I'm about to play you two audio signals that are total opposites and I bet you won't hear a difference at [Music] [Music] all even though those two signals were total opposites they still sounded almost exactly the same let's open up a speaker to visualize what's happening here this speaker has a positive wire red and a negative wire black these wires are two ends of a coil of wire and within the speaker that coil of wire resides within a magnetic field if I apply an electric current across the coil with this battery what do you think
will happen go ahead and leave a comment below when I touch the red wire to the positive terminal on the battery nothing happens but watch what what happens when I touch the black wire to the negative terminal it completes the circuit and results in an outward Excursion of the speaker what do you think will happen if I reverse the polarity of the circuit touching the black wire to the positive and the red wire to negative this time the speaker cone pulls inward rather than pushing outward this battery is a source of DC or direct current
this speaker isn't really designed for a direct current signal like this so I don't want to keep the battery connected for too long as it will eventually result in excessive heat across the coil the speaker is designed to play audio which is alternating current or AC alternating current is a series of positive and negative voltages and we can visualize this by quickly alternating the polarity of the battery the series of positive and negative voltages across the coil causes the speaker cone to move outward and inward which results in a series of positive and negative pressure
changes in the surrounding area also known as sound waves this battery demonstration helps to get a basic understanding of how a speaker works but let's look at this transducer for a more realistic example this transducer operates on the same Principle as the speaker there's a positive and negative terminal which are attached to a coil of wire within a magnetic field rather than nearly instantaneous positive and negative voltages from a battery this amplifier is supplying a sine wave at the specified frequency and you'll notice that the transducer is moving outward and inward more smoothly as I
increase the frequency of the sine wave generated by the amplifier naturally the outward and inward Cycles happen more frequently what do you think will happen if I reverse the polarity now negative voltages from the amplifier might result in outward Excursion of the speaker but is there really a difference the result is essentially the same the transducer moves outward and inward at the specified frequency visually there's no difference but can we hear a difference first let's adjust this sine wave up to a frequency that we can hear then we'll compare that to the sound when we
invert the polarity by switching the wires from the amplifier there's no audible difference we hear a 300 HZ sign tone in both cases over here in the Daw we have a 300 HZ sign tone that begins with a positive inverting the polarity means the sine wave will now begin with a negative because all positives become negative and all negatives become positive when you invert polarity there's still no audible difference because the two signals are really identical after the initial positive or negative start do you think the difference would be more audible if we used a
more musical signal like a snare drum right here I've loaded a snare drum sample into the timeline and if we Zoom closer we can see that the waveform starts out with a very quick positive transient surely we'll hear a difference now with such a transient signal right there's still no difference to my ear I've heard some claim they can hear a difference here and that might be true but I don't hear a difference at all if you can hear a difference let us know in the comments below so does all of this mean that there's
no audible difference when speakers are wired backwards well yes and no if you just have one speaker you probably won't hear a difference even if you reverse the positive and negative on your speaker cables but when you add in additional speakers it becomes much more important to get the wiring right because now the two speakers will either work together or work against each other I've duplicated the 300 HZ tone to another track these two signals are now exactly the same I'll begin with one muted and we'll see that the signal level from the one that
is unmuted comes in at about minus 18 DB full scale what do you think will happen to the meter when I unmute the second [Music] copy the two copies sum together and the meter increases by 60p okay now let's invert the polarity of one copy so that the positive sections become negative and the negative sections become positive what will happen to the meter now when the two copies are summed [Music] together we see just as much level on each copy but because they are total opposites they now cancel each other out when mixed together and
this results in no signal level at all the same thing can happen if you have two speakers in the room wired with inverse polarity the speakers will each sound identical on their own but when you play them both together they'll work against each other and cause cancellations generally speaking you should wire the positive terminal on the amplifier to the positive terminal on the speaker and the negative terminal on the amplifier to the negative terminal on the speaker though you won't hear a big difference if all the speakers are wired the same way you will hear
a big difference if the speakers in the system are wired differently so be sure that all of the speakers are wired the same way so they can all work together while this is a good starting place getting the speakers to work together is a bit more complicated in the physical world because space Time acoustic Reflections and phase will be added into the equation that's what we'll be talking about in this video that's on your screen now go ahead and click that link and I'll see you there
