Suppose you start with the process of summing two frequencies, 22.5 and 17.5 resulting in a particular wave shape. You propose that a carrier then exists at 20? If it does, then what happens when you try to filter out only 20, then only 22.5 and 17.5 left? What happens when you filter out 22.5, both 20 and 17.5 left? Did you really end up with three frequencies or only the appearance of three?
Compare the above results with what happens to produce the same particular wave shape as in the above when the process is modulation. Any difference in the results after filtering?
You have to remember that math is modeling of reality, not reality itself. The math for describing a wave shape does not necessarily tell you the waves that are producing the shape.
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Thank you.
First is good, second is good, but the discussion is not about the product of two hf sines, but modulation of high and low.
If you add 17.5 K and 22.5 K, it is mathematically equivalent to multiplying 2 times (amplitude) the sine of 20 K times the cosine of 2.5K.
jn
First is good, second is good, but the discussion is not about the product of two hf sines, but modulation of high and low.
If you add 17.5 K and 22.5 K, it is mathematically equivalent to multiplying 2 times (amplitude) the sine of 20 K times the cosine of 2.5K.
jn
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Ah, now I get what you mean. Alas, the zero-crossing distances undergo the same restriction as the spectrum peak when trying to eye-ball carrier freq from it: no additional EQ!
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I do not propose anything. The math states that the sum is exactly equivalent to a sine modulated waveform with the average of the two frequencies as the carrier, modulated by the cosine of 1/2 the difference between the frequencies.
jn
😕 Makes no sense to me. Anybody ever see a multitone (summation) generate sidebands in low distortion system?
The math states that wave shape looks the same, not necessarily that the same waves are producing the shape.
It is entirely consistent with the trig identity. Well, yours was 18 khz instead of 17.5 khz, I have no explanation for that discrepancy.
But again, thank you so much for your efforts, I really appreciate it.
My point is, overlapping the two signals, that of filter in and filter out, they are not identical. I blame the loss of sideband information for that.
John
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No, the math is a trig identity. Exact, they did not use the "~" sign. (I've no idea what that is called, is it a tilda?)
jn
Fully separated from the ongoing discussion that doesn't have my attention, I have the impression that we did not do precisely the same.
Shown below is the FR and GD of the Fir filter that I used and as mentioned before 'not exactly a brick wall filter', but the best I could get in LTSpice with a constant GD for a "quick and dirty test".
But what a difference from your FR ?
The second image shows the output signal of the filter, still completely analogue without any of the staircase-steps that you showed ?
And brickwalling while saving is not what ever happened.
I just made .wav files from the analogue in- and output and played them back in RMAA, because LTSpice makes a mess of displaying a .wav file.
See the 3 RMAA files below.
So in my LTSpice sim I did not do any (re-)sampling, I just made a 44.1/16 .wav file from an analogue signal that was Fir filtered, a thing that LTSpice can do very well.
A proper brickwall as in Audition will of course get much more accurate results.
The quick and dirty job was seemingly informative enough after all.
Your upsampled spectrum to 384K is probably screwed-up because of doing something wrong in LTSpice.
Hans
Doesn't matter.
The waveform itself has only one representation in the frequency domain however it is produced.
For human perception it matters if the ear/brain detects/recognizes frequencies or time domain waveforms. There is some research on that, but others probably know what it says better than I do.
Modulation, summing, digital synthesis are some processes that can be used to produce waveforms. There have been claims in this thread about processes and about waveforms, sometimes mixed up in ways that don't fully jive. Hence, the need for a clear statement about what exactly is under consideration. Audibility of waveforms? How waveforms may be produced in digital audio?
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Hans, thank you again.
Note that your filter output also has a longer carrier wavelength, and is rather consistent with the spectrum plots.
If you overlap input and output, they are again, not the same.
jn
They are magical on voices. Transform Mickey in Sinatra. I never used them on cymbals apart if I wanted a big heavy sound.
I had been told that Americans and English people were not jealous of the fortunes of others. An urban legend?
That said, think about it. You pay for the CD burning, the cover and the transports. It's free for downloadable files: less expensive..
I'm retired, not heeled at all, and want high definition files. Because it doesn't cost more, because I can always reduce its size and quality if I want. because more is better than just enough.
No one thinks of shaming you because you are satisfied with the little red book. Not my notion of democracy, whatever I find CDs quite satisfactory ... but not perfect.
it don't males a lot of difference if you enjoy music, more if you are a passionate audiophile. That is not a sin neither ;-)
As we say in France: "Butter plus the money of the butter and the smile of the creamery".
Any resemblance to "The last tango in Paris" would be pure coincidence.
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The proof is in the pudding. Both Hans and KSTR have now provided exactly the same evidence.
The carrier is shifted in frequency away from the initial one.
jn
Thank you for this. Much more eloquent than my "have a close look at the animation I posted....." 🙂
There never was a carrier per say, since that implies creation of a waveform by the process of modulation. Some of the confusion in this thread seems to arise from overly loose use of technical terms.
...says that more than one process can create a particular waveform. Are we looking at processes that can affect audibility or waveform audibility however a waveform comes to be?
What's this 180 degree phase changes all about. Flipping back and forth with polarity reversal cant be something to improve the sound quality.
-RNM
-RNM
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No idea what you are trying to say here!
most of the time hi def ARE more expensive. When it's the same price of course I take that download option.
Some try they fail. But I just picked up another mono Furtwangler recording at the post office which will be tonight's enjoyment.
I remain convinced that with some people there is a Pavlovian response to the high-res LED on the DAC. Mine doesn't have one so I am denied the dopamine hit that might help me see what I am missing.
FWIW I run my miniDSP at 24/96. Cos I can...
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