI can carry digital picture and sound over one cable, for example from a Blu-ray player to an AV receiver and then to a television. It can also connect a player directly to the TV.
To return TV sound to a receiver, connect the sockets marked HDMI ARC or eARC at both ends. The equipment and settings must support the feature. Buy a cable certified for the resolution, refresh rate and features you actually need, not a costly cable with vague promises.
Older European analogue AV
SCART brings several signals together.
SCART, also called Euroconnector or Péritel, was common on European televisions, DVD players and VHS recorders. One wide plug can carry analogue stereo audio and video. Depending on the equipment and cable, video may be composite or higher-quality RGB.
SCART is not HDMI and does not carry a digital signal. If you need to connect SCART equipment to a modern HDMI-only television, use a suitable active converter and check which direction it converts.
Take a portable player to the stereo
Small jack, full system.
A MiniDisc player, Walkman, portable CD player or other device with an analogue headphone or line output can play through a home amplifier.
Use a 3.5 mm stereo jack to two RCA plugs.
Plug the small stereo jack into the player's HEADPHONE or LINE OUT socket. Connect the red and white RCA ends to a LINE IN, AUX IN, TAPE IN or REC IN on the stereo. Select that input and start with both volumes low.
Some portable players have a fixed-level line output. Others use a volume-controlled headphone output. If the sound is too quiet or distorted, adjust the portable player's volume gradually. Check the player manual for the right output.
This is an analogue connection, so no Wi-Fi, mobile data or special app is needed. The music comes from the disc or tape in the portable player.
The final connection in a passive speaker setup
Speaker wire carries amplified sound.
Each passive speaker needs two conductors from an amplifier's speaker terminals. Keep the positive and negative sides matched at both ends.
Two conductors, one speaker
Amplifier speaker out to speaker in.
Speaker cable is usually a pair of insulated copper conductors. One goes from the amplifier's red or positive terminal to the speaker's red or positive terminal. The other runs from black or negative to black or negative.
The photo shows the distinction on a real amplifier: line-level RCA inputs accept sources such as a CD player, while the speaker terminals send amplified power to passive speakers.
- Switch off the amplifier before connecting or moving wires.
- Keep stray copper strands from touching the other terminal.
- Do not connect a speaker output to AUX, RCA, PHONO or a headphone socket.
- Powered speakers usually receive line-level audio, and use their own mains power. Follow their manual.
Read the labels before you plug in
One amplifier, several kinds of input.
This rear panel brings together familiar RCA inputs such as AUX and PHONO, plus digital connections including coaxial, optical and USB. It also has speaker terminals for passive speakers.
Match the source output to the amplifier input. A turntable may connect to PHONO if the input suits its cartridge, while a CD player can use an analogue line input or a compatible digital input. The exact options vary by model.
| One-way cable run to each speaker | Practical metric starting point | Approximate US gauge (AWG) | What to check |
|---|---|---|---|
| Up to about 5 m | 1.5 mm² or 2.5 mm² copper | About 15 AWG or 13 AWG | For many ordinary home systems, this is a sensible short-room run. Choose the larger size if your speakers are low impedance or the wire is routed tightly. |
| About 5 to 10 m | 2.5 mm² copper | About 13 AWG | A thicker conductor helps keep resistance down as the cable gets longer. |
| Longer than 10 m | Consider 2.5 to 4 mm² | About 13 to 11 AWG | Speaker impedance, amplifier power and installation matter. Check the amplifier or speaker maker's guidance for the actual run. |
AWG means American Wire Gauge. The equivalents above are approximate nearest sizes, since metric cross-sections and AWG sizes do not match exactly. For reference, 16 AWG is about 1.31 mm², 14 AWG about 2.08 mm², 12 AWG about 3.31 mm² and 10 AWG about 5.26 mm². These are beginner-friendly starting points, not a universal engineering limit. Length means the one-way distance from amplifier to speaker. Cable resistance is in the full out-and-back circuit, and lower-impedance speakers make that resistance more significant. Belden / Alpha Wire's AWG conversion chart.
A real speaker terminal example
Bi-wiring, binding posts and banana plugs.
These KEF Q700 photos show a speaker with two pairs of binding posts and speaker cable terminated with banana plugs. The upper and lower pairs connect to different sections of the speaker's crossover when the speaker is configured for bi-wiring. Banana plugs make a neat, secure connection to compatible binding posts, but ordinary bare wire can work just as well.
Keep it simple if you are starting out. Use the speaker's normal single-wire setup unless you have a compatible amplifier and a clear reason to bi-wire. With the amplifier switched off, follow the speaker manual exactly. Leave the terminal links fitted for single wiring, and remove them only when the manual calls for it. Never connect two amplifier outputs to one speaker terminal pair. Bi-wiring is different from bi-amping, and does not guarantee an audible improvement.
Bare wire
Strip only enough insulation to fit the terminal. Twist the strands together, insert them fully, then tighten the post or clamp. Check no loose strands can touch the other pole.
Banana plug
A banana plug makes plugging into a compatible binding post quick and tidy. Confirm the amplifier accepts banana plugs, and remove any terminal plugs or safety caps only as the manual allows.
Spade or Y plug
The fork sits around a compatible binding post and is clamped by its collar. Match the fork width to the terminal. Do not force a plug that does not fit securely.
Polarity matters. Connect red to red and black to black on both speakers. If one speaker is reversed, the system may sound weak in the bass or unfocused. Follow the markings on the cable and the equipment.
Spend on the right things
OFC, thin wire and common sense.
Good cable is useful. Cable marketing can make simple decisions sound mysterious, but length, conductor and safe connections do most of the practical work.
What is OFC?
OFC means oxygen-free copper. It describes a copper purity grade used in some cables. It can be well made, but the letters do not automatically make a cable sound better than another correctly sized copper cable in a normal home system.
Choose a genuine copper conductor with enough cross-section for the distance, a durable jacket and terminals that make a secure contact. Avoid paying a large premium for claims that cannot be tied to a real installation need.
Why very thin, very cheap wire can disappoint
Very thin conductors have more electrical resistance. Over a long run, that wastes some amplifier output as heat and can slightly change what reaches the speaker. Copper-clad aluminium cable also has more resistance than copper of the same size, so when using it, choose a larger conductor to compensate.
A sensible, well-made copper cable is enough for most systems. A super-thick cable is awkward to route and may not fit the terminals. There is no prize for choosing the biggest one.
Before you buy or plug anything in
Read the labels, then connect.
Most connection problems come from using the wrong input, expecting one cable to do several jobs, or confusing a line signal with speaker power.
Find the output
Look at the source device. Is the socket labelled LINE OUT, AUDIO OUT, OPTICAL, COAXIAL, HDMI or HEADPHONE?
Find the matching input
Check the receiving device has the same type of input. A plug that fits does not prove the signal type is right.
Use the cable for that job
RCA line cable is not speaker cable. Toslink is audio only. HDMI carries digital video and audio. SCART is older analogue AV.
Start with the volume down
Turn equipment off for speaker wiring, check polarity and input selection, then power up and raise the volume gradually.
Quick answers
Cable questions, made simple.
If a sound or picture does not appear, start by checking the device labels and settings at both ends.
Can I use any RCA cable for a digital coax connection?
A short RCA lead may work in some setups, because the connector fits. A cable made for 75-ohm digital coax is the right choice for a coaxial S/PDIF connection. Check that both sockets are labelled for digital coax.
Does an RCA cable connect an amplifier to passive speakers?
No. RCA carries a low-level audio signal between source and amplifier. Passive speakers connect to the amplifier's speaker terminals using two-conductor speaker wire. Powered speakers may accept RCA or another line-level input.
Can I connect a MiniDisc player to my home stereo?
Yes, if the player has a headphone or line output and the stereo has an AUX, LINE IN, TAPE IN or equivalent input. Use a compatible cable, often 3.5 mm stereo jack to two RCA plugs, then select that input.
Can I use a portable MiniDisc player in my car?
If the car stereo has a working AUX input, connect the player's headphone or line output to it with the matching audio cable. A 3.5 mm AUX socket usually uses a 3.5 mm stereo cable at both ends. Check the car stereo manual, start with the volume down and keep the player secured while driving.
Do I need an expensive speaker cable?
No. Choose the right conductor size for your speaker and cable run, use safe insulation and make secure connections. More expensive or thicker cable is not automatically better for every setup.
Manufacturer and engineering references
Check the specific model.
Ports and supported formats vary. These primary references show why the labels and manuals matter.
HDMI Licensing Administrator, cable types and certification ↗
Denon PMA-1600NE, optical and coaxial digital inputs ↗
Toshiba TV manual, optical digital audio output ↗
Analog Devices, what SCART carries ↗
Yamaha, speaker cable lengths for specific amplifier loads ↗
Yamaha, cable resistance and amplifier damping ↗
Rane, grounding and shielding for audio connections ↗
Sony, connect a portable player to a stereo system ↗
Sony, connect a portable player to a car AUX input ↗
Belden, speaker cable conductor materials and sizes ↗
Equipment makers can use the same socket shape for different functions. Always confirm the input and output labels in the manual for the exact model.