The result is a signal that is twice the amplitude of each individual signal. This is called constructive interference. Anytime two identical signals are mixed together with inverse polarity, the signals cancel out.
In this case, one wave is positive while the other is negative, and vice versa. The result is silence. This is called destructive interference. There is a big difference between polarity and phase! A speaker and a microphone operate on the same basic principles.
In a microphone, electricity is created when sound causes the diaphragm to move. In a speaker, movement is created when electricity passes through the wires. You can learn more by reading this article I wrote about how microphones work.
When no electricity is being sent through the speaker wires, the speaker rests in its default position. When an alternating electrical current, such as an audio signal, is sent to the speaker, it starts to push outward and pull inward.
You can see this in the following image. As a speaker vibrates forward and backward, it displaces the air particles in the atmosphere, forming negative and positive changes in pressure. This causes a chain reaction through the air from the speaker to our ears. Understanding how sound waves can interact will help you understand why speaker polarity is so important! When the wires from the amplifier to the speaker are crossed, the speaker polarity will be inverted.
This means that the speaker will move inward when it is supposed to move outward, and outward when it is supposed to move inward. The sound wave created by the speakers will be the exact opposite of the signal recorded by the microphone. How will this change the sound?
If only one speaker is being used, the effects of reversed polarity will not be noticeable. Listen and compare these two audio clips. The first one is in the correct polarity, while the second is in reversed polarity. You will not notice the difference between these clips, because the frequencies contained in them are identical. Sound waves are alternating pressure fluctuations and audio signals in a wire are alternating electrical currents.
This means that virtually every positive change will be met with a nearly equal but opposite negative change. For this reason, there is almost no audible difference between an audio signal in polarity and out of polarity. Reversing polarity with multiple speakers can cause more noticeable effects. If both speakers are wired the same, whether in the correct polarity or reversed polarity, there will be virtually no effect.
Soundwaves actually come in the form of an actual wave wherein the highs are the positive pressures, and the lows are the negative pressures. The sequencing is determined by which between the positive and the negative pressure comes first. For example, when you strike a drum, the fact that the upper part of the drum moves down creates a negative pressure in the air, thereby making the first part of the soundwave negative, which is then followed by a positive pressure when the upper part of the drum begins to pop back up.
So, in other words, when we talk about the polarity of soundwaves coming from a speaker, we are talking about the wavelength created between the amplifier and the speaker. The same goes for the negative terminals. Car speakers work in the way that electric current passes from the amplifier over to the speakers through a wire that connects them.
The amplifier is the one that first receives the electrical signal, and it will then allow it to pass to the speakers, which will then move forward and backward depending on the polarity of the signal it is getting from the amplifier.
However, when they receive a signal from the amplifier, they will begin to move backward and forward. The backward movement represents a negative pressure, while the forward position represents the positive pressure the speakers make in the air particles in the car.
In that regard, polarity becomes important because the electrical current that is coming from the amplifier to the speakers should match the terminal. For example, even if the current sent to the speakers from the amplifier is positive, but you connected the wire to the negative terminal, the movement the speaker will be making will be backward even though the sound it produces is positive.
This could create weird distortions and changes in the quality of the sound coming from the speakers. Speaker tester is a tool that is specifically made for these cases and is not even very expensive. It does not only test the wires but also checks if the speaker works properly. Pac tester is available on Amazon, so if you are going to test either wires or speakers, click this link and check the latest price.
In most cases, you simply have to look at the labels on the speakers and the wires to know which ones are positive and which negative. The plus and minus symbols will clearly indicate which ones are negative and which ones are positive. Meanwhile, in some cases, red color indicates positive, while a black color indicates negative. That is why you must use a different method to learn which one is the positive wire and which one is the negative wire.
A lot of people make this mistake because it can be quite common, depending on the circumstances. In a lot of situations, the most common reason for messing up the wiring can be due to a lack of information or even carelessness. Even if the wires and the speaker terminals are labeled and are colored, it can still be quite easy to mess things up, especially if you do not know how the labels work and what polarity means for your car speakers.
But I've never worked with Audyssey-type equipment, which I'm assuming we're talking about here. Evan E wrote: But I've never worked with Audyssey-type equipment, which I'm assuming we're talking about here. It's a Yamaha RX 7. I assume it's nothing special because NewEgg threw it in for free when I ordered a set of Klipsch speakers from them.
Where do they record an orchestra from? Sufficiently far in front that swapping the left and right speakers places you well behind the orchestra, or just in the back? With apologies if the back row of the orchestra is occupied by musicians of a lower standard or anything.
Standard orchestra seating, since the end of the 19th century, is violins stage right on the audience's left , violas in the middle, and cellos stage left. Prior to that the 1st and 2nd violins were often split up on the outsides, so that it would be 1st violins - violas - cellos - 2nd violins, and there can be pieces where there clearly is a call-and-response thing going on between the violin sections that's enhanced by having them physically separated. The change didn't happen all at once, so you see that still in Russian works like Tchaikovsky's symphonies.
But the two violin sections often play such similar parts that it makes sense to have them together so the conductor can cue them all by looking in one direction.
Ideally your principal miking micing? For years Deutsche Grammaphon tried, whenever possible, to just use two mics to capture the entire orchestra, so that they weren't just recording the directional volume of the sound but also the directional delays, both from the orchestra directly and from the reflections off the rest of the concert hall - if you mix in a spot mic set in the middle of the wind section, you're kind of ruining the distance information.
Long story short, if I hear all the violins coming from the left speaker, I think either the speakers are reversed or someone recorded upside down.
Then there are Ribbon-speakers which works slightly different, and Electrostatic speakers which works in a whole other way. Ulf wrote: One thing that annoys me about my current receiver is that it whines that the speakers are reversed when I know for a fact they are not.
Your mic is getting a reflection which is screwing up the room calibration algorithm. Either ignore it, or try to figure out where the reflection is coming from and apply absorptive material there. Of course he would say put in some absorptive materials. He'd have you sit in a wire cage, surrounded by triangular pointy things covered in felt. DriverGuru wrote: To add a point that I don't think has been spelled out well enough: it wasn't spelled out at all, reading first answers one would conclude polarity always matters, no matter on one or both speakers.
The problem with two speakers being out of phase is caused by the fact that your ears receive both waves added together, so if they were degrees out of phase they'd cancel each other out ignoring the fact that reflections off the walls are going to have different phase differences because of different travel lengths. With headphones, there's no mixing of the waveforms, and your brain doesn't get phase information.
Like I just said, there's no interference unless the waves have been combined before getting to your ear. This is a known and tested thing. Anechoic wrote: Your mic is getting a reflection which is screwing up the room calibration algorithm. Makes sense. I live on the top story of a multifamily house, I don't have square rooms to begin with. Evan E wrote: Like I just said, there's no interference unless the waves have been combined before getting to your ear.
There's no interference you'll hear both channels , but your brain can perceive a phase or polarity difference, even over headphones where the two channels are completely isolated from each other; phase delays between the sounds heard by each ear are part of how your brain localizes sound, especially at low frequencies. It's pretty easy to do in Audacity if you want to try it and see. See if you can separate them into two groups, write the two groups down, then click the link at the bottom to see which are which.
I can't really tell the difference, even though I know which are which. I'm unaware that encoding the files in a lossy format would make any difference, but just to be sure I put them up as WAV files, so the page may take a while to load. I'll be honest: I can't. I can't reliably distinguish a 1 kHz sine tone and its phase shift, one in each ear, from just two identical tones. If I add some crossover with a small delay, I can then instantly tell the difference reliably over headphones.
I can rapidly distinguish, reliably, the same test done over speakers. I can hear it consistently: it's 3, 5, 6, 7, and 9. And, no, I didn't cheat; was using headphones my MDR-V6s and didn't look at the answer page until after I'd listened to each sample and decided which was which. The out-of-phase sounds just as loud, but sounds "stereo" in that it sounds like it's coming out of the headphones rather than originating somewhere in the middle. They sound very distinct to me; only needed to listen for a second or two to distinguish each.
Maybe I have weird ears or something. Also verified on my IEMs just in case the Sonys were biasing the results somehow. I can hear it clear as day, out of phase is very different from the in-phase samples, sounds like stereo out of phase vs mono like Jonathon described. Sennheiser HD Listening on Apple Earpods: 3, 5, 6, 7, and 9 are out of phase, immediately obviously.
This is not some subtle effect, it is not voodoo, and it is not rocket science. I can't reliably tell the difference via Sennheiser PX headphones, but the difference is night and day when I listen through speakers. Also unmistakable when I listen through my iPad, which has only one speaker, which would be the "duh, that's obvious" control. And, for people who actually put the results in their posts - you biased the test for anyone else who wants to take it.
I've re-shuffled the files. Anyone else who wants to give it a shot and post their results - it might be useful to post what kind of headphones you're using. I doubt that's an issue, but more data is always good. It also occurs to me that if someone's listening through something that applies some sort of fake "surround" effect that would kill the reliability of the test. Audiophiles: Question about speaker polarity? Hat Monster.
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