Demian, John
I apologize, I was on a flakey wireless connection last week and had nothing but charbucks for coffee. I wanted to make the point that the noise contributed by the bias return resistor in an input stage is a generic one. At frequencies of interest the source impedance shorts it and its noise simply does not matter. Take for instance a 50K volume control and the 22Meg input bias resistor. At worst a 25K resistance is in parallel with the 22Meg almost a factor of 1000, root sum squared this is a noise contribution of -120dB.
Taking components out of context to point out defects is an interesting exercise, but judgment needs to be applied. As horrifying as it may seem putting a 22Meg carbon resistor in parallel with a precious signal path, it in fact does not contribute noise.
I think I understand the methodology of “why not take the -160dB components” but I would rather see people trying things out with whatever they can get.
I apologize, I was on a flakey wireless connection last week and had nothing but charbucks for coffee. I wanted to make the point that the noise contributed by the bias return resistor in an input stage is a generic one. At frequencies of interest the source impedance shorts it and its noise simply does not matter. Take for instance a 50K volume control and the 22Meg input bias resistor. At worst a 25K resistance is in parallel with the 22Meg almost a factor of 1000, root sum squared this is a noise contribution of -120dB.
Taking components out of context to point out defects is an interesting exercise, but judgment needs to be applied. As horrifying as it may seem putting a 22Meg carbon resistor in parallel with a precious signal path, it in fact does not contribute noise.
I think I understand the methodology of “why not take the -160dB components” but I would rather see people trying things out with whatever they can get.
I gave our hifi community a task to tell differences between several 16/44.1 wav files. They did not find the difference between original file and file distorted by 2H -26dB, 3H -46dB and 5H -60dB (Keith Howard AddDistortion SW). They easily told the difference between the files where the only difference was LM4562 vs. OPA2134 exchange, however. The guys with purely engineering approach are having problems with that.
I am finding this hard to believe. Very hard.
I am finding this hard to believe. Very hard.
scott wurcer said:
Maybe this analogy goes through: the standard 47kohm input resistor in a phono stage contributes zilch, zip, nada, to the output noise. It's shorted by the cartridge low impedance, which noise's square added to the phono stage internal noise.
syn08 said:
This is often true, but I would qualify it to read the real part of the cartridge impedance. National had a nice 1977 app note on this. The old standby Shure carts had a nasty inductance that also made the current noise of bipolars matter in the noise figure.
BTW that's why I use Grado 😉
dimitri said:
I said an analogy, not an exact description. BTW, there's a standard 200pF cap in parallel with 47kohm as well.
Cart impedance at 10K will not be insignificant. See Dennis Colin's phono-amp article from AA. Hence the reason JFET's do make good front end's for phono amps.
Syn08, 1/2 the time, these days, you would be correct. 1/2 the time, especially with cheap Shure cartridges, etc, you would not be correct. You should understand the situation more completely, before you conclude. It confuses others, less educated in this field.
john curl said:
Yes syn08, shame on you! Stop confusing us simpleminded pitch-fork-wielding villagers
PS Happy Easter to all, enjoy your eggs!
Jan Didden
Well Jan, Syn08 IS confusing the situation. Is this what you want? Why? Because I am well known and he is not? It is unfortunate that my associates and I have to step in because someone makes a series of sloppy comments on this thread. I won't call it a complete waste of time, because someone who is truly interested in the subject may pick up a concept or two, but it surely doesn't enhance reputations of the commentators on either side.
Demian has agreed to be one of my associates. I hope to formally enlist Dimitri, and others as well, with their permission.
Someone just passed this on to me. It explains the reasons why this place is so unpleasant. As a huge Jimi Hendrix fan, I found this to be doubly funny!
~~~~~~~~~~
From the relatively new book 'Stuff White People Like' based on the hilarious blog of the same name.
Number 110: Trying Too Hard (abbreviated from p. 147)
"It is widely accepted that all white people feel the need to be an expert on something. Most white people will be satisfied with being recognized as the expert among their friends, but there are others who need to take it to an entirely different level.......the story is always the same. You will be in a group and casually mention something like "I really like Jimi Hendrix", then out of the corner of the room you will hear "What's your favorite album?" Just as you are preparing to give your answer, the person who asked will jump in with a rapid fire series of questions: "Do you have 'Loose Ends'? How much vinyl do you own? Did you get the bootlegs with B.B. King and Jim Morrison? Did you read Electric Gypsy?" and before you know it you are reeling and feeling as though you are the victim of some sort of inquisition.
"Your first reaction might be to call the person a nerd and tell them to "take it easy." though that might bring about a short-term laugh from the group, it will engender hate and resentment from the white person you have burned."
~~~~~~~~~~
Jam, I know that you're not white. Is this why you don't argue with people on this website? Any other non-white people out there?
~~~~~~~~~~
From the relatively new book 'Stuff White People Like' based on the hilarious blog of the same name.
Number 110: Trying Too Hard (abbreviated from p. 147)
"It is widely accepted that all white people feel the need to be an expert on something. Most white people will be satisfied with being recognized as the expert among their friends, but there are others who need to take it to an entirely different level.......the story is always the same. You will be in a group and casually mention something like "I really like Jimi Hendrix", then out of the corner of the room you will hear "What's your favorite album?" Just as you are preparing to give your answer, the person who asked will jump in with a rapid fire series of questions: "Do you have 'Loose Ends'? How much vinyl do you own? Did you get the bootlegs with B.B. King and Jim Morrison? Did you read Electric Gypsy?" and before you know it you are reeling and feeling as though you are the victim of some sort of inquisition.
"Your first reaction might be to call the person a nerd and tell them to "take it easy." though that might bring about a short-term laugh from the group, it will engender hate and resentment from the white person you have burned."
~~~~~~~~~~
Jam, I know that you're not white. Is this why you don't argue with people on this website? Any other non-white people out there?
john curl said:
Ok, so I'm NOT your associate 🙂
Good, this fact goes straight on my resume
Charles Hansen said:
Try harder; you may end up luring GR, JC and his associates, etc... to the other place. There's so much more quiet and pleasant BS flying over there!
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