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Analysing hi-res files

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Sylvain View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sylvain Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jun 2013 at 4:05pm
please please Fatmangolf, Moris-Minor and others Please Keep it up.....This is very interesting for me..My Reue 24  bit DAC does make a significantly better hifi reproduction, significantly better not marginally, with DVD audio tracks than with CD,,,,but please this is an interesting area and I look it up eveyday as Hugwith a good significant chapeter on High resolution file does not provide what you are providing.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote morris_minor Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jun 2013 at 4:31pm
I'm at the limits of my understanding here Sylvain - so don't know if I can keep it up for much longer! Shocked

What I would say is that not all DACs are equal - even with basically the same specifications. Borrowing a Bitzie USB DAC (which doesn't do 96/24) gave me a performance virtually on a par with a more expensive 176/24 DAC (newer versions to 192/24). Logic (well the kind of logic I had at the time!) made me expect a far, far bigger difference. That there was a difference I put down to one DAC being powered by the USB bus, the other by a hefty dedicated power supply.

My inclination now is to propose that the "best" digital sound comes from a happy marriage of these two attributes:

1. A DAC with a current convertor, needing no more than 48/24 - and 44.1/16 is perfectly valid, but which has a properly engineered analogue stage, and

2. A recording made with loving care which extends to the mastering (for whichever format is chosen).

I don't believe you *need* anything else . . . 

YMMV of course!
Bob

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Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jun 2013 at 4:50pm
What Bob just wrote.
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mitch65 Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jun 2013 at 5:09pm
Makes sense to me Big smile
Greg

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sylvain Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jun 2013 at 10:13pm
very sincerely  thank  you...Picked up  '' intro. to Digital Audio by John Watkinson'' and have yet to  be better '' illuminated'' but from your post....BUt one final point and I do accept that the word length or BIt must be 24 Bit and as Tweeters and Midrange cones have improved significantly with new materials ...only 88.2 or 96khz allows the bandwith to exploit the qualities of music content in the mid and high frequencies or the wider the bandith the easier to reproduce the high mids and treeble freuencies ...and YES INDEED THE ANALOGUE OUTPUT MUST BE PROFESSIONALLY PASSIONATELY CRAFFTED and here again the wider bandwith allows more sohisticated filtering techniques...... I read these things but I 'll be a fool to say that I understand it.Tongue     
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jun 2013 at 6:31am
Why does the word length have to be 24 bit?

Isn't this simply playing into the hands of the marketing man who keeps repeating the same message?

Didn't xiph.org explain the only difference between 24 bit and 16 bit... a noise difference? Noise you'll not hear.

(http://www.xiph.org/video/vid2.shtml: the chapter on bit depth)

Now, has anybody considered whether that low 24 bit noise (which is "silence" and not music) actually survives the analogue output stage of the DAC?

Let's stick a valve output stage right after the DAC chip. Do you get that 24 bit -120dB noise?

No!

Do you even get 16 bit -96dB noise?

You'll be lucky!

And how many swear they can hear the difference between 24 and 16 bit using a valve output stage that totally masks any difference whatsoever?

Yes plenty! Because the marketing told them what they hear!

Are these controlled AB tests? Obviously not!

Graham
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jun 2013 at 8:29am
Sampling theorem explains that two samples are all that are needed to reproduce a sine wave (according to Nyquist, Shanon et al).

44.1kHz offers a maximum of 22,050Hz as commented earlier in this topic.

The reason for 44.1kHz is down to clock frequency derived from a crystal oscillator being the nearest available to twice 20kHz.

Can a 20kHz square wave be sampled? With only two points no. A square wave is a multiple of its harmonics. Do we need a 20kHz square wave? Can we hear a 20kHz square wave?

I doubt if human hearing could detect the difference between a 20kHz square wave and a 20kHz sine wave. For a start, can you hear 20kHz at all?

Have a listen to this: http://ia700202.us.archive.org/9/items/20kHz_tone/20kHz_audacity.wav

No, I didn't hear it and so I can't hear the difference between 20kHz sine or square because I can't hear that high.

It means I can't hear the 1st harmonic of a 10kHz square wave either so I would not be able to hear the difference between a 10kHz sine wave or a 10kHz square wave.

However, I can hear the difference between a 5kHz sine wave and a 5kHz square wave because I can hear the first harmonic which is 10kHz.

If you could just hear the 20kHz sound file above then you'll be able to hear the difference between a 10kHz sine wave and a 10kHz square wave...

...and if you can you'll be able to hear the early harmonics of virtually all musical instruments.

By self testing like this you can decide for yourself if you can hear anything in the region of 20kHz or above.

My understanding is adults can't usually hear 20kHz. Children can sometimes hear a little bit higher.

I conclude that all musical instrument harmonics are faithfully reproduced within a 20kHz bandwidth just as much as if they were being heard direct.

We being natural beings and with the high frequencies rolling off at some point will possibly witness our very own -6dB per octave filter - this is a natural filter rate.

At the frequency our hearing starts to register a fall in level it therefore follows there must be phase shift as there is for a natural filter rate of -6dB per octave.

This phase shift is 45 degrees. Therefore I guess we could be sensitive to a 45 degree phase shift at the point our hearing "rolls off".

So what if somebody adds more phase shift?

Would things then sound different? Perhaps not sound different but feel different?

By upping the sampling frequency we won't hear more but we can set the electronics roll-off higher... that moves the phase shift it introduces away from our sensitive area (if done correctly).

In trials we tested the above. If the phase shift from the electronics was close to our hearing's roll-off phase shift it sounded highly signatured (false). If we moved the phase shift so it had a lesser effect on our natural phase shift it sounded more "real".

There are two ways of enabling this phase shift to be moved away from our own natural phase shift...

One is to go hell for leather in demanding the system can record and replay greater and greater sampling rates.

The other is quite simple and less costly in all things: it is called over-sampling and has been in existence for years. It allows existing music (on CD for example) to be played.

The big problem with over sampling was not the over sampling but the understanding of how to make the analogue filter not have the unnatural phase shift - the combination of our natural phase shift and the electronic one being too close that it is noticeable.

However, rather than understanding the problem and dealing with it, manufacturers race on to produce something that isn't really required and marketing the hell out of it.

It happened with phono stages. This "sickness" is nothing new to me. I battled with it before many years ago. Eventually people started to realise I had something there. One day the same realisation may happen with what I'm saying about digital.

Anybody remember me going on about phase integrity?

Graham
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