How to Connect a Subwoofer

Match the jacks before you connect anything

We’d look at the subwoofer’s rear panel first, because its inputs tell you which signals it can use. A powered sub has a power cord and built-in amplifier. A passive sub needs an external amplifier and may have speaker terminals or a specified connector, so check the model’s connection before choosing wire.

Your receiver has a Sub Out

You don’t need a Y-splitter for a single SUB OUT hookup; start with one RCA cable.

1. Turn off the receiver and unplug the sub. Connect SUB OUT or LFE OUT to the sub’s LFE or marked mono input with an RCA cable. If neither input says LFE, use L/Mono or Left. The cable should sit firmly at both ends.
2. Restore power and turn the sub on. Set its gain knob near the midpoint, about 12 o’clock. In the receiver’s speaker layout, select a connected subwoofer; a cable alone may leave that output silent.
3. Start the receiver’s speaker crossover around 80 Hz. Set the main speakers to Small so bass below that crossover reaches the sub. If the sub has its own low-pass knob, choose LFE or bypass, or turn it to maximum, because the receiver is handling the crossover.
4. Run the receiver’s subwoofer test tone. You should hear it from the sub. Then play music or a scene with clear bass and adjust the sub’s level until it blends with the main speakers.

Your stereo amp has no Sub Out

REC OUT or tape out is usually fixed level, so its bass would stay at the same level while you change the amp’s volume. A stereo PRE OUT often sends full-range sound, which means the sub’s own low-pass control must set where its bass stops.

1. Turn off the preamp, power amp and sub, and unplug the sub. Connect left PRE OUT to the sub’s left line input and right PRE OUT to its right input. If the PRE OUT pair already feeds a separate power amp, put one RCA Y-splitter on each PRE OUT so each channel feeds both the power amp and sub.
2. Restore power, set the sub’s low-pass control near the lower end of your main speakers’ usable bass range, and set its level near the midpoint. Play music with bass while changing the preamp volume. Both the main speakers and sub should rise and fall together.

If the sub stays at one loudness, the chosen output is fixed rather than volume-controlled. If the main speakers or sub are silent, turn the system off and trace both left and right PRE OUT connections, including the feeds through any Y-splitters.

You only have speaker outputs

A powered sub with marked left and right high-level or speaker-level inputs can take a feed from the amp’s speaker outputs. Keep the main speakers connected to the amp terminals when those terminals securely hold both wire runs; otherwise, use the sub’s marked speaker-level pass-through terminals. A pass-through does not necessarily remove bass from the main speakers. Look for an explicit high-pass specification before relying on it for filtering.

1. With the amp unplugged and sub unplugged, run speaker wire from the amp’s left positive and negative terminals to the sub’s left high-level positive and negative inputs. Repeat for the right channel. Use a wire stripper if needed and leave no loose strands.
2. Secure the main-speaker wires at the amp terminals when they accept both runs; otherwise, run them from the sub’s marked speaker-level pass-through outputs. Gently tug each wire to confirm it is held, then restore power.
3. Set the sub’s low-pass control for the main speakers’ bass range and play bass-rich music. The main speakers and sub should all play and follow the amp’s volume. If the sub is silent, power off and retrace the channel and polarity markings.

Your powered sub has RCA inputs only

When the amp has only speaker outputs, use a two-channel speaker-to-line converter that accepts its output voltage and grounding arrangement. The converter lowers the amplified signal to a level the sub’s RCA inputs can accept.

1. Unplug the amp and sub. Connect the amp’s left and right speaker outputs to the converter’s marked channel and polarity inputs with speaker wire.
2. Connect the converter’s left and right RCA outputs to the sub’s matching stereo line inputs. Keep all bare wire strands inside their terminals.
3. Restore power, set the sub’s low-pass and level controls, and play bass-rich music. The sub should follow the amp volume without distortion or a protection shutdown.

If it distorts or the amp shuts down, switch it off and inspect the converter’s voltage and grounding compatibility before retesting.

Your subwoofer has no built-in amplifier

A passive sub needs a dedicated subwoofer amplifier. Read the sub’s nominal impedance and continuous RMS power rating from its label or specifications. Choose an amplifier rated to handle that impedance, then compare its continuous RMS output at that same impedance with the sub’s continuous rating. Peak-watt figures are not the matching figure.

1. Switch off and unplug the receiver and subwoofer amplifier. Connect receiver SUB OUT or a variable PRE OUT feed to the dedicated amplifier’s RCA line input. If that source sends full-range sound, use the amplifier’s low-pass control to filter the signal.
2. For a passive sub with conventional positive and negative terminals, run speaker wire from the dedicated amplifier’s speaker output with matching polarity; for a specified connector system, use its matching amplifier and connector. Secure every strand so none touches another terminal or the chassis.
3. Restore power, enable the receiver’s subwoofer output if you used SUB OUT, and play its sub test tone or bass-rich material. The external amplifier should power on and the passive sub should produce bass.

If it stays silent, verify power at the external amplifier, its selected input, the signal cable and both speaker-wire ends. An RCA-to-bare-wire lead cannot replace the amplifier. For more on comparing amplifier impedance and power ratings, see speaker impedance and amplifier ratings.

You want bass from your TV or soundbar

A soundbar with an analog SUB OUT can feed a powered sub’s matching RCA input with one cable. A wireless soundbar sub pairs within its maker-listed soundbar system; confirm its paired indicator before choosing a replacement. If the link indicator keeps blinking, the wireless soundbar pairing guide covers that separate problem.

For a direct TV connection, find an actual analog AUDIO OUT or headphone output, not an input. A variable output follows TV volume; a fixed output does not. A headphone connection can mute the TV’s own speakers. If the TV sends audio to both outputs, connect its analog output to a powered sub with left and right RCA line inputs, set the sub’s low-pass control, and play TV content to confirm that both the main speakers and sub are audible.

HDMI ARC, eARC and optical carry digital audio, so a passive cable cannot turn them into an analog RCA sub feed. An active optical-to-analog converter takes the TV’s optical signal and supplies stereo analog RCA output to the sub when the TV’s audio format matches the converter’s input; the TV must still send sound to the main speakers. The TV speaker connection guide covers that main audio path.

The sub is connected but silent

Turn equipment off before reseating a cable or moving speaker wire. Trace the cable from the actual output to the matching input; an unrelated RCA jack may carry no sub signal.

If it stays silent, a known-good signal cable helps separate a bad cable from a remaining receiver-output, subwoofer or external-amplifier fault.

If you’ve traced the output to input, confirmed power and settings, and run the sub test tone without sound, the owner checks are over. Contact the sub or receiver maker for an equipment fault, or a qualified home-audio installer for an unresolved connection. Give them the output and input labels, cable or converter used, power-indicator state, receiver layout and test-tone result. For a passive setup that needs an amplifier, a dedicated home subwoofer amplifier has a priced example of $330 to $700 before wiring and setup.

You can use a receiver’s main speakers while sorting out the sub. Switch off and unplug the receiver and sub, and, if the main speakers are wired through the sub’s speaker-level pass-through outputs, reconnect them to the receiver’s matching front speaker terminals with correct polarity before disconnecting the sub. Secure unused bare speaker-wire ends so they cannot touch each other or the receiver chassis, set Subwoofer to No or None, then restore power and check that the main speakers play without a protection warning; if the warning returns, switch off and unplug the receiver before inspecting their wiring.

Questions about the remaining connections