Sumo is one of the coolest names anybody came up with for an amp line…somebody should revive that name and make a new tough looking amp.
264 responses Add your response
Of course the real point is that EMI is not magnetic field. Which is what my original post was addressing. I.e., that shielding is effective for RFI/EMI but not for either external magnetic fields such as those produced by transformers or induced magnetic fields such as produced by current running through cables and wires. I used to work on the ELF program which transmits at 75 Hz so yes, I’m quite familiar with low frequency radio frequencies. Just because some people might not consider it a radio frequency it actually IS a radio frequency.Its apparent to me that you did not look at the Wikipedia link I posted earlier for your convenience. EMI really is a magnetic field and one that can occur at almost any frequency. So is RF, as they originate from the same principle of electricity. We usually use 'RFI' to refer to higher frequency phenomena (an example might be an oscillation in a circuit) but its just a polite nomenclature. What is generally different about the two is that for audio purposes, RFI **usually** originates via an antenna (driven by an RF source), whereas EMI generally does not (likely instead radiates from a power transformer or power lines, or any source that is powerful enough to radiate directly without the need for an antenna, although power lines might well be argued to be antennae. I recommend you take a look at the link I posted or ask your colleagues at the ELF station. |
Actually radio frequencies are electromagnetic waves. I realize it sounds repetitive but RF is not magnetic fields, which are stationary fields. It should be obvious that magnetic fields are not the same thing at all as electromagnetic waves. If they were the same then magnetic fields would be flying all around the room at light speed, which of course they are not. They’re stationary. Recall the experiment with iron filings and a magnet? The magnetic lines of flux are stationary. Everyone and his brother knows that the intensity of the magnetic field is inversely proportional to the distance from the conductor in the case of induced magnetism. This is not true for radio waves. And the fact radio waves don’t attenuate like magnetic fields allows extremely low frequency radio waves like ELF at 75Hz to be used for long distance communications. The last time I looked nobody is using magnetic fields for communications. Even the units are different, V/meter and Gauss. Thus, when setting out to eliminate or reduce magnetic field intensity one requires high permeability materials, not shielding. |
Thanks Dracule1 For pointing out there is no such thing as "neutral" in the recording/listening chain. Any musician like you, or myself, or any recording/sound engineer can tell you that...how do you measure neutral? What are the standards utilized to measure it? Every room is different, every combo of equipment is different, the electric signal varies from home to home, minute by minute and so on infinitely. Talk about a "moving target"...this is it. Best, Rob |
Well you got the first sentence right. The rest of it seems to point to the area of confusion. You might want to think about the fact that radio waves can very much metals.... An example that most of us know about are microwaves. I think maybe where you are having the disconnect is this: Recall the experiment with iron filings and a magnet? The magnetic lines of flux are stationary.What you are talking about is a simple magnet- much like what would happen if you put DC into a field coil. But that does not cause EMI- but if you use AC as a source now it can. IOW a simple magnet does not cause EMI only because it operates at DC. As best I can make out that must be where your confusion lies. An example of an AC source powering what otherwise might be considered a magnet is a tape head degausser. It is an electromagnet; different from a power transformer in that the core is the load rather than a secondary winding. If you get it near the tape head you will see a prodigious signal through the playback electronics if they are on. But you might be surprised to find out that if you take a simple magnet and bring it near the head the same thing will happen- not because the magnet is creating a field so much as the act of moving it is putting the field in motion and inducing something in the head as a result (thus the use of the term V/meter instead of Gauss). RF most definitely follows the inverse square rule BTW. The reason ELF works is that the ground wave can extend around the planet whereas at higher frequencies (FM for example) don't. Take a look at this Wiki page: https://en.wikipedia.org/wiki/Ground_wave_propagation I really recommend you read Wiki pages at the links I have posted!! |
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: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 |
Al, The idea of relative neutrality is as you say, self evident. As my system has improved over the years, very subtle incremental musical information is definitely more distinct, the very fine tooth comb analogy. Contrast becomes more stark and apparent with simple system changes. This would suggest less sonic character imposition from the system components . Absolute neutrality is different matter. Charles, |
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. The reason ELF works is actually because the transmit power is 1M watts and because the preamps on the receive side are extremely sensitive. But getting back to my real point for just a sec, shielding protects the conductor from external EMI/RFI but not from it’s own induced magnetic field. That’s why I said cables and power cords shoot themselves in the foot. End of argument. |
^^ Do you really believe that?? Here’s another link from Wikipedia: https://en.wikipedia.org/wiki/Radio_propagation -wherein we find this text, pretty much the same as they teach in school:
The math is shown on the Wiki page. If you click on the inverse-square law link above, you will see why this is so. |
| Post removed |
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 |
| Post removed |
What does all that have to do with the price of spinach? The shielding in cables protects the cables from external radio frequencies but does nothing to protect the audio signal from the induced magnetic field. And the reason is because the induced magnetic field is a different issue and requires a different solution. It's name is high permeability. But I repeat myself. You guys can’t seem to see the forest for the trees. And for transformers the (induced) magnetic field is an even bigger issue. And manufacturers apparently do precious little about it from what I can see. It's almost like they're oblivious. The electron tubes are usually sitting right out in front on those big old transformers. Like sitting ducks. |
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....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 |
| Post removed |
Al wrote, "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." No problem, Al. But that’s what the discussion happens to be about. I hate to judge too quickly but it appears I'm the only one here with actual experience in controlling magnetic fields, the induced magnetic fields in cables, power cords and transformers. |
Back to the topic of neutrality, I agree shooting for neutrality is a good thing. Lab measurements are a useful tool. Lower noise and distortion is always better. How one connects to the music emotionally and why is a very subjective thing. Neutrality may or may not be part of that. Regarding my own voyage along these lines, I feel I have achieved a good place in regards to neutrality and low noise and distortion with greatly diminishing returns for pushing any more forward there. I am interested in other approaches now and comparing. Ones that are more purely "subjective" in terms of being able to connect to the music. I have a pair of decent efficiency speakers (Triangle Titus) that I would love to try of a low power and not necessarily expensive tube integrated amp. Something along the lines of GLOW Amp 1, Jolida FX10, or maybe Decware. I’ll be replacing rotted surrounds on an old pair of Boston A40 speakers soon. I may try these as a stand in for the Triangles in order to free the Triangles up for a new system to experiment with. I have a large nicely finished but acoustically lively living room dining room area with no sound in it currently, and I’m thinking a small setup like this for more casual listening would work well. |
"If what you 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!" That’s what Parabolic Reflector Antennas are for, in BOTH transmitting and receiving RF https://books.google.com/books?id=zIuiupZBcqkC&pg=SA5-PA28&lpg=SA5-PA28&dq=parabolic+in+transmitting&source=bl&ots=TlEm2J_VD0&sig=PgM6zc7uHCBjmeaW5dOTTM3uCqw&hl=en&sa=X&ved=0ahUKEwjV-uanstnKAhUC9WMKHb41AtMQ6AEIRDAG#v=onepage&q=parabolic%20in%20transmitting&f=false . |
| Post removed |
Geoff I think you are a control freak and exhibit symptoms of narcissism. Some megalomania perhaps to. It seems to affect your reading comprehension and ability to comprehend or accept anything anyone else says. Its all about you it seems. It might still be treatable. Try some humility or at least maybe thanking people when they correct you or try to help. Does not have to be me. And don't give up on the thought of maybe developing a conscience. Yes you might find it interesting. Just my constructive feedback based on observation. Not a personal attack. |
The shielding in cables protects the cables from external radio frequencies but does nothing to protect the audio signal from the induced magnetic field. And the reason is because the induced magnetic field is a different issue and requires a different solution. It's name is high permeability.Again your first sentence is correct but what follows is not. One reason balanced lines work is because the system is relatively impervious to induced magnetic fields. This is because the magnetic field is impinged on the shield of the cable and the two conductors within. Since the shield carries no signal current whatsoever there are no worries there- it can't induce noise in the ground plane since ground is ignored. The internal connections carry the signal in two phases, 180 degrees opposed. When it arrives at the input (amplifier) the Common Mode Rejection Ratio (CMRR, https://en.wikipedia.org/wiki/Common-mode_rejection_ratio) of the amplifier then comes into play. If properly designed, the result will be that EMI imposed by the magnetic field cannot get amplified. This is because the input of the amplifier is looking for what is **different** between the two input signals and the EMI is the **same** to both inputs. Because the amp is looking for what is different, EMI gets rejected. The result is that the cable plays little or no role in the overall sound of a system. There are other factors that contribute to why this is so that have not been discussed. I find it quite odd that this technology has existed now for close to 70 years but still gets a lot of resistance (if you will pardon the expression) from audiophiles; eliminating cable interactions is a big part of obtaining neutrality in an audio system. I was designing satellite systems when you were wearing bell bottoms.It could be that you know so much that you have forgotten more than I will ever know. That *could* explain your lapse of basic communications knowledge essential to satellite technology. But Occam's Razor https://en.wikipedia.org/wiki/Occam's_razor suggests a simpler explanation. |
@Al- The Dunning-Kruger Effect is another possibility. (https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect) The initial propositions, not the corollaries. |
geoffkait may be one of those people who believe math and science are intuitive. Perhaps - for real math wizards - it is intuitive. But for most of us, it isn't. Even Einstein said he struggled with math. It's probably futile to try and explain this to geoffkait, although atmasphere deserves kudos for trying. |
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. |
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. |
"geoffkait may be one of those people who believe math and science are intuitive. Perhaps - for real math wizards - it is intuitive. But for most of us, it isn't. Even Einstein said he struggled with math. It's probably futile to try and explain this to geoffkait, although atmasphere deserves kudos for trying." i do not believe math and science are intuitive. I am actually a big believer in experimentation. An experiment is worth a thousand words. Am I an experimental physicist? Probably, although my education was theoretical physics. I'm with Einstein, I'll let others do the math. But I know what numbers mean. |
Last_lemming 02-02-2016 5:04pmDracule1, 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 |
Al, my understanding is that perceived brightness has to do with the fact that our ears do not have flat frequency response and are more sensitive to some frequencies than others, and that some forms of harmonic distortion tend to attenuate those frequencies that we hear best and are more sensitive to. So the lack of "neutrality" of our ears are as much a factor as that which comes out of the transducer. Here is a link to the chart I’ve referenced many times (and I have framed and hanging in my listening room, a nice audiophile work of art and science) that shows at what frequency music things occur and the corresponding sensitivity of the human ear: http://www.independentrecording.net/irn/resources/freqchart/main_display.htm So for example if the system is perfectly flat or "neutral" what we hear is not. We will hear more of the frequencies that our ears are more sensitive to than the others which might be considered a natural colorization that we all share to some extent. How each individual reacts to that in terms of musical enjoyment, fatigue, etc. may in fact vary widely, which would account for why there is little agreement on what sounds "best". The studies Ralph cites on how humans hear may be consistent with the idea that the frequencies that our ears are most sensitive to are the most important ones in regards to listening pleasure and minimizing "fatigue" in general. But it does not mean that what is most "neutral" or flat" coming out the speaker will necessarily sound the best to many. |
The human ear is tuned to be the most sensitive at bird-song frequencies. It also uses higher ordered harmonics to calculate how loud a sound is- its not doing that from the fundamental frequencies as such are quite rare in a pure form in nature. So if the system generates these harmonics (5th and above) even in trace amounts our ears are so sensitive to them that they will be heard, even though the distortion of the amp might be 0.005% THD. The converts distortion into tonality. So the presence of these distortions is heard as both brightness and harshness (the 7th in particular having been known since the 1930s as a source of a metallic coloration), even though on the bench or in the room the system might measure perfectly flat. In fact the ear has tipping points wherein tonalities created by distortion can be favored over actual frequency response errors. So in some cases its better to have none of these distortions rather than perfectly flat frequency response. |
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 |
Al I agree with all your points. I want my recorded music to convince me it's live, warts and all. So I want it to be neutral and accurate. If it sounds any way all the time, even smooth and relaxing, that is not a good thing to me. Its not good either if the sound is continuously irritating and chases me out of the room. Its OK if some recordings are and come out that way. I know all is well when I hear a lot of variety and want to just keep on listening rather than wanting to turn it off. Only in recent years have I achieved that. |
I'm only speaking for myself of course but IMO audiophiles tend to over analyze this kind of stuff too much. It's only natural considering the money involved. I've given up the need to over analyze frequencies or any other such stuff to come to a conclusion about my gear. The only thing that maters is what sounds neutral to me. In the end It may not sound neutral to anyone else. In the search for "neutrality" you can go and blame the electronics, the electricity from the walls, the rotation of the earth for that matter. Your chasing a perfect circle. Meaning it's a concept that cannot truly be achieved. So the only person you have to convince is yourself. None of it amounts to anything unless you like it yourself. All this talk about what is and what isn't neutral is a waist of time IMO - interesting to talk about but ultimately a black hole for your time. We are all trying to achieve a sound the we - individually - like so there can never be one truth about any of this stuff. Just groups of people who cluster together at different points of the spectrum of what they consider correct. We all intuitively know this but I guess we are gluttons for punishment cause we keep going in circles about it. 😜 |
Neutral is too ill-defined as it applies to audio but it seems to be used frequently and many are not sure what it means. If I was interested in purchasing a particular piece of gear I might for a very brief moment want it to sound neutral, forgetting that the end result of any system is based on the combination of several other components. Someone made that word up, so get rid of it. |
Dracule1, I too see no use for the concept of "neutral." I think realism is the goal I seek. One has to know what instruments sound like and hear the human presence around their playing or singing. But recently, I have heard realism at the fringes of the orchestra that are new. The illusion of a three or four person group seems easy but that of a symphonic orchestra or big band is not. I heard it somewhat in the Zandon suite at CES but much more with the new H-Cat X-10 MkIII amp. I no longer will be without this total realism. |
