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I want you to experience this ecstasy (Read 7108 times)
veryoldcat
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Re: I want you to experience this ecstasy
Reply #30 - 07/19/09 at 06:19:17
 
"can't disagree with the NOS philosophy."


i'm wondering what this "NOS philosophy" is, if you don't mind...

Karl
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ptime
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Re: I want you to experience this ecstasy
Reply #31 - 07/19/09 at 06:44:05
 
steve basically sums it up with his write up...but basically the part under "FIR FILTERS".

47 labs also has an article out there:
http://www.sakurasystems.com/articles/Kusunoki.html

that said, some actually think the cons out weigh the pros...like in this article:
http://hagtech.com/pdf/not16bit.pdf

the non over sampling philosophy is a good one, but imo the key is in its implemention to mitigate the cons.
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veryoldcat
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Re: I want you to experience this ecstasy
Reply #32 - 07/19/09 at 20:39:22
 
ahh, ok

Thx!

Karl
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Steve Deckert
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Re: I want you to experience this ecstasy
Reply #33 - 07/20/09 at 01:05:50
 
The two papers are quite a good representation of the two views on oversampling vs. non-oversampling.

Myself, I have to go 100% with Kusunoki, who's excellently written paper demonstrates a fork in the road where engineers had to choose between frequency domain or time domain.  They chose frequency. They chose wrong.  As small excerpt from his paper:

Quote:
Since the sampling frequency of CD is 44.1kHz, each delay time for the 1 x sampling is 22.ms per tap. To achieve 8 x sampling, SM5842 repeats 2 x sampling three times, and each step incorporates the taps of, 169 degrees for 2 x, 29 degrees for 4 x, and 17 degrees for 8 x. The accumulated delay of each step becomes, 1.92ms, 0.16ms, and 0.05ms: total of 2.13ms.
    Our auditory sense does the frequency analysis at every 2ms interval, and 2.13ms of delay can be caught by our ear.


This 2.13ms is likely what gives consumer grade digital it's signature in my opinion.  And why I've always preferred listening to analog.   I would recommend reading both papers.  You'll see it's possible to make an oversampling DAC sound good which explains why there are so many that do.  However, only if you reduce the number of taps to keep the delay less than 2 ms.  Myself, after hearing a variety of NOS dacs, be they perfect or not, all had far less of whatever it is that makes digital sound so lame next to analog.

I highly recommend reading both papers.  However, I will admit that after hearing my first NOS dac I had to know why oversampling apparently ruins the playback and why 44.1kHz 16 bit Redbook format suddenly seemed to have many times more information in the top end, my biggest complaint against CDs.  I found Kusunoki's paper a refreshing and satisfactory explanation for what I was hearing and shifted my attention of figuring out what implementations worked best.

Steve
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