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A surprising number of “broken” systems are really a wrong input, a loose cable or a setting buried in a menu. This guide follows the same logic a technician would: start with the simplest causes and work along the audio chain.
Turn the volume down before changing cables, and switch off amplifiers before touching speaker wires. Never open mains-powered equipment unless you are qualified.
No sound at all
Check the obvious
Is everything powered on? Is mute active? Is the volume up on both the source (phone, TV, computer) and the amplifier?
Check the input
Make sure the amplifier, receiver or soundbar is set to the input your source is connected to.
Check the output
On computers and phones, confirm audio is going to the right device. On TVs, check the audio output setting (TV speakers vs external / optical / HDMI ARC).
Check speaker switches
Many amplifiers have Speaker A/B buttons. If headphones are plugged in, speakers are usually muted.
Swap one thing at a time
Try another source, another cable or another input to find which link in the chain has failed.
Hum or buzz
A steady low hum (50 or 60 Hz, depending on your country’s mains frequency) is one of the most common problems.
| Symptom | Likely cause | Fix |
|---|---|---|
| Hum from a turntable only | Missing ground wire | Connect the turntable’s ground wire to the amp’s GND terminal. |
| Hum when a TV, cable box or computer is connected | Ground loop between devices | Plug all devices into the same power strip; use an optical connection or a ground-loop isolator for the problem cable. |
| Buzz that changes when you move a cable | Loose or damaged cable | Reseat or replace the cable. |
| Hum in powered speakers near a phone or router | Electromagnetic interference | Move phones, routers and power adapters away from cables and speakers. |
| Hum that gets louder with volume | Usually a source or cable problem | Disconnect sources one by one to find the culprit. |
Never remove the earth/ground pin from a mains plug to cure hum — it is dangerous.
One speaker isn’t working
Check balance
Make sure the balance control on the amp, and any balance setting on your computer or phone, is centred.
Swap the speaker cables
Swap left and right cables at the amplifier. If the problem moves to the other speaker, the issue is the amp or source; if it stays, it’s the cable or speaker.
Check connections
Look for loose binding posts or stray wire strands. If the speaker has two pairs of terminals, make sure the jumper links are in place.
Check the source
Try a different source or cable. A faulty RCA cable often kills one channel.
Distortion or crackling
- Only at high volume: the amplifier may be clipping or the speakers are being overdriven. Turn down, and turn off bass boost or loudness.
- Crackle when turning knobs: dirty volume or selector controls — often fixable with contact cleaner by a technician.
- Distorted vinyl: worn or dirty stylus, wrong tracking force, or a line-level turntable plugged into a phono input.
- Distortion in one driver: a damaged tweeter or woofer; test at low volume and inspect the speaker.
Turntable is very quiet or thin
This almost always means the phono stage is missing. A turntable without a built-in preamp needs a PHONO input or an external phono stage. If your turntable has a PHONO/LINE switch, set it to LINE when using a normal AUX input. See our turntable guide.
Bluetooth problems
- Won’t connect: remove (“forget”) the device on your phone, restart both devices, and put the speaker or headphones into pairing mode again.
- Dropouts: keep the phone within a few metres and in line of sight; walls, bodies and Wi-Fi routers can interfere.
- Connects to the wrong device: turn off Bluetooth on other phones or laptops that were paired before, or disable multipoint.
- Poor quality: check which codec is in use and whether a “call” profile has taken over after using the microphone.
Lip-sync: sound and picture don’t match
Processing in TVs, soundbars and wireless speakers adds delay. Look for an AV sync, lip sync or audio delay setting on the soundbar or receiver and adjust it. Enabling the TV’s game mode, using a wired connection instead of Bluetooth, or setting the TV’s audio output to pass-through can also help.
Weak, thin or boomy bass
- Thin bass: check speaker polarity (+ to +, – to –) on both speakers. One reversed speaker cancels bass.
- No subwoofer output: make sure the receiver has a subwoofer enabled in its speaker setup, the sub’s power is on and its level isn’t at minimum.
- Boomy bass: move speakers out of corners and away from walls, use foam port plugs if supplied, or reduce the sub level. See room acoustics.
When to get professional help
If you smell burning, see smoke, hear loud pops at switch-on, or a fuse keeps blowing, switch the equipment off and unplug it. These are signs of a fault inside that needs a qualified technician.
Frequently asked questions
Why does my system hum only when the TV is connected?
This is usually a ground loop through the TV aerial or cable connection. Using an optical connection instead of an analogue cable, or a ground-loop isolator, typically fixes it.
Why is there a pop when I turn my amplifier on?
A small thump is normal on some equipment. Turn on sources first and amplifiers last; turn amplifiers off first. A very loud bang is a reason to have it checked.
My headphones only play in one ear — is it the headphones?
Try another device and, if possible, another cable. Also check the plug is pushed fully in — a half-inserted plug often plays only one channel.