What's phase inversion?
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- Опубликовано: 12 июн 2024
- We hear the term phase inverted, or it's out of phase. But, what does that mean and why are some amplifiers advertising the fact their outputs are inverted?
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@6:52
"Flip your speakers around"
He meant to swap the end-points of the cables going to each speaker. In other words, the cable that you would normally connect to the "positive" speaker terminal would, instead, connect to the "negative" speaker terminal. Likewise, for the other cable.
The same cables that would normally go to your left speaker still goes to your left speaker. You just connect those cables to that speaker the opposite way you would normally connect them. Ditto for your right speaker.
You are not flipping your speakers around. You are not sending the right channel to the left speaker, and the left channel to the right speaker.
By the way, if your stereo is good, then you can tell when the music is out of phase.
It is not always apparent. It depends on the song. Some songs really get wrecked when they are out of phase. All songs get worse. It is just that your perception will vary depending on the song.
If you want to hear it, just swap the connections on the back of your speakers.
If that does not reveal enough, then swap the connections on the back of only one of your two speakers. That will really destroy the imaging.
Oh, I thought he meant to literally turn them around, toward the wall.
Never experienced any noticable differenbce when doing that on both speakers.
But if you only do it on one speaker then yes.. But that mostly destroys the bass since left and right then will cancel eachother out (one speaker moves forward and the other backward).
There is not positive and negative on a speaker input. It's an AC signal. All that matter is that all the channels are connected in the same way.
Very disastrous on John Tavener's Liturgical works given that in live situations the overall sound levels on this kind of music seldom rises above 45dB SPL.
and how do we do that cable inversions to studio monitors which have either XLR or TRS inputs. 😕
Thanks for this Paul, I have a hybrid integrated amp that has a single tube in the pre-amp stage and the owner's manual says to reverse the speaker cable connections, so now I understand why :)
....I used to make the BBC's Infinite Monkey Cage programme (and podcast) many moons ago, with Brian and.......Robin Ince!....always like your thoughtful videos Paul - so feelings are mutual! Keep up the good sharing...
Thank you for turning me on to The Infinite Monkey Cage.
I had an early Adcom CD player and a tuner/preamp. One of them had an absolute phase button. To save my life I could never tell any difference whatsoever. I hypothesize the reason to be that it was switched on and off under main CPU control and so it had a split second of dead time in between states, preventing me from hearing the transitional point.
BBC Radio 4 can be very snobby and patronizing, but when it is good it is the best radio out there. My dad got me into it as a kid and it opened me up to so much I'd never have picked up in a library or online.
Some songs are released from the record companies as out-of-phase.
It is not them trying to stand out. Rather, it is their incompetence.
This is why some pre-amps allow you to reverse the phase (saving you the trouble of swapping connections on the back of your speakers, in order for you to properly hear the occasional out-of-phase song).
If it is a digital song, and you do not have a "phase" button for your pre-amp, then you can use music editing software to reverse the phase of the samples. This puts it back into phase. The record company mistakenly reversed the phase of the samples, and now your reversal (via your music editing software) reverses that reversal (or undoes their mistake).
Another screw-up, albeit rare, is that record companies will release a song with the channels reversed. The sound coming out of your left speaker should be coming out of your right speaker. Ditto for your other speaker.
I am not aware of any pre-amps that have a button to correct this. Your only fix is, short of swapping either interconnects or speaker cables, is to use (if it is digital) music editing software to reverse the channels.
The arturia pre1973 has a phase button, it makes analog bass from a matrix brute sound amazing
This was very helpful. Thank for the explanation.
Thanks for letting me know.
Great informative video!
Totally audible is the difference between normal,one channel reversed,both channel.Swap polarity on one speaker: unfocused centerless image weak bass.Moving towards one side the total image shifts to that side,this is also audible on mono signal where everythig must sound from the middle.
Total inversion,both speakers polarity swapped.less significant but it sounds different.
Another problem can be the acoustic bass cancellation.I had two speakers that had 30 cm woofers,but I heard not enogh bass in the centerpoint.Turned it up but from outside it was too much.
Someone explained that low bass notes wawelenght is bigger than the room,so it does not fit in so when the wawes meet in the middle they quench each other.That is also phase problem.
Here is what Seymore Duncans has about phase -
Every pickup coil has two properties that affect how they will sound when they are combined with others. These properties are called phase and polarity. Phase is the direction current travels through the pickup, and polarity is the direction of the magnetic field. With both properties, there are only two options. Phase can either be “top coming” or “top going”, and polarity can either be “south” or “north.”
The same must be true alout all other electrinics wth magnants and amplifers. THANKYE YOU, bEtter I trust anenjineer than a fysicgts ona web paiges.THUMBBSUPS!
When combining signals from multiple pickup devices, it is definitely important for all of them to have the same sense. But that is a different question.
What is debated, is whether changing the sense of *all* pickup devices at the same time, would be audible.
Marianne Oelund: Thanke Youe. Yues have alway ebeen a goods frends!
Maybe you could digress on the asymmetry of positive versus negative portion of the waveform?
What about the Infinity RSa's that use the woofer as the midrange out of phase?? And my IRS IIIa's the Emits are wired out of phase.
Is that a tall boy beer under the bench by your knee Paul?
Interesting topic. I ran into a phase problem on stage with floor monitors. They were two being used on either side of the lead singer and she kept complaining something sounds really strange.
After investigating, I found all speaker cables were wired correctly. So later I took the floor monitors apart and found that one of the speakers were reversed with their positive and negative wires on the cross over board! Must of happened at the factory. Both speakers were the same model and if used separately would have gone unnoticed.
If you can predict what your signal is you could mess with its phase, but not typically an audio signal. If you have 2 different signals you could invert one so they don't additively mix, but it could do the opposite as well, depending on the signal. If you inverted the same signal you get closer to totally cancelling the signal, depending on the phase. The phase may be really offsetting the in line delay that could cause problems in a multi unit audio setup.
The driver will move inwards for a positive voltage, not outwards, when looking at it steady state, above the characteristic frequency, and assuming a minimum phase driver. The main reason you can hear absolute phase is that the ear is a nonlinear system.
Yep, that happened to me. After some work done at my home, I reconnected everything and when I finally could listen to music I noticed that the bass was much less then I was used to with my system.
After fearing that something was broken, I found out that on on of my speakers I by mistake flipped the cable on the speaker side. So I guess that ,that’s why this speaker moved out of fase. So the bass was partly canceled. After flipping the cable I had full bass again
Sorry in advance for all these questions... What is the role of the "phase inversion switch" on DACs ? Is is only to adapt to a system with inverted polarity or does it have another purpose such as sounding better ? How can you check you're correctly "on phase" ? And last, if you don't hear a difference, does it matter ?
You can check if an audio file has correct or inverted polarity with an audio editing software. But when streaming music only your ears can tell. And only if you have a good enough system and know what to listen for. That's why I advise you, if you cannot hear any differences then don't bother, just leave that setting on NORMAL position and simply enjoy the music.
I listened carefully to in vs. out of absolute phase and to me it sounds like a person playing a trumpet is sucking instead of blowing when out of phase.
Howdy. In my mind.
One should talk about phase inversion or phase mirroring. One should not talk about 180 degrees out of phase. That would suggest a shift in time. The time being half a cycle time.
I suggest having the input and output phase mirrored decreases the risk of oscillation.
Regards.
people always confuse phase with polarity.
What about phase when it comes to external speakers such as a subwoofer that's separate from your 2 channel HiFi speakers? Ones that have "phase control"? Is that more referring to the speed of the audio signal to your ears or is it an electrical thing such as what you're referring to in this video? And what about subwoofers that don't have phase control? What happens then?
I'm not exactly sure but a lot of speaker manufacturers change polarity on the midrange of three way speakers and this is why as it was explained to me. Each order crossover is out of phase
1st order 90°
2nd order 180°
3rd order 240°
4th order 360°
So if I make a 2nd order speaker my midrange will be 180° off my woofer and tweeter because a midrange is a 2nd order high pass and a 2nd order low pass connected together. So if I reverse the polarity it becomes in phase with the woofer and tweeter
Yamaha receivers have had problems with phase since they tell users their speakers are out of phase when they are not.Yamaha states that if out of phase message comes up in YPAO calibration and you know they are not out of phase, ignore the message.
The best example I know is with my Fisher 800B. They were from the early days of stereo using one amped separate channel for AM and one for FM. iT has a strong AM to coincide with the FM circuit. It has an actual phase inverter switch so its easy to tell the difference. It has 22 tubes with a circuit for multiplexing the two separate circuits. It was called ":multiplexing" back in the day, and in high demand back in 1962-63. They sold for between $450-600 at the time. About the price of a decent used car. It sounds wonderful but I'm using Sansui 3000 speakers. Although it does still sound great and I get many compliments on the system.
aeaaudio.com/portfolio-item/fisher-800-b/
SIMULCASTING a terminology rarely heard of or used anymore. Sometimes TV stations even paired up with receivers.
I have a very resolving system and I can hear changes to the sound even with little tweaks here and there. My DAC has a phase inversion option and for the life of me, while I hear "something" in the sound changes when I invert phase, I have a very, very hard time pinpointing exactly what changed! It's so subtle. Am I alone here?
I'm guessing that phase inversion option allows sound engineers to listen critically to each channel. Inverted left compared to right channel eliminates combination (addition/ subtraction) of wave forms.
....i feel/hear what you are saying about the tweaks. About "fase"; there are moments/hours that it is hard to hear a difference when i switch the ac connector to hear it is in or out of fase. Other moments it is more easy. It also depends on the type of music /song etc. But there is a difference. To me it's like a chocolate ice cream of 2 different brands; the one tastes better then the other when you compare. Eating the lesser tasting one is nice, especially in summer...but at the same time taking a bite of the other brand makes u dislike the lesser brand... and make you think/know that that is the better one.
😂😂😂😂Easy to make fun of me now..and i don't give a shhhhiiii....icecream.
I have some experience bij switching cables etc. because of changing my set up and then take a listen and it sound great, it is all good and then listen for days. But in that same days i notice thats something is not right, i am not enjoying my music as i want. Is it me, is it my mind state or? And then i turnaround the ac connector from the equipment i have changed or another one that i had disconnected and start listening again..... And the it is all back...the emotion i was missing. Fase is an important thing...
It is subtle indeed and one should listen very carefully to hear the difference. But once you've learned what to listen for then it becomes way more easier to identify the correct phase, it sounds more natural. The better the system you have, the easier it should be to identify the correct polarity.
@@leonarddaneman810 Very curious what DAC you have ?
@@ohnonate Analog Devices AD1955 . . . HD 990 employs two high-performance stereo digital-to-analog converters to deliver third-generation Real-time Linear Smoothing (RLS III), creating a spacious, richly detailed sound that other players simply cannot duplicate. Uncompromising quality combined with audiophile engineering let the Harman Kardon HD 990 single disc CD player give near-perfect reproduction for your favorite discs. And, it is fantastic . . . it was designed to accompany the HK990 . . . I use it with an HK 3490.
I'm sure some hybrid pre-amp DAC units can outperform the twenty-year old AD1955, but I haven't heard anything better yet.
Phase only matters when there's more than one driver ( or more than one speaker system)
Is this the articl yoeu were thinkig of -
The Technics 7 was the prototype for the linear-phase series developed to address phase issues in multi-way speakers. The most characteristic feature of the Technics 7 was its unique design based on linear-phase theory. Excellent sound localisation was achieved with flattened sound-pressure frequency response and phase frequency response by arranging the sound source centres of all the units in one straight line as seen from the side, as well as staggering their positions somewhat in the forward and reverse directions in order to provide correction
THNK YOU AND TUHUMBS UPS!
on my car subwoofer use in phase equal to loose -2db of sound pressure.
I do not believe I can hear any differences by flipping the phase of my speaker wiring 180 deg, as long as I change the phase of both speakers. I have found though, that amplifiers with uniform phase across the band, (particularly at the low end) are better behaved, to my ears, when setting loudspeakers up in a listening room.
Can someone hear the difference in the sound of a kick drum listening in front of the drummer compared to listening at the back of the drummer??
Are we talking here about Nelson Pass' "Zen" and "Bride of Zen"?
REL subs give you a choice of Phase too?
Yes they do.
Most subs do, the better ones are variable.
So maybe someone here can tell why that, back in the early days, JBL wired all of their speakers out of phase. Ie the first movement of the cone going backward instead of forward? Why did they do that?
Phase inversion.....A new term for the current situation.
Is there a way to find out if my amp does phase inversion?
Howdy. Yeah.
Monitor the input and the output with a two channel oscilloscope.
Regards.
Phase 0 - 180 is the same as changing the polarity of the speaker cord! Phases 0 - 180 are used offte on an active bass box. It's the same as if you had to change the polarity of the speaker
If you connect a cord to one speaker incorrectly you will hear the bass become weird as one blows in and the other speakers blows out.
Absolute phase makes absolutely no difference! Relative phase between drivers or channels makes a difference, because phase cancellation can occur and this affects what you hear...or don't hear. The crashing symbol example makes no sense, sound is by nature a signal that is changing at some rate. Your ear can't tell if the signal is positive going or negative going. If the speakers are out of phase relative to each other, and you are standing in a spot where cancellation occurs, you won't hear all the audio.
Take a pair of binoculars. Look through them and see how everything appears closer than they are. Now, turn them around and look again. Everything appears further away than they are. Optical polarity reversal.
On my mono subamp in my car I can adjust the phase from 0 to about 300 degrees or something like that. No steps in between.
On my Velodyne sub at home I can choose between 0, 90, 180 and 270 degrees with the remote.
Do any of them sound different
@@ar_xiv It's used to get the sub in phase with the rest of the speakers.. So yes it sounds different. When the sub is out of phase it kills the bass. When it's in phase it gives great bass.
But if you play ONLY with the sub there is no difference since there would be no speakers it needs to be in phase with
Having correct phase of the sound can also be a challenge for recording. Especially if you have several microphones recording the same signal at the same time. If they are not perfectly aligned, it will be easy to make them out of phase and the result will be terreble sounding.
Most Speaker Manufacturers turn Polarity of their tweeters (180° Phase), because they are not able to handle phaseshift of their passive crossovers in other ways.
Kick response is rubbish then. When kick comes, the tweeter goes negative first, all others positive - but continuous response is kind a in phase...
But correct Kick response is so important, on this is the most attention of human hearing made by Evolution!!
That Point is unfortunately mostly underestimated.
Thank you Paul, its always a pleasure listening to you!
This reminds me of a time when I was sitting in a physics class where a professor said any wave function could be stated as a summation of a series of sine waves of various intensities and frequencies and I asked him about the phase of those oscillators and he looked at me as if I was nuts. Perhaps I am nuts but I sure don't think that is the reason. It seems like a reasonable question to me.
You're correct. The phase of each partial must be set appropriately, in order for them to yield the desired waveform when added together. Conversely, when decomposing any periodic signal into its partials, failure to note the phase of each is discarding information.
On the other hand, the *audibility* of phase is highly controversial. Mathematically we know that the resulting waveform will change if the phase of the partials is changed, but can human hearing detect that waveform change? Many studies have been done, but unfortunately using mostly analog phase-shift filters - which are not perfect and perturb frequency response slightly, in addition to adjusting phase. So that approach is not conclusive.
Another method is to use digital delays with multiple sources; the delay line doesn't perturb anything except timing. I've done experiments like this, where I add two sources with a tiny frequency offset (one source is fundamental only, the second source contains harmonics), so that their phase drifts at a steady rate. Even while watching the sum waveform gradually morphing on a scope, I still can't hear any change in the quality of the sound - at least for frequencies in vocal range or higher.
Phase shift of bass frequencies may become audible, as then we're getting into time shifts measured in milliseconds. Perhaps especially in a transient case, where there is a "thump" or "boom" along with a sharp burst of higher frequencies, the phase of the low-frequency component could be audible. I haven't experimented with that case, yet.
@@marianneoelund2940 I really enjoyed reading your response. Thank you for talking about the subject. I would expect that phase would be less important for higher frequencies since you can't feel higher frequencies and the hairs in our inner-ears seem to detect vibrations without phase info. In contrast, parts of the sound that can actually be felt like strong transients are likely to have their phase/plarity detected by our touch sensors. Cool subject matter if you ask me. :-) Thanks again for responding. I guess if I am crazy, it's not because of this subject matter. :-)
het wait a minute... i thought this was a family show??!! who you calling an _invert_
Hi Paul,
You are wrong here. And the funny thing is you are wrong with exactly 180º!
When the current is at its peak in positive direction the cone is at its most inward postion (voltage is irrelevant for a speaker, it is all about the current, as we all know from high school).
The current creates the force, the force create the acceleration. And the acceleration is at its peak (in positive direction) when the cone is changing in direction from going inwards to going outwards. And at that moment the cone creates the highest pressure, exactly in phase with the input current.
All I do know is that when I'm feeling a bit out of phase, I tend to become argumentative.
@Fat Rat I think I'd like to try the 5-minute argument, please. Pushing and pulling tends to drain my energy.
@Fat Rat Did you catch my mosfet reference? Let's review, shall we? Phase inversion, push/pull, drain...
@Fat Rat Ten minutes in your corner will suffice. Enjoy your Ramen noodles for breakfast.
My wife could tell you very well about phase inversion the sweet little chick-a-dee thing...wink wink.
You can use pase inversion in a noise canceling headphones Oh yeah
Wow...all these people asking questions that can be answered in 30 seconds of googling...
@ pepeshopping....because sometimes the answer isn't so clear on Google. I've not checked for this particular question, I already understand.
It's nice to get a clear and simple answer, without rummaging through pages until you find something that makes sense.
Not everybody is an expert.
Cheers. 🎶🎶🎶