John Curl's Blowtorch preamplifier part II

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And just in case there is not enough misinterpretation in this thread I give you It's Official: People Can Hear High-Res | AudioStream

I contend that the best upgrade audio needs is the journalists. He references a simple primer on Nyquist to claim
the recent paper from Tim Wescott "Sampling: What Nyquist Didn’t Say, and What to Do About It" which calls into question many people's [mis]reading of the Nyquist-Shannon sampling theorem thereby shaking the very foundation of the digital world that many people have chosen to build upon.

Whilst people like this are allowed to review equipment we are mired in 'a good story trumps engineering excellence'.
 
It is difficult to imagine what this sentence might mean, but it appears to say that the noise in each channel should be correlated with the noise in the other channel. If so, all that gives is a central noise source in the stereo image. I would have thought that highly uncorrelated noise would be preferable and easier to ignore.
Yes, you nearly got it right.
I am saying forceing system intrinsic/excess noise to mono centre and it essentially disappears.
Secondary effect is that embedded programme noise then subjectively reduces also, giving better apparent SNR and programme content clarity.
How, is another subject.

Dan.
 
So a central noise source (which may be audible) helps mask uncorrelated noise (which probably would have been less audible anyway).

How does one correlate channel noise without employing a Maxwell demon? I get it: that is how the Bybee works!! It forces the two stereo channels into quantum coherence. And all the time I just thought it was, at best, an RF filter.
 
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So a central noise source (which may be audible) helps mask uncorrelated noise (which probably would have been less audible anyway).
No, reducing and monoing system excess noise reduces system 'pollution' of throughput signal, and embedded program noise becomes subjectively reduced....to be expected.
How does one correlate channel noise without employing a Maxwell demon? I get it: that is how the Bybee works!! It forces the two stereo channels into quantum coherence. And all the time I just thought it was, at best, an RF filter.
Why can't you affect the system without affecting the signal ?

Dan.
 
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Warning... audio related post. Quality of radio formats.

Mention of FM radio crops up in this thread now and again and although in the UK we have had DAB (Digital Audio Broadcasting) for many years I thought it would be fun to try an old Sony ST515L tuner that is around 40 yrs old vs DAB.

Thoughts of vinyl vs CD came to mind :D

I switched to DAB around 10+ years ago but thought a revisit of the old vs new might be instructive. I've recorded two 3 minute clips both of which have the same content. One is FM and one DAB. Both are clearly marked in the file name. The DAB version is UK digital at its finest and highest bit rate ;) I'll not tell you what that is yet, but suffice to say that this is as good as it gets. Many stations are on much lower bitrates, some very very much lower.

If anyone is interested I've put the audio file on Dropbox which is linked to at the end of this post (go on, have a listen). They are only 320kbs MP3's so no big downloads.

Have to that I'm slightly surprised at just how good the ancient and original Sony actually is. Unfortunately I haven't an outdoor FM aerial, just a loft job. Its not so bad though.

One of the two seems to have a much wider soundstage than the other.

The digital tuner is a dedicated 'high end' offering. A Pure DRX701ES.

Also shown here is the spectrum of both. No guess for which is which. And what's that spike at the end of one of them ;) I used to be able to hear that once... from this very tuner.

Spectra

DAB.JPG

FM Spectrum.JPG

And here is the audio. Its a zipped folder containing one DAB file and one FM file. Both are MP3's

FM vs Digital Radio
 
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No guess for which is which. And what's that spike at the end of one of them

Mooly you mean: can you here the 19kHz stereo pilot?
I am surprised it is in the spectrum at all. Wouldn't the MPX filter be expected to make short shrift of that??
FM is supposed to be sharp filtered at 15kHz.

Jan
 
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