Mapman’s last post is correct. EMI can occur, for example, at 60 Hz, which is not generally considered to be a radio frequency. EMI can also occur at pretty much any other non-radio frequency, as well as at RF (radio frequencies). Regarding neutrality, those who are sufficiently interested may want to read through the 9 pages of the following thread. BTW, the post above by Wolfie, dated 1-26-16, and also the first of his posts dated 1-28-16, make essentially the same point as the OP in the other thread. https://forum.audiogon.com/discussions/how-do-you-judge-your-system-s-neutralityMy opinions on neutrality were expressed in that thread, and were in essential agreement with its OP (Bryoncunningham). Frankly, I was surprised that his points, which I considered to be almost self-evident, aroused so much controversy in that thread. Regards, -- Al |
Hopefully this won’t rekindle a nine page debate as occurred several years ago in Bryoncunningham’s neutrality thread that I referenced a few posts back, but I thought it would be appropriate at this point to cite a few excerpts from his original post in that thread: Your system is becoming more neutral whenever you change a system element (component, cable, room treatment, etc.) and you get the following results:
(1) Individual pieces of music sound more unique.
(2) Your music collection sounds more diverse....
If, after changing a system element, (1) individual pieces of music sound more unique, and (2) your music collection sounds more diverse, then your system is contributing less of its own signature to the music. And less signature means more neutral....
This is only a way of judging the relative neutrality of a system. Judging the absolute neutrality of a system is a philosophical question for another day....
I don’t believe a system’s signature can be reduced to zero. But it doesn’t follow from that that differences in neutrality do not exist....
I’m not suggesting that neutrality is the most important goal in building an audio system, but in my experience, the changes that have resulted in greater neutrality (using the standard above) have also been the changes that resulted in more musical enjoyment. IMO those are propositions that are essentially self-evident. As I said earlier, it surprised me that his post stimulated nine pages of debate. The concept of neutrality should be viewed in a manner similar to the concept of perfection, IMO. We can’t achieve perfection, at least in most kinds of endeavors, but it can serve as a useful goal. And in most kinds of endeavors, at least, there are ways in which we can judge whether we are approaching it more closely or not. Regards, -- Al |
Geoff, note the reference to a point source in the quote Ralph (Atmasphere) provided just above. The reason the amplitude of electromagnetic waves goes down in free space as distance increases is that they "spread out" to some degree. If they are emitted by a point source, and therefore are radiated essentially equally in all directions, the energy received at any given point will decrease in proportion to the square of the distance, since (as stated in the reference Ralph provided) "the surface area of a sphere increases with the square of the radius."
That is the same reason, btw, that the SPL produced by a relatively small box-type speaker (which from the perspective of a listener seated some distance in front of the speaker can be considered as roughly approximating a point source) drops off at 6 db per doubling of distance (putting aside the effects of room reflections). Planar speakers and line sources of course behave differently, and SPL falls off more slowly in those cases, as distance increases.
What makes communications with satellites and inter-planetary probes possible is that the antennas are designed to focus the RF energy much more sharply than a point source, so that the energy "spreads out" as little as possible as distance increases.
Consider the example of a flashlight being shined against a wall, in comparison to a laser pointer being shined against the wall. As distance increases, the diameter of the spot that is illuminated by the flashlight will INCREASE much more than in the case of the laser pointer. While the brightness of any given point within the spot that is illuminated by the flashlight will DECREASE much more, as distance increases, than in the case of the laser pointer.
Regards,
-- Al
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What does all that have to do with the price of spinach? Geoff, in case it wasn't clear my last post was in direct response to your contention that: Radio waves do not follow the inverse square law like magnetic fields.
If they did we would be unable to talk to astronauts on the moon or to
send transmissions out into the galaxy you know SETI and all that. Radio
waves don’t attenuate in vacuum of space and the only reason they
attenuate in free space of Earth’s atmosphere is because of losses due
to absorption and scattering....
If what you [Atmasphere] are attempting to claim was actually true they would need
repeaters every twenty feet as opposed to every 25 miles or whatever.
When transmitting to a satellite at 23K miles there are no repeaters!
Hel-loo!
I did not and do not express any opinion about the effectiveness of shielding with respect to magnetic fields. I don't feel I can comment on that question in a knowledgeable manner without devoting more time to studying it than I care to devote. Regards, -- Al |
Last_lemming 02-02-2016 5:04pm
I tend to describe a neutral set up based on hearing many different "albums". If they all sound unique, meaning if some recordings sound bass heavy, some bright, some just fine then I figure the system isn’t tilting the frequency in any one direction. I would call that system neutral. However if everything sounds bright well it’s obviously not neutral.
Dracule1 02-02-2016 10:24pm
Last_lemming, to be more objective why don’t you just measure the frequency response of your system at your listening position? If you’re concerned about something bass heavy or tilted frequency, that is easily measured. It’s harder if not almost impossible to measure something more subjective as sound staging, imaging, or palpability. Dracule1, brightness, bass heaviness, or other deviations from neutrality that may be perceived as frequency response anomalies are also not necessarily measurable in a manner that is practical or meaningful. First, as Ralph (Atmasphere) has often pointed out, perceived brightness is often caused not by frequency response errors, but by trace amounts of certain forms of distortion. Second, a microphone and its associated instrumentation will not interpret arrival time differences between various frequencies, or multiple arrivals of the same frequencies, in the same way our hearing mechanisms do. Arrival time differences occurring as a result of both room reflections and the fact that most speakers are not time coherent. So what may be perceived as a frequency response anomaly is not necessarily any more readily measurable than the other kinds of sonic issues you referred to. Regarding Last_lemming’s underlying point, I of course agree, as it is consistent with what I and Wolf_Garcia said earlier in the thread, as well as with what I quoted from Bryoncunningham’s post of several years ago. Regards, -- Al |
Hi Mapman,
Yes, consistent with Ralph’s response it’s certainly true that our hearing mechanisms do not respond equally to all frequencies. And as shown in the chart you referenced their deviation from flatness is different at different volume levels.
And so distortion components, noise components, and deviations from flat frequency response will be objectionable to a degree that varies widely depending on where in the spectrum they occur.
But an obvious point that nevertheless seems worth stating is that our hearing mechanisms have the same characteristics, including lack of flatness, when we listen to live music as when we listen to our audio systems, at least if volume levels are similar. So while an understanding of the hearing characteristics you (and Ralph) cited can be important in prioritizing the kinds of distortions and colorations that are most important to minimize, we also don’t want to have the system introduce colorations (i.e., deviations from neutrality) that "correct" our hearing. Assuming, of course, that our hearing is functioning normally.
As you said earlier in the thread, "if neutral = accurate then sign me up."
Best regards,
-- Al
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I thought audio waves moved at the speed of sound, and light waves moved at the speed of light? This is the kind of crap I’m talking about. At most frequencies, audio waves that are in the form of electrical signals travelling through cables travel at a substantial fraction (generally upwards of 100,000 miles per second) of the speed at which light moves through a vacuum (approximately 186,000 miles per second). The exact speed varies depending on the characteristics of the cable, especially what is known as the "dielectric constant" of its insulation. An exception to that is audio at deep bass frequencies, which travel through cables more slowly but still at speeds of thousands of miles per second. Audio waves that are in the form of sound travelling through air travel vastly more slowly, at roughly 0.2 miles per second, depending on the humidity and several other variables. As mentioned, the speed of light in a vacuum is approximately 186,000 miles per second. It is somewhat slower in other media, such as glass, just as the speed of electrical signals is dependent on the characteristics of the cables that are conducting them. I hope that addresses the concerns expressed in the second of the two sentences that I quoted from your post. Regards, -- Al |
Thanks, Geoff. I read through that page, and as I interpret it he's basically referring to how his design minimizes or eliminates phase jitter and other unwanted phase shifts and timing errors. Still not sure how that has anything to do with the speed of sound in air. Also, I agree with Ralph's comments in that thread to the effect that the claim of "velocity countermeasures" ("countermeasures" meaning "corrections," as I understand it) in the area of 700 or 800 db seems nonsensical. I suspect those numbers would equate to resolution that is even in conflict with the Heisenberg Uncertainty Principle. The universe itself isn't that precise. Regards, -- Al |
Houston we have a problem. Most recordings, including many of the ones audiophiles cherish, actually invert polarity. Geoff, I have no knowledge of the polarity database you referred to just above, but I would wonder how the polarities it alleges for the various recordings were determined. Was it all based simply on what sounded "right" to the individuals who created the listings? Or did they go to the trouble of examining waveforms on an oscilloscope or a computer? And if the latter, were they thorough enough to examine the phasing of each of the different instruments and/or singers on the recording? My understanding is that the majority of recordings are neither inverted nor non-inverted. Instead they are a conglomeration of different sounds that are likely to have been mixed together with each of them being phased essentially at random relative to the others. Take a look at this photo of one of the "state of the art" mastering rooms at Abbey Road Studios, which one of our members called attention to in another recent thread. After what has been captured from a multitude of different mics has been put through all of that equipment and subjected to mixing, compression, limiting, equalization, and most likely numerous other effects, it’s hard to imagine how the end product can have any semblance of meaningful phasing, inverted or not. It would be a different story, of course, with the relatively small number of recordings that have been engineered with just two or three mics, and with minimal post-processing. Also, since you mentioned database statistics for the DG label I’ll add, as you probably realize, that over the years many and perhaps most of their recordings have been notorious for heavy-handed multi-mic’ing. With literally dozens of microphones having been used on many of their orchestral recordings, as I understand it. Requiring, btw, a mixing console even more elaborate than the one shown in the photo I linked to. In any event, though, there are countless other ways in which the recording and mastering process can be less than ideal. Why focus on this one? As for the other issue that has been under recent discussion in this thread, I too am confused about what the speed of sound in air has to do with amplifier circuitry. Regards, -- Al |
Thanks for the responses, Ralph & Geoff. I read through Mr. Louis’ introduction to the polarity list. He makes clear that all of the entries in the list have been determined by him, simply by listening and "discerning polarity by deciding which polarity sounds more like live music." The only recordings he appears to recognize as being comprised of a mix of sounds encompassing both polarities are Phil Spector’s wall of sound recordings. Given those facts, as well as the incident Ralph cited, I would have to agree with Ralph that the list should not be taken seriously. Also, in the case of preamps which provide polarity switches, and accomplish polarity reversal in the analog domain, I wonder if in many cases those who report major sonic differences when changing the setting of that switch are actually hearing differences in the sonics of the preamp itself, resulting from the change in circuit configuration that occurs when the setting of the switch is changed. At least, that is, in the case of preamps having unbalanced internal signal paths, where accomplishing the polarity reversal might involve switching an active stage into or out of the signal path, or some other circuit change that might have audible consequences. (That concern would presumably not apply to balanced designs such as Ralph’s preamps, where the reversal can be accomplished simply by interchanging the inverted and non-inverted signals at some point in the balanced signal path). Geoffkait 03-03-2016 4:47pm
The reason I brought this up on this particular thread is because you had just asked what the speed of sound had to do with the price of spinach. Which was actually the question I asked last week on another thread and which Roger answered. The connection of course is that Roger claims that the speed of sound in air should be preserved by the amplifier. Hopefully Roger will provide further clarification, as a claim that "the speed of sound in air should be preserved by the amplifier" (that being Geoff’s restatement of Roger’s position), or to use some of Roger’s words earlier in the thread, "emulating the properties of air" and "addressing the delivery speed" are statements that have no meaning as far as I am concerned. Regards, -- Al |
Same question for Al: do you think the polarity issue is bunk or only George’s list. As I alluded to in my post of 4:27 p.m., I believe that for the majority of recordings there is no polarity that is "correct," although one polarity may in some of those cases sound "better" to some listeners with some systems than the other polarity. I also believe that in the case of the relatively few recordings that have been mic’d and mastered with purist techniques (just two or three microphones and minimal post-processing), that there can be a polarity that is correct, and a polarity that is incorrect. Can you point to any recordings on George’s list that are R that you think should be N Or vice versa? Just one of the preamps I’ve had over the years included a polarity switch, and I did not do a great deal of experimenting with it. Regards, -- Al |
Roger, I of course don’t question the innovative nature of your design, or the quality of the results. But to provide some perspective on the numbers that have been cited:
A million is of course a 1 followed by 6 zeros.
A billion is a 1 followed by 9 zeros.
A trillion is a 1 followed by 12 zeros.
The human brain contains approximately 100 billion cells (a 1 followed by 11 zeros), according to various references on the web.
800 db, as used to represent the ratio between two quantities of voltage or current or sound pressure level or various other variables, corresponds to 1 part in (1 followed by 40 zeros). ("Other variables" does not include power, for which 800 db corresponds to 1 part in (1 followed by 80 zeros)).
As cited in various references on the web, the number of atoms in the planet Earth is roughly in the vicinity of (1 followed by 50 zeros).
1000 db, expressed as a ratio, corresponds to 1 part in (1 followed by 50 zeros), and therefore corresponds to the ratio between the number of atoms in the planet Earth and a single atom.
As cited in various references on the web, the number of atoms in the known universe, extending about 13.8 billion light years in all directions, is roughly in the vicinity of (1 followed by 80 zeros).
1600 db, expressed as a ratio, corresponds to 1 part in (1 followed by 80 zeros), and therefore corresponds to the ratio between the number of atoms in the known universe and a single atom.
(1000 db and 1600 db have of course not been previously cited in this discussion, but I include those figures to provide additional perspective on your 800 db figure).
Regards,
-- Al
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