Link please?I noticed today in PS Audio’s Copper magazine an article discussing spinorama where they used a graph provided by ASR! Potential for cooperation? @amirm , will you test their FR-28?
Link please?I noticed today in PS Audio’s Copper magazine an article discussing spinorama where they used a graph provided by ASR! Potential for cooperation? @amirm , will you test their FR-28?
How to understand far field, 3M or 10M?The whole point of NFS is to solve your last sentence. It measures in near-field, but then computes the far field.
As to line source, it all depends on complexity of its soundfield in near field. If it is very complex then you may need a lot of measurement points, and lots of computation time.
If the line source is made out of individual drivers, then each one can be measured independently and them summed together. That is an extra cost option which I did not purchase.
I think it is best to first define what far-field (and near-field) means. In internet audio fora such as this one, people often use the term "nearfield" to mean something that is completely unrelated to its meaning in acoustics. (See this article by E. Sengpiel)How to understand far field, 3M or 10M?
Extremely grateful.I think it is best to first define what far-field (and near-field) means. In internet audio fora such as this one, people often use the term "nearfield" to mean something that is completely unrelated to its meaning in acoustics. (See this article by E. Sengpiel)
Briefly, in what most internet audio forum posts, "nearfield listening" means the listening distance is close and the majority of the sound heard is direct sound from the speakers (i.e. direct field listening). The opposite case is "far-field listening", and in this case the majority of the sound heard is from reflections (i.e. reverberant field listening). Here I took the from one of Genelec's monitor selection guides and use the model 8350A for illustration.
View attachment 193610Correct Monitors - Genelec.com
A monitor, by definition, observes, checks, controls, warns or keeps a continuous record of something. An audio monitor, studio monitor or monitoring speaker is more than just a good-sounding loudspeaker. It is a device used in the process of recording, mixing or broadcasting audio in any...www.genelec.com
The red zone is the acoustical "near-field". It is where the listening distance to the speaker is too short for its 2 drivers to integrate. In the acoustical near-field, frequency response change with listening distance because of lack of driver integration. Once beyond the red zone, we are in the acoustical far-field. The green zone is where direct sound dominates. The black vertical separator is the critical distance. This is the point the direct sound energy (which decreases with listening distance) and the reflected sound energy becomes the same. The critical distance is room dependent (mostly volume and reflectivity).
Beyond the critical distance, as in reverberant field listening, the sound heard is dominated by reflections and therefore room effects are much more prominent.
In acoustics, far-field means the listener is far enough away from the sound source that the source appears to be compact, and thus behaves like a point source. For a speaker with multiple drivers, that means the sound radiated from the drivers are well integrated at that distance. If you look at the Genelec chart, the far-field for the 8350A begins at ~2.5 m. For the 8351B, which has the same SPL output rating as the 8350A, because of its coaxial design, far-field begins at a much shorted distance of ~1.5 m. Where farfield begins is determined by the speaker design, and is not room dependent.
In the acoustical far-field, the sound radiating properties of the speaker only depends on distance. If you have measurements at one distance (in the far-field), you can easily scale it to a different distance by using the 1/r relationship (i.e. SPL decreases by 6 dB every doubling of distance). Therefore, there is little difference between the reporting numbers at 3 m and 10 m. They are just a scaling factor offset of each other. The ANSI/CTA2034 standard for anechoic chamber measurement is to measure at 2 m, and report the scaled measurements at 1 m.
Except for where he said “from reflections (i.e. reverberant field listening)”. They are two different things (with partial overlap) and the reverberant field does not occur in small rooms ie home hifi. The sengpielaudio article also fails to make this clear, although I think it is talking about performance spaces where this distinction is not as important as it is in home hifi.Extremely grateful.
Well put together. Many people listen much to far away from their speakers. And expect sound pressure levels that are not possible when they are ten to 12 feet away. They loose the impact and immediacy that you can get when you are correctly setup. I will keep this for a few clients to look over. Saves me having to type it all. One thing I take umbrage with is the fallacy that you cannot hear below 16 hertz. Very well proven to be false. In fact given sufficient volume and clarity from harmonic and intermodulation distortions from mediocre drivers you can hear to below 5 hertz. And there are plenty of studies that have proven this. My favorite one is a compendium of the various low frequency surveys.I think it is best to first define what far-field (and near-field) means. In internet audio fora such as this one, people often use the term "nearfield" to mean something that is completely unrelated to its meaning in acoustics. (See this article by E. Sengpiel)
Briefly, in what most internet audio forum posts, "nearfield listening" means the listening distance is close and the majority of the sound heard is direct sound from the speakers (i.e. direct field listening). The opposite case is "far-field listening", and in this case the majority of the sound heard is from reflections (i.e. reverberant field listening). Here I took the from one of Genelec's monitor selection guides and use the model 8350A for illustration.
View attachment 193610Correct Monitors - Genelec.com
A monitor, by definition, observes, checks, controls, warns or keeps a continuous record of something. An audio monitor, studio monitor or monitoring speaker is more than just a good-sounding loudspeaker. It is a device used in the process of recording, mixing or broadcasting audio in any...www.genelec.com
The red zone is the acoustical "near-field". It is where the listening distance to the speaker is too short for its 2 drivers to integrate. In the acoustical near-field, frequency response change with listening distance because of lack of driver integration. Once beyond the red zone, we are in the acoustical far-field. The green zone is where direct sound dominates. The black vertical separator is the critical distance. This is the point the direct sound energy (which decreases with listening distance) and the reflected sound energy becomes the same. The critical distance is room dependent (mostly volume and reflectivity).
Beyond the critical distance, as in reverberant field listening, the sound heard is dominated by reflections and therefore room effects are much more prominent.
In acoustics, far-field means the listener is far enough away from the sound source that the source appears to be compact, and thus behaves like a point source. For a speaker with multiple drivers, that means the sound radiated from the drivers are well integrated at that distance. If you look at the Genelec chart, the far-field for the 8350A begins at ~2.5 m. For the 8351B, which has the same SPL output rating as the 8350A, because of its coaxial design, far-field begins at a much shorted distance of ~1.5 m. Where farfield begins is determined by the speaker design, and is not room dependent.
In the acoustical far-field, the sound radiating properties of the speaker only depends on distance. If you have measurements at one distance (in the far-field), you can easily scale it to a different distance by using the 1/r relationship (i.e. SPL decreases by 6 dB every doubling of distance). Therefore, there is little difference between the reporting numbers at 3 m and 10 m. They are just a scaling factor offset of each other. The ANSI/CTA2034 standard for anechoic chamber measurement is to measure at 2 m, and report the scaled measurements at 1 m.
One thing I take umbrage with is the fallacy that you cannot hear below 16 hertz. Very well proven to be false. In fact given sufficient volume and clarity from harmonic and intermodulation distortions from mediocre drivers you can hear to below 5 hertz. And there are plenty of studies that have proven this. My favorite one is a compendium of the various low frequency surveys.
Your links indicate perception, not necessarily audibility, of infrasonic stimuli. Not everyone and not at typical SPL.
Generalizations suck.
Those links don’t actually say we can hear below 20 Hz. Vibrating body parts is a different issue. Hearing is what the eardrum responds to with vibration and auditory nerve signal.
What you are talking about belongs in the same category as bone conduction, ie non-auditory response to sound waves.
Touché.Generalizations suck on both sides of that coin.
Long held ideas are tough to let go of. But research continues. And if it is grounded research what is the problem with accepting it. There are many more studies. I simply put up a link to an easily accessible one.
IMHO the Klippel NFS does seem to be better for loudspeaker measurements than a typical anechoic chamber.Is Klippel NFS more accurate than any anechoic chamber? Even those large fully anechoic chambers?
The key thing to understand is that the gold standard is NOT anechoic chamber, but "free field." That is a speaker suspended mid-air with large distance between it and any reflection source. At the extreme, this is impossible to do. But assuming so, an anechoic chamber is a step down from this depending on how large it is.Is Klippel NFS more accurate than any anechoic chamber? Even those large fully anechoic chambers?
...and in utter silence from the environment!That is a speaker suspended mid-air with large distance between it and any reflection source.
From: https://mp.weixin.qq.com/s?__biz=Mz...r_shareid=e969fd6ae8369cd534d57dceb76c07ed#rdThe key thing to understand is that the gold standard is NOT anechoic chamber, but "free field." That is a speaker suspended mid-air with large distance between it and any reflection source. At the extreme, this is impossible to do. But assuming so, an anechoic chamber is a step down from this depending on how large it is.
Klippel NFS is another approximation of free field. It has strong advantage of being accurate to very low frequencies. And by measuring in near-field, it doesn't suffer from environmental issues that impact far-field measurements in anechoic chamber or free field (unless very fancy temperature/humidity control is used in the former).
I also saw some comments from other people.The key thing to understand is that the gold standard is NOT anechoic chamber, but "free field." That is a speaker suspended mid-air with large distance between it and any reflection source. At the extreme, this is impossible to do. But assuming so, an anechoic chamber is a step down from this depending on how large it is.
Klippel NFS is another approximation of free field. It has strong advantage of being accurate to very low frequencies. And by measuring in near-field, it doesn't suffer from environmental issues that impact far-field measurements in anechoic chamber or free field (unless very fancy temperature/humidity control is used in the former).