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Old 8th February 2013, 09:43 PM   #34531
Pano is offline Pano  United States
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Quote:
Originally Posted by DF96 View Post
Inject a little RF noise, and add 'air' around the musical instruments.
Well, you know, that's been one of the explanations of the "sound" of Class-D. The RF carrier does something to the wires, voice coils, whatever. Not a bad hypothesis.
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Old 8th February 2013, 09:52 PM   #34532
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Originally Posted by Pano View Post
The RF carrier does something to the wires, voice coils, whatever.
I don't thing so. (And don't believe in 'something'). Just a switching amp has high slew rate, by definition.
Anything special with the sound of a good class D comparing with a good high slew rate non switching one ? They can be very similar in presentation.
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Last edited by Esperado; 8th February 2013 at 10:01 PM.
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Old 8th February 2013, 10:25 PM   #34533
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It maybe "pixie dust" but it's not “Floobydust”.

In the 1976 National Semiconductor - Audio Handbook the word “Floobydust” is defined as:

“Floobydust” is a contemporary term derived from the archaic Latin miscellaneus, whose
disputed history probably springs from Greek origins (influenced, of course, by Egyptian
linguists) - meaning here “a mixed bag.”

Later in 1991 Bob Pease (RIP)(Staff Scientist at National Semiconductor) defined the word in his
Book “Troubleshooting Analog Circuits” as:

“Floobydust” is an old expression around our lab that means potpourri, catch-all, or miscellaneous. In this chapter, I’ll throw into the “Floobydust” category a collection of philosophical items, such as advice about planning your troubleshooting, and practical hints about computers and instruments.

Bob Pease often used the word in his columns in Electronic Design Magazine.
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Old 8th February 2013, 11:09 PM   #34534
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Quote:
Originally Posted by john curl View Post
Kindhornman, many phenomena cannot be easily understood, including type 2 superconductivity.
What's this Type 2 stuff? Everything Bybee has spewed about the BQP's has been straight out of the BCS theory of superconductivity, which as far as I'm aware, only appears to explain superconductivity in Type 1 superconductors, not Type 2.

se
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Old 8th February 2013, 11:11 PM   #34535
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Originally Posted by SY View Post
No, I showed explicitly that this doesn't happen.
And even if it did, I've always wondered how it could discriminate between 1/f noise and a music signal.

se
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Old 9th February 2013, 12:24 AM   #34536
gpapag is offline gpapag  Greece
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Quote:
Originally Posted by john curl View Post
That sort of AC 'clipping' appears to be an artifact of the display. I can get the SAME sort of 'clipping' from one of my early graphic calculators when showing a sine wave. Get real guys!
Quote:
Originally Posted by PMA View Post
Only usual power mains network distortion. Measured thru 1:2 voltage divider.
This is from a series of utility’s 230V/50Hz measurement at my workshop.
The measurements were done with the “Live Probe” (built after an article in WW), the output of which was connected to M-Audio Audiophile USB sound card.
When the input is 230V, the output of the "Live Probe" has an amplitude of 687mV rms, which corresponds to the –6db in the measurements shown.

George

>Edit. The AC “clipping” (Flats at top and bottom peaks) is real. The higher the impedance of the utility’s branch and the lower the impedance of the connected equipment, the worst this clipping becomes.
On the FFT of Live to Earth measurement , the amplitude of the 3rd, 5th 7th and 9th harmonics is an indication of imbalance. So is the amplitude of the fundamental on the FFT of Neutral to Earth measurement.
Attached Images
File Type: jpg Live Probe.JPG (88.0 KB, 158 views)
File Type: jpg Live to Earth.JPG (80.9 KB, 152 views)
File Type: jpg Neutral to Earth.JPG (83.0 KB, 153 views)
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Last edited by gpapag; 9th February 2013 at 12:49 AM.
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Old 9th February 2013, 12:36 AM   #34537
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If the graph in the Bybee measurement is actually measuring the input sine wave, then the circuit has a lot of second harmonic, AND DC in the mains.
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Old 9th February 2013, 12:50 AM   #34538
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Default Perceived Sound...

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Originally Posted by SY View Post
Just one, but John says I only have crappy midfi components and I'm deaf, so don't take it too seriously.
Ok, so did you try repeated (sighted) A/B testing and glean any sound differences ?.

Dan.
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Old 9th February 2013, 01:00 AM   #34539
gpapag is offline gpapag  Greece
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Quote:
Originally Posted by john curl View Post
then the circuit has a lot of second harmonic, AND DC in the mains.
Even harmonics are present when waves are non symmetrical. Such an asymmetry adds a DC component.

George
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Old 9th February 2013, 01:49 AM   #34540
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Quote:
Originally Posted by gpapag View Post
This is from a series of utility’s 230V/50Hz measurement at my workshop.

>Edit. The AC “clipping” (Flats at top and bottom peaks) is real. The higher the impedance of the utility’s branch and the lower the impedance of the connected equipment, the worst this clipping becomes.
On the FFT of Live to Earth measurement , the amplitude of the 3rd, 5th 7th and 9th harmonics is an indication of imbalance. So is the amplitude of the fundamental on the FFT of Neutral to Earth measurement.
This is farely common when old lines get added onto until overloaded. But the distortion isnt too bad for a clipped waveform.... 1% and less. But, there are plenty of HF harmonics to get past the internal power supply if not careful in design.

Now take a look at current waveform on the ac line with just a lamp dimmer turned on -- 82% THd and only 1 amp current draw. Even if you have great, clean - non clipped - ac power, you get this with just one consumer product on the ac line within the home. I have shown earlier that the spectrum can go out to many 10's of Mhz. These shown harmonic levels of the ac 60Hz are pretty high.
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File Type: jpg Dimmer current on ac line.jpg (384.9 KB, 146 views)

Last edited by RNMarsh; 9th February 2013 at 02:00 AM.
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