It is. Think of this as being a very low-Q filter where the poles (however many there are) are separated by a couple of octaves. Just a matter of adjusting component values to make that happen. And, of course, including the driver's natural acoustic response in all of that.
There is none if the crossover is well designed, others may have differing opinions. Depending on crossover frequencies and driver slopes, a 12db network may be 18 or 24dB acoustically, so it is important to simulate.
Well, if you have a large deviation and don't time align, the design axis might be tilted. You can usually compensate for this in the crossover. If you use shallow slopes and have a rapidly changing phase difference, you could have a design axis that changes appreciably with frequency. Again, measurement and simulation is your friend.
Your question is the type of question that a lot of people hold inexplicably strong opinions over, so you get what you got. The mainstream audio press seems to use the word phase for everything that is right or wrong with sound - perhaps leading people to believe it is more than just a function of the response shape....
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Hi,
About the humans ability to detect absolute phase, or polarity, maybe see this presentation about human hearing physiology:
www.clsp.jhu.edu/~sriram/lectures/hearing_1.ppt
Quote:
"The picture shows a cut through so called “organ of Corti”. This organ consists of two membranes, the basilar membrane (which is frequency selective as we have discussed earlier), and the tectorial membrane. Hairs are growing from the basilar membrane and into the tectorial membrane. As the basilar membrane moves, the hairs bend. The inner hair cells emit spikes of action potential whenever the hair bends of one direction. There is no spike when the hair moves in the other direction – the hair cells do one-way rectification of the acoustic signal. "
Since the half wave rectification process, reversing signal polarity would cause different signal in the inner ear if the signal is unsymmetric. It seems clear that there exists the required means in human hearing organs (including brains) to detect the reversed polarity.
Of course it is also signal dependent and more unsymmetrical signal would be easily detectable than if the signal symmetry is high.
Perception is a personal experience so the audibility of all this depends on the person.
- Elias
About the humans ability to detect absolute phase, or polarity, maybe see this presentation about human hearing physiology:
www.clsp.jhu.edu/~sriram/lectures/hearing_1.ppt
Quote:
"The picture shows a cut through so called “organ of Corti”. This organ consists of two membranes, the basilar membrane (which is frequency selective as we have discussed earlier), and the tectorial membrane. Hairs are growing from the basilar membrane and into the tectorial membrane. As the basilar membrane moves, the hairs bend. The inner hair cells emit spikes of action potential whenever the hair bends of one direction. There is no spike when the hair moves in the other direction – the hair cells do one-way rectification of the acoustic signal. "
Since the half wave rectification process, reversing signal polarity would cause different signal in the inner ear if the signal is unsymmetric. It seems clear that there exists the required means in human hearing organs (including brains) to detect the reversed polarity.
Of course it is also signal dependent and more unsymmetrical signal would be easily detectable than if the signal symmetry is high.
Perception is a personal experience so the audibility of all this depends on the person.
- Elias
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If someone is identifying labels as inverting signalvs or not, I would guess they have found a musical instrument with an identifiable asymmetrical waveform and searched through their records for the polarity of that instrument. Of course it is nonsensical to think that every recording a label puts out would have the same polarity or that even individual tracks of a multitrack recording would be consistant. How many devices are patched into the chain? Any one of them could be inverting. How many (even or odd number) of inverting stages did track 14 have?? How many times did we overdub it? How many times did we run it through an EQ?
Or was he judging by sound character alone?
David
I was just at a friend's audio store last night to listen to a set of cables (dare I mention this?
). One of the CDs he pulled out was a free CD from the recnet Hi End show here. When we started to listen, I detected the sound to be "funny" so I mentioned that I recall this CD should be listened to with inverted polarity. His response was "all tracks on this CD?" I said, "most of them, but not all". So he quietly stood up and reversed the polarity at the power amp, and then agreed that it was the right polarity. When we got to track 8, he said "I think we need to change the polarity back." After that, he was satisfied (so was I).Of course, in multi-track recording where each mic might be a different model, we cannot be sure that every track has the same polarity, but here are some things we listen for.
1. The bass bunch. If it sounds muffled, then normally the polarity is inverted.
2. Loss of image depth. Generally, this happens when the recording is made in a hall where the hall reflections are in the recording. Then the polarity is not correct, the relation between the reflection and performance causes spacial distortion making the playback sound flat with no depth.
3. Instrument focus and detail. When the polarity is inverted, the fine details in vocals and instruments are smeared.
A system's capability to clearly make the right polarity distinguishable is one of my personal ways of determining whether the system is clean and worth further evaluation.
Now, when the recording is heavily mixed and EQed, the recording is already messed up, thus the difference in polarity is not as evident.
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And how can you make these claims when you have absolutely no idea whether the recordings are inverted or not?
David
Every test I've read of has said, that outside of some specialized test signals, this is true. Absolute polarity is not detectable on music.
David
Thanks for that POV. I always found it funny that my AVRs would tell me my speakers were out of phase during calibration.
I have some recording of performances I listened to at the same time. So I know what the original performance sounded like. It's also not just me, but many people using various systems have confirmed this. At least this is the way we determine the preferred polarity which we find most enjoyable.
This last listening that I mentioned also revealed how different people might focus on various aspects of music during listening. I focused on overall image depth, focus, detail and cleaness of overall performance, whereas the store owner focused on the agility in vocals. Not to conlude what is right or wrong, I also noticed such change in vocals as I changed the characteristics of the interconnect.
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If polarity is audible with music for whomever, should whomever flip polarity on their speakers for every recording to see which way that recording is better sounding to them since there is no way for most of us to know what absolute polarity the recording is mastered in or which is more accurate for that particular set of instruments? It would be more convenient to through a switch somewhere in there somewhere so the oddiophile could easily switch back and forth. Of course no real oddiophile would dare throw an extra switch in their signal chain.
on the tough road to Audiophilia,
Dan
on the tough road to Audiophilia,
Dan
on the tough road to Audiophilia,
And a whole lot of uncontrolled,subconscious, widely differing conclusions day to day.
I would never want to visit audiophilia
This discussion has me wanting to do that for each song. I use the DCX2496 so its really easy to do.
If you have a prefered polarity, thats fine. There is just no way of knowing whether it is absolute polarity positive, or negative. (And I'd be very impressed if you could prove that you can consistently pick out a polarity in a blind test.)
David
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