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#1
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Phasing of the speakers
A thread about phase alignment reminded me of another question:
Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) Regards, Alex |
#2
Posted to rec.audio.tubes
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Phasing of the speakers
Alex wrote: A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) Regards, Alex When a drum is beaten, the skin is forced down creating a suction wave. Meanwhile a compression wave is created out the bottom of the drum. The two waves sum together and the mic records the pressure changes then the signal is processed in the studio gear and recorded onto CD maybe and sent to the record cutting head amp to make an LP. Its anyone's guess which way the initial drum bang is phased. In amplifiers at home there may be several stages of amplification and maybe the signal gets inverted or maybe not. I don't know what importance is given to phase when recordings are made. The initial bang of a drum consists of a large number of sine wave harmonics which start together but with all rapidly decay in amplitiude. Most people would not notice if all or some of these wave forms were phased oppositely to others; we would merely groove along with the obvious bang of a drum and all the more so if there is a suitable rythym of drumming. If we recorded an explosion then you'd expect to be hit by a blast of blowing air rather than a sudden suction towards the source of the explosion sound. A hand grenade let off in a living room will make a hell of a bang which may rupture both your ear drums. It'd be impossible to recreate the sound with a normal hi-fi sound system. Both sucks or blows of serious magnitude would be perceived as awful noise. Music is carefully arranged noise which is meant to have use muse, and be delighted, and distracted from the world or work and troubles. I have two 12" bass reflex drivers in reflex speakers capable of going down to 20Hz, and the Fb is about 30Hz, and just what phase reversals occur is something I have either forgotten or never measured. At below about 40Hz the sound comes from the port of the box. But In perceive the bass to be quite excellent and very much like bass heard from bass instruments or large drums. I just spent another pleasant evening listening to music at a friend's place where he has a sub-woofer and bass speakers also capable of going down to 25Hz. I built all the amps and speakers and the sub and when I set up the sub position I wanted to get maximum flatness of response at the listening chair and so we tried the sub in many positions and with reversal of speaker leads at the sub amp to get the best flat response with minimal peaking and troughing due to phase adding and cancelations. The sub amp filter is has only 50 degrees of phase shift at the -3dB point but then has a much increasing rate of attenuation. Some filters might have a huge phase "turnover" at the -3dB point, making the integration of sub and existing bass speakers very hard to achive without unwanted peaks and troughs in the response. I like bass I get with my two bass units which cover 20Hz to 250Hz with perhaps a slight broad lump in the low bass response. Perhaps the drum sound I get is better than what my friend has, but its hard to say because our rooms are different. I've been to some loud rock music gigs wearing ear plugs because ot the SPL and found my chest heaving with low bass and the boom chucka boom. I never bothered to ask myself is my chest being compressed at each drum beat or stretched; you just feel pummelled by the sound anyway. The transition reponse between bass and midrange and how the filter crossovers are set up will affect the perceived transient sound quality. Sometimes one has to reverse phase connect mids relative to bass, then treble relative to mids, depending on the response. Its a very tricky business to set up speaker drivers for minimal phase change and yet achieve a smooth response through the crossover regions without a big peaks each side of the crossover F or two or a big trough where each driver tries to cancel the sound at the trough. I think getting the smooth response with rapid cut offs at least 12dB/octave away from the Xover F is the most important thing to get right. This means a slightly over damped second order filter. Big old woofers meant to be cut off at sat 250Hz may need much more steep filtering beyound 500Hz lest the transients muddy the sound meant to be handled by the smaller midrange driver. Patrick Turner. |
#3
Posted to rec.audio.tubes
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Phasing of the speakers
Alex wrote: A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? If you want some bass, it makes a spectacular difference. Graham |
#4
Posted to rec.audio.tubes
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Phasing of the speakers
Patrick Turner wrote: Alex wrote: A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) When a drum is beaten, the skin is forced down creating a suction wave. Meanwhile a compression wave is created out the bottom of the drum. The two waves sum together and the mic records the pressure changes then the signal is processed in the studio gear and recorded onto CD maybe and sent to the record cutting head amp to make an LP. Its anyone's guess which way the initial drum bang is phased. In amplifiers at home there may be several stages of amplification and maybe the signal gets inverted or maybe not. I don't know what importance is given to phase when recordings are made. In the past very little probably but designers such as myself always strive to keep all ins and outs on say a mixing desk in the same polarity ( phase is really the wrong word ). Apologies for my flippant response to my misunderstanding of your question elsewhere. I doubt even the CD standard has a polarity requirement. Graham |
#5
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Phasing of the speakers
On Apr 25, 4:59�pm, Eeyore
wrote: Apologies for my flippant response to my misunderstanding of your question elsewhere. Hi RATs! You're a better man than I am, Gunga Din. Happy Ears! Al PS The relative phase of the listener's space to the original space is something some folks study and expound on to display their dedication to Truth, or Honesty or something. It may be possible to enjoy listening to Music without such effort. Life is so unfair We can only hope Death is more even handed ... |
#6
Posted to rec.audio.tubes
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Phasing of the speakers
"Patrick Turner" wrote in message ... Alex wrote: A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) Regards, Alex When a drum is beaten, the skin is forced down creating a suction wave. Meanwhile a compression wave is created out the bottom of the drum. The two waves sum together and the mic records the pressure changes then the signal is processed in the studio gear and recorded onto CD maybe and sent to the record cutting head amp to make an LP. That is how we set that experiment. Firstly, we checked with an oscilloscope which polarity the first drum bang signal wave was at the amplifier output. Then we visually found out, using a DC voltage (battery cell) which polarity corresponds to which direction of the speaker cone movement. Then we inserted a 4-pole double throw relay to simultaneously reverse connection polarity of both speakers from time to time. We also blocked their ports off. As an indicator to the "expert audience" a lamp would light up in case the relay is energised. Then the "experts" (several uni students) were sitting listening to sseveral passages of music with distinctive drums, trying to find any difference between "Lamp on" and "lamp off" positions. The listeners did not know in advance which position corresponded to which polarity, but only they knew which position it was at any moment. The "experts" were making notes in their notepads, voting for one or the other position for different pieces of music. Then their votes were counted. It turned out that there was a marginal preference towards "cone pulled in on the firs bang" position. Personally I did not perceive any difference. Regards, Alex |
#7
Posted to rec.audio.tubes
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Phasing of the speakers
Alex wrote: "Patrick Turner" wrote in message ... Alex wrote: A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) Regards, Alex When a drum is beaten, the skin is forced down creating a suction wave. Meanwhile a compression wave is created out the bottom of the drum. The two waves sum together and the mic records the pressure changes then the signal is processed in the studio gear and recorded onto CD maybe and sent to the record cutting head amp to make an LP. That is how we set that experiment. Firstly, we checked with an oscilloscope which polarity the first drum bang signal wave was at the amplifier output. Then we visually found out, using a DC voltage (battery cell) which polarity corresponds to which direction of the speaker cone movement. Then we inserted a 4-pole double throw relay to simultaneously reverse connection polarity of both speakers from time to time. We also blocked their ports off. As an indicator to the "expert audience" a lamp would light up in case the relay is energised. Then the "experts" (several uni students) were sitting listening to sseveral passages of music with distinctive drums, trying to find any difference between "Lamp on" and "lamp off" positions. The listeners did not know in advance which position corresponded to which polarity, but only they knew which position it was at any moment. The "experts" were making notes in their notepads, voting for one or the other position for different pieces of music. Then their votes were counted. It turned out that there was a marginal preference towards "cone pulled in on the firs bang" position. Personally I did not perceive any difference. Regards, Alex I recall reading an old 1970s Scientific American article about 14 years ago and their conclusion was that human hearing is unable to detect the phase of sound. However, nature evolved living creatures to have TWO ears and TWO eyes probably because with twin sensors you could afford to loose one and still survive. Not only that, with two hearing sensors **the phase difference** at each ear allows critters to determine the direction of the sound, and where their next feed is positioned, or where a threat is located. Two eyes means stereo vision which is better than mono vision. As the millions of years went by the ears and eyes got better and encouraged the brain to develop. But we have never needed to know exactly what the phase of a signal is so nature didn't allow us that capability. Yet when we try to sing in tune with music we know exactly when we are in tune, and "in phase" with another singer or a piano. Other critters hear a lot better than humans do. Patrick Turner. |
#8
Posted to rec.audio.tubes
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Phasing of the speakers
On Mon, 27 Apr 2009 14:56:47 GMT, Patrick Turner
wrote: But we have never needed to know exactly what the phase of a signal is so nature didn't allow us that capability. Yet when we try to sing in tune with music we know exactly when we are in tune, and "in phase" with another singer or a piano. This is just wrong. Neither do we have the slightest idea of when we are in phase with a musical instrument, but nor can we sing a steady enough note to remain that way. Somewhere near the same note is the best anybody can do. And what phase would we synchronize with anyway? A piano tuner offsets the tuning of the triples slightly to fatten the sound, which means that the net phase of the note is sliding around as it decays. No, we have no phase perception - the only way we can get to it is by the indirect method of hearing an amplitude variation when two signals at the same frequency reinforce or cancel each other. d |
#9
Posted to rec.audio.tubes
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Phasing of the speakers
Eeyore wrote:
Patrick Turner wrote: Alex wrote: A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) When a drum is beaten, the skin is forced down creating a suction wave. Meanwhile a compression wave is created out the bottom of the drum. The two waves sum together and the mic records the pressure changes then the signal is processed in the studio gear and recorded onto CD maybe and sent to the record cutting head amp to make an LP. Its anyone's guess which way the initial drum bang is phased. In amplifiers at home there may be several stages of amplification and maybe the signal gets inverted or maybe not. I don't know what importance is given to phase when recordings are made. In the past very little probably but designers such as myself always strive to keep all ins and outs on say a mixing desk in the same polarity ( phase is really the wrong word ). Apologies for my flippant response to my misunderstanding of your question elsewhere. I doubt even the CD standard has a polarity requirement. Graham Positive pressure on the diaphragm cause a positive voltage on XLR pin 2. |
#10
Posted to rec.audio.tubes
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Phasing of the speakers
PS The relative phase of the listener's space to the original space is something some folks study and expound on to display their dedication to Truth, or Honesty or something. It may be possible to enjoy listening to Music without such effort. Life is so unfair We can only hope Death is more even handed ... it's called "absolute polarity" and it IS very important, under certain conditiona, and others it does not make any discernible difference. |
#11
Posted to rec.audio.tubes
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Phasing of the speakers
wrote: But we have never needed to know exactly what the phase of a signal is so nature didn't allow us that capability. Yet when we try to sing in tune with music we know exactly when we are in tune, and "in phase" with another singer or a piano. This is just wrong. Neither do we have the slightest idea of when we are in phase with a musical instrument, but nor can we sing a steady enough note to remain that way. Somewhere near the same note is the best anybody can do. And what phase would we synchronize with anyway? A piano tuner offsets the tuning of the triples slightly to fatten the sound, which means that the net phase of the note is sliding around as it decays. No, we have no phase perception - the only way we can get to it is by the indirect method of hearing an amplitude variation when two signals at the same frequency reinforce or cancel each other. "Phase" refers to two different signals, always. One sine wave by itself does not have phase in free space. It DOES have polarity in three axes with respect to any fixed plane. We humans are VERY sensitive to phase between two signals, we are NOT sensitive to POLARITY in free space. We do not listen in free space. Most musical or sound signals are asymmetrical, they are not sine waves and they are not center referenced to "ground" .Also, we are in an atmosphere which can be compressed to infinite pressure but which can only be "expanded" to an absolute vacuum. For this reason, absolute polarity does matter as a documentary issue. It matters in practice under some specific conditions and not others. For example, if you have a singer singing vocals along with him- or herself, flipping the PHASE 180" will screw the singer up royally. It has been proven time and time again in cinema ADR and in tracking harmonies. A good preamp like the Marantz 7 or Mc C22 will allow one to flip L for R, but flipping plus for minus is not easily done in a n unbalanced environment, except at the speakers. A big argument for balanced chains, that. |
#12
Posted to rec.audio.tubes
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Phasing of the speakers
In article , "Alex" wrote:
A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) Some people can detect absolute polarity of an impulsed sound. There is no single frequency on most instruments or music in general. Its lows and highs. The bass is going to lag the highs because the woofer takes longer to travel if its trying to produce the same frequency. Its funny, a woofer also cannot reproduce very low frequencies well below resonance without lagging behind. The flexible membranes have a stickiness to them. greg |
#13
Posted to rec.audio.tubes
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Phasing of the speakers
"dave" wrote in message ... Eeyore wrote: Patrick Turner wrote: Alex wrote: A thread about phase alignment reminded me of another question: Does speaker connection polarity (+/-180 degrees of phase) make any difference? I remember in my young years we experimented and sort of came to a conclusion that the correct phase is when the cones of the speakers suck in with the first beat of a big drum. The sound was "deeper" this way. However, the difference was marginal and barely perceplible. Personally I did not hear any difference. What is the modern take on that? Do manufacturers of the top-end CD players, amplifiers and speakers specify their gear as "inverting" or non-inverting"? (I believe they do not) Do the recording studios observe "polarity" from the microphone to the digital values actually recorded on CDs? (Probably not) When a drum is beaten, the skin is forced down creating a suction wave. Meanwhile a compression wave is created out the bottom of the drum. The two waves sum together and the mic records the pressure changes then the signal is processed in the studio gear and recorded onto CD maybe and sent to the record cutting head amp to make an LP. Its anyone's guess which way the initial drum bang is phased. In amplifiers at home there may be several stages of amplification and maybe the signal gets inverted or maybe not. I don't know what importance is given to phase when recordings are made. In the past very little probably but designers such as myself always strive to keep all ins and outs on say a mixing desk in the same polarity ( phase is really the wrong word ). Apologies for my flippant response to my misunderstanding of your question elsewhere. I doubt even the CD standard has a polarity requirement. Graham Positive pressure on the diaphragm cause a positive voltage on XLR pin 2. Not only of the speakers.... This maxim is a standard set by the-powers-that-be to coordinate manufacture of micropones with their XLR3M termination, ahead of their being used by mixing or summing their outputs. Using one mic alone in circuit creates neither a phase nor a polarity problem, as these are 'relative' terms; bipolar mics have in-phase and anti-phase faces. The same convention is supposedly observed by the industry for, say, cone loudspeakers and earphones when driven by dedicated amps. 2 speakers in dual-mono mode need to be wired in phase [or observing same polarity] to prevent differential cancellation of soundwaves in air. Active modules and the like are placed in a [linear] chain so that the finished product at all take-off and test points as well as at the speakers/cans] are designed to be in phase with the audio input to the first stage, spared from intrusive response-shaping gizmos [which serve to ruin any prior integrity]. The same care applies for audio transformers, whose phase-angle error between source and its secondary/ies should be minimum at 800Hz. The ear-trumpet routine: while live sound relay in small rooms benefits from maintaining absolute phase (but kept well short of that point where acoustic feedback howls), IMO 'absolute' phase of retrieved/reproduced material is a lot of hype and phooey.... It's just an historical acoustic illustration. Jim |
#14
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Phasing of the speakers
GregS wrote: There is no single frequency on most instruments or music in general. Its lows and highs. It's the fundamental plus harmonics for tuned instruments. The bass is going to lag the highs because the woofer takes longer to travel if its trying to produce the same frequency. ********. Graham |
#15
Posted to rec.audio.tubes
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Phasing of the speakers
On Apr 28, 2:50 am, flipper wrote:
On Mon, 27 Apr 2009 18:19:41 -0700 (PDT), wrote: wrote: But we have never needed to know exactly what the phase of a signal is so nature didn't allow us that capability. Yet when we try to sing in tune with music we know exactly when we are in tune, and "in phase" with another singer or a piano. This is just wrong. Neither do we have the slightest idea of when we are in phase with a musical instrument, but nor can we sing a steady enough note to remain that way. Somewhere near the same note is the best anybody can do. And what phase would we synchronize with anyway? A piano tuner offsets the tuning of the triples slightly to fatten the sound, which means that the net phase of the note is sliding around as it decays. No, we have no phase perception - the only way we can get to it is by the indirect method of hearing an amplitude variation when two signals at the same frequency reinforce or cancel each other. "Phase" refers to two different signals, always. One sine wave by itself does not have phase in free space. It DOES have polarity in three axes with respect to any fixed plane. We humans are VERY sensitive to phase between two signals, we are NOT sensitive to POLARITY in free space. We do not listen in free space. Most musical or sound signals are asymmetrical, they are not sine waves and they are not center referenced to "ground" .Also, we are in an atmosphere which can be compressed to infinite pressure but which can only be "expanded" to an absolute vacuum. For this reason, absolute polarity does matter as a documentary issue. It matters in practice under some specific conditions and not others. For example, if you have a singer singing vocals along with him- or herself, flipping the PHASE 180" will screw the singer up royally. It has been proven time and time again in cinema ADR and in tracking harmonies. I don't follow your example. Do you mean a singer singing along with a prior made recording of themselves? Or do you, as I suspect, mean a singer hearing their own voice 'live', like in an earpiece or headphones? In the 'live' case, that would be a matter of the 'playback' phase relative to their own head (bone conduction). I.E. Constructive or destructive interference. Singing along with themselves, overdubbing harmonies or ADR, or with other harmony singers. Throws them off horribly. That's different than an audience listening for a 'better drum beat' because they have no 'in their head' phase relationship to the sound. A good preamp like the Marantz 7 or Mc C22 will allow one to flip L for R, but flipping plus for minus is not easily done in a n unbalanced environment, except at the speakers. A big argument for balanced chains, that. Inserting an inverting stage does it simple enough even with 'unbalanced' chains. Not saying that's preferable, just that unbalanced doesn't make it 'impossible'. Yes, you'd have to insert or remove a stage, which has to be unity gain and the two need to be identical. Balanced is just a lot better all the way around. We have unbalanced hi-Z in modern audio as a tube holdover even though 1) only a percent or so of commercial hi-fi is tubes and of that that is 2) they more and more like having transformers. |
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