AFAIK Welwyn came out as one of the better ones in the excess noise comparison that resurfaces from time to time on this site.
Modern resistors (meaning those made in the last 20 or 30 years), do nothing bad to sound, nothing at all; and on the other end, can not put into sound what was not there previously, so they won't "improve" soundstage/warmth/smoothness/female voice/jazz trios/piano music/Pavarotti/whatever.
Those who desperately want to show "how bad" standard, over the counter resistors are, supply graphs showing inaudible 0.000000001% distortion, or -140dB distortion components or link to You Tube videos where somebody applies 2KV to a 1/4W resistor and say: "see? see? it burst into flames!!!) 😱
Those who desperately want to show "how bad" standard, over the counter resistors are, supply graphs showing inaudible 0.000000001% distortion, or -140dB distortion components or link to You Tube videos where somebody applies 2KV to a 1/4W resistor and say: "see? see? it burst into flames!!!) 😱
JM, it is actually a bit more complicated than that, but it depends heavily on the location. Excess noise can be very different for different makes. In a feedback loop drawing considerable current to keep Johnson noise as low as possible, excess noise from a bad resistor can easily swamp the benefits gained by using a relative low value in the feedback path.
Maybe is true but another also cheap series (unbranded) always bought at RS seemed, and i stress seemed, less good
I was playing with op-amps at that time
And the nice thing is they are very cheap indeed.
Like 1 euro for 10 pieces.
http://docs-europe.electrocomponents.com/webdocs/0bfc/0900766b80bfc67d.pdf
this is the better series, of course much more expensive and looking like Holco
http://docs-europe.electrocomponents.com/webdocs/0099/0900766b80099677.pdf
I was playing with op-amps at that time
And the nice thing is they are very cheap indeed.
Like 1 euro for 10 pieces.
http://docs-europe.electrocomponents.com/webdocs/0bfc/0900766b80bfc67d.pdf
this is the better series, of course much more expensive and looking like Holco
http://docs-europe.electrocomponents.com/webdocs/0099/0900766b80099677.pdf
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Yeah, well, I'm not paying $13 and up for each metal foil resistor when I can get a metal film for less than a $1 each and they are almost as good.
Possible explanation of resistor sound quality
Well, this is not so scientific, because I haven't done any measurements, can't provide nice graphs, can't give the math behind it, but anyway:
Each resistor has a TK value, be it specified by the manufacturer or not. This value tells how much percent does the room temperature value change for 1° temperature variation. Now, during normal operation the resistor dissipates heat. If an audio signal is flowing through it, it does that in an AC rate. That heat dissipation modulates the resistance more or less, depending on the TK. This signal induced unwanted variation of resistance might cause distortion of the audio signal. Of course, it all depends on the function and position of the resistor in the actual circuit. I would suppose a resistor in the negative feedback path is more critical than a grid leak resistor.
It the above is true, a higher power resistor of the same type should have better sound quality. Anybody has a matching experience?
Well, this is not so scientific, because I haven't done any measurements, can't provide nice graphs, can't give the math behind it, but anyway:
Each resistor has a TK value, be it specified by the manufacturer or not. This value tells how much percent does the room temperature value change for 1° temperature variation. Now, during normal operation the resistor dissipates heat. If an audio signal is flowing through it, it does that in an AC rate. That heat dissipation modulates the resistance more or less, depending on the TK. This signal induced unwanted variation of resistance might cause distortion of the audio signal. Of course, it all depends on the function and position of the resistor in the actual circuit. I would suppose a resistor in the negative feedback path is more critical than a grid leak resistor.
It the above is true, a higher power resistor of the same type should have better sound quality. Anybody has a matching experience?
That is correct. Keep in mind tempco does not have to be linear. So an S curve of tempco swinging around a straight line would be misleading.
Also low value resistors often have thicker films than high resistance values and so have more thermal mass. The lower the frequency of the signal the longer time it has to act on heating the resistor. So thermal mass is of some importance.
most of my metal film (Vishay 600mW, 1% 50ppm) are around $1.50 per hundred.
I just bought another 35 values mostly 500mW, 50 or 100 off each, from Farnell for <£24 incl 20% VAT. That's ~1.7cents each.
Osh,
if your AC signal changes the temperature of the metal film by 10C degrees over the cycle of the waveform, then a 100ppm resistor will have a change in resistance of 0.1%.
But if two resistors make up an NFB pair then it's the difference in temperature change that will determine the gain change with temperature effect.
Using a 50ppm resistor in both parts and doubling the High Power resistor to reduce it's 10C Tdelta to say 7C and the lower power resistor is Tdelta= 3C then the change in gain would be [7C-3C] * 50ppm ~0.02%.
That 0.02% change in gain would happen when the hotter resistor has a Tdelta=7C degrees. I would hope that ONLY happens when the equipment is passing a signal that is almost at clipping level.
if your AC signal changes the temperature of the metal film by 10C degrees over the cycle of the waveform, then a 100ppm resistor will have a change in resistance of 0.1%.
But if two resistors make up an NFB pair then it's the difference in temperature change that will determine the gain change with temperature effect.
Using a 50ppm resistor in both parts and doubling the High Power resistor to reduce it's 10C Tdelta to say 7C and the lower power resistor is Tdelta= 3C then the change in gain would be [7C-3C] * 50ppm ~0.02%.
That 0.02% change in gain would happen when the hotter resistor has a Tdelta=7C degrees. I would hope that ONLY happens when the equipment is passing a signal that is almost at clipping level.
Sad to see a reputable company like Vishay spreading FUD via an advert masquerading as an article, which contains a subtle mix of good engineering and audio myth. I guess in a worldwide recession, everyone has to create business however they can.
Agree. I'm guessing that at this level of analysis the thermal inertia needs to be included in the calculations.
No, I'm not volunteering.🙂
Voltage coefficient is often much worse than power dissipation temperature effects for modern resistors. Both effects are drastically reduced by using a few resistors in series.
My rule of thumb is lower Tc = better quality overall. A RN55E is 25 ppm and generally available at a reasonable price. Doesn't hurt to go to RN60E or RN65E even if dissipation is no more than 1/4 watt.
You hit the nail straight on the head.
Just as a curiosity, these are some of the reader responses found at that very article:
Experiment:
Build one active xover with metal film Vishay/Dale (100 ppm) and PRP resistors (100 ppm). Build another identical xover with KOA/Speer resistors (50 ppm). All values checked with accurate LCR meter, all within 1%.
Result, from listening over several hours (sorry, you measurement mavens, but this really IS the ultimate test of audio circuits): Vishay/Dale xover has better highs. Better, as in more lifelike in every respect, not at all subtle, easily detectible by a blind test (no, I didn't attempt one). No fancy descriptives, but I could offer them if you insist. And I wanted the KOA's to sound better or at least as good, so, if anything, this test was biased against the results. I was not trying to prove superiority of either, but I was disappointed and learned something.
End of experiment.
AFTER the listening test, confused and frustrated, a single simple test revealed: Vishay/Dale and PRP not attracted to magnet in any way. KOA body stuck on magnet, leads not. End caps made from steel? Possible cause of inferior sound? Resistor with superior TC spec sounded worse.
Conclusion: Materials swamp spec, at least in this case, at least as determined by objective listening, if that has any value to you.
I wonder if the easily audible difference would show up on a 'scope. If it does, then I bow to the technologists. If it doesn't, then you got some 'splainin' to do.
Peace,
Tom E
Build one active xover with metal film Vishay/Dale (100 ppm) and PRP resistors (100 ppm). Build another identical xover with KOA/Speer resistors (50 ppm). All values checked with accurate LCR meter, all within 1%.
Result, from listening over several hours (sorry, you measurement mavens, but this really IS the ultimate test of audio circuits): Vishay/Dale xover has better highs. Better, as in more lifelike in every respect, not at all subtle, easily detectible by a blind test (no, I didn't attempt one). No fancy descriptives, but I could offer them if you insist. And I wanted the KOA's to sound better or at least as good, so, if anything, this test was biased against the results. I was not trying to prove superiority of either, but I was disappointed and learned something.
End of experiment.
AFTER the listening test, confused and frustrated, a single simple test revealed: Vishay/Dale and PRP not attracted to magnet in any way. KOA body stuck on magnet, leads not. End caps made from steel? Possible cause of inferior sound? Resistor with superior TC spec sounded worse.
Conclusion: Materials swamp spec, at least in this case, at least as determined by objective listening, if that has any value to you.
I wonder if the easily audible difference would show up on a 'scope. If it does, then I bow to the technologists. If it doesn't, then you got some 'splainin' to do.
Peace,
Tom E
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Yup, have to agree - magnetic leads or body are detrimental to sound at many small-signal locations. I noticed this with some resistors which are otherwise very nicely spec'ed: Panasonic ERX1 and ERX2 metal films, Koa CF1/2 carbon films. The leads are non-magnetic, but the bodies are weakly magnetic. I'm guessing it was Nichrome film or end-caps in the MFRs, and maybe just the end-caps in the CFRs, which probably have some nickel in them. BTW, old-school Holcos are completely non-magnetic, not sure about the new ones.
Hi Tom,
Your story reminds me of a similar experience I had some years ago.
I had a KT88 PP amplifier that used Dale CMF65 resistors, it sounded very good.
Curious if I could make it any better(circuit was already optimized) I replaced the CMF65 gridstoppers with caddock MK132 resistors.
Immediately I could hear the difference and I didn't like it: it sounded dull, especially the highs had lost snap:
like listening to an acoustic guitar with a blanket thrown over it.
I thought the MK132 should sound better according to the specs but in reality it was the opposite.
A few hours later I (re)replaced the MK132s with the CMF65 and back came the involving natural sound.
Later I tried the vishay bulk foils as grid stoppers and they sounded also good.
The only thing that I concluded from this experience is that I didn't like MK132 in the signal path as gridstoppers.
Your story reminds me of a similar experience I had some years ago.
I had a KT88 PP amplifier that used Dale CMF65 resistors, it sounded very good.
Curious if I could make it any better(circuit was already optimized) I replaced the CMF65 gridstoppers with caddock MK132 resistors.
Immediately I could hear the difference and I didn't like it: it sounded dull, especially the highs had lost snap:
like listening to an acoustic guitar with a blanket thrown over it.
I thought the MK132 should sound better according to the specs but in reality it was the opposite.
A few hours later I (re)replaced the MK132s with the CMF65 and back came the involving natural sound.
Later I tried the vishay bulk foils as grid stoppers and they sounded also good.
The only thing that I concluded from this experience is that I didn't like MK132 in the signal path as gridstoppers.
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If genuinely present (does it take a "several hours" for an "easily audible" difference to become apparent?) then a spectrum analyser might be a more appropriate tool for investigations.madisonears said:
You will understand that by finding something would be "easily detectible by a blind test" yet no such test was done you are leaving the door open for us to dismiss your result.
There is anecdotal evidence for ferromagnetic end-caps causing problems, but I am not aware of any test results confirming this. I'm sure others will put me straight on this!
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