gmgraves Posted August 23, 2014 Share Posted August 23, 2014 It is very easy to do a blind test to check claims differences in audio equipment exist and often in fact prove they do. The crowd that thinks they don't (usually based on a pre-conceived notion from what I can see) say you have to do a DBT because you can pick up cues from the person that does the switching of the gear. The same is true of wine tasting - you can pick up cues from the person pouring the wine yet it does not seem to be an issue in that setting because many people are surprised when it is revealed what wine they gave what marks to. My opinion for what its worth is DBT zealots have a pre-conceived view and when evidence comes along at variance with that view look at the methodology rather than the result and complain it was not done correctly. I am simply pointing out in other contexts people don't do that - they accept the result rather than attack the methodology. Thanks Bill While I agree that it's best to have a DBT, I find that for audio (if not for wine) that it's not really necessary. When I do informal listening tests with my audio buddies, we just make sure that which ever of us is doing the switching has his back to the listening area. If we can't see his face or his hands, that pretty much eliminates the body language and facial expressions from the equation and it seems to work very well. It didn't matter that the switcher knew which was sample A and which was sample B, we can't see him switch (or not switch). I'm pretty skeptical of blind testing for most audio comparisons anyway at this point. It works well for some things such as cables and interconnects, but not so well for others such as amplifiers and DACs. George Link to comment
gmgraves Posted August 23, 2014 Share Posted August 23, 2014 i think this is an illustration of how most of listening as we do it is learned. I suspect that if you could find an aboriginal human today (one without a cell phone) and planted him or her in front of an audio system he or she would not recognize the sounds beyond a familiar word or sound. None of the detail we explore would be audible. Absolutely. We audio types have "trained" ourselves to hear things in reproduced sound that the average listener doesn't even recognize as being things! An analogy would be the difference between you or I going to the art gallery to look at paintings. We stand in front of a Renoir, for instance and we either like it or we don't. It might earn an emotional response from us at some level, and we might even notice things like composition, how the pain was applied in layers, the play of light on the objects in painting, and then we move on. The next guy behind us, might be an art expert and connoisseur and he exclaims, "It's a fake!" Why does he know that and we don't? Because he has trained himself to notice subtleties of composition and technique that we don't even know to look for, much less make a value judgement about. It's the same with audio enthusiasts. We have "golden ears" because we have trained ourselves to look deeper than just the tune being played. Most listeners don't do that because the do not care about the minutia of recording or playback, they only care that it sounds reasonably good enough for them to enjoy the music - and believe me that bar is pretty low for most people! George Link to comment
gmgraves Posted August 25, 2014 Share Posted August 25, 2014 Hi George, I am a confessed proponent of DBT-testing, although I find it of very little interest here on CA because the majority of CA-members are subjective-oriented. However, I am quite curious to know why you believe DBT-testing works for cables, but not so much for other components which, in my opinion, are far more likely to show audible differences. Personally, I am able to "DBT" *all* audible differences I hear in a subjective fashion, but I must also say that I do not have that high a quality of equipment, my listening-conditions are not favorable, and I am experiencing deterioration of hearing-capabilities. Regards, Peter Well, to be honest here, I have to say that I probably accept DBT results for cables and interconnects because those tests confirm what I would expect to be the result from my engineering background; I.E. that there is no sonic difference between them. OTOH, there is a difference, and often a profound difference between amplifiers (and preamps) and DACs and disc media players. Unfortunately, DBTs more often that not (at least the ones that I have been privy to), return a null result with those components as well. When I audition a DAC or an amplifier, I'm not looking for instantaneous differences between the DUT and my "reference". I listen to many types of music on many different media and listen for long-term differences under differing conditions. For instance, I listen for sound-stage presentation and image specificity as separate parameters neither of which are apt to show up in a DBT, because they're subtle and the information with which to gauge these parameters simply does not exist on all recordings (A multi-miked orchestral recording where there is a microphone in front of every instrument (or section) has no image specificity, and certainly no depth. Pop recordings are generally three-channel mono, so they have no real soundstage attributes either). Also, in the case of amplifiers, two different brands/models may sound very similar at "normal listening levels" but put under audio stress with real wide dynamic range material, these amps may sound very different from one another, and the one with the more robust power supply will usually sound better. There is no guarantee that any DBT will use program material that will stress the two units under test in this manner while such a test is always part of my long-term evaluation procedure. Also, I tend to use material with which I am intimately familiar (often recordings that I have made, myself), and I tend to use the same recordings all the time. In my experience, most DBTs are conducted using material with which none of the listeners' are familiar. With regard to DACs, there are other parameters that simply will not show up in most DBTs for reasons mentioned above. This is not to say that DBTs couldn't be designed to take all of this into account, but my experience is that they never (or at best, very rarely) are. So I tend to not believe that DBTs or ABX evaluations, as usually conducted, are very reliable or even very illuminating. George Link to comment
gmgraves Posted August 25, 2014 Share Posted August 25, 2014 Even if they believe in what they are doing, they know the parts cost of their products. Taking a reasonable profit for knowledge, manufacture etc is fine. The kinds of profits these cable makers enjoy are obscene, ethically disgusting, and they cannot fail to know what their profit margins are. I would be tremendously ashamed to offer products with profit margins they have. I simply could not sleep were I to do what they do. Boy is that the truth! I was at the CA Audio Show a week or so ago, and was listening to some superb Sound Labs speakers that cost $40,000/pair. They were connected to the $18,000/pair Ayre Acoustic mono bloc amps with 8 ft speaker cables costing $47,000/pair! I'm sorry, but 16 feet of cable for $47,000 would be about $3,000 a foot. If the cables were pure gold (I don't remember the brand), then $3K/ft isn't enough, neither is it enough for pure silver, but it is 10X too much for even linear crystal copper!. The attendant in the room said that the cables were copper as far as he could tell. Now, what could anyone possibly do to 16 ft of thumb-thick copper cable to make it worth $3K/ft? When not conducting music, do they double as an auto-eroticism aid? I doubt it. Since cables are not active components, they can only subtract performance from a perfect conductor, and the only "perfect" conductors are those operating at absolute zero temperature, Which these are most decidedly not. I suspect that any improvement (if any) provided by such expensive cables is going to be very subtle. Talk about overpriced! Forget the standard industry 6X pricing over manufacturing costs or even 10X, these cables must be garnering their manufacturer 100X or perhaps more! And here I thought that MIT speaker cables were overpriced! And a final note. Who would spend more on their speaker cables than they spent on their very expensive speakers? George Link to comment
gmgraves Posted August 26, 2014 Share Posted August 26, 2014 George, you can rest assured that the Exhibitor didn't pay even a small fraction of $47,000 for the speaker cables, if he spent anything at all. But, for the buying public, I totally agree with your logic. I was criticized when I wrote something similar about spending $9,000 for a USB cable, so I won't be surprised if the same thing happens here. Well, of course he didn't. But that's not really the point. The point is that some company has the cajones to charge $47K for a pair of 8ft speakers cables! Talk about temerity! It does show me that I'm in the wrong business. Make a dozen pairs of cables like that a year, and live like a frick'in king. George Link to comment
gmgraves Posted August 26, 2014 Share Posted August 26, 2014 The very famous Alfred J. Prufrock get banned thread. Back from the dead. I thought we had all decided that we would agree that well made cables (Example: Blue Jeans Cables) were better that the junk that comes in the amplifier box. I also thought we all agreed that the very expensive cables were nothing more than snake oil. Well, that is certainly my experience: Buy well made, reliable cables using wire suitable for the purpose. Beyond that seems to be snake-oil. I buy interconnects from 'My-Cable-Mart' on the Web. They are gold plated connectors with good strain relief connected to real RG-59U cable. They are uber cheap and I have NEVER had one fail. Can't see doing any more than that. George Link to comment
gmgraves Posted August 11, 2015 Share Posted August 11, 2015 Things like slew rate, transient intermodulation distortion, etc were identified by dedicated audiophiles in pursuit of sonic excellence. I'm sure there will be many more metrics to fuel our fires. We just have to keep in mind the same difference that divides the best doctors from the rest - there's a huge and critical difference between "I can't find anything there, Mrs Jones" and "There's nothing there, Mrs Jones". Actually, Bluesman, things like slew rate, transient intermodulation distortion, etc were not identified by dedicated audiophiles, they were first noticed by dedicated audiophiles who realized that early solid-state electronics didn't sound very good when compared to tubed equipment. It was dedicated audio engineers who identified these new forms of distortion that seemed to be unique to then-current solid-state design practices. People like Matti Ottala of Finland, Walt Jung et al did the research, figured out how to measure these phenomena, and ultimately find the cause and correct the flaws in solid-state design practices to minimize these problems. George Link to comment
gmgraves Posted August 11, 2015 Share Posted August 11, 2015 What would such a demonstration entail? Offhand, I would say, repeatability of results under any and all varying test conditions. Example would be like an astronomer claiming to have found a new planet hiding in the Kuiper Belt. If it really is there, given the co-ordinates, any astronomer, anywhere in the world should be able to find it as well providing he/she has an adequate telescope. George Link to comment
gmgraves Posted August 11, 2015 Share Posted August 11, 2015 I love the evocative prose Audioquest use to describe their elements series of cables, they really have pulled out the stops, deserves an award just for that alone. I don't know why objectivists can't appreciate the lengths the manufacturers go to. This from their wind (up) cable Elements Series "In the simplest sense, wind is air in motion produced by the uneven heating of the Earth’s surface by the sun. Because our planet is made of various land and water formations, from the severe heights of K2 to the placid Chicago River, it absorbs the sun’s radiation unevenly, creating differences in air pressure and the ensuing movement of air from high-pressure areas to lower ones. Wind is also one of our most valuable natural resources: As an alternative to fossil fuels, wind is plentiful, renewable, widely distributed, clean, produces no greenhouse gas emissions, and uses little land. While wind power may be more important today than ever before, it is by no means a new concept. Representations of ships under sail date as far back as 5500 B.C., while windmills may have been first used in Persia in 200 B.C. Among the classical elements, wind’s close relative, air, is pure, powerful, and fundamentally important to life. In Japanese philosophy, wind is a symbol of all things that grow, expand, and enjoy freedom of movement, in some ways best represented by the human mind. People born under the astrological signs of Gemini, Libra, and Aquarius are thought to have dominant air personalities, marked by kindness and social grace. Of course, wind itself may be the most graceful of all elements. It fans the flames of our deepest passions, dances atop the surfaces of our longest rivers, sings in the rustling of the largest leaves, and carves its initials into our mightiest rocks. The physical effect is often astounding: From the forever-swirling formations of Coyote Buttes in Utah, to the sculpted cypress trees seemingly frozen in time along California’s coast, wind holds a place as one of nature’s most masterful artists." Wasn't Coyote Buttes a joke from the Simpsons ? Does AudioQuest supply hip-boots with that prose? George Link to comment
gmgraves Posted August 13, 2015 Share Posted August 13, 2015 Walt Jung & Matti Otala (with 1 T) were both dedicated to great audio. Jung is best known for his op amp work (I still have my 1st edition Op Amp Cookbook) - but I first knew him from his Marantz 7c mod, a version of which was the reason my 7c was undesirable to collectors when I was ready to move on. Otala was an early opponent of global negative feedback in power amps because he believed it limited sound quality, of which he was an excellent judge. He designed early amps for ReVox & B&O to sound better than their rivals. No one would have noticed anything had pioneers like them not heard the differences first, studied them to identify the causes, & designed devices that embodied what they heard. They were far more than engineers making observations on their oscilloscopes - they were dedicated to great sound quality in audio reproduction. That's an audiophile to me. I recall when the "Transistor Sound" was touted as a feature and an advantage of the then new transistor gear just becoming available. George Link to comment
Popular Post gmgraves Posted April 16, 2020 Popular Post Share Posted April 16, 2020 On 6/22/2012 at 7:32 AM, prufrock said: Have decided to create a blog on this issue. Will name it similar to the above and have the link on my posts. This will avoid, from my point of view, any further personal confrontation on the issue. And hopefully endless repetition and groundhog day type arguments. If I see a poster asking advice on cables/interconnects I will drop in and direct them to the blog and leave it at that. If it seems a cable discussion may be influencing other readers I may do the same. The link on my posts will also hopefully provide a counterbalance to the those who list their cables in their system setups. Would appreciate other's contribution as well. What I hope is to be able to write a very succinct, under 2 page entry about how this whole issue evolved; how it started and what keeps it going. If you are on the opposite side, I would request that you don't post on this thread please. Not because I don't want debate. Its just that I want ideas that will help with my blog and these will be best gotten from people on the skeptics side of the fence. I think it would be a good idea if others from the opposite side of the debate did something similar as well. Basically my argument is this: the unique characteristics of audio have provided an environment where this phenomenon has been able to gain traction. You would not expect to, and will not find an analogy in photography for example. Due to current legislation the companies who peddle this expensive stuff are able to get away with not proving up their claims. Audiophile land is a bit of a backwater, so this is not surprising. It seems the con has gained enough momentum now for it to have reached the stage where the sheer number of believers has given it an elevated status. Anyhow look forward to comments. Will likely need help getting the significance of the null testing right and other bits. Will write sections of it up here as I get time and ask for feedback. However, other skeptics feel free to post your ideas anytime without waiting for me. I agree that audio is almost unique in providing an environment where this “notion” has been able to gain traction. Here’s the problem as I see it. Now, These comments are mostly aimed at interconnects. Speaker cables are somewhat different and I’ll get to them later. If we assume for a moment that interconnects do have a “sound”, since they are passive components, not active, they can’t really add anything to the signal passing through them. That would mean that the cables were amplifying some portion of the spectrum, and that’s impossible. So therefore, if two cables sound different from one another, then it’s only logical to conclude that one or both cables are attenuating some portion of their pass band. IOW, some portion of the spectrum is being transferred with less attenuation than some other portion making the un-attenuated portion of the spectrum seem louder than the portion attenuated! In fact, the cable becomes a “fixed” tone control. Now, the maths say that this shouldn’t be. Short “audiophile” runs of coax simply don’t have enough inherent capacitance, resistance, or inductance to attenuate any portion of the audible spectrum. And if it did, it would attenuate the top end of the band. Belden’s specs for RG59 coax, for instance, says that at a length of 15 meters (roughly 50 ft), RG59 will attenuate a 20 KHz signal by about 1 dB! Nobody can hear that, and you can imagine that if it requires 15 meters of coax to attenuate a 20 KHz signal by one dB, how much attenuation at 20 KHz, will occur at say 1 meter? But let’s forget the theory, and concentrate on what people report as the differences they hear in cables. I’d say that most audiophiles buy cables ”sound unheard”. Most seem to buy based on reviews or ads from the cable companies. I never hear anybody say that their new $200 interconnect sounds worse than the cheap Best Buy cable that they are replacing. Why is that? It should be quite the possibility that some expensive cables would sound worse than the cheaper ones that they are replacing, yet one rarely, if ever hears anyone say that. The emperor’s new clothes syndrome perhaps? Also, since any cable performance is source and load dependent, just because some reviewer gives a particular cable a glowing evaluation, in no way means that said cable will sound the same way in some other system! I maintain that purchasers of expensive cables are buying a pig in a poke. When you buy a cable based on sound quality, unless you can try lots of cables, in your own system, before choosing one, you will never (except perhaps by accident) find the best cable for your particular application. This blind purchase phenomenon applies to speaker cables as well, where finding the right one has much more profound consequences than it does for interconnects because the source and loads in speaker systems vary so much more. More than any other reason, that’s why I buy cables based on build quality rather than sound. Since I don’t know how any cable will change the sound of my system, I assume that RG59 based interconnects with good quality RCAs and decent strain relief are going to affect the sound as little as possible. Now, I might be wrong about this, and perhaps a good pair of expensive “boutique” interconnects would improve the sound of my system by attenuating a less noticeable portion of the spectrum from what I’m wired with now (mycablemart.com premium interconnects made with pure copper RG59 coax), but I’m not going to open that can of worms. Teresa, daverich4, Seraph and 1 other 2 2 George Link to comment
gmgraves Posted April 16, 2020 Share Posted April 16, 2020 41 minutes ago, sandyk said: Hi George That is absolutely incorrect. In the current series of Dolby-A correction tests that several members are involved with in a small PM group with John Dyson, we routinely notice differences even as tiny as 0.1dB !!! Even Archimago concedes that this is indeed possible. Regards Alex At 20 KHz? I don’t buy that - at all! Maybe you noticed differences of 0.1 dB at 1 KHz, maybe even 7 KHz, but not at 20 KHz! Most men over about 35 can’t even hear 20 KHz much less tell a 1 dB difference in level at that frequency. If you’re saying that you or John, or anyone can not only hear 20 KHz, but can detect a 0.1 dB difference in level at that frequency, you’re going to have to prove it to me. Teresa 1 George Link to comment
gmgraves Posted April 16, 2020 Share Posted April 16, 2020 2 minutes ago, Speedskater said: Yes, with trained, skilled listeners in stringent A/BX tests it's very possible to hear this small a difference. Even though they are way to small to describe. But in real world music listening, no way, no how! Experts that use stringent A/BX tests, complain that they are too sensitive to small uncontrolled differences. The tests require a lot of time and effort to minimize these differences. Again, the operative phrase here is that the attenuation for 50 ft of RG59U coax is -1 dB at 20 KHz! I certainly hope that you are not going to also insist that anyone (not even the proverbial 12 year old girl) can hear that! Teresa 1 George Link to comment
gmgraves Posted April 17, 2020 Share Posted April 17, 2020 6 hours ago, sandyk said: I am simply pointing out to the resident cable agnostic that it is possible to hear differences as low as 0.1dB , NOT the original 3dB that used to be claimed many years ago. What makes you so sure that there can't be other small frequency anomalies in other parts of the spectrum in some implementations, not a theoretical cable implementation ? Add to that, that not all cables are perfect in their RF/EMI rejection abilities, and there may also be some low level crap getting into some cables as well But, I never said that differences of around 0.1 dB couldn’t be heard. I merely said that an attenuation of -1 dB @ 20KHz for a 50 foot (15 m) run of RG59U couldn’t be discerned. You took that comment out of context to make it seem that I was saying that a -1 dB attenuation couldn’t be heard across the board, when I never said or intimated, or thought anything of the kind. George Link to comment
gmgraves Posted April 17, 2020 Share Posted April 17, 2020 6 hours ago, sandyk said: Multiply that by the number of interconnects in many systems,some of which may be longer than 2M in length, and the effects may become quite noticable in relaxed listening . Recently, to pass time, I made small improvements in the internal 0 volt/"earth" returns of my DIY DAC, Preamp and Class A P.A. Each individual change was barely audible, and unlikely to be demonstrated to any degree of confidence in Blind Testing. However, the overall improvement was even appreciated by my 17yo grandson. Is there something about the air in OZ that makes you guys able to hear things that the rest of us can’t? Along with Frank, you sometimes make statements that are difficult to reconcile with the reality that many of we non Aussies understand. 😉 daverich4 1 George Link to comment
gmgraves Posted April 17, 2020 Share Posted April 17, 2020 13 hours ago, sandyk said: In some cases even you may be able to hear them when they are pointed out to you. Some of us aren't hobbled by EXPECTATION Bias to the same degree as people like yourself are. BTW, many DIY people have more developed listening skills. P.S. I would also rank the previous posters listening skills well above average too. Alex, I am not hobbled by expectation bias, I just know when my ears are being fooled by expectation bias. 😉 George Link to comment
gmgraves Posted April 18, 2020 Share Posted April 18, 2020 1 hour ago, sandyk said: In that case you would be pretty unique, even for an EE . As for the sly digs at Aussies, do I once again need to prove myself to you ? P.S. Did you get around to listening to that copy of an extremely dynamic Classical recording that I sent you? As good as your own are, when compared with many other Classical recordings, it shows just how good the humble CD can be. The “dig” at Aussies was mostly a joke, Alex. There was a component of seriousness in my quip, but it was meant in a lighthearted manner. Both you and Frank make extraordinary claims sometimes, and all I’m doing is to re-iterate the old axiom that extraordinary claims require extraordinary proof. I was specifically referring to your statement that the anomalies that many hear in cables are cumulative across all the cables in a system. I would think that this might possibly happen if all the cables in a system were the same make and models, but even so, most paths, phono, CD, streamer, etc. are just a few interconnects. I.E. phono>preamp>amp>speakers. But if one’s interconnects are a mix of types, I would expect that these cable anomalies would average-out, but maybe not. Remember, all cables have losses; none add anything. If two sound different it’s because one (or both) losses are in different parts of the audio spectrum. Ideally, all interconnects would be pure conductors and therefore absolutely neutral. I tend to take the view that interconnect sound is unpredictable, not controllable, and very subtle. So as I’ve said, I, personally, don’t pay any attention to the very subtle but possibly audible anomalies between cables that should be totally transparent. I certainly won’t pay hundreds or thousands of dollars for pigs-in-a-poke. If you took umbrage at my quip, I apologize. I had hoped that the emoji at the end of my post would have highlighted the lighthearted tongue-in-cheek tone of my post. P.S. I listened to the files you sent to me. Yes I agree. This is an excellent recording with incredible dynamic range. It shows clearly what the state of the recording art can do, if used correctly. The fact that few recordings live up to this one, just shows how lazy many studio engineers are. Teresa 1 George Link to comment
gmgraves Posted April 18, 2020 Share Posted April 18, 2020 2 hours ago, fas42 said: I doubt that they would average out ... if there are a number of weaknesses in the various cables then the overall result would be a loss of detail, resolution - in the subjective sense. What I find happens as each cable area is resolved is that more can be heard, discerned on the recording, but that an underlying 'edge' to the the SQ becomes more distinct - and to many, more disturbing. Until the very last cable anomaly is finally knocked off - and the SQ then fully "blooms" ... the distortion anomalies, when they are many, "average out", blur to some degree - but when there is only a single cable distortion element in the picture, it sticks out like the proverbial sore thumb. Not objective, yes, but I'm going through this very process right now - got Bev dancing in the kitchen while she's trying to make soup, as classic juke box era hits are being pumped out, 😁 ... headin' in the right direction ... 🙂 Apparently there are weaknesses in all interconnects, because if many here are to be believed, even interconnects costing thousands of dollars have a “sound”. not a very encouraging testimonial for expensive “boutique cables if you ask me. And only defective cables with corroded connectors or poor solder or crimp work introduce distortion, and again, even the best, most expensive cables subtract information, they cannot add it (except, perhaps, the aforementioned distortion, caused by the “diode effect” of poor connections). George Link to comment
gmgraves Posted April 18, 2020 Share Posted April 18, 2020 1 hour ago, Audiophile Neuroscience said: George, I realize you say "I just know when my ears are being fooled by expectation bias" tongue-in-cheek but for the benefit of the mythical novice and gullible audiophile neophyte .....> boys and girls, Uncle George was just kidding,okay🤷♂️🤡 Well, of course uncle George was just pulling Uncle Alex’s leg!😉🧐 Audiophile Neuroscience 1 George Link to comment
gmgraves Posted April 18, 2020 Share Posted April 18, 2020 On 4/17/2020 at 6:39 AM, CG said: This is supposed to be a sub-forum based on objectivity, isn't it? That kind of implies keeping the facts straight. Arm waving isn't allowed. First, RG-59 cable loss is specified for matched source and load impedances. In this case, 75 Ohms, which we pretty much never have in an audio system. The source impedance might be close enough to 75 Ohms, but the load impedance of an amplifier or preamp input is usually much, much higher. Starting at around 10K Ohms, typically. (Many input impedances drop as the frequency rises due to the use of an input filter, various compensation devices, and the actual capacitance of the input devices. But, let's ignore that, for now.) In addition, the loss is rarely measured for these kinds of cables at very low frequencies. Instead, what you get is extrapolated data from the loss curves generated where the loss is more significant. But, if you trust this data, the loss of RG-59 cable at 20 KHz is insignificantly different than it is at 20 Hz. As in, a couple milli-dB for a 10 foot length, for matched source and load impedances. At least according to the cable manufacturers. OK, perhaps this isn't an accurate portrayal. So, why not just consider this short cable to be a simple series resistance and inductance lumped component with the cable capacitance lumped as a shunt element at the load end? It's easy enough to simulate. Oliver Heaviside thought so. When you do this, you get similar results. Try it for yourself. In fact, according to the simulation, the amplitude actually can rise a milli-dB or two at 20 KHz compared to 20 Hz, depending on the source and load impedances. Or, drop, again depending on the source and load impedances. The reasons for this are an exercise left for the reader. (Note: This simple analysis does NOT include the effects of Eddy/Foucault's currents, subsequent skin effects, or a bunch of other details. That might or might not be significant in a cable this length at these frequencies.) But, don't trust me - verify this for yourself. While there, you may want to examine the square wave response for such a network. So, the cable loss, assuming dielectric material that is not intentionally conductive or lossy and ignoring those other little details that may or may not matter, probably isn't an issue. However, as just one aspect of the system analysis, you might want to consider the effect of this lumped RLC on the behavior of the output circuit of the source. And, on the input circuit of the load (preamp or power amplifier.) And on the feedback system of the power amplifier, assuming it uses overall loop feedback - most do. I agree with everything you said. The 75 Ohm spec of RG59U is, as you say, largely irrelevant in audio. As I recall the -1dB at 20 KHz for 50 feet, is of course, at 75 Ohms. *I* want it for my interconnects because if the RG number is on the cable jacket, it guarantees a commonality of characteristics from cable to cable that allows uniformity. IOW, not a pig-in-a-poke! George Link to comment
gmgraves Posted April 19, 2020 Share Posted April 19, 2020 1 hour ago, sandyk said: The internal Calculator on the blink perhaps ? ????!!! George Link to comment
gmgraves Posted April 19, 2020 Share Posted April 19, 2020 2 hours ago, sandyk said: The -1dB attenuation at 20kHz for 50 feet is WAY too high , at least when correctly terminated . I’m just relating what Belden specs said. Even if I remembered it wrong, my point is still valid. 50 feet of cable won’t attenuate an audio signal for beans. George Link to comment
gmgraves Posted April 19, 2020 Share Posted April 19, 2020 3 hours ago, sandyk said: George You are at risk of losing your credibility in this area ,which is why I dropped a few hints for you to check your figures. It's obviously not just about attenuation. It's also about effectiveness of the shielding at attenuating RF/EMI as well. Belden 9275 RG59 75 ohm Coaxial Cable Specifications Attenuation at:-100mhz - 2.6dB / 30mt -300mhz - 4.45dB / 30mt -600mhz - 6.20dB / 30mt. I don’t understand what attenuation at VHF frequencies over a length of 90+ ft, has to do with 20 KHz attenuation over 50 ft except that I misremembered the spec. Ok, so the attenuation at audio frequencies is even more minuscule than I said it was. THAT’S the point here, as far as I’m concerned, not the numbers. Bring on the pedanticism. daverich4 1 George Link to comment
gmgraves Posted April 19, 2020 Share Posted April 19, 2020 7 hours ago, Speedskater said: That's an example of audio snake oil taken to the highest level. It's taking engineering knowledge, out of context and misapplying it, with great skill. Sometimes it’s applied without skill. Like the boutique cable companies that talk about “skin effect” at audio frequencies and how their cables handle it better than others. Skin effect at audio frequencies; there’s snake oil for you. lucretius 1 George Link to comment
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