'Splainin' once you actually do a blind test. I've sadly experienced lots of easily audible differences that magically went away once I only had my ears to rely on.
I particularly am puzzled by people who will assiduously avoid any magnetic metal in their resistors but cheerfully use vacuum tubes... Perhaps that's why I'm waiting for someone to actually demonstrate the audibility of this rather than just assert it with an air of certitude incommensurate with the quality of the evidence.
Actually, temperature coefficient is one of the distortion mechanisms of resistors which can be measured. The nonmagnetic bit, I have never heard of anybody being able to measure the effect of magnetic endcaps.
Especialy under the influence of ac signals
Under the Influence by seela | Song | Free Music, Listen Now
I can think of 3 physical mechanisms straight away:
1) Increased lead inductance, since the leads are now passing effectively through 2 ferromagnetic beads with relative permitivity in the low 100s. These inductances are also much more non-linear than the free-space inductance of a non-magentic lead.
2) Eddy-current losses in the ferromagnetic end-caps.
3) Increased EMI/RFI radiation as well as pick-up. This is probably the most significant effect for a small-signal, high-impedance node.
At one time, I too thought that the effects would be inaudible, but after actually experimenting with non-magnetic resistors like Holcos, and comparing them to generic parts with magnetic leads, I'm now convinced that it is materially significant at small-signal nodes at least, and of utmost importance in a voltage-series feedback network.
The distortion is proportional to the current and distance. Shows up on many measurements. Of course since most higher current tube applications involve transformer coupling the construction effects are probably swamped out.
Tempco does not include thermal mass. High resistance films such as carbon are often thinner for the same value of resistance than metal films.
I think that besides any "magnetic" influence, on which I won't comment, the main point is that here "magnetic" means "iron", which means "cheap" compared to copper or brass terminals.
Not from the strict meaning of price, but because of higher resistivity, poorer contact, poorer mechanical properties, poor corrosion resistance, etc.
Plus another important point: iron endcaps imply iron part legs, so you are introducing poor conductor iron wiring in an otherwise "all copper" connection.
Not from the strict meaning of price, but because of higher resistivity, poorer contact, poorer mechanical properties, poor corrosion resistance, etc.
Plus another important point: iron endcaps imply iron part legs, so you are introducing poor conductor iron wiring in an otherwise "all copper" connection.
Of course, low current tube applications require tubes, which have magnetic leads and all sorts of magnetic components in their structure. Danny's circuit is very low current (active crossover), so I have some trouble attributing current effects to his report.
For resistors used at audio applications, the "measurable" effects reported to date are orders of magnitude below any accepted detection threshold (with the exception of pathological cases like the Half Watt resistor article I've cited before). And of course, "ears only" listening data is lacking entirely. Get some of that real listening test data and then it's something worth spending some angst about; without it, there's no more support than the Peter Belt frozen photograph claims.
You can take your pick, the carbon film resistors do have higher distortion even at low current, the magnetic effects show up (although they seem to be a bit lower at 1/16 watt into 1/4 watt R's by about 15 db.), he and many others are in error reporting similar results, a null test proves null or your idea of an accepted detection threshold is in error.
I'd go for the last. When you look at the inverse Fletcher-Munson curves, the energy curve of music and the compound distortion of all the stages in a sound system, you just might have boosted the distortion to levels that are at or above the threshold of detection.
(Just for those not following;
Fletcher-Munson shows about a 25 db threshold shift 120-3,000 hz.
Energy content of music 125 hz compared to 3,000 hz. can range from 12 to almost 30 db.
The ear's ability to pick signal out of noise is another 30 db.
There are multiple harmonics so even without in phase addition this adds another 3-6 db to the distortion level.
So 25 + 30 + 30 + 6 = 91 db possible detection below the broadband signal level.)
Carbon film resistors distort above than, metal films below.
But SY hasn't found that to be the case in his experiments.
I'd go for the last. When you look at the inverse Fletcher-Munson curves, the energy curve of music and the compound distortion of all the stages in a sound system, you just might have boosted the distortion to levels that are at or above the threshold of detection.
(Just for those not following;
Fletcher-Munson shows about a 25 db threshold shift 120-3,000 hz.
Energy content of music 125 hz compared to 3,000 hz. can range from 12 to almost 30 db.
The ear's ability to pick signal out of noise is another 30 db.
There are multiple harmonics so even without in phase addition this adds another 3-6 db to the distortion level.
So 25 + 30 + 30 + 6 = 91 db possible detection below the broadband signal level.)
Carbon film resistors distort above than, metal films below.
But SY hasn't found that to be the case in his experiments.
I'd be more interested in hearing the results of 25ppm or better metal film resistors (Vishay/Dale PTF series, for example), since that's what I try to use when budget doesn't permit bulk foil resistors. While the magnetic end caps (which should be more reliable in making durable connection to the metal film) might be contributing something to the sound, there may differences in the metal film composition that haven't been accounted for.
There's still a lot of room for testing and experimentation before reliable conclusions can be drawn.
There's still a lot of room for testing and experimentation before reliable conclusions can be drawn.
You left out the part about that 30dB threshold being the case in the absence of signal. And the automatic attribution of current-related distortion to the presence of magnetic material. Not that you would ever cheat with your numbers. For a reality check, I'd invite anyone to do a distortion loopback test using their soundcard (which doubtless contains multiple resistors of non-exotic origin).
One of the other numbers caught my eye. For a line level crossover, voltages are going to be below 2.5VAC. Let's consider a circuit with that voltage impressed across a 1k resistor in a feedback circuit (worst case position). P = V2/R = 6.25mW, a couple of orders of magnitude lower than your estimate.
Again, lots of people (myself included) have done loopback distortion measurements with decidedly non-exotic soundcards and routinely show distortion levels at -95dBFS and lower- and even then, only in the presence of a full scale signal. No human is going to hear that.
Nope, I don't buy the plausibility argument. A well-controlled ears-only test would be convincing.
For a reality check, I'd invite anyone to do a distortion loopback test using their soundcard (which doubtless contains multiple resistors of non-exotic origin). One of the other numbers caught my eye. For a line level crossover, voltages are going to be below 2.5VAC. Let's consider a circuit with that voltage impressed across a 1k resistor in a feedback circuit (worst case position). P = V2/R = 6.25mW, a couple of orders of magnitude lower than your estimate.
Again, lots of people (myself included) have done loopback distortion measurements with decidedly non-exotic soundcards and routinely show distortion levels at -95dBFS and lower- and even then, only in the presence of a full scale signal. No human is going to hear that.
Nope, I don't buy the plausibility argument. A well-controlled ears-only test would be convincing.
Sy and others, your dismissal of people's listening experiences is really growing tiresome. If so many people claim to hear the same thing, can't you at least open the door to the possibility that there is some validity to their claims? C'mon, quit running every discussion about sonics into the ground. I'm not making any outrageous claims here that blue caps sound better than red caps. There is a real physical difference between these resistors, and it, or something, results in a real difference in performance. Don't insult me again by claiming that none of this is valid. If you can't accept it, please at least stay out of the way of an adult discussion.
As far as taking hours to hear an easily detectible difference, I wanted to make the point that, although I immediately heard that something was "wrong", I took several more hours to make certain that what I was hearing really existed, and that it didn't change after passing signal for a while or my ears "adjusting to it." I tried to be careful. I swapped channels. I listened in stereo and mono to one speaker at a time. I played different kinds of music. I am interested in meaningful results, not wanting to be swayed by bias one way or the other. As I mentioned, I was disappointed that the results went against my bias, and I think that flies in the face of the double blind proponents.
If I could do such a test properly, I'd be happy to perform one, and I think that careful listeners would clearly hear the difference. I guarantee that I could. But I'm afraid I could never satisfy the obsession with clinical standards for acceptable testing, so I won't even try. Objectivists are relentless, and frequently misguiding others here. People who can hear, know there is a difference. Stubbornly repeating denial of it does not result in advancing the science.
I don't know if magnetism is the operative mechanism here. I don't claim to know what causes this unpleastant sound. I do know that resistors of respectable quality with "superior" specifications but attracted to a magnet, did not sound as good as those, with "inferior" specifications, that weren't. That is my ONLY conclusion. I will leave theory to the experts. There might be resistors out there that are attracted to a magnet and sound perfectly wonderful. These certainly do not, and there is no doubt about that. So please stop all the silly handwaving about DBT and validity and get on with discussing the sound of resistors, which is the topic of this thread.
Peace,
Tom E
As far as taking hours to hear an easily detectible difference, I wanted to make the point that, although I immediately heard that something was "wrong", I took several more hours to make certain that what I was hearing really existed, and that it didn't change after passing signal for a while or my ears "adjusting to it." I tried to be careful. I swapped channels. I listened in stereo and mono to one speaker at a time. I played different kinds of music. I am interested in meaningful results, not wanting to be swayed by bias one way or the other. As I mentioned, I was disappointed that the results went against my bias, and I think that flies in the face of the double blind proponents.
If I could do such a test properly, I'd be happy to perform one, and I think that careful listeners would clearly hear the difference. I guarantee that I could. But I'm afraid I could never satisfy the obsession with clinical standards for acceptable testing, so I won't even try. Objectivists are relentless, and frequently misguiding others here. People who can hear, know there is a difference. Stubbornly repeating denial of it does not result in advancing the science.
I don't know if magnetism is the operative mechanism here. I don't claim to know what causes this unpleastant sound. I do know that resistors of respectable quality with "superior" specifications but attracted to a magnet, did not sound as good as those, with "inferior" specifications, that weren't. That is my ONLY conclusion. I will leave theory to the experts. There might be resistors out there that are attracted to a magnet and sound perfectly wonderful. These certainly do not, and there is no doubt about that. So please stop all the silly handwaving about DBT and validity and get on with discussing the sound of resistors, which is the topic of this thread.
Peace,
Tom E
Voltage coefficient is also a factor in resistor construction: carbon composition, very bad and bulk metal foil and low Tc wirewound extremely good. In between, very thin films can exhibit non-linear effects with voltage swing; I suspect very low Tc resistors are much better in this regard for a given resistance because they may have thicker films, or are somehow stabilized through, say, annealing and/or choice of alloy. Bulk metal foil and wirewounds simply don't have this problem.
And we're talking extremely low levels of distortion that even a Radiometer CT-100 or better is challenged to measure, and that instrument is especially designed for this purpose.
And we're talking extremely low levels of distortion that even a Radiometer CT-100 or better is challenged to measure, and that instrument is especially designed for this purpose.
Is it unreasonable to think our ears and our brains are more capable than the machines with which these things are measured? They are both involved in the listening experience, hopefully. Not being sarcastic, but asking serious question. Are we to assume that a machine can quantify everything we experience in this world through our natural sensory abilities.
You left out the part about that 30dB threshold being the case in the absence of signal. And the automatic attribution of current-related distortion to the presence of magnetic material. Not that you would ever cheat with your numbers.
One of the other numbers caught my eye. For a line level crossover, voltages are going to be below 2.5VAC. Let's consider a circuit with that voltage impressed across a 1k resistor in a feedback circuit (worst case position). P = V2/R = 6.25mW, a couple of orders of magnitude lower than your estimate.
Again, lots of people (myself included) have done loopback distortion measurements with decidedly non-exotic soundcards and routinely show distortion levels at -95dBFS and lower- and even then, only in the presence of a full scale signal. No human is going to hear that.
Nope, I don't buy the plausibility argument. A well-controlled ears-only test would be convincing.
SY,
I am not sure what you're going on about.
For speech intelligibility a signal to noise ratio of 0 db is just fine. The ability of one's ear to pick out a tone 30 db below the broadband noise level is what I was talking about. What were you talking about in your 30 db number?
I published on 1K resistor distortion at 1/4 power. That does require more than 2.5V RMS. However higher value resistors often have thinner films that increases some forms of distortion even at lower levels. The low cost miniature carbon film resistors in values of say 10,000 ohms show 20 db more distortion at 1/4 power and re-rate the same 3 db less distortion for each halving of power.
So even at 2.5 V RMS they have almost dead on the same distortion as 1K 1/4W same family resistors at 7.9 volts. (I assume you picked 2.5 V RMS out of a hat and didn't do Sqrt (1000 * .25 * .25)/3.16 as my prior testing would have predicted!)
Now My Audio Precision System 2 is only good for 102 db-ish so I'd love to check the actual accuracy of your -95 db accurate decidedly non-exotic sound cards.
Now I am sure that it is complete coincidence that much earlier in this thread someone listed his favorite carbon film resistors in order, even noting that two brands sounded almost the same, that exactly matched the measurement results in reverse order! (He like the highest distortion best!)
So as I think we agree doing any test requires adequate controls to be sure we are actually testing what we think we are. This is a bit easier for electrical tests than other. However this is often a lot of misunderstanding even of the basic electrical tests.
lets imagine you have mounted a special component you can hear is better, but just 'barely'
then imagine I take it out again and replace it with what was mounted before, and without you knowing anything
then I return a month later and ask if you have noticed that I changed it back
and you will say 'what', yeah, you remember 'something', but had forgot all about it
then imagine I take it out again and replace it with what was mounted before, and without you knowing anything
then I return a month later and ask if you have noticed that I changed it back
and you will say 'what', yeah, you remember 'something', but had forgot all about it
- Status
- Not open for further replies.