I would like to remind everyone that there are a number of people who regularly look at this thread. Some are PhD's in something, some are design engineers, and still others are closer to repair techs and the rest are just plain audiophiles trying to learn the best way to design audio electronics.
This means that there is nothing pertinent that is below discussion. So, Richard's comments of distance between caps can be potentially useful to many here.
This means that there is nothing pertinent that is below discussion. So, Richard's comments of distance between caps can be potentially useful to many here.
Now one of the issues that JC has mentioned is that when he does the EQ for a phono preamp he prefers to use shunt filters. The original idea is that they are out of the signal path. Of course since they effect the signal that ain't quite so.
However placing them as shunts does have some interesting effects. If the original pre-emphasis capacitors were in series then having the matching filter in parallel will give a more accurate match to the desired response.
Even if that is not the case a shunt capacitor will have excess attenuation of the harmonics compared to the fundamental. As most are aware energy that doesn't belong is more striking than energy that is missing. Yes this is a very small difference but has been anecdotally been mentioned by a number of folks.
Now in designing coupling capacitor circuits it is common practice to pick a corner frequency such as 20 hz and then calculate the value of capacitor that will have it's reactance equal the load resistance at that frequency. One then actually uses a capacitor ten times that value. (This does result in more V dc/dt issues.) This should result in a difference between the fundamental and an annoying harmonic such as the ninth of less than a tenth of a db.
So the issue becomes is there excess low frequency loss in some types of capacitors and what is a sensitive method to determine that?
However placing them as shunts does have some interesting effects. If the original pre-emphasis capacitors were in series then having the matching filter in parallel will give a more accurate match to the desired response.
Even if that is not the case a shunt capacitor will have excess attenuation of the harmonics compared to the fundamental. As most are aware energy that doesn't belong is more striking than energy that is missing. Yes this is a very small difference but has been anecdotally been mentioned by a number of folks.
Now in designing coupling capacitor circuits it is common practice to pick a corner frequency such as 20 hz and then calculate the value of capacitor that will have it's reactance equal the load resistance at that frequency. One then actually uses a capacitor ten times that value. (This does result in more V dc/dt issues.) This should result in a difference between the fundamental and an annoying harmonic such as the ninth of less than a tenth of a db.
So the issue becomes is there excess low frequency loss in some types of capacitors and what is a sensitive method to determine that?
It ain't so at all. The concept of 'signal path' has limited usefulness, and is often misused. A common error is to believe that series elements are in the signal path (presumably because the signal 'goes through them') while shunt elements are not. In many cases shunt elements can have a greater effect because they usually have the whole signal voltage across them, while series elements (except in filters) do not. Surely JC does not make this mistake - are you misunderstanding him?simon7000 said:
Alternative version: if the original pre-emphasis was correct then a correct de-emphasis, however we choose to achieve it, results in a correct signal. If the original pre-emphasis was wrong and we know exactly how it was wrong then the appropriate wrong de-emphasis will correct for it. No magic results from a series--parallel version.
A correct filter is a correct filter, however it is achieved. All correct filters will attenuate harmonics exactly the same. Note that we are not talking about RF, where component parasitics become important.
I don't understand the point you are making here. Choosing an appropriate LF rolloff has almost no effect on harmonics, and anyway is highly frequency dependent. LF rolloffs do not create harmonics, and only affect the relative amplitudes of harmonics if the LF rolloff is far too high in frequency. Correct LF rolloffs should show less capacitor distortion, not more, because there is less signal voltage across most coupling caps.
Correct arrangement of LF rolloff means less signal voltage across all coupling caps except the one setting the rolloff. If that one is sufficiently early in the system then it will have a small voltage across it anyway, so little distortion. If the amp designer does not set the rolloff, then all that happens is that the job is transferred either to the source or the speakers. CD can of course go down to DC, but turntables and speakers cannot.
My cryo treated coat hangers sound great as long as they are polarized correctly
still too few do it right --
I noticed there have been a couple million hits on this site's forum. I would NOT assume they are all sophisicated and knowledgeable in electronics; Though there are only a few who do most of the commenting here - it would seem that way. but even these few wise men havent had anything at all new to add to the body of knowledge as far as i have read. Except from JC who integrates best a wide range of knowledge into his designs -- thus, has the best designs and is a leader in his field.
Now, I still see from engineers from low end recievers to high end designs.... a power supply with bypassed cap over here and the circuit over there with wiring run around all over. Apparently, it needs to be brought up again for those who didnt get it the first go around. A high-end design and build is a lot of small, almost insignificant, details.
Since this is a DIY site, the info is for all those other poeple and the millions who have been here and will be here. It is good to remind each new generation of the lessons learned from the past.... even if a very few know it still. I try to write to the wider audience so everyone can understand it. So get used to it.
Thx,
Richard
I noticed there have been a couple million hits on this site's forum. I would NOT assume they are all sophisicated and knowledgeable in electronics; Though there are only a few who do most of the commenting here - it would seem that way. but even these few wise men havent had anything at all new to add to the body of knowledge as far as i have read. Except from JC who integrates best a wide range of knowledge into his designs -- thus, has the best designs and is a leader in his field.
Now, I still see from engineers from low end recievers to high end designs.... a power supply with bypassed cap over here and the circuit over there with wiring run around all over. Apparently, it needs to be brought up again for those who didnt get it the first go around. A high-end design and build is a lot of small, almost insignificant, details.
Since this is a DIY site, the info is for all those other poeple and the millions who have been here and will be here. It is good to remind each new generation of the lessons learned from the past.... even if a very few know it still. I try to write to the wider audience so everyone can understand it. So get used to it.
Thx,
Richard
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Richard;
in order to judge knowledge and contributions of others everyone needs to understand their value. Or, misunderstand equally. May be somebody will come back to this thread 1-10 years later and find that there were lots of wisdom that participants of discussions did not understand.
"Archaeologists found in the cave fossils with TCP/IP packets incorporated in it." What can be learned from this fossils, Scott Wurcer is bad teacher. He is great Engineer, but could not explain you your obvious mistakes, because you still don't understand them.
Sorry for my response to your judgment of contribution of participants in this thread. It is technical forum, and such judgment should be left for your private conversations, not for the forum. It is not the first time you did that but I feel like finally I can't resist, and have to point you that it is not appropriate.
in order to judge knowledge and contributions of others everyone needs to understand their value. Or, misunderstand equally. May be somebody will come back to this thread 1-10 years later and find that there were lots of wisdom that participants of discussions did not understand.
"Archaeologists found in the cave fossils with TCP/IP packets incorporated in it." What can be learned from this fossils, Scott Wurcer is bad teacher. He is great Engineer, but could not explain you your obvious mistakes, because you still don't understand them.
Sorry for my response to your judgment of contribution of participants in this thread. It is technical forum, and such judgment should be left for your private conversations, not for the forum. It is not the first time you did that but I feel like finally I can't resist, and have to point you that it is not appropriate.
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Really? Perhaps you should read more. Start with the fellow who designed the capacitor test that John relies on- and the chips needed to do it. As well as a few million circuits out there.
Well that sure hit a sore spot!
I am a familiar with most everything ever published on analog circuits... Including everything I have seen mentioned here by anyone. Thats all i do. At least 4 hours of technical reading per day for 40+ years.
I have been a member of IEEE for decades, for example, and keep up with the latest in SS and many other areas.
I havent found anything pertaining to high-end audio design here that is new. Only what JC does/did is interesting to me. How he thinks and integrates info from all over and folds it in until his product is far and away over the top of others.
I understand that DA is only one parasitic. I understand that FFT/THD/IM and all show no distortion that could be heard. It too is old news.
So where's the beef?
Thx,
Richard
I am a familiar with most everything ever published on analog circuits... Including everything I have seen mentioned here by anyone. Thats all i do. At least 4 hours of technical reading per day for 40+ years.
I have been a member of IEEE for decades, for example, and keep up with the latest in SS and many other areas.
I havent found anything pertaining to high-end audio design here that is new. Only what JC does/did is interesting to me. How he thinks and integrates info from all over and folds it in until his product is far and away over the top of others.
I understand that DA is only one parasitic. I understand that FFT/THD/IM and all show no distortion that could be heard. It too is old news.
So where's the beef?
Thx,
Richard
That's what I'm trying to figure out from your rather astonishing complaint.
An apology for bad manners might be more appropriate, if you wish to be taken seriously.RNMarsh said:
That is a bold claim. Does "most everything" include British publications?RNMarsh said:
That has been obvious for a while.RNMarsh said:
When you first popped up in this conversation some people seemed to regard you as some sort of expert. I am still unclear why. You keep telling us how smart you are (much smarter than us) yet you seem to just throw out random comments which, when challenged, you seem unable to back up with real facts. When we pick up on something you say, it always seems to turn out that you weren't really talking about that.
here vs. There --
I thought about it for a few minutes --- it must be the thought that here has been taken to mean there. I know S.W. has contributed outside of here - this DIY forum. I havent seen anything new here, though.
I would appologize to Scott if he took it as to belittle his contributions to the world.
I said here on this forum I havent read anything new.
-RNM
I thought about it for a few minutes --- it must be the thought that here has been taken to mean there. I know S.W. has contributed outside of here - this DIY forum. I havent seen anything new here, though.
I would appologize to Scott if he took it as to belittle his contributions to the world.
I said here on this forum I havent read anything new.
-RNM
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