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Old 19th February 2013, 09:21 AM   #35441
gk7 is offline gk7
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Originally Posted by fas42 View Post
Happy now ... ??

Frank
No. The coriolis effect has nothing to do with some "memory" water should have
(which it does not) nor with other forces that move water in some direction.

Last edited by gk7; 19th February 2013 at 09:24 AM.
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Old 19th February 2013, 09:26 AM   #35442
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This might be relatively significant, especially when compared to other noises and distortion mechanisms.
Max, i admire your efforts to find a new evil and feed your anxieties. Just consider the amplifier with low IM that all self friendly music lover is supposed to use. With two signals of high frequencies and high levels, you read some 0.002% ?
What do you expect the IM level with 1/f noise ? One thing is for sure, there is a chance this noise you do not hear will be a little distorted by the signal.
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Old 19th February 2013, 09:32 AM   #35443
DF96 is offline DF96  England
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Originally Posted by Max Headroom
I would expect 1/f noise to add 'jitter like', 'intermodulation like' products, except the modulation source is constantly moving/changing.
This would add a random 'haze' to the audio, diminishing depth information, and generally screwing up audio signals.
It sounds like I am in good company, and thanks for the encouragement.
Do some maths. Let us pick some figures out of the air: a decent amplifier might have 0.1% second-order distortion at full output (0.01% for SS, 1% for valves, so take the geometric mean?). Noise might be -80dB below full output. (If you don't like my figures, substitute your own). Second-order distortion scales with signal level. As the noise is 80dB below the signal, then the noise modulation will be 160dB below the signal. You would need very golden ears to hear that?

OK, not a fair comparison as we don't run at full output all the time. Drop the volume. Noise may stay roughly the same or fall a bit (depending on where in the signal chain it arises). Intermodulation will fall with signal level, so the noise IM will still be 160dB below signal.

Looking at the problem from the other end: what do you need to do to maximise noise IM from 1/f? First you need DC coupling to allow the noise to propagate through the circuit. Then you need active devices whose gain depends critically on their bias, such as BJTs (to them 1/f noise looks like a changing bias). If you can arrange it so their internal capacitance changes with bias too then even better: you can get phase IM too. Have I just demonstrated why valve audio sounds so good? 8-)
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Old 19th February 2013, 09:37 AM   #35444
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I'm still trying to figure out the assertion that 1/f noise and its effects are somehow not measurable by conventional test means. Where do those 1/f noise plots come from, the head of Zeus?
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Old 19th February 2013, 09:37 AM   #35445
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Default It's All Relative....

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.....Just consider the amplifier with low IM that all self friendly music lover is supposed to use.
Not all amplifiers are this 'blameless', especially when driving a reactive (loudspeaker) load.

Dan.
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Old 19th February 2013, 09:40 AM   #35446
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Not all amplifiers are this 'blameless', especially when driving a reactive (loudspeaker) load.
Very true. Look at the Wavac (at over $300k) for a perfect example. More conventional amps, however, do fall in the "blameless" category more often than not.
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Old 19th February 2013, 09:41 AM   #35447
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Originally Posted by gk7 View Post
No. The coriolis effect has nothing to do with some "memory" water should have
(which it does not) nor with other forces that move water in some direction.
Deary, deary, me ... I do have to go through this painful exercise, do I? ,

Okay. I used the term "memory" as a "fancy" way to indicate that the mass of waters ends up having a tendency to revolve in one direction or the other. From inertia mainly, thermal effects, even someone vibrating the floor under the wash basin at one point, you name it. It "remembers" everything that's happened to it, like a brick wall "remembers" how much sun has struck it by the temperature gradient through it, well beyond the time the sun has gone down ...

Getting closer ...?

Frank
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Old 19th February 2013, 09:45 AM   #35448
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I'm still trying to figure out the assertion that 1/f noise and its effects are somehow not measurable by conventional test means. Where do those 1/f noise plots come from, the head of Zeus?
Yes SY, the advantage of the measurements is that they take all phenomenas in consideration once. Even Zeus's ones.
Now it's time to produce a new magic device to kill this new evil. Oh ? It already exists under the name "Low pass filter" or "DC Servo" ?
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Old 19th February 2013, 09:49 AM   #35449
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.....Where do those 1/f noise plots come from, the head of Zeus?
Click the image to open in full size.
Sampling Quality - Developer Zone - National Instruments
Pretty much any other 1/f noise white paper states the same.

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Old 19th February 2013, 09:53 AM   #35450
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OK, so you understand that your statement about 1/f noise being undetectable by standard equipment was in error. This is progress!
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