What Happens When You Wire Speakers Backwards? 

If you wire your speakers backwards and listen to country music, the guy actually gets back his horse, his job and his wife

I learned about the importance of polarity when I was young. I received a ghetto blaster for xmas and I was shocked that AM radio sounded so much better than FM. AM was in mono and only came from the left speaker but FM being stereo came from both. My natural curiosity got the better of me and I opened it up 2 days after getting it. My mother was furious. I had no idea what I was doing or should be looking for but I knew the difference between positive and negative and colour coding. I saw the left speaker was wired white to + and black to - which seemed normal to me. But the right speaker was wired white to - and black to + which seemed wrong. I had already been soldering for a few years so I desoldered the wires from the right speaker, switched them and soldered them again. I put it on FM and was amazed at how good it sounded. My mother was so happy that it worked but still never gave me any credit for fixing/improving my gift. For years she would say "Do you remember that xmas you took apart your radio?" and I would always ask her if she remembered that not only did I put it back together but that it was better than when I had taken it apart. Never got any credit for that.

Having some education in electronics and a half century experience with home stereo, I can't say I learned from the video. But oh how I enjoyed seeing it explained so well. This young man has a gift for explanation.

When you listen to the initial hit of a kick drum there is a definite change of sound and feel with a single speaker wired with reverse polarity. Especially with a PA sub system that covers the 25Hz range. If everything is wired correctly you should feel the air hitting your chest. If the sub polarity is reversed then the kick drum completely loses it's impact. This because the first positive peak of the sine wave is the largest and sound pressure waves in compression have better projection than ratification of sound waves.

"Why are my speakers not speaking" "They don't agree with each other'

Years ago, I found I had accidentally wired one of my two subwoofers in reverse (in my mobile DJ rig). When I saw how I had screwed it up, I laughed so hard! I had been struggling for several months with my system - asking myself, "Why can I hear the base coming out of each sub when I stand right in front of it but when I move to the center of the dance floor, I don't hear or feel it?" No amount of EQing or compression made any difference. When I saw I had the cable to one sub wired backwards (positive to negative and negative to positive), man oh man, I was relieved. I still laugh today thinking about it.

i was taught this about 30yrs ago from some sound engineers for both studio and live situations. there's also been several articles in guitar magazine about this because especially important to the life of your gear and what's going to go on record. the last interview i read about this was from one of the sound engineers who worked on crew for Jimmy Hendrix on tour. it is as follows: when you wires your speakers backwards your cones hit in reverse. the initial blast from the speaker, i.e. that first vibration should always be the cone pushing outwards to deliver that first hit. when you wire them backwards the cones take a breath instead. i.e. pull in instead of pushing forward. that's going to affect the sound quality and volume of your session and speakers. if you got several amps going and one is in reverse, your phase is going to be messed up. it won't be something crazy like a full cancellation but your signals won't be balanced. over time, if the speakers are wired in reverse, the initial hit from your speakers will lead to damage from always sucking in at first instead of blowing outwards.

I knew this but this was the absolute best depiction of the principal I have ever seen. Well done!

This how noise cancelling systems work, listen to the unwanted sound and invert it add back to cancel the unwanted sound dynamically.

Very simply, when one speaker is out of phase (wired backwards) in a stereo system, they cancel each other out. Mainly heard in the lower frequencies, but also affecting image and sound staging.

They start speaking Spanish

In a world of misinformation, particularly on audio, this channel is such a breath of fresh air! Superbly explained too.

Fun fact: I once installed a dual subwoofer setup in my Nissan 100NX (yes it's been a while) .. After installation I played some subwoofer test music and was disapointed by the lack of bass from the subwoofers. I didn't understand, I had two subwoofers and still heard almost nothing. It was at this point I thought about polarity and I changed the phase setting (on one of the amplifiers). It was at this moment I learned that I should not have done that while the system was running a subwoofer bass test on 80% volume. The moment I flipped that switch I was scared to death, the system was playing so load suddenly. Learned some lessons that day!

If you have two stereo speakers wired with opposite polarity (a.k.a half a cycle out of phase), you get an interesting effect because the signals cancel each other out in a fringe pattern which generally makes it feel like the sound is coming from around or behind you, because it will bounce off the room walls before it reaches your ears. This effect is used in legend of zelda ocarina of time for the sound of the townspeople in the castle town courtyard, and in the movie twelve monkeys for the mystery voice he hears in his head Flipping the polarity of one of the channels in a pop song can also work as a useful hack to get something approximating an instrumental version of the track, because generally the vocal is dead centre but the backing is not so the vocal gets cancelled out

Really interesting to see how little most people (including myself) actually know about these simple concepts. I was taught I could blow up or short circuit speakers when I connected them wrongly

We used a battery to figure out the polarity of the speakers;when trouble shooting a previous installation. A dead give away is solid bass when turned to one channel or the other, but when balanced no bass out of either indicates inverted polarity on one or more speakers depending upon setup. Our shop used to troubleshoot a lot of other shops work. Motor noise used to be a huge issue for some shops.

You should take a pair of those linear transducers and have them agitate a shallow pool of ~dyed water. In theory, we should be able to see how the delay required to propagate the signals through the media affect constructive and destructive interference at different frequencies, distances, polarities, etc.

On a side note, the term phase and polarity are often used to describe the same thing but are actually different. Polarity inversion (flip or swap)is what is described in this video and is a 180 degree phase inversion. It is possible to have phase discrepancies that are not a full 180 degrees.

I can hear the difference. Its the start of the tone. Most people dont hear the end of the sound a snare makes but the sharp initial strike. Might be part of why the + and - sound different at first but played longer they sound more alike.

From a guy who got his MECP back in the early 90s, which is pretty much being a professional in creating and building high-end stereo systems in automotive and also in homes. And I have to say this may be one of the best breakdowns in the simplest forms to make sense of this. If you are a beginner, this I think is a great example to get the basic idea. I think he did a great job at this, and realistically that is what a teacher should do Now on a little side note, when I first started out, I had two 12-in subwoofers side by side in a hatchback, 3rd gen Camaro, and I wired the subwoofers positive to negative positive to negative, remember mono amps and dual voice coil subwoofers we're not as accessible as they are now. Regardless, this does help simplify my example. So I'm testing & tuning my sound, & when i had one sub connected it would always be louder & deeper than when adding the 2nd. It was technically wired correctly. And I just couldn't figure out how this was possible. Long story short, eventually I learned how the Box the subs are in are built, the environment they're in, and other factors can actually affect phasing. Somebody told me to reverse the positive and negative on one of the subs, negative to positive and positive to negative, and I heard the immediate difference. So if you are putting together either a home and or car audio system, be mindful that this could happen. And you may want to try something like this. Obviously when you get into much higher end audio systems there are a lot of equipment to help you through this.. some of the tuning equipment can pick up this type of issue and where it possibly is coming from, all types of crossovers, equalizers and amplifiers that can adjust phasing for individual channels, etc etc, and sometimes still you have to do it the old-fashioned way

It's actually fun to experiment with out of phase speakers and placement. If they are directly facing each other with the listener in between, you get a push-pull effect that's pretty cool. It depends on the spacing and frequencies as well.

Back in the mid 1970's I worked installing PA systems in a grocery store chain, the system was a 70 volt system that was used to play mono background music when it was not being use for announcements. The speakers were mounted in the ceiling of the stores and to keep the speakers from canceling one another out we had to space the speaker properly to take in account the delay of the audio from each of the speakers and we had to switch the polarity of each of the speakers because of that delay to keep them in phase with one another. This was to minimize the locations in the shopping aisle that presented cancellation zones. It worked very good.

This just happened to of popped up on my RU-vid. I spent many years in the automotive stereo industry, starting out very young. I could never hear the difference AS long as everything was wired the same. But wire one speaker wrong in a stereo system and you most assuredly can and will hear it. That was almost 40 years when I started, and nothing much has changed. Very important to get it right and right the first time. Nothing worse than having that person coming back because you got it wrong.

I had some fun trying this out once. Playing the same audio on two speakers, but having one inverted. When putting your ear in a place with the same distance to both speakers, it really gets more quiet (still far from 0, but very noticable). But if you move your head so the distance to both speaker is different (by maybe 10 or 20 cm), it get's louder again, because the waves are ever so slightly out of sync and can't cancel each other out as well.

Right foot first or left it doesn't matter unless you want to coordinate with another. Just like dancing.

Coincidentally last week I was installing an home theater in my room (the old style one, not a sound bar) and I was wondering why the speakers had polarity and I was very afraid of inverting wires. Now everything is very clear. Thanks for the video!

Thanx for the thorough explanation of speaker function, especially w/ the visuals of the oscilloscope. I was becoming doubtful that you were going to explain the effect of swapping polarity of one side of a stereo speaker arrangement, and I was ready to comment w/ the question "What if...?", when you resolved the question w/ an answer. I was also pleased to learn that I was correct in my assumption of a "cancellation" effect. Using a pair of Sansui SPA-3700s here... that I bought new in 1981... they are properly wired. Thanks again.

I've been doing sound in many forms professionally for over 40 years. A lot of crazy things can happen with sound. Let me first say that with a really good and highly tuned stereo system you not only get right to left imaging, (like you can here the saxophone mainly coming from the left speaker and the guitar coming from the right) , you can also get front to rear imaging. So if your listening to a well recorded symphony recording, especially with eyes closed, you can hear the violins at the front and kettle drums in the rear. If you wire both speakers backwards (both speakers are - black wire to red terminal and red wire to black terminal), at first listen they will sound normal. But if you listen more closely, you will hear the kettle drums at the front and the violins at the rear.

This is the best audio engineering channel on RU-vid.

I noticed a difference in sound decades ago on my Dad's stereo. Maybe it's not noticeable on headphones, but if the speakers are far enough apart, the inverted wiring caused it to sound very hollow.

On a side note - you *_can_* wire the speakers in the reverse polarity _(positive to negative, and negative to positive),_ and in some cases _(especially for subwoofers)_ you *must* do it _(because of the phase shift due to passive filters)_ - just be sure to wire *all* the speakers the *same way,* be it either the "regular" polarity or the reverse, because all speakers should be *in phase.*

I actually have reversed the polarity of my high end speakers, because i noticed a phase issue with my active subwoofer's internal crossover even if i use the preset that was made for the exact speakers i have. Not sure if this is caused by using balanced to a power amp for my speakers and rca for subwoofer, or if it's just my room being weird. but i've never had any issue this way. Glad I don't have to worry about this

I don’t think it was mentioned in the video, so I just wanted to add that the common naming when speakers are wired the same is “in phase” and when they are wired with different polarities is “out of phase”. There are some interesting acoustic characteristics when speakers are wired out of phase in a home listening environment where the sound seems to appear diffuse and almost like it’s “floating around your head” with no distinct source. There are some fun examples elsewhere on RU-vid where you can listen to in-phase and out-of-phase white noise that demonstrate this.

It's possible to isolate the voice in all songs that have a similar instrumental version by inverting one of the two audio files. It doesn't work perfectly because of audio compression and sometimes the original song includes more or less sounds than the instrumental. But with a bit of luck you can get pretty good results.

The cancelling out of of opposing signals is why XLR cables don't reproduce induced noise, and can therefore use long runs in noisy environments. The signal is sent down two wires, but opposing each other (with a common ground being the third wire). Any signals that are induced become opposing when one of the signals is inverted at the end and cancel out just the noise. (This is a rather simplified explanation just to get the concept across) 🙂

5:02 I can hear a difference. With the negative first the start of the hit sounds sharper and more pronounced and that's with my TV/computer monitor speaker volume at 19 without hardly any area background noise since it's mostly quiet where I live.

I saw a perfect example of this in application - there’s a documentary on making of Metallica’s Black Album where the sound engineers had James Hetfield sing in a booth with two monitors wired in opposite phase so that the mic would only pick up his voice. He was having trouble wearing headphones for some reason. It was truly mind blowing how this worked.

Years ago when speakers didn't give polarity we used to put them face to face about a half inch apart and reverse the wires on one. Which ever way sounded better is the way you would leave it. We called it putting them in the same phase.

An excellent, illustrated, detailed, demonstration of speaker polarity, an important factor one that I have been promoting for over 50 years!

A little known thing about 2-channel automotive amplifiers that are bridgeable: One channel has it's terminals labeled backwards from what it really is. That channel also has it's RCA input reversed. The input signal is being sent into the amp out of phase, but since you are actually wiring that channel backwards, it all comes out correctly and in phase. This is done to make bridging the amp easier.

Many, many years ago (like 1970s), I installed 2 speakers in my car's front doors for my Pioneer Super Tuner stereo system. Somewhere, I saw an article about adding a 3rd speaker and mounting it on the rear deck of the car. I took a positive lead from the left and right channels and connected them to the 3rd speaker. Whether or not or was good for the electronics, I don't know, but it made for an interesting effect since the only sound coming from the 3rd speaker was the difference between the 2 channels. Like sounds were filtered out.

There is one case in which connecting stereo speakers in reverse polarity is a GOOD thing. The best imaging and sound stage is acquired by placing a twin set of tweeters and midrange drivers on the outside of your main speakers and wiring them to the opposite channel in reverse polarity to cancel crosstalk. That's how the Polk Audio SDA's work.

Just stumbled across this video. I've always heard about this and always made sure to wire correctly, but now I feel like I need to experiment and actually listen to this cancelling effect.

There are times when reversing polarity is a good thing. I have an SQ build in my car right now with a 3 way set up up front and my midrange are reversed polarity compared to my mid bass and tweeters. It helped me achieve a brighter “center stage” .

This is true that there should be no audible difference when your DAC, amp, and speaker are all operating linearly. However, in practice there are nonlinearities and biases in all these systems. I would imagine it would be easier to A/B test polarity inversion on cheaper systems or at very high sound pressure levels.

Actually, engineer here, speaker does not have positive and negative terminals. As you said it is just a coil, which is an inductor wound to a circle. Some electronic components and machines does have polarity because it is important where does the current flow and in which direction. That is why you must put DC voltage in correct polarity on input. But as you connect coil to an AC power source you can imagine it not just changing the ammount of current/voltage but also its polarity (sine wave). That means it does not matter which way you plug it in. What were you talking about in video (the speaker muting while "reversed") is phase shift. You phase shifted the signal on one speaker so when the signal on number one is in top + section, the signal on second one is in top - section and then they indeed disturb each other.

Whether or not there's an audible difference will depend on the driver and/or enclosure. The signal is identical, but if the driver performs differently when pushing out vs pushing in, for dynamic audio (basically anything except a tone generator) it will color the sound differently. Like the snare hit example, the largest amplitude is in the 1st movement. If the cone is not equally flexible in both directions, and more flexible in the direction of 1st motion, that period will be louder than when the signal changes direction electrically (i.e. moves under the line). So, if you have good ears, and you have good drivers and enclosures and yet you can hear a difference when reversing the wires that's actually an indication that your drivers or enclosures aren't good as they do not perform equally in both directions of cone movement. With good equipment, good ears will be just as oblivious to this kind of phase change as bad ears.

Reverse wiring does have an effect depending on the type of sub, enclosure and power. A sub designed for outward throw if wired backwards can cause bottoming out and or reduced sound at higher power input. A backwards design is usually one for mostly enclosure tuned ported, so backwards throw can cause over heating of the coil from travel outside the magnet. And neutral throw, same in as out isn't effected as much by reversal input. The signals are ac current, but just like ac house current, one direction is longer than the other. Your primary signals is for sound, the reverse helps with return and dampening. A forward throwing sub in a sealed enclosure will have reduced sound, where as a forward throw in a ported enclosure can have increased tuned volume but greatly reduced outside of the bandwidth. At low volumes especially with computer or TV speakers which are normally neutral throw for best SQ and don't need high outputs, of course you won't hear a sound difference

Listen to the stereo copy of the debut album by Moby grape. The producer, David Rubinson, put a lot of the backing vocals (and sometimes the main vocals) out if phase; left channel vocals were positive red and right channel was negative red. If you play the stereo copy on a mono player which were prevalent in 1967, the backing vocals and sometimes lead vocals disappear. The producer also did this on a few songs on their second album called ‘Wow’.

i "hear" the difference in the snare, but honestly i think it's more about feeling it. the pressure difference in a speaker pushing the note vs pulling the note into existence. sound waves are just a transfer of energy from one object to your eardrum. under normal conditions, the eardrum is pushed first, then pulled by the sound made by the speaker, where as with inverted phase the eardrum is being pulled first, then pushed by the soundwave produced by the speaker, and i think that subtle difference is what people are noticing.

Waaaay back in the mid 70s we had a stereo console with turntable that wasn't working. I was 14 and I started messing around with the player and all that. Just tinkering I got my hands on Quadrophenia. I had heard it was supposed to be in quadrophonic. Somehow by playing with the speakers and crappy old equalizer, I managed to isolate the whole drum track to Love Reign O'er Me; albeit, I could still hear echoes of vocals and other instruments. It was so good, that before the final drumming piece, I could hear one of the band members either sniffle or cough. I'll have to try it again with my gold cd I have of that album.

Extremely clear and methodical explanation. Well done.

Very professional as a teacher for the audience. Great speaker-tone, good info. You have a gift to teach

I've said it before but I'll say it again: you are an incredible teacher!

For a single frequency of sound, when two speakers are separated in space, there are positions in the room where the sound waves constructively interfere (such as the point exactly between them) and places where they destructively interfere (such as a point between them that is a bit closer to one speaker than the other (the "bit" being exactly one quarter of a wavelength). If you plot out these points of constructive and destructive interference, you get lines of constructive and destructive interference that are separated by distances in the range of 1/4 of the wavelength. Even when the speakers are wired "correctly", you STILL get spots that have destructive interference, but where the spots are depends on the frequency/wavelength of the sound. Flipping the polarity of one of the speakers should just move the various quiet and loud spots around the room. If one speaker is flipped, the position half-way between the speakers is one of those destructive interference spots. Importantly, this spot has destructive interference for EVERY frequency of sound. Middle C is around 256 Hz, so about 78 cm of wavelength, with higher frequencies having shorter wavelengths. For the very low frequency sounds (60Hz has a wavelength of around 5.3 metres (18.3 feet), the destructive interference zone would be a large part of the room. Thus you probably would be unable to notice a reversed polarity speaker for any of the high frequencies, but could for the lowest frequencies. Thus, if you have mismatched polarity on your pair of speakers in two corners of the room - the centre line of the room will be quiet for all frequencies, and for the lowest frequencies, the quiet area will extend well beyond this centre line. For higher frequencies, even a little distance from the room's centre line, all other places in the room will sound pretty much the same as if the speakers were "properly" hooked up.

Apropos of near nothing, way back afore most of you were born, AR LST was a happening speaker. It was said to be able to handle the output of the Crown DC-300 and SAE amplifiers. They did a multi speaker test using a steady tone to see which speaker could handle how much power. The LST's voicecoil lit up like a lightbulb at 8w and smoked at 12w... but today we have 200 watt speakers - progress!

WAOW... the quality of your content is impressive 😄 So sharp and clear, I love it !

2024 and most of us are still listening to mono audio😂

Well explained! It's about adding waves. Thanks!

I paused the video to write what will happen when you attach a speaker to a battery. The cone will either go forward or backward and stay there, as long as it is connected to the battery or until the battery goes dead.. if you do not know which terminal is positive, this is a way to find out, with a battery terminal marked positive connected to a speaker terminal, the wiring that makes the cone come forward away from the magnet is the identifying telltale sign. Which ever terminal you have connected to the battery when the speaker cone moves forward, Then the terminal on the speaker that you have the positive wire from the battery connected to is the positive wire on the speaker.. Being in rock bands through the 70s 80s and 90s, I have fried my share of speakers and a few amplifiers

Man spent 7 minutes explaining ANC

they do sound different - but it is very subtle...one sounds 'softer' and the other 'sounds annoying' ever so slightly haha great educational video on this. phase inversion is great for filtering/accenting or isolating. keep it up!

And this is exactly how noise cancellation works The microphone on the outside hears the incoming audio and plays a "flipped" version in the earpiece, the sound from outside and the sound from the earpiece cancel eachother and you don't hear outside interference

An old trick for interesting "Surround sound" is to connect a third speaker to the positive output of the left and right amplifier outputs and put it behind you... this third speaker only produces the difference signal (out of phase or otherwise), and adds a lot of "depth" to the image produced by the main stereo pair. If you add a speaker-level "L-Pad" in series with the third speaker, you can dial in a lower volume setting. We used to do this with a single speaker and a modern car stereo rig installed on 60's cars that had a single speaker mounted high up in the middle of the dashboard or back seat cushion, and a pair of door speakers in the front. We would connect the rear speaker to the rear amp outputs and use the front-to-rear fader to control the amount of "surround" output.

in fact this was the topic of my Master study in Physics. I discovered that the non-linearity of our hearing system can make polarity differences audible. This was the case with headphones and in the anechoic room with signals with distinct higher harmonics. In a "normal" room, the reflections mess up the phases of a the frequency components (Fourier) and there is no more interference with the auditory distortion products. Therefore, in a normal room you cannot hear the effect of polarity.

after the initial bit of the flipped sound, they basically sound the same but i could tell something was off in the start. Its like a gut feeling something was wrong or off, probably because listening to the two back to back the initial bit went to opposite directions and that's something i could pick up on. But as the audio continued i couldn't really tell the difference.

When you wire one bass driver normally and the other one inversed, you can use isobaric push-pull coupling to make them behave like one with double the stiffness. You either mount them cone-to-cone inside a cube-shaped box with a bass reflex tube for an opening, or you can use a big short tube as your bass box and put the speakers on both end facing outwards.

Thank you very much for taking the time making this video….it is appreciated

I think the hearing of the snare differently does happen but only when the speakers are a distance away from your ears. With your headphones on, they are right next to each other thus any air pressure difference is directly picked up. With speakers a distance away, however, the following effect gets more pronounced - how blowing (outward movements) go forward strongly like a laser and sucking (inward movements) suck from all around. This is why your speaker playing a sine wave can actually blow a net force of air forward and blow out a candle -- and means that the initial spike of the snare will be stronger if it starts in the positive and you are a distance from your speakers - as the air pressure will travel further if the cone moves outwards

This is a fantastic explanation. Great job!

Hence, a great example of noise cancelation. This was a very well done video, thanks!

in my youth years, back in the 60's, I couldnt afford a Fuzz box for my guitar so I soldered a Rectifier Diode across the negative and positive terminals and instant Fuzz, though permanent Fuzz, loved it..

I remember installing speakers in my one car well over 30 years ago and was wondering when I centered the balance that I lost almost all bass response in my 6 x 9 speakers. I flipped the polarity of one after tracking my wires down and it was correct then and sounded way better. Although I'm usually very careful about wiring, somehow that one got past me. That was a phenomenal system.

If I am wiring speakers with inverted polarity and the symmetry is adjusted correctly to zero (balanced amp output) the sound will be as usual (in stereo both speakers then are to be wired that way of course). With a more simple amp which only pushes the speaker into one direction, depending on the polarity (asymmetric/grounded amp stage), it might be not so good. Means either outward or inward. Because pulling the coil inward has some more "substantial" mechanical limits I suppose.

I am quite familiar with this concept but this video was very well done to explain it to those who are not. Bravo.

At live events you'll often see arrays or fills aimed backstage and wired out of phase. This cancels the sound from monitors and main PA. While the crowd is getting blasted. The crew backstage can speak normally and often don't need ear pro while working. They do the same thing to create "dead zones" in large clubs - areas like the lounge or the bar. Those speakers over the bar that don't appear to be on are actually doing a big job. Theme parks even use phase cancellation to kill mechanical noise.

Excellent presentation. When the two equal and opposite waves cancel each other, where does the energy goes? Must be dissipated as heat energy of the medium i.e. air.

I once accidentally inverted one of the rear speakers in my car. At first, everything seemed fine. But when I listened from my front seat, I noticed there's much less sound and especially bass coming from behind. The center (mono) waves are mirrored and cancel each other out when they meet in the air. Stereo waves are different from eachother anyway so they're not affected. But in music, usually instuments like bass and kick, are mixed in mono. L & R waves are equal, so if you invert one, you'll hear less of those instruments.

The inverse wiring can be tailored to a room. If you hold dinner parties and want background music, but not so that it overcomes conversation, then put your stereo speakers behind the furniture, but wire one backwards. The people seated can hear the music, but the people standing cannot (or significantly reduced). Also, putting a microphone in your car, and playing the inverse wave back over the speakers will soften the road noise. Great video.

The algorithm was strong with this one. Very cool!

If you connect a 3rd speaker to stereo, by connecting the positive from both sides to the 3rd speaker, tou create a 3rd channel (or just hook up one speaker using the positive of right to positive of speaker and positive of left to negative of speaker) you get a new channel. Flip that and see what it does (you need actual audio like music or other media and not just single tones). If you hook up a DC motor to speaker outputs, you can hear the media play through it.

Back when I was building and tuning subwoofer enclosures, and learned all about proper tuning for clipping avoidance, I accidentally mis-wired the internals of one enclosure. (Lousy blue/blue stripe wiring convention!) Anyway, had it all nicely tuned for max wattage at 60hz and I could hear "bass" but it was like weirdly quiet. No boom. No SPL compression on my chest. Yeah. . .a quick recheck of everything, discovering my mistake, fixing it, and retry almost left my ears bleeding. 😂 First hand experience in cancelling sound waves! Thanks for the vid too! Excellent scientific description of my "oops!"

Aside from stereo cancellation, sawtooth ramps and timbres are effected, sine waves not so much. It's less noticeable on cheaper speakers and higher frequencies where the amplitude shape tends to round itself closer to a sine wave anyway.

Yes, there is a difference in the audio. back in the days in high school ive been repairing my messed up headphones or earphones and i experiments it by changing the polarities of my the stereo earphones and they sound almost the same but not immersive, as it usually does. It was different so I can say that these two type of sound may sound similar, but they are not the same

For a single speaker in open air, I guess it won't matter much. But for a subwoofer in an enclosed box, it may make a big difference. Correct me if I'm wrong but when a big bass comes and the speakercone goes outwards, it creates underpressure inside the box which will sound different compared to when it goes inwards, creating an overpressure inside the box. If it's a perfect sine wave, this won't matter at all but with audio, which is hardly a perfect sine wave, this may actually make a difference. Also what you described as both speakers that will cancel eachother out will only be this way when you're in the middle between both speakers. If both speakers are on opposite sides of a room and have reversed polarity, you should not be able to hear (much) when you're in the center of the room but you should be able to hear the music when you're closer to one speaker compared to the other since soundwaves need time to reach your ears due to the distance they have to cross. This distance doesn't have to be much since you hear the same sound with both ears but due to the distance between both ears, you're able to pinpoint where the sound is coming from due to the slight phaseshift between both signals at your eardrums.

Phase is shifted 180 degress. Thank you. This was my ted talk.

You can demonstrate the effect of the phase inversion more thoroughly using a stereo audio track and output for your listener, in addition to the examples you provided. Flip the polarity on left or right channel while leaving the opposite channel untouched.

Wow, awesome video! I have always wondered what would happen and noticed no diference... great explanation man! Thanks

Eyy, I finally have a use for the stuff I learned from my somewhat crazy science teacher in High School who was really exited to teach us how sound waves, etc work.

Position also matters. The center line between to speakers ads up when in phase. However, when an observer isnt in the centerline position. In phase can become suboptimal.

This is good to know. Wind noise is always an issue when it comes to motorcycle helmets and trying to listen to the integrated Bluetooth at highway speeds can be an issue. So I'm going to cut out the speakers and splice in a set of earbuds. The earbuds looks similar to ear plugs so I'm hoping they will act as ear plugs for external noises (wind and engine) but since they are earbuds, they'll deliver sound directly in my ears. My concern was splicing the wires backwards, especially if they are not colored differently beneath the outer insulation. So it is good to know that it shouldn't make a difference since each earbud is delivering sound directly to each ear so there won't be any sort of destructive interference. My only concern would be if each ear is getting a signal that is 180 deg out of phase from the other, would it be detectable then?

2 speakers that works together in opposite polarity is the main concept of a noise cancelling headphone. Pretty cool stuff. Generally, there are 2 types of noise cancelling; the one that reduce the air pressure around or in your ear and the one that uses the concept that was shown in the speaker. Pretty cool stuff

i can hear the difference in very specific frequencies and its very subtle. that is only if they are played back to back though. i couldn't tell you where on the wave a note started lol

This makes it a lot easier for me to understand noise cancelling speakers because they would be actually be pushing the opposite direction from usual even though the signal is so similar

Nice concise presentation. Thank you.

So for stereo sound it is now clear: Use correct plus and minus wiring. But what about subs for surround systems? My sub has a setting called phase, and it can be altered in steps between 0 and 180. Seems to be the same thing like plus and minus (subs are wired typically with coax cables, which can not be used wrongly). How can I find out the correct phase setting, with no special tools? Maybe only a wave file?

yes, they signals would cancel if you were in the correct location hearing the 300 hertz, but that wavelength at 300 hertz is about 1.1 meter, so with mono tonal stereo kyou could move about a room and in theory find quiet canceling nodes and loud reinforcing nodes. Or in the case of doing the wiring right the nodes would be reversed, but still exist.

Great Info ! Although I plugged the speakers all the same way I always wondered about that.

I reverse the polarity of tracks i want to stick out like main vocals when mixing. Great video!

The reason for polarizing the connections is to force the speaker to move in the same direction for the same signal… ie they are in phase … out of phase setups can be detected by equipment but not necessarily to the normal listeners