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Doubling the power supplied to speakers raises the sound level by about 3 dB. Twice the watts does not mean twice the perceived loudness.

In a stereo system, a voice can seem to come from exactly between the speakers, even though there is no speaker there. This effect is called a phantom centre.

Bass depends on where you listen as well as on your speakers. Sound reflections can make the same note boom near a wall and almost disappear elsewhere in the room.

A subwoofer in a corner usually sounds louder, but not necessarily more even. Its position affects which bass notes the room reinforces most.

Active speakers have amplifiers built into their cabinets. Passive speakers need a separate power amplifier.

Sound travels roughly one metre through air in three milliseconds. Even a small difference in distance from the speakers changes when the sound reaches you.

At 50 Hz, a sound wave is about seven metres long. That is longer than many living rooms.

Going up one octave means doubling the frequency: for example, from 440 to 880 Hz.

On each side of a typical vinyl record, the music is recorded in a single continuous spiral groove.

A single groove on a stereo record holds two channels: the left and right channels are recorded on its different walls.

A DAC converts digital audio data into an analogue signal. It can be a separate device or built into a player, amplifier or active speakers.

On an audio CD, each second of sound is represented by 44,100 digital samples per channel.

Lossless compression reduces an audio file’s size while allowing the original digital data to be reconstructed exactly.

Headphones with active noise cancellation produce an additional sound that helps reduce outside noise.

In a room, we hear both the direct sound from speakers and its reflections. The reflections arrive slightly later and affect the clarity of the sound.

As a starting point, place the two speakers and your listening position at the corners of an equilateral triangle. This helps create a stable stereo image.

Speaker height affects tonal balance. The acoustic axis specified by the manufacturer is usually aimed at the listener’s ear level.

Placing speakers symmetrically relative to the side walls helps maintain balance between the left and right channels.

A desk between the speakers and listener reflects sound. These early reflections can alter the tone even with high-quality speakers.

A deep bass dip caused by reflections is often better addressed by moving the speakers or listening seat. Boosting that frequency with an equaliser may simply put more strain on the system.

An equaliser helps balance frequency response, but it does not replace acoustic treatment and correct speaker placement.

If one speaker’s positive and negative connections are reversed, bass can weaken and the stereo image can lose focus. Keep the wiring polarity consistent across both channels.

An amplifier needs space to release heat. Clear ventilation openings and the spacing specified in its manual help prevent overheating.

When choosing speakers, check the amplifier’s supported load impedance. A 4-ohm speaker is not suitable for every amplifier designed for 8-ohm speakers.

A balanced connection helps reject electrical interference picked up by a cable. The output and input must also be balanced, not just the cable.

A subwoofer’s phase setting affects how it combines with the speakers. If bass is weak around the crossover region, checking this setting may help produce a more even response.

If in-ear headphones sound bass-light, check the seal of the ear tips. A poor seal can noticeably reduce low frequencies.

A turntable’s PHONO output needs a phono preamplifier. Its LINE output is intended for a normal line input on an amplifier or powered speakers.

If a turntable’s built-in phono preamplifier is enabled, connect it to a line input. Additional amplification through PHONO can cause overload and alter the tone.

Set stylus tracking force within the range specified for the cartridge. Too little force can also impair the stylus’s ability to follow the groove.

Clean a turntable stylus with a suitable brush, moving from the back of the cartridge towards the stylus tip. Brushing in the opposite direction can damage its suspension.

Store vinyl records vertically, away from heat and direct sunlight. Stacking records and exposing them to heat increases the risk of warping.

Hold records by their edges and label area. Fingerprints on the grooves attract dirt and make cleaning harder.

Converting an MP3 to a lossless format does not restore data discarded during compression. A larger file alone does not improve the sound.

For uncompressed PCM, file size depends on sample rate, bit depth and channel count. One minute of stereo audio at 16-bit / 44.1 kHz takes about 10.6 MB.