Which Input Does the Speaker Connect To?

Which input does the speaker connect to? Short answer

A passive speaker has no built-in amplifier of its own. It draws the energy to move its drivers from an external amplifier. For this reason, the amplifier has not an "input" for the speaker but a speaker output. On the rear panel of the device, usually under a "SPEAKERS" heading, there are screw terminals or spring clips labeled with channel names (FRONT L, FRONT R, CENTER, etc.). Behind the speaker is a similar pair of terminals. These are the speaker's input.

In short, the answer to "which input does the speaker connect to" is this: The speaker cable is connected between the amplifier's speaker output and the speaker's own terminal. If you are curious about what an amplifier does and its place in the signal chain, you can check our article on what an amplifier does.

How do you identify the speaker output on an amplifier?

On a stereo integrated amplifier, there are typically four terminals: one positive and one negative for the left channel, one positive and one negative for the right channel. On AV receivers, this number increases according to the number of channels. The easiest way to distinguish speaker outputs from other sockets is to look at their structure. Speaker terminals are screw terminals or spring clips that accept bare wire, banana plugs, or spade lugs. They do not resemble signal sockets like RCA, XLR, or HDMI.

Speaker terminal types

• Binding post: These are threaded caps that are tightened by turning. They accept bare wire, banana plugs, and spade lugs. They are the most common type in hi-fi and home cinema equipment.
• Spring clip: These are terminals that open when a button is pressed and bare wire is inserted. They are found on entry-level equipment and some architectural speakers. They may not accept thick cable.
• Bi-wire terminal: Some speakers have two pairs of terminals with a jumper between them. We address this topic in more detail below.

Which color does the speaker connect to?

The rule is simple: red terminal is positive (+), black terminal is negative (−). The conductor coming from red on the amplifier connects to red on the speaker, and the conductor from black connects to black on the speaker. The speaker cable itself may not have red or black color. On most cables, one of the conductors is marked with a stripe, text, an embossed surface, or a different colored conductor (such as copper and silver colored). What matters is not which conductor you choose as positive, but that you apply this choice consistently on both ends and on every speaker.

TerminalPolarityConnection point

Red (or colored)

Positive (+)

Speaker red (+) terminal

Black

Negative (−)

Speaker black (−) terminal

Color-coded AV receivers

Some AV receivers have the positive terminal of each channel marked with a different color. In this system, black is still negative. The colored terminal is positive, and its color only indicates which channel it belongs to. For example, on this type of device, a red terminal may mean "the positive of the right front channel." The color scheme varies by manufacturer and model. For this reason, rely on the channel label on the device and the user manual.

Let us also clarify a common confusion: The red plug on RCA cables indicates the right channel, not polarity. The red on a speaker terminal is positive polarity. These are two different things.

How are speaker cables connected? Step by step

• Turn off the device. Make the connection with the amplifier or AV receiver off, preferably with the plug removed from the outlet. If done while powered on, touching wires together can trip the amplifier's protection or damage the output stage.
• Prepare the cable. Separate the conductors a few centimeters apart and strip approximately 1–1.5 cm of insulation from the ends. Twist the wire strands together into a single bundle.
• Identify the polarity. Choose the marked conductor as positive and maintain this rule across all speakers.
• Connect the amplifier side. Insert the marked conductor into the amplifier's red (+) terminal and the other into the black (−) terminal and tighten.
• Connect the speaker side. Connect the same conductors to the speaker's same-colored terminals.
• Check for loose strands. Make sure that a single strand of wire sticking out from a terminal does not touch an adjacent terminal or the metal chassis.
• Test at low level. Turn on the device, start with the volume low, and confirm that each channel comes from the correct speaker.

Cable connector: bare wire or banana plug?

There is no significant electrical difference between a tightly secured bare wire and a quality banana plug. The main advantage of banana plugs and spade lugs is convenience. The connection is neater, the risk of loose strands decreases, and the system is easier to disconnect and reconnect. What determines cable choice is less the connector type than the cable cross-section. We explained in detail the relationship to cable length and speaker impedance in our article on speaker cable gauge. You can find ready-made cable and connector options in our cable category.

What happens if the polarity is reversed?

Reversing the polarity of a single speaker does not damage the equipment. However, that speaker's drivers move in the opposite direction compared to the other. That is, the two speakers operate out of phase with each other. At low frequencies where the wavelength is long, the sound from the two speakers partially cancels each other. As a result, the bass is noticeably weakened. The stereo image also fails to focus: the vocal does not stay at a clear point between the two speakers but sounds "floating" and scattered.

A simple check method is as follows: Put the amplifier in mono mode or play a mono-recorded track. With correct connection, the sound comes from exactly between the two speakers, as if from a single source. If the sound is scattered and the bass is weak, check the polarity of one of the speakers. In home cinema, some automatic room calibration systems can warn of suspected reversed polarity as an alert. You can examine an example of how measurement-based calibration changes practice in our article on Audyssey calibration.

In home cinema, which speaker connects to which channel?

Each pair of terminals on the back of the AV receiver is dedicated to one channel. The front left and front right speakers connect to the FRONT L/R terminals, the center channel below or above the screen connects to the CENTER terminal, and the side and rear speakers connect to the SURROUND and SURROUND BACK terminals. Ceiling or height speakers go to terminals labeled HEIGHT or similar. On many AV receivers, which channel some terminals will serve is selected from the menu. This setting should be checked together with the device's rear panel label and setup menu.

Planning the speakers' positions in the room beforehand also makes cabling easier. You can use our home cinema speaker placement calculator for this.

Which inputs should not have speakers connected to them?

Not every socket on the rear panel is for speakers. The following carry line-level signals, which are weak. They cannot drive a passive speaker:

• RCA and XLR inputs/outputs: These are for receiving signals from source devices or sending signals to another amplifier.
• PRE OUT: This is for sending signal to an external power amplifier. The speaker is not connected here but to that power amplifier's speaker output.
• SUB OUT / LFE: This connects to the line input of an active subwoofer. For details, see our article on how to connect a subwoofer.
• Headphone output: This is designed for headphones, not suitable for speakers.

The reverse also applies: Active speakers with built-in amplifiers are not connected to the amplifier's speaker output. They are fed from the line output of the source device or a preamp via RCA, XLR, or digital connection. Sending an amplified signal to the line input of an active speaker can damage that input.

What should be done with a bi-wire terminal speaker?

If your speaker has two pairs of terminals, they typically allow separate feeding of the bass and treble sections. If you are connecting with a single cable pair, leave the metal jumpers (jumpers) between the terminals in place and connect the cable to one of the pairs. If the jumpers are removed, some drivers will receive no signal. If you are making a bi-wire or bi-amp connection, you will need to remove the jumpers. In this case, also follow the speaker manufacturer's instructions. Our article on speaker ohm value guides you in ensuring that the total load on the amplifier side is within the impedance range the device supports.

Conclusion

A passive speaker connects to the speaker output of an amplifier or AV receiver. Red goes to positive, black to negative, and the same conductor connects to the same polarity on every speaker. Make connections with the device off, do not leave loose strands, and finish with a quick phase check using a mono track. Keep line-level sockets and active speakers outside these rules. These few steps lay the foundation for starting your system with correct setup, the basis of measurable performance.