What Happens When You Wire Speakers Backwards?
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- Опубликовано: 27 июн 2024
- Have you ever wired a speaker backwards? What happened? See and hear it for yourself in this video.
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00:00 - Opening
00:29 - Experiment #1: Speaker & Battery
02:25 - Experiment #2: Transducer
03:51 - Experiment #3: DAW - Sine Wave
04:24 - Experiment #4: DAW - Snare Drum
05:03 - Experiment #5: DAW - Multiple Speakers
07:30 - NEXT VIDEO: • Everything You Need To...
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If you wire your speakers backwards and listen to country music, the guy actually gets back his horse, his job and his wife
LMAO 😂
Yes, but now his existential angst is too much to handle, thus Emo is his new jams.
And if you are listening to Blues music, all the above plus it stops raining.
Plus, he quits drinking
you forgot his truck
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.
Hope you kept that thought process in your older years. You did what 99% of the people won't bother with these days and just throw it away.
@@PauldeVries I still regularly take things apart. Often only to see what's inside. I've gotten a LOT better at putting them back together again as well. lol But yes, 99% of the time I will try and fix it. I'm cheap and would much rather spend a couple of bucks on parts and a little bit of time instead of tossing it out and replacing it. That's one thing my grandparents taught me: Repair it until it can't be repaired any longer and then salvage whatever parts you can and repurpose what can't be salvaged.
@@Enjoymentboy Yes, things are more useful than meets the eye sometimes. Hope you gave yourself credits for that ;)
Pretty sure she would have given you credit if someone had thought her how and why to do it. Don't think she intentionally held back on giving you credit. But yeah man, sometimes those unimportant moments for adults can become lifelong memories for kids.
@@exshenanigan2333 well said
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.
I like that it was explained without assuming every member of the audience already knew the basics. People often skip the basics, and those are so important in building a good foundational knowledge. I agree. He did a great job, and his voice is calm and soothing. He makes good eye contact, and speaks without ums and ahs.
Thanks!
Yeah you are right bro, all people can broadcast information however what make difference is the Way of delivering that information. This respectful Guy touched the top of perfection in his explanation.
Every time I wired up my speakers backward's,, They wouldn't play but only listened.
once somebody put the batteries in backwards on the energizer bunny, and he kept coming and coming and coming.
LOL! Seriously! bahahahahahaaaa! *Dad Jokes
"Why are my speakers not speaking"
"They don't agree with each other'
As a musician, this is genius
Putting them in different closets in the dark for six months may cure this.
@@johnb3141cancel culture is literally destructive interference ...
Might try this with my gf, thanks. Hope she doesn't come out gay. @@raymota4515
I would have thought that disagreement would cause a 6db increase in sound level.
This how noise cancelling systems work, listen to the unwanted sound and invert it add back to cancel the unwanted sound dynamically.
Yes, except it has to be done fast otherwise it wouldn't work
Is it done fast or do they guess what sound will come in the future? I know some years ago it was just trying to predict the sound, but maybe nowadays devices are fast enough to do it on the run
@@tatomar001 Pretty sure it's a combination of both
@@tatomar001 They passively listen, basically you have microphones facing outwards recording the world, then some clever signal processing analyses and inverts the signal and adds it to whatever you want to hear. When playing this new signal most of the noise from outside gets canceled out, leaving only the intended audio track. This is called active noise cancelling (ANC), there is also passive noise cancelling which just plays some grey noise (or similar) to drown out the unwanted outside noise. Most systems use a combination of both, as passive noise cancelling is far easier. This is also why you sometimes hear a soft hiss when you activate ANC.
@@lbgstzockt8493 passive noise cancelling is basically what earplugs do, no noise is used.
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.
Absolutely correct. I was going to post similar comment. If that would be no difference at all then drummer can put his kick pedal in front of bass drum and play that way. But nobody ever played such way in a music history for obvious reason. You need LF sound kick to propagate toward audience. However I agree that it would be no difference in mid and high freq ranges.
very important !
This. Difference between a pressure wave and a lack of pressure wave.
If that were remotely true JBL would have never wired their bass drivers reverse polarity.
@@keithmoriyama5421 😂
I knew this but this was the absolute best depiction of the principal I have ever seen. Well done!
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.
So you experienced wave cancellation by first hand 😂
I worked on a recording system that sounded perfectly fine but when you tried to record you got nothing. Someone wired one of the inputs backwards so the mono signals from the mic were being cancelled.... The tech who installed it couldn't figure it out for 2 weeks.
@@BrettDaltonLOL!! It happens to the best of us
Haha that's a good laugh. I mean in the sense that we've all made simple mistakes but genuinely bothered us. Then we happen to stumble upon the solution like it felt sorry for us lmao
Bro’s made of positivity👍
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.
It's heard in all frequencies that are pannes with an identical signal to both speakers. It's the same as a common mode interference supressor in a balanced signal chain. There is usually just one bass and bass drums are usually not panned so that is why they dissapear more than other instruments, has nothing to do with them being low frequency though.
I once played at a psytrance party where one of two subs was wired incorrectly, resulting in the bass literally disappearing right in the middle of the dance floor. 😂 Since is was open air, you hadn't even echoes from walls. Super weird.
@@NeovanGoth The person that made those speaker cables really messed up. Should never happen in a PA system since the speaker cabler are hard wired unless there is a phaze switch somewhere in the system.
I heard about phase back in the 70's. I don't recall being able to hear a difference, but I didn't have speakers that reproduced heavy bass. I've always tried to wire correctly anyway.
Is this how noise cancelling headphones work? They layer on top of your audio an inverted waveform of whatever ambient sound you're hearing?
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.
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!
My college roommate blew out his rear glass because he was trying a test and realized a wire came loose or something. Suddenly bbbrrrrrrrtttttt and he was covered in little glass cubes.
Both subwoofer were trading the airflow they were producing.
After I saw a friend of mine fry his car amp doing what you did, I always turn off the power before switching wires around.
I had an NX2000.
Out of principal you should only do wiring with everything turned on 😂....we did that with our cncs also😮
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
my science teacher did this in school with speakers out of phase and made us walk around the room, the volume changed depending on where you were in the room because of the phase cancellation
But that messes with the "dubbing"
The effect is still in play when recorded, and requires micro editing in the DAW where cancelations occur in track adding...
Someone once suggested changing the waveform, but it's still the inverse frequency loss to deal with.
I seem to recall an old CD player stereo my sister got for Christmas had this as a feature?
(I think it was intended as a Karaoke mode?) I don't remember much other then it was weird to child me for the vocals to just all the sudden disappear like the vocals were on some different audio channel getting disabled.
If you mess with polarities you'll destroy low freqs and some mids as well
Zackley
This just happened to of popped up on my RUclips. 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.
This is something I've never really even thought about although I essentially knew what the effect would be but I'm glad this video was suggested to me, nonetheless. Very well done and interesting topic! Fantastic visualization and explanation
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.
Also, polarity is a reversal of a physical or electrical connection that results in a 180° phase shift.
Many issues can create phase shift. Polarity reversal is just one that has a singular shift.
you must be fun at parties.
You can but they will be different at all frequencies. Simply having one speaker further away from your ears than another will give you a phase change - could be partial or the full 180 depending on frequency.
Yes but phase shift varies with frequency, so you cannot simply apply it to music as a way to counteract poorly-wired speakers.
exactly
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.
I hate that effect. Gives me a weird feeling in my ears.
Deafening silence
@@jnawk83 You do not get silence, only damped bass and the higher frequencies is pretty much unaffected but with weird / cool sound effects of "sound phasing".
It can result in a kind of "fake stereo" effect. When I was a kid I got a kick out of doing that. Even better was setting up an AM radio and FM radio on the same station (here in NZ at the time we had stations that broadcasted on both) for whatever reason there was a significant time difference between the two, causing a fairly extreme slapback echo effect. It was a trip.
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.
This is the best audio engineering channel on RUclips.
Facts
Anyways, thanks for the suggestion!@@corporealundead
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.
Cool idea!
I used the "Chaldini" plates with small metal slivers and video taped them in the 80's. I recall Velvet Underground being quite interesting.
Installing a stroboscope illuminating the water at the same frequency as the waves, will also make it so that the waves appear stationary, so the differences can be pictured better
@@rojirrim7298 I think showing the agitation of the water would be better. Otherwise, when you have a spot with looks like it hasn't moved is that because it cancels or because it just isn't moving at that point.
Alternatively, the stroboscope slightly off frequency, so you can see the waves moving and interacting.
huh huh....you said words.
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.
Thank you very much for taking the time making this video….it is appreciated
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!
Right foot first or left it doesn't matter unless you want to coordinate with another. Just like dancing.
Until you step on your partner's foot.
@@codahighlandThat would impede the good ol' rhythm, no?
Dancing is sinful.
@@BeforeAndAfterScienceI guess Psalm 149:3 is sinful then... maybe the Bible is sinful. Maybe God is sinful. Maybe God is Satan...and Satan is God.
@@BeforeAndAfterScienceNo Scientist makes such an open ended statement without qualifying the parameters thereof.
There is a fascinating explanation within this video (starting at 5:02) of constructive/destructive interference in wave patterns using sound waves instead of the typical light waves. Well done.
Well explained! It's about adding waves. Thanks!
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.
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 RUclips where you can listen to in-phase and out-of-phase white noise that demonstrate this.
What you describe results because vocals and other instruments that are intended to be front and center experience more interference than those panned more to one side or another because they are essentially equal in each speaker. This causes more cancellation of anything in the center.
Im not 100% sure I am correct, but i heard somewhere over the years that some high end speaker manufacturers using a lot of X-over points design speaker cabs with the low bass drivers intentionaly wired 180 degrees out of phase to take advantage of this phenomenon and give the low end a wider sound stage
@@Angel-fq7ww Interesting idea, however, I wonder about this. Bass frequencies are extremely problematic when out of phase between multiple speakers. I would expect dissonant artifacts that would be anything but audiophile, from such a setup.
I don't know the specific acoustic properties, but in the concert PA world, it's fairly common now to physically reverse several of the subwoofer boxes, but not to create phase artifacts. It's done to acoustically cancel bass frequencies behind the subwoofes. It's the speaker equivalent to phase ports on the back of directional microphone capsules. The steers the bass towards the audience and away from the stage where it can be problematic vibrating the performers, their gear, and the microphones on amplifiers and other instruments.
Thank you for a simple and understandable demenstration . I've always been very careful when hooking up my speakers correctly . Just never knew how important the audio results would be ...........DGR
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.
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.
Fascinating. I worked on that stuff too.
Although music is all different frequencies, so there's no one distinct phase change, so may as well just keep all the speakers in phase imo.
Yes. But you guys make me think about something here but not here. We don't have it.
Let me imagine this for a moment or so .. Can't we have a button on our so, advanced remote that we can flip polarity around?
You have to do the math between the ohms of the speakers and series and parallel loads on the amp. You just can't hook them all up in parallel like most people would. Thankfully those days of problems are loin behind me. Uh I meant long behind me. Same thing I guess, oh well.
@@TimpBizkit You are correct that music is all different frequencies, but when you reverse the polarity of one speaker you are reversing or changing the phase of all of the frequencies to that speaker in relation to the other speakers by 180 degrees, so *_PHASE MATTERS._*
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.
Playing the difference between channels (left minus right) usually cancels out the lead vocal and the bass because the lead vocal and bass are usually mixed dead-center. You get some of the instruments and some of the harmony vocals. It can be mildly amazing. Try it on Olivia Newton-John tunes (she's almost a choir). "Saturday in the Park" by Chicago some surprises that cancellation brings to the front.
@@qazmatron It all depends on the mixing. Many recordings, to save money or because the engineers have tin ears, record the vocals or guitar solos or bass monaurally, and then pan them to the center of the mix. With a single monaural source it's relatively easy to inject a 180º opposite and thus cancel out the original. With true stereo recordings, not so easy.
@@rcarlberg Just flatten the stereo signal to mono...
@@rcarlberg Just flatten the stereo signal to mono
Hence, a great example of noise cancelation. This was a very well done video, thanks!
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.
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.
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.
I've felt headphones change my head shape, and damage hair follicles. I'm going to have to play with this, someday.
Actually if you wire your headphones backwards and out of phase with the earth's magnetic field, it causes and aluminum foil hat to grow right out of your head between the hairs, this is fed from the years and years of using underarm deodorants and taking excessive jabs (those "j's" especially as hey go right to the brain which is in close proximity) to the "hat" growing area! Napoleon Hill was experimenting with this, you can tell from his pictures, even tho b&w.... you can see the tell tale peak starting to grow - this is probably WHY his book *"Stink and Grow Rich" was transcribed to cassettes later on :P (*Written after "Think" due to people who avoided the deodorants to stop "hat growth")
Called "balancing phase-shifts"
An excellent, illustrated, detailed, demonstration of speaker polarity, an important factor one that I have been promoting for over 50 years!
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.
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.
would this still work or would it be obsolete with newer technology?, im sure i can look this up but i want your opinion and im a little lazy
@@dom_xi-dzopa720 I think it would still work. The signal going to the speakers is analog.
It works... Poor man's surround sound...
this was pseudo quadrophonic sound system developed by a bloke called Hafler. i have had my stereo setup like this using 2 speakers for the rear wired in series but opposite polarity since the seventy's.
What a flashback! I had a 1970 Mustang Mach 1 with a Pioneer Supertuner hooked up to a Pioneer 100W amp. 2 bookshelf speakers with 8 in woofers seatbelted in the back seat, each with about 30 feet of wire. When we were hanging out at the park, speakers spread apart and awesome tunes!
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.
I found your comment after I posted mine.
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” .
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
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.
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.
That last bit is wrong. The coil and therefore cone excursion is held in an equilibrium and the availability of excursions in and out are the same therefore there is not any damage to the speaker that sucks in first. It does that hundreds or thousands of times, a second anyway.
@@jamesm90 I wonder if damping circuits are expecting specific phase on the initial signal and could that have something to do with whether or not the damping is effective on the first impulse?
I suppose this would be most of the concern for powerful low and very low end signals like sub-bass since now we're concerned with these things down to 5 CPSand such
This honestly makes me feel better about repurposing speakers without clear labels on the wiring to a new receiver. They say the positive usually has dashes or text. Well, I had dashes on one wire and text on the other. Took my chances with dashes on positive, and made sure to keep it consistent.
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!"
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
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 noticed this on at least one of their songs about this. The vocals were very low.
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.
Gracias, ahora entiendo perfectamente, muy buena explicacion
In a world of misinformation, particularly on audio, this channel is such a breath of fresh air! Superbly explained too.
The "audiophiles" as they call themselves are also incredibly toxic. Ask any questions and you'll get smugly talked down to for not knowing. Disagree with them and you'll get the most vile insults. Stay far away from them.
@@PunakiviAddikti Not only will you get ridiculed for not knowing, but you'll be buried under a mountain of wildly inaccurate or downright wrong information right after.
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.
What does bridging an amp do??
More than you wouldn't believe I was getting ready to throw him away when I realized I had a branched it which I branched it correctly I was shocked at its performance
@fastone371 Bridging just takes 2 channels and combines them to create a single channel with double the power. So 100x2 becomes 200x1, only a bridged amp treats whatever load (8-Ohms, 4-Ohms, etc.) as half the resistance, so a good amplifier delivers twice the power. So that 200x1 can become 400x1. Power is determined by the load. When you halve the load, you double the power, but only if the amp is designed for it.
The old school Orion HCCA amps that were 25x2 @ 4 Ohms were 100x1 @ 4, 200x1 @ 2, or 400x1 @ 1 Ohm.
I am quite familiar with this concept but this video was very well done to explain it to those who are not. Bravo.
Phase is shifted 180 degress. Thank you. This was my ted talk.
I've said it before but I'll say it again: you are an incredible teacher!
Thank you!
I'm Subbed now. You bring back old memories.@@AudioUniversity
Very professional as a teacher for the audience. Great speaker-tone, good info. You have a gift to teach
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.
Excellent video.
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.
So what your saying is if I know which way to wire it before hand like if I mark one red and one black and call it forward for up and reverse for down then we will know hownto connected the speaker just in case they make a mistake like in the factory and forget that hey don't wire that speaker backwards because the customer won't know the difference but don't tell them it's a dc speaker. Sounds good 👍 where did you go to school?
i will add more. waveform don't has any connection to speakers.
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.
Kind of like the same effect as a fan - there's strong directed flow out of the front, but no strong directed flow into the back?
A snare is usually tuned to ~ 170 hz so that initial "pull" is only 0.0029 seconds (2.9 milliseconds) long before there is a "push" and the cycle repeats.
I'm fairly sure you hear placebo. It makes no difference to a speaker whether it starts the waveform this or that way.
@@hughobyrne2588 No, a fan does not produce a waveform (unless you have a rotary subwoofer). A speaker does not blow air like a fan. The only time you feel air move is when you have a vented sub where air starts to move relatively fast or a horn speaker playing bass at loud volume. But since sound is a waveform, there is no front or back per se, it varies like AC varies in electric grid. Doesn't matter which way you put the plug in.
@@Munakas-wq3gp that is true, a speaker doesn't care, but your inner ear does.
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.
Really well explained.
WAOW...
the quality of your content is impressive 😄
So sharp and clear, I love it !
Man spent 7 minutes explaining ANC
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.*
Unless you want one to be on reverse polarity to create intended zones of sound reduction
The best explanation ever!
They start speaking Spanish
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2024 and most of us are still listening to mono audio😂
Why though
Great explanation thanks
Thank you for this video
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!
Agreed, version B irritated me somehow.
@@liberatumplox625 B Is out of phase, very noticeably softer in mono while stereo in that scenario will be unable to give focus in the middle because the 2 speakers are canceling out each other. Some recordings may be done out of phase deliberately for a much softer and less focusing music reproduction.
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.
I reverse the polarity of tracks i want to stick out like main vocals when mixing. Great video!
*BEAUTIFUL EXPLANATION*
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
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
When I worked on cars as a Auto Electrician in late 80’s. So many cars had owner installed stereo’s with no regard to polarity! I could hear the dullness and fixed many.
What you demonstrated with the "Cancelation" is a great demonstration of How Active Noise Cancelling headsets work, Like My Jabra 75 Evolve at work...I can't HEAR the sub-audible noice Cancelation...But at the end of the day, I can feel it...if that makes sense...it's almost like a slight ear ache, like a sore muscle, so that's why I try to only use it when it's loud in the office...I wonder if others have similar issues? - I have 2 Identical Headsets...and they both do that to my ear drums...Not that I am complaining, 8hrs of wearing headset is not hard work.
I built a speaker box years ago where they were bolted face to face with one inside a sealed box and the other outside the box. Inside the box was wired normal and the outside speaker wired backward. It worked great.
Love the explanation in this video extremely informative! I just have one question, will having 2 speakers wired oppositely effect the sound coming from headphones? Since the 2 audio waves never meet each other before reaching your ears? Would there still be no audible difference to the person wearing the headphones since the sounds coming from the speakers are audibly the same?
Wow, awesome video! I have always wondered what would happen and noticed no diference... great explanation man! Thanks
Great explanation of how speakers work!
Great. That was nicely done. Thank you.
Beautifully explained.
Fantastic explanation ❤
Awesome exposition!
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.
When I was in school, this was one of the reasons I loved physics class. It's kinda insane to me to realize that speakers can in fact cancel each other out, but in the real world, such things don't happen that often or not as badly. The reason, as stated at the end of the video, is that the sound waves do not travel only directly into your ears from the speakers, but are also being reflected by walls, for example, thus coming into your ear just a little later than a second speaker might and the waves overlap diffently. So if you position two speakers with opposite polarities at the same distance from you, you might actually hear the sound less loud because the opposite polarities end up canceling each other out when they hit you or just before that.
That was very interesting. Thanks
I learned this a long time ago before even viewing this video. The speaker will work either way but if you connect them backwards, they will be "out of phase", the cone of the speaker moves in the opposite direction as it should which affects it's performance.
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.
Well explained. Thanks... ❤
The algorithm was strong with this one. Very cool!
Audio signals, as you correctly point out, are oscillating polarity (AC) so there is no "backwards" or "forwards" in wiring up a speaker -- as long as all your drivers are wired with the same polarity. The phenomenon you're describing is called "absolute polarity" and it posits that, with a "correct" wiring, the attack of a drum hit will drive the cone forwards into the room first, the same as the skin of the drum. However, as the drum skin quickly bounces back in the other direction, the wiring of the speaker becomes a non-issue. The ears aren't capable of hearing the difference. It DOES make a difference that all your speaker cones be time-aligned, so all your drum hits occur in unison instead of canceling each other out, but that's kind of a separate issue.
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.
Just to clear some things up here. If the driver is wired to move outwards at DC, this does not mean that it moves outwards for a positive voltage across the entire frequency range. Below its fundamental resonance frequency, it does move outwards for a positive voltage (assuming one polarity of the two choices). However, then it moves INWARDS for a positive voltage at higher frequencies well above it fundamental frequency. This is typically also what you want, because the inwards movement will result in a positive pressure when the driver is loaded with a free-field-ish condition, which a room pretty much is at higher frequencies (excluding at lot of details here). This goes against most acoustical engineer's intution, but the theory as well as simulations will reveal this. So the battery test is merely a proxy for what is actually going in the frequency range of interest; the pass-band of the driver.
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
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.