Most hi-fi''s or amplifiers have the speaker connections marked red and black, along with the cables to the speakers. Why is this polarity important? In my system it doesn''t seem to make any difference to the sound which way I connect. | Notes and Queri (2024)

Most hi-fi's or amplifiers have the speaker connections marked red and black, along with the cables to the speakers. Why is this polarity important? In my system it doesn't seem to make any difference to the sound which way I connect.

Sean, Belfast N. Ireland

• If both leads are wrongly connected there won't be any difference, but if one speaker is connected correctly and one incorrectly, the speakers will be out of phase resulting in the stereo imagery being lost, and mono records sounding very fuzzy.

  J Vagg, Beckenham UK

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• You should be able to. The standard test for checking that you have the correct polarity is to change it over on one speaker and see which position is the loudest. Since the sound is produced by speaker cones moving in and out in line with the frequency of the signal, it is better that they move in synchrony. If one moves in while the other moves out, the sound waves cancel each other out to some extent, thus reducing the volume.

  Terence Hollingworth, Blagnac France

• The sound is reproduced buy your loudspeakers moving back and forth. If one of your speakers is wired up the wrong way it will be 'out of phase'. In other words it will be moving 'back and forth' while the other speaker is moving 'forth and back'. Your ears may not notice it but this results in the stereo seperation and sound quality not being as good as they could be. However if BOTH speakers are wired wrongly it shouldn't make any difference.

  Alan Keggie, Penarth, UK

• The answer depends on whether you're a purist or not.If you're an audiophile, you'll notice, or pretend to notice, that the speakers 'are out of phase' if you connect red to black on just one of the speakers. What will be happening is that one cone will be 'pushing' while the other will be 'pulling air'.On the other hand, in a blindfold test,nobody could ever tell. Just don't let a hi-fi buff SEE your speaker cables the wrong way round!

  Marc Wisbey, Rome

• If one speaker is wired correctly, and the other in the reverse polarity, one speaker will be 'pushing' as the other is moving in the 'pulling' direction resulting in a loss of volume. In modern stereo 'separation' much of the signal is delivered to both speakers, and differing polarities would have the slight efect of cancelling each other out.In industry one way of reducing noise is to feed a similar sound to the source, and this has a similar effect of reduction of volume, which demonstrates this principle.

  Jonathan, Lancaster, UK

• If you can switch one of your speakers to "anti-phase" while listening to the sound you should notice a "hollow" effect compared to the correct "in-phase" connection. With speakers connected in "anti-phase" stereo placement of sounds can also become undefined, if the sound is monitored in mono it can decrease in volume markedly. This decrease is due to the varying voltage (which represents the recorded sound) being cancelled out by its equivalent but opposite (anti-phase) voltage.

  John Norris, Ashingdon, UK

• Stereo speakers need to be "in phase", ie the bass driver (black round paper thing inside) in each moves in and out at the same time. This is controlled by the two wires. If one has the wires reversed, the speakers are out of phase and the bass component of the sound disappears.If the wires have no distinguishing colours, you can test for phase by facing the speakers 9" apart and playing music. If the wiring is correct they''ll sound as loud as you''d expect from the amplifier setting: if not, one is wired wrong. You can then swap the wires over in one speaker. Incidentally, the colours red/black or whatever don''t mean anything significant like live/neutral so it''s all perfectly safe.

  Carla, Crewe, UK

• Speakers create a noise by creating pulses, or waves in the air. This is done by attatching a magnet to a bit of shaped paper, and using electricity to yank the magnet - and therefore the paper cone - in and out very fast.However, in stereo systems, it is important that the two speakers work together. You don't want one speaker to "suck" whilst the other "blows" - the waves from each speaker may cancel each other out to a small degree, making the result sound hollow or dull. If the sucking and blowing synchronisation is its self varying, you get a phasing effect much beloved by seventies supergroups on guitar solos. Cf feedback, but I digress.Therefore, it is merely necessary to ensure that both speakers are consistent in their black/red connection. Unless you're an audiophile.

  Matt, Cippenham Berkshire UK

• For a dramatic demonstration of this principle, place two out-of-phase speakers face to face. The sound will actually be louder when one speaker is turned off than when they are both turned on.

  Jim Dixon, St Paul USA