IIRC Bruce Hofer said to avoid NPO/C0G rated below at least 50v or 100v, as they are less linear than the higher voltage versions.
EDIT: I will leave his full 2013 presentation card deck in my dropbox for a few days if anyone wants to see it: https://www.dropbox.com/scl/fi/3yup...n-AP.ppt?rlkey=qlmm9amfx8oz3vj6cy5dqlpz8&dl=0
They tried sine waves. JC told me about it. The interesting effect only occurred with complex/assymetrical waveforms.
Hi Bonsai,
Well yes. The extra amount of feedback headroom drops with frequency (as expected). That will reduce correction and increase distortion as frequency increases. I do test with 19 kHz and 20 Khz tones for that reason.
I think modern designs suffer much less from some of the weird problems early amplifiers had. We got smarter about layout and circuit design. I bet you wince when looking at some earlier products! lol!
Well yes. The extra amount of feedback headroom drops with frequency (as expected). That will reduce correction and increase distortion as frequency increases. I do test with 19 kHz and 20 Khz tones for that reason.
I think modern designs suffer much less from some of the weird problems early amplifiers had. We got smarter about layout and circuit design. I bet you wince when looking at some earlier products! lol!
I use 18+19 kHz, but the idea is the same. I doubt they expose anything that the multi-tone measurement doesn't.
SID is a solved problem, by the way. It's easy to check in simulation (and reality) that the internal stages of an amp aren't slewing. Of course, that requires that the circuit designer has a reasonable level of competence and pays attention in the design phase.
He says specifically, "Avoid the lowest 25 V rating in critical audio designs" (page 26 of the .pdf). That's an easy requirement to meet as 50 V types are plentiful.
Tom
Hi Tom,
Agree 100% with everything. Yes, SID was solved a long time ago.
I use the higher voltage caps as I work on tube amplifiers as well. Reducing skews. The physical size doesn't change much between 100 V and 500 or 630 V types. For the larger PP caps it does, so I use the parts that fit.
Agree 100% with everything. Yes, SID was solved a long time ago.
I use the higher voltage caps as I work on tube amplifiers as well. Reducing skews. The physical size doesn't change much between 100 V and 500 or 630 V types. For the larger PP caps it does, so I use the parts that fit.
We probably agree that everything physical (which audio is physical) is in principle measurable, right? Maybe the issue in this case is that Curl et al were looking at DA using a particular test, but maybe its not the only test that potentially could explain the audibility of DA. Do I know what test would be better for DA? Not offhand, but I don't have a good measurement for soundstage either, even though I can hear it and I know in principle it must measurable.
My only point is that we shouldn't jump to conclusions about what can or can't be audible just because as of right now, today, we don't have a good way of measuring everything we can hear. Otherwise according to the logic of the quote above about not having good measurement to show why DA can be audible, when that same type of logic is applied to soundstage would seem to imply that soundstage must be imaginary because so far nobody has figured out a good measurement for it either (IOW, we lack a measurement which sensibly correlates well with human perception of soundstage, much like is the case for DA).
Who says DA can be audible in a well-designed audio circuit? This sounds like another thread diversion.
Tom
Tom
You guys were talking about DA. I didn't start it. But, I have reported before on experiments that are hard to explain by anything other than DA. Therefore, I believe it is probably audible under some circumstances. And I think that is a valid scientific and engineering viewpoint.
And what is with is the BS about its okay to say DA is inaudible, but its a diversion to tell the truth and say it can be audible? Look, the guys who worked on trying to measure DA could hear it. You don't hear it. Primarily on that basis and because we don't have a better test, you declare that you are right and they were wrong. Well, I have news. They weren't wrong.
Hi Mark,
It's painfully easy. Ignore what goes on between your ears. We can't control it for one, and it is a variable for you, then totally different for every individual.
Cool, that mess is out.
Anything that causes any type of nonlinearity will create distortion by definition. Through THD and multitone testing at various power levels, we can fully characterise any device. We have references and standards, so everyone can agree on a test method - and the numbers. Wonderful!
We can easily "see" well below the human bodies ability to sense in any way. We can argue on the exact level, but we can detect problems so far below our threshold (the most optimistic ones) that problems can be measured and quantified. One thing that is I think common knowledge, humans are terrible test instruments, but we are pretty good at comparing things. Well, that is unless our brains get involved then all bets are off.
I said it before. If we can create the same air pressure variations at your ear as the original sound, you cannot hear the difference. Your brain may mess you up, but then it is lying to you. Period.
It's painfully easy. Ignore what goes on between your ears. We can't control it for one, and it is a variable for you, then totally different for every individual.
Cool, that mess is out.
Anything that causes any type of nonlinearity will create distortion by definition. Through THD and multitone testing at various power levels, we can fully characterise any device. We have references and standards, so everyone can agree on a test method - and the numbers. Wonderful!
We can easily "see" well below the human bodies ability to sense in any way. We can argue on the exact level, but we can detect problems so far below our threshold (the most optimistic ones) that problems can be measured and quantified. One thing that is I think common knowledge, humans are terrible test instruments, but we are pretty good at comparing things. Well, that is unless our brains get involved then all bets are off.
I said it before. If we can create the same air pressure variations at your ear as the original sound, you cannot hear the difference. Your brain may mess you up, but then it is lying to you. Period.
Hi Mark,
First, you made a conclusion without actual proof (assuming the issue is DA), then followed it with another conclusion (probably audible under some conditions). Neither is valid.
There are so many things that can cause a problem that isn't a capacitor. Circuit interaction with the parts, stray capacitance to other things that may cause instability. You never know. Each instance of an audible problem has to be investigated until the source is located, then proved by eliminating just that one variable. Basic troubleshooting.
No.
First, you made a conclusion without actual proof (assuming the issue is DA), then followed it with another conclusion (probably audible under some conditions). Neither is valid.
There are so many things that can cause a problem that isn't a capacitor. Circuit interaction with the parts, stray capacitance to other things that may cause instability. You never know. Each instance of an audible problem has to be investigated until the source is located, then proved by eliminating just that one variable. Basic troubleshooting.
"Absence of evidence is not evidence of absence" is a logical concept that a lack of supporting evidence for a proposition should not be automatically interpreted as evidence against its existence or truthfulness.
Yes, agreed. The only thing that was changed was the polarizing voltage on the cap. It was reversed after letting cap settle for two weeks. After polarity reversal it took about another week for it to settle back to is equilibrium state. Nothing else was changed, since the cap was on a gold pin header. It was unplugged, turned 180-degrees and plugged back in.
Great. And what does this have to do with audio? I'm guessing you then made a sighted listening trial and concluded you heard a difference. That's my guess. Please tell me if I'm wrong here.
Are you 200 % confident that your memory didn't change during the two weeks? It's well established through controlled scientific experiments that episodic memories are re-encoded during recall and can be altered during the re-encoding. Do you know for sure that nothing corrupted your memory during the two weeks?
If you have a reference to a scientific study that shows the audibility of DA (preferably versus DC bias across the capacitor) I would be very interested in a reference. I respect your personal experience, but sadly it doesn't carry any weight in a scientific setting.
Tom
Are you 200 % confident that your memory didn't change during the two weeks? It's well established through controlled scientific experiments that episodic memories are re-encoded during recall and can be altered during the re-encoding. Do you know for sure that nothing corrupted your memory during the two weeks?
If you have a reference to a scientific study that shows the audibility of DA (preferably versus DC bias across the capacitor) I would be very interested in a reference. I respect your personal experience, but sadly it doesn't carry any weight in a scientific setting.
Tom
If you have a reference to a scientific study that shows the audibility of DA (preferably versus DC bias across the capacitor) I would be very interested in a reference."
"Absence of evidence is not evidence of absence" is a logical concept that a lack of supporting evidence for a proposition should not be automatically interpreted as evidence against its existence or truthfulness.
If I said "I hear" why is it "sad" that it doesn't carry any weight in the scientific community? Is science emotional?
"Absence of evidence is not evidence of absence" is a logical concept that a lack of supporting evidence for a proposition should not be automatically interpreted as evidence against its existence or truthfulness.
If I said "I hear" why is it "sad" that it doesn't carry any weight in the scientific community? Is science emotional?
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