Positive and negative speaker connections

[raygreen]

What happens if I connect speaker cables the wrong way round by accident. The only reason to ask is I am connecting a car cd/radio to a set of speakers I have made for a VW camper. It is difficult to trace the wires buried in the dash and will be a real pain to have to remove them.

Can I damage the speakers or will they just not work until connected the correct way round?

[Macca]

They will work you just wont get any bass. It wont do any harm.

[The Barbarian]

Ray:
Don't you have a multimeter with continuity bleep? one lead on one end the other lead on other end, it bleep its the same wire simples..

[istari_knight]

Always used a battery [AA or AAA] to test polarity when cables arent marked... Get it right & the cone moves outward, get it wrong & the cone moves inward.

[The Grand Wazoo]

Just to confirm a couple of things - nothing will blow up, snap or catch fire and you will get some bass.

[agk]

Chances are that in a damper van the leads from a meter won't be long enough.
Good shout on the battery James.

[technobear]

You will only lose the bass if one speaker is wired one way and the other speaker is the other way. If both speakers are wired + to - it won't hurt at all. Many CDs are produced with inverse phase anyway so you can never be sure you are hearing absolute phase. This is why some components have a 'phase invert' switch so that people with the hearing of a bat can experiment.

[raygreen]

Always used a battery [AA or AAA] to test polarity when cables arent marked... Get it right & the cone moves outward, get it wrong & the cone moves inward.
Can you explain James. Sounds like this is basic stuff but I don't follow what the process involves. What and how to connect with a battery.

[istari_knight]

Unplug the speaker cables at the amplifier end [one speaker at a time] then touch those cables against the +/- terminals on a 1.5v battery, if the driver moves out when you touch the battery you have the polarity correct but if the driver moves in polarity is reversed so you need to swap which wire goes to each end of the battery. Mark them with electrical tape or similar as you go.

Sorry I'm crap at explaining these things, heres a picture

http://www.troelsgravesen.dk/polarity_files/polarity-drivers.png

[guy]

beautifully explained :)

[Naughty Nigel]

http://www.troelsgravesen.dk/polarity_files/polarity-drivers.png

Nicely explained James!

Can I just emphasise that the output from audio amplifiers is AC or 'alternating current' (which alternately pushes and pulls the loudspeaker cones to create the sounds that we hear). This means that there is no polarity as such, and you can safely connect your loudspeakers either way round. It doesn't matter.

However, it is important that all loudspeakers in the system are connected the SAME way round, so that the cones push and pull at the same time. This is known as being 'in phase'. If your loudspeakers are 'out of phase' their cones will push and pull in opposite directions, and bass will be lost. This will be especially noticeable in a confined space like a camper van (or a small room).

James' suggestion of using a 1.5 volt cell is a good one. However, as the system is being installed in a motor vehicle, which has a metal chassis, you could identify the cables by connecting one of each pair to the chassis at one end. A multimeter (set to Ω) can then be used to check which cables are connected to ground, as these will show a low resistance (maybe 1 or 2 Ω maximum). The cables which are not connected will show ∞ (infinite) or open circuit.

If you don't have a multimeter, James' 1.5 volt cell could be used with a torch bulb to do the same thing.

Nigel.

[anthonyTD]

+1
Always used a battery [AA or AAA] to test polarity when cables arent marked... Get it right & the cone moves outward, get it wrong & the cone moves inward.

[raygreen]

Very well explained so that even I can understand. Thanks James and everyone for your replies.

[YNWaN]

Except it doesn't really matter if the positive terminal on the speaker goes to the negative terminal on the amplifier as long as it is the same for both speakers - that is the key point. If you get it wrong and one speaker is wired positive to negative and the other is wired positive to positive you will get bass cancellation (and right up in to the mids). Even if you do get it wrong, no physical damage will happen to the speakers or the amp.

[alexm84]

+1

+1 again,

I lived with an installer and this is the way they pretty much all do it, Speaker pop test with the battery. If it pops out, the postive on the battery is the positive to the amp. If it goes in, the reverse.

[Paul Hynes]

Actually signal polarity is important because it affects the leading edge of musical transients.

For example take the pedal beater strike on a kick drum. If you are in front of the drum (normal) when the beater hits the drum skin it generates a positive pressure wave compressing the air in front of the drum. If the audio equipment inverts the signal then the leading edge generates a negative pressure wave decompressing the air in front of the drum. This is both heard and felt and the inverted signal just does not sound or feel right compared to the non-inverted signal. Of course the transparency of the audio system will affect how easily this effect is heard and on a transparent system the effect is not negligible.

Signal inversion can occur either in the recording studio, which we have no control over, or the domestic sound system, which we have some control over. A signal polarity switch is a useful addition somewhere in the domestic audio system signal processing chain as it can compensate for studio signal inversion too.

[YNWaN]

Actually, polarity may or may not be important - although there is plenty of research that suggests we are not sensitive to absolute polarity. However, whether it is audible or not is academic as absolute polarity is often ignored by recording studios and it is common to find that some instruments in a mix have been recorded in positive phase and others in negative. Therefore, no matter what phase you wire your speakers in it will sometimes be wrong and on some occasions it will be right and wrong at the same time!

The battery test is fine for mid and bass but not much use for tweeters.

[Paul Hynes]

Mark, I guess I was not being as thorough as I would normally be, due to time constraints, but you are correct regarding polarity being often ignored by recording engineers. There is nothing that can be done with signals that have been mixed without regard to signal phase, so the signal polarity switch is of no use with this type of material. However there is enough good music out there where this is not a problem, but the overall phase may have been reversed while passing through the recording process, and in these circumstances a phase reversal switch can be very useful and it is certainly good for compensating for system phase reversal.

[walpurgis]

+1 again,

I lived with an installer and this is the way they pretty much all do it, Speaker pop test with the battery. If it pops out, the postive on the battery is the positive to the amp. If it goes in, the reverse.

Bit trickier with a tweeter. If you're lucky you may just discern some minute forward or backward movement of the diaphragm. But bear in mind, batteries can melt the fine wire of tweeter coils, so use the smallest and lowest amperage battery you can find and only use very brief on off contact.

[istari_knight]

IME you'll get one brief initial crackle from a tweeter before the series capacitor puts a stop to it. If you have separate tweeters then it would be preferable to use a DVM... You can always lash up probe extensions with croc clips / electrical tape and some old cable.

[alexm84]

Bit trickier with a tweeter. If you're lucky you may just discern some minute forward or backward movement of the diaphragm. But bear in mind, batteries can melt the fine wire of tweeter coils, so use the smallest and lowest amperage battery you can find and only use very brief on off contact.

I've never had to do a tweeter. If installing new speakers you already have the polarity on the tweeters wires. If you are tracing back existing ones, they are close enough to the crossover to trace the colour back. Other than that there are standard colour codes for most brands of cars so its easy enough to find out.

[walpurgis]

IME you'll get one brief initial crackle from a tweeter before the series capacitor puts a stop to it. If you have separate tweeters then it would be preferable to use a DVM... You can always lash up probe extensions with croc clips / electrical tape and some old cable.

You wouldn't be able to polarity test a tweeter with a battery if a is cap in series.