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#81
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Low noise resistors
"Arny Krueger" wrote in message ... Not sure how you would know whether it's the equipment or the record? Keep the equipment properly tuned up. Sure, but proves nothing by itself, without a reference for each recording. How do you know if it's supposed to sound like that, or the cutter or stamper is worn out? If they put test tones on every record you may have a shot. I do have a number of test records, spanning decades. So do I, but I prefer to listen to music myself. Not necessarily. If the record has say 3dB droop at HF compared to the master tape, That would be an artistic choice made by the mastering engineer. Or a worn cutter, stamper, stylus. Lot's of possibilities. then the cartridge/pre-amp with a 3dB rise will be more accurate for that record. That would be a FR error I seek to eliminate. Fair enough, I seek maximum listening enjoyment. Each to his own. I already stated that you should set the response flat using a good test record. Then you can ignore the 1-2 dB variations from RIAA that your cartridge/pre-amp might have, safe in the knowledge that the records you play will be far more than that anyway. Compensate with EQ as necessary. Works for me, but I want to minimize the need for added eq. No argument there, but I just smile at the people who play vinyl with all controls flat, and think they have a sound the same as the original :-) Of course you can, but that doesn't mean they will all sound similar in tone, or similar to what the mixing or mastering engineers heard. I can if I presume he set up his playback system competently, and I do the same. Were talking about vinyl here right? (I'll ignore speakers for the sake of argument) You can't even expect that from CD's. I surely expect that from CDs. I won't ignore speakers and listening rooms here though. CD just eliminates part of the corruption chain. Yep, and everybody's is different. To be a reference, you need a common standard. Well yes, but common experiences can be the basis for an approximate ad-hoc standard. Yes, well, sorta, maybe :-) TonyP. |
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#82
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Low noise resistors
"Arny Krueger" wrote in message ... Not sure how you would know whether it's the equipment or the record? Keep the equipment properly tuned up. Sure, but proves nothing by itself, without a reference for each recording. How do you know if it's supposed to sound like that, or the cutter or stamper is worn out? If they put test tones on every record you may have a shot. I do have a number of test records, spanning decades. So do I, but I prefer to listen to music myself. Not necessarily. If the record has say 3dB droop at HF compared to the master tape, That would be an artistic choice made by the mastering engineer. Or a worn cutter, stamper, stylus. Lot's of possibilities. then the cartridge/pre-amp with a 3dB rise will be more accurate for that record. That would be a FR error I seek to eliminate. Fair enough, I seek maximum listening enjoyment. Each to his own. I already stated that you should set the response flat using a good test record. Then you can ignore the 1-2 dB variations from RIAA that your cartridge/pre-amp might have, safe in the knowledge that the records you play will be far more than that anyway. Compensate with EQ as necessary. Works for me, but I want to minimize the need for added eq. No argument there, but I just smile at the people who play vinyl with all controls flat, and think they have a sound the same as the original :-) Of course you can, but that doesn't mean they will all sound similar in tone, or similar to what the mixing or mastering engineers heard. I can if I presume he set up his playback system competently, and I do the same. Were talking about vinyl here right? (I'll ignore speakers for the sake of argument) You can't even expect that from CD's. I surely expect that from CDs. I won't ignore speakers and listening rooms here though. CD just eliminates part of the corruption chain. Yep, and everybody's is different. To be a reference, you need a common standard. Well yes, but common experiences can be the basis for an approximate ad-hoc standard. Yes, well, sorta, maybe :-) TonyP. |
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#83
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Low noise resistors
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#84
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Low noise resistors
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#87
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Low noise resistors
(Detector195) writes:
[...] Where I have seen it make a difference is in something like a transimpedance front end for optical detection, where the resistor is often the dominant noise source. What about a differential receiver or instrumentation amplifier where you're trying to establish a given input impedance? -- % Randy Yates % "How's life on earth? %% Fuquay-Varina, NC % ... What is it worth?" %%% 919-577-9882 % 'Mission (A World Record)', %%%% % *A New World Record*, ELO http://home.earthlink.net/~yatescr |
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#88
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Low noise resistors
(Detector195) writes:
[...] Where I have seen it make a difference is in something like a transimpedance front end for optical detection, where the resistor is often the dominant noise source. What about a differential receiver or instrumentation amplifier where you're trying to establish a given input impedance? -- % Randy Yates % "How's life on earth? %% Fuquay-Varina, NC % ... What is it worth?" %%% 919-577-9882 % 'Mission (A World Record)', %%%% % *A New World Record*, ELO http://home.earthlink.net/~yatescr |
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#89
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Low noise resistors
Randy Yates wrote in message ...
(Detector195) writes: [...] Where I have seen it make a difference is in something like a transimpedance front end for optical detection, where the resistor is often the dominant noise source. What about a differential receiver or instrumentation amplifier where you're trying to establish a given input impedance? Ah, I had not thought of that application. And I think there are actually low inductance wirewound resistors on the market, where they run half of the turns backwards on the coil form. |
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#90
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Low noise resistors
Randy Yates wrote in message ...
(Detector195) writes: [...] Where I have seen it make a difference is in something like a transimpedance front end for optical detection, where the resistor is often the dominant noise source. What about a differential receiver or instrumentation amplifier where you're trying to establish a given input impedance? Ah, I had not thought of that application. And I think there are actually low inductance wirewound resistors on the market, where they run half of the turns backwards on the coil form. |
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#91
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Low noise resistors
Randy Yates wrote in message ...
(Detector195) writes: [...] Where I have seen it make a difference is in something like a transimpedance front end for optical detection, where the resistor is often the dominant noise source. What about a differential receiver or instrumentation amplifier where you're trying to establish a given input impedance? Ah, I had not thought of that application. And I think there are actually low inductance wirewound resistors on the market, where they run half of the turns backwards on the coil form. |
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#92
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Low noise resistors
I just saw this thread and noted, by the way, prompt accurate information
from IsaacWingfield responding to the original question. "Detector195" in om... . . . I took two resistors as "signal sources" to compare their noise spectra. One was a 100k 1/4 W metal film, the other was a 100k 1/8 W carbon film. (Careful -- two variables changed at once. An issue of possible distraction to some readers, more really than of misleading conclusions.) The carbon film had 6 percent more voltage noise from essentially zero up to 20 kHz, give or take 1 percent. This is about 0.5 dB. Does anybody out there have a real "professional" spectrum analyzer or digital scope? This should be an easy measurement if you have the right equipment. Those data sound reasonable to me. Without going into details, I have done many measurements as queried above. I use some very exquisite equipment for low-noise measurements, some of the best available in the last few decades; we have a lab full of it for such purposes. (By the way, you generally want analog, or at least good-analog-front-end, instruments to measure low-freq. noise spectra with low floors. And/or, build outboard low-noise preamps for the purpose and keep them in the same lab.) My end applications were not specifically audio, but I measured in the same frequency range. (I was concerned with "making" resistors in monolithic form, and possible sources of "excess" noise). The whole issue here is the "excess" noise that Isaac Wingfield already concisely explained. Typically it arises not in uniform resistive materials but in interfaces between different materials, or between different crystals or clusters of material. Commercial component resistors of metal or metal film, common and fairly cheap anyway, have the general reputation of the lowest excess noise, followed by carbon film. Carbon composition resistors (polycrystalline I think, and very common construction for wired reasistors when I was younger) have the worst reputation. Issues of the power rating of a resistor are only peripherally related to its noise sources. Self-heating capable of significantly raising a resistor's Kelvin temperature (which is what counts) from the usual 300-350 found in operating electronic equipment would mean that the resistor is run at a high power level, which argues independently for a higher power-capable resistor, regardless of noise considerations. (Resistors, like people, are most reliable when not overheated.) I still think Isaac Wingfield said it more concisely. -- Max Hauser |
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#93
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Low noise resistors
I just saw this thread and noted, by the way, prompt accurate information
from IsaacWingfield responding to the original question. "Detector195" in om... . . . I took two resistors as "signal sources" to compare their noise spectra. One was a 100k 1/4 W metal film, the other was a 100k 1/8 W carbon film. (Careful -- two variables changed at once. An issue of possible distraction to some readers, more really than of misleading conclusions.) The carbon film had 6 percent more voltage noise from essentially zero up to 20 kHz, give or take 1 percent. This is about 0.5 dB. Does anybody out there have a real "professional" spectrum analyzer or digital scope? This should be an easy measurement if you have the right equipment. Those data sound reasonable to me. Without going into details, I have done many measurements as queried above. I use some very exquisite equipment for low-noise measurements, some of the best available in the last few decades; we have a lab full of it for such purposes. (By the way, you generally want analog, or at least good-analog-front-end, instruments to measure low-freq. noise spectra with low floors. And/or, build outboard low-noise preamps for the purpose and keep them in the same lab.) My end applications were not specifically audio, but I measured in the same frequency range. (I was concerned with "making" resistors in monolithic form, and possible sources of "excess" noise). The whole issue here is the "excess" noise that Isaac Wingfield already concisely explained. Typically it arises not in uniform resistive materials but in interfaces between different materials, or between different crystals or clusters of material. Commercial component resistors of metal or metal film, common and fairly cheap anyway, have the general reputation of the lowest excess noise, followed by carbon film. Carbon composition resistors (polycrystalline I think, and very common construction for wired reasistors when I was younger) have the worst reputation. Issues of the power rating of a resistor are only peripherally related to its noise sources. Self-heating capable of significantly raising a resistor's Kelvin temperature (which is what counts) from the usual 300-350 found in operating electronic equipment would mean that the resistor is run at a high power level, which argues independently for a higher power-capable resistor, regardless of noise considerations. (Resistors, like people, are most reliable when not overheated.) I still think Isaac Wingfield said it more concisely. -- Max Hauser |
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#94
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Low noise resistors
I just saw this thread and noted, by the way, prompt accurate information
from IsaacWingfield responding to the original question. "Detector195" in om... . . . I took two resistors as "signal sources" to compare their noise spectra. One was a 100k 1/4 W metal film, the other was a 100k 1/8 W carbon film. (Careful -- two variables changed at once. An issue of possible distraction to some readers, more really than of misleading conclusions.) The carbon film had 6 percent more voltage noise from essentially zero up to 20 kHz, give or take 1 percent. This is about 0.5 dB. Does anybody out there have a real "professional" spectrum analyzer or digital scope? This should be an easy measurement if you have the right equipment. Those data sound reasonable to me. Without going into details, I have done many measurements as queried above. I use some very exquisite equipment for low-noise measurements, some of the best available in the last few decades; we have a lab full of it for such purposes. (By the way, you generally want analog, or at least good-analog-front-end, instruments to measure low-freq. noise spectra with low floors. And/or, build outboard low-noise preamps for the purpose and keep them in the same lab.) My end applications were not specifically audio, but I measured in the same frequency range. (I was concerned with "making" resistors in monolithic form, and possible sources of "excess" noise). The whole issue here is the "excess" noise that Isaac Wingfield already concisely explained. Typically it arises not in uniform resistive materials but in interfaces between different materials, or between different crystals or clusters of material. Commercial component resistors of metal or metal film, common and fairly cheap anyway, have the general reputation of the lowest excess noise, followed by carbon film. Carbon composition resistors (polycrystalline I think, and very common construction for wired reasistors when I was younger) have the worst reputation. Issues of the power rating of a resistor are only peripherally related to its noise sources. Self-heating capable of significantly raising a resistor's Kelvin temperature (which is what counts) from the usual 300-350 found in operating electronic equipment would mean that the resistor is run at a high power level, which argues independently for a higher power-capable resistor, regardless of noise considerations. (Resistors, like people, are most reliable when not overheated.) I still think Isaac Wingfield said it more concisely. -- Max Hauser |
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