Distortion and image collapse with SACD thru headphones?
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JaZZ

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Alexx...

...you're mixing up bits and samples...

While samples stand for time dimension, bits stand for word length/amplitude values. 1 bit represents two virtual states, 2 bit represent 4 states, 3 bit 8 states, etc....

The sample rate only comes into play insofar as with the 1-bit technology the amplitude value change per sample can only be one step up or one step down – other than with the multibit technology. So there's not enough samples to achieve more than the equivalent of 7.47 bit at 16 kHz (e.g.), = 176 steps (not bits in the sense of a multibit system!). 176 bit would mean about 10^52 steps – an unspeakable number, which is far from any digital reality.
 
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Alexx

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Quote:

Originally posted by JaZZ
So there's not enough samples to achieve more than the equivalent of 7.47 bit at 16 kHz (e.g.), = 176 steps (not bits in the sense of a multibit system!). 176 bit would mean about 10^52 steps - an unspeakable number, which is far from any digital reality.


Let's calculate one more time: 176(bits) x 16000 (samples per second) = approx. 2.8 million bits per second. That's exactly SACD' bitrate. Where do you see a mistake?
 
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JaZZ

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Alexx...

...once again you're mixing up word length and sample rate. A word length (!) of 176 bit corresponds to a number of 10^52 states or steps, as mentioned. You can't invent your own system. While in reality the number 176 stands for the (calculated!) number of steps which SACD as a one-bit system has at the disposal for a 16 kHz sine wave. I wonder where you take your «176» (so-called «bits») from...
 
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Alexx

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Quote:

Originally posted by JaZZ
While in reality the number 176 stands for the (calculated!) number of steps which SACD as a one-bit system has at the disposal for a 16 kHz sine wave. I wonder where you take your «176» (so-called «bits») from...
[/B]


What do you mean by the word "steps"? Is it identical to the "states" you've used before? If so, SACD bitrate would be 7.47 x 16000 = 119520 bits per second. It's somewhat less than real life 2.8224 Mbits, isn't it?

Ones again: for each period of 16 kHz sine SACD uses 176 bits(!) to recreate the sound wave. As you've said, they are not "bits in sense of multibit system". But they are also not STEPS "in sense of multibit system"! They can't be compared directly, because, unlike PCM, SACD uses them not ALL AT ONCE, but rather ONE BY ONE, sequentially. But the fact is, that in NO WAY can SACD be compared with 6/44.1 PCM!
 
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JaZZ

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Alexx...

...you can't multiply bits with hertz! Bits are amplitude values, hertz are time values. Also keep in mind that 4 bit isn't twice as much as 2 bit, but 2² as much! You have created an immensely huge word length by just multiplying (!) bits and hertz... that's absurd.

All you can do is calculate the steps (= states) available at a certain frequency with the premise that there's just 1 step from sample to sample and the sampling rate is 2,822,400 cycles per second, and finally you can convert the resulting number of steps into bits – just to have a basis of comparison related to multibit systems.

Maybe the 7.47 bit is even too optimistic in practice. This range of 176 possible (amplitude) steps is only exhausted with a saw-tooth signal. A sine wave would require some 0s in between instead of constant 1s because of the curve shape and therefore not reach the maximum...

I agree: the SACD over-all sound is far above 6 bit level and probably clearly superior to the CD. The more so as the (virtual) word length / amplitude depth is just one criterion; the other is sampling frequency – and there SACD is even clearly superior to DVD-Audio. But the DVD-A's 192 kHz could very well be enough, so possibly the SACD's 2.8224 MHz aren't a real improvement, and finally the lack of high-frequency amplitude resolution remains as a deficit.

To meet the thread topic: Isn't it possible that the amp used in the IAR test has been highly susceptible to the SACD's HF interferences?
 
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AndreYew

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You can't directly scale bits and sampling rate to compare DSD to PCM, because DSD uses noise-shaping to lower its noise-floor. From measurements of SACD players, it's quite clear that DSD has more than 7 or 8 bits of resolution in 10 to 20 kHz region.

--Andre
 
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kelly

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Sorry I can't add anything to the technical merits of this thread. In my subjective experience, SACD has had preferable imaging with all of the headphones and amps that I use. But then, I think all of headphones and amps I have extensive experience with meet a standard of quality that it is possible the engineer from Telarc wasn't meeting. (Ie, maybe he was running a pair of $10 headphones from the headphone jack in an SACD player.) I like the Telarc SACDs I have quite a bit via headphones.
 
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JaZZ

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Andre...

...I do hope so. Otherwise: reduced noise isn't identical with increased resolution.
 
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JaZZ

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kelly...

...did you ever compare SACD and DVD-Audio?
 
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post-227001
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kelly

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JaZZ
No and I don't even know of a valid test for that considering the differences between recordings and the lack of components that are said to have good performance across both SACD and DVD-A at present.
 
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Calanctus

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Quote:

Originally posted by JaZZ
Alexx...
To meet the thread topic: Isn't it possible that the amp used in the IAR test has been highly susceptible to the SACD's HF interferences?


An interesting speculation, especially considering that this test used DSD direct from a hard disk--much like what I assume the original poster that I referred to at the start of this thread was using (he's a recording engineer presumably using professional equipment in the studio).
 
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