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"Hi Res" Tracks Spectrum Analysis


The Monkey
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I just bought Fleetwood Mac's "Rumours" from HD Tracks. It is supposedly 24/96, but with some of the recent hubbub about what is really going on inside the tracks, I downloaded Audacity and ran a Spectrum Analysis on "Never Going Back Again." The screenshot is attached. I don't know how to read these things. Can someone let me know what, if anything, can be seen here? EDIT: Added Plot Spectrum.

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post-205-0-78225600-1320895170_thumb.png

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Just look for well mastered versions. Hi res is hooey in my book (I know lots of people disagree).

Also I'm not entirely sure what deepak mean by rips of an SACD because ripping an SACD into other than 1bit formats requires some pretty heavy math and getting DSD data off the disc is impossible without breaking copy protection (which assuming the licensing is valid they probably are allowed to do).

Edited by Dreadhead
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I'd just the best mastering, even if it may be redbook. Like Dreadhead I don't place much stock in high res, the mastering will make a much bigger difference (compression, EQ, etc).

Just look for well mastered versions. Hi res is hooey in my book (I know lots of people disagree).

Also I'm not entirely sure what deepak mean by rips of an SACD because ripping an SACD into other than 1bit formats requires some pretty heavy math and getting DSD data off the disc is impossible without breaking copy protection (which assuming the licensing is valid they probably are allowed to do).

There are a couple of ways to convert the DSD to PCM. One is using an older Oppo DVD player and another is the PS3 method.

See how HDTracks does it: https://www.hdtracks...DSD_to_LPCM.pdf

While I can appreciate that HDTracks are proactive about taking down upsampled lower res being sold as high res (at least from what I have read), I don't find them completely innocent in that they must have some suspicion when they offer these files for sale.

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I know Linn also just records in high res too. I should have said that I believe high res is hooey for final listening..... for mastering it makes good sense much like shooting pics in raw. The bit depth and sample rate keep all processing crap out of the audio band. The only hard part is the final downsample and dithering which does need to be done right.

Edited by Dreadhead
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I really like some of the stuff on HD tracks and feel most are worth the cash. Audacity's tools are not the most accurate (or so I am told) but they give you a rough idea.

I'm sure someone will correct me but your first plot shows frequency activity above 22khz so likely it is 24/96 (no that you'd hear distortion and artifacts above 22khz)

I'm pretty flip floppy on the whole issue. Recording needle drops high res makes a difference when encoding the analog signal and applying the RIAA curve digitally. Playback is tougher and 24/44.1 is ok or the movie standard of 24/48 is cool as well while I've heard plenty of 24/192 that sound awesome I'm not sure its needed for all recordings.

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I'd just the best mastering, even if it may be redbook. Like Dreadhead I don't place much stock in high res, the mastering will make a much bigger difference (compression, EQ, etc).

Same here, bit depth alone will have a hard time messing up a well mastered AND well processed recording. Looking at those spectros (and judging from the pixels I've seen in my time) I'd say that these might as well be different masters. Of course that the HD version will have stuff going on in upper frequencies, but my hearing cuts off at 19kHz so unless I project the sound with a BPP Supertweeter in my face... Also the stuff going on in higher freq can be just noise, beats me- I have a degree in talking out of my ass, not interpreting acoustic data.

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Dinny, it's possible we could see clearer differences (if they exist) on top harmonics (let's say from 18 to 22KHz) if you can

- Adjust spectral analysis on Audacity at 1024 points (window size), increase dynamic range up to 120dB and use Blackmann-Harris window instead of hanning.

- Then take a 2 seconds fragment rich on high frequency harmonics and zoom the analysis on it on both files.

If they look the same, in any case we could see if the high Freq. energy on the HDT has some harmonic structure or is mainly noise.

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Hi-fi News have been doing some work on this very issue and indeed exposing "mislabled" releases left and right. They had to develop their own software to see this which I believe was offered as a free download. I never cared enough to search for...

As for Rumors, I have the DVD-A rip and it sounds stunning. :)

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Linkys

HD download debacle!

Thread: HiFi News Investigates the Truth Behind HD Downloads

Spectragraphs are useful tools but are often misinterpreted. Some observers see bands of color in the ultra sonic range and claim, "they've a lot of detailed HF content" on a particular track. The fact is the low level stuff that's often represented is just noise that's been moved out of the audio band.

http://www.itrax.com...cording-quality

The Stones "Route 66": HD or Not?

Given that it's possible to rip the High Rez Audio tracks from DVD-A's ( E.g. using foobar2000 )

+ there are means for SACDs , you can check to see if they have any "real" High frequency content.

It's also interesting as to where people think this high frequency information comes from,

if you look at, say, the frequency response of studio microphones, especially those in use when the original recording was made smile.png

Edited by Grahame
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if you look at, say, the frequency response of studio microphones, especially those in use when the original recording was made smile.png

That's an excellent point Grahame. Limitations in the recording process are seldom considered in audiophile discussions.

My thoughts about sample rates are this: When possible, I like to record at 88.2 to push unwanted conversion artifacts out of the audible range. Mastering to 44.1 simply involves dropping every other sample (bit depth reduction still needs a proper dither.) For playback I upsample back to 88.2, once again, to push conversion artifacts out of the audible range. I do hear a slight improvement vs. 44.1 playback out of my Lavry Black. I've never been ambitious enough to set up a blind test though.

Justin has obviously made upsampling work well with the Pico. I would expect interpolating files from 44.1 to 96 would slightly degrade the signal. Maybe it does, but I can't hear it. That little thing still sounds awesome to my ears.

Eventually, I want to set up matching files of the same recording to see if my approach yields any subjective difference compared to a pure 88.2 file. Of course, if it doesn't, one could argue it's because my mics and A to D are no good.

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For those that actually follow the link to the SoundStage!HI-FI article "Understanding Digital Music -- Hi-Rez or Not?" and choose to download the Microsoft version of Sonic Visualiser -

I've validated that the Windows XP 32-bit version can be run on Windows7 64-bit, as long as you install the executables in the (x86) Program Files directory.

T.

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