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Help! Sacd Good Or Bad?, Does SACD ought to sound like crud?
Joe Bloggs
post Sep 9 2002, 12:33
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I've listened to SACD once and it sure sounded good...

I've heard people say that SACD ought to fail in transient reproduction, (because it can only encode a rise and fall relative to the last time step) so I did some calculations:

'Sampling rate' of SACD = 2.8MHz = 64x 44.1kHz

For encoding tones up to 44.1kHz at full scale, it has to reach full-scale from 0 in 64 steps, that is, at any given time there can only be 64 possible positions for the waveform.

This gives it 6 bits resolution to CD's 16 bits??

OK, suppose you only need to encode up to 22.05kHz at full scale, the number of possible positions increases from 64 to 128--7 bits resolution, big improvement blink.gif

I doubt this is how DSD actually works, but this article http://www.iar-80.com/page40.html (I linked to page 40, but it seems page 1-39 may be going on and on about the sonic flaws of DSD as well) seems to take this view seriously and goes on to talk about how you try to recover musical information from the 6 bit stream. blink.gif
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Pio2001
post Mar 4 2003, 01:06
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I've got a 24/96 soundcard, and HD 600 Headphones.

30 kHz at -3 db
38 kHz at -10 db

But I've got no 96 kHz material.

Robux4, what you describe about the transient response is perfectly right. But it doesn't support your point. A delayed slow response to a 30 kHz transient is nothing else than a clean lowpassed version of the transient. The pulse has a flat frequency content from 0 to 30 kHz. The delayed version has a flat frequency content from 0 to 16 kHz only. The removal of the inaudible frequencies acts exactly like inertia.
See a more detailed explanation at http://forum.cdfreaks.com/showthread.php?s...1864#post376461

However, the "periodic" behaviour against "transient" one is a valid question. In mathematical terms, we ask if the ear is a "linear" device. Linear meaning roughly that the effect of the sum equals the sum of the effects, and therefore a pulse being a sum of frequencies from 0 to N, if the ear is linear, it should react as a lowpass filter, the resulting lowpassed pulse actually heard being the "sum of the effects", that is, the sum of all reactions to audible content in the pulse.
But if the ear is not linear, it won't necessarily lowpass the pulse. The pulse heard won't necessarily be the sum of the effects that each frequency component in the pulse would have.

The most basic test is the intermodulation one. Say that you can't hear above 16 kHz. Generate a 6 kHz square wave in cooledit. And for god's sake, perform a spectrum analysis of it... I tried 3 times to generate square waves in Cool Edit before actually getting a true one. A true square of frequency N must have a frequency content of N, 3N, 5N, 7N ect... and nothing else ! The square generator in CoolEdit is completely wrecked. But it works at 6 kHz for a 48 kHz sampling rate.

Then, you have a 6 kHz sine, plus a 18 kHz one. If you compare it with a 6 kHz sine alone, all you'll hear is a volume difference (the square being louder because the level of the N frequency is above the peak level of the square).
Rising the volume, a ghost 12 kHz tone should appear. It's intermodulaton distortion in the ampli or speakers.
Now, playing a 6 kHz sine in one speaker and a 18 kHz one in the other, there is no intermodulation, no 12 kHz tone in the room.
WARNING : it is said that 18 kHz sines can fry tweeters !!!
Check with a microphone, that your speaker actually plays a 18 kHz tone.
If you hear a 12 kHz tone anyway, check with a microphone, that it is not in the room, and if it's not, you're hearing the effect of inaudible frequencies.
I've tried it, and could hear nothing at a level that would have been 100 db if it has been a CD playback. So tell me about 40 kHz @40 db !
I can't find the report of the other people that have tried the same experiment and failed too, but Nika says it's in there :
George, Watch this!!!....(96k) @George Massenburg, abstract in page 33

QUOTE
Actually, according to Paul Frindle........no. According to experiments that were described in pages past, this phenomenon does not happen with the ear if either of the two fundamental tones is higher than the ear can hear. I have actually substantiated this myself as well. My hearing caps off at around 17.5kHz. I played a 16.5kHz signal and an 18.5kHz signal through two separate pair of speakers in a room and listened for the 2kHz tone and it never shows up. Therefore, limiting the signal to above what humans can hear does not inhibit our ability to capture the performance as naturally as we would hear it live.


And last, there is Oohashi's experiment ( http://jn.physiology.org/cgi/content/full/83/6/3548 ) in which people say they couldn't hear the difference, but the electroencephalogram showed one (delayed). They say also that people said they were more comfortable when the ultrasonic content was played, but they don't say how many people said it. This should be analysed like an ABX result : if you ask people to choose which performance they prefer, and that a little more than half the people tell they prefer the ultrasonic one, it can very well be pure chance. They don't state the level of confidence of the correlation between people's statement and the performance played (=same kind as the level of confidence between your ABX choice and the samples really played).

I've just thought of a non linear behaviour of the ear... The ear, as a lowpass filter, should act like an IIR filter isn't it ? But a true linear behaviour would be the one of an FIR (well, a symmetric IIR one, with pre echo).
Wouldn't there be something here to discuss ?

IIR/FIR filters explanations :
The audio engineer's approach to understanding digital filters. For the idiot such as myself by Nika Aldrich
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Posts in this topic
- Joe Bloggs   Help! Sacd Good Or Bad?   Sep 9 2002, 12:33
- - Joe Bloggs   Ok, um, does DSD assume delta modulation or delta-...   Sep 9 2002, 13:33
- - Peter   well, some people are apparently having problems w...   Sep 9 2002, 13:50
- - Joe Bloggs   Problem is, the bits are not employed in the same ...   Sep 9 2002, 14:15
- - Joe Bloggs   This is an example of Sigma-Delta, or Pulse Densit...   Sep 9 2002, 15:16
- - Jasper   The general idea is correct, but SACD quality does...   Sep 9 2002, 16:29
- - Joe Bloggs   So the encoding system is really just plain delta ...   Sep 9 2002, 16:39
- - Jasper   Sorry to have confused you, I didn't have a go...   Sep 9 2002, 16:54
- - 2Bdecided   IIRC, the difference between delta and sigma-delta...   Sep 9 2002, 17:49
- - n68   yup... call it what you wan`t... (i assume...   Sep 9 2002, 18:24
- - mcg1969   I don't think you can fairly say that SACD is ...   Sep 9 2002, 23:42
- - Frank Klemm   QUOTE (2Bdecided @ Sep 9 2002 - 06:49 PM)IIRC...   Sep 10 2002, 01:25
- - crazyboy_T   > - Very critical signal needs time resolution ...   Sep 10 2002, 04:22
- - n68   QUOTE (mcg1969 @ Sep 9 2002 - 10:42 PM)I don...   Sep 10 2002, 10:44
- - Pio2001   QUOTE (crazyboy_T @ Sep 10 2002 - 06:22 AM)Is...   Sep 10 2002, 11:47
- - Frank Klemm   QUOTE (crazyboy_T @ Sep 10 2002 - 05:22 AM)...   Sep 10 2002, 11:57
- - 2Bdecided   It's possible to detect an interaural time del...   Sep 10 2002, 12:36
- - petracci   QUOTE (2Bdecided @ Sep 9 2002 - 06:49 PM)Howe...   Sep 10 2002, 14:53
- - Joe Bloggs   QUOTE Another point: I have serious doubts about t...   Sep 10 2002, 15:01
- - Joe Bloggs   OT: I'd finally figured out what the correct g...   Sep 10 2002, 15:09
- - KikeG   QUOTE (Joe Bloggs @ Sep 10 2002 - 03:01 PM)I ...   Sep 10 2002, 21:27
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 06:09 AM)OT...   Sep 10 2002, 22:33
- - Kim_C   QUOTE (KikeG @ Sep 10 2002 - 11:27 PM)QUOTE (...   Sep 11 2002, 02:51
- - Artemis3   So in other words, the answer to the thread's ...   Sep 11 2002, 04:19
- - Joe Bloggs   Huh? Plain DVD does 24/96? What's DVD-A for th...   Sep 11 2002, 05:42
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 08:42 PM)Hu...   Sep 11 2002, 05:52
- - Joe Bloggs   Any DVD-A records with DRM?   Sep 11 2002, 06:45
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 09:45 PM)An...   Sep 11 2002, 07:12
- - Joe Bloggs   Oh, I mean, any DVD-As without audible watermarks?   Sep 11 2002, 07:37
- - n68   QUOTE (bryant @ Sep 11 2002 - 06:12 AM)All DV...   Sep 11 2002, 08:08
- - bryant   QUOTE (Joe Bloggs @ Sep 10 2002 - 10:37 PM)Oh...   Sep 11 2002, 09:24
- - Pio2001   QUOTE (Kim_C @ Sep 11 2002 - 04:51 AM)Audio N...   Sep 11 2002, 11:46
- - Joe Bloggs   So would you agree with this kind of design? What...   Sep 11 2002, 13:33
- - ChristianHJW   Sorry for stepping is so late .... DVD-A vs. SACD ...   Sep 11 2002, 14:26
- - Frank Klemm   QUOTE (ChristianHJW @ Sep 11 2002 - 03:26 PM)...   Sep 11 2002, 14:54
- - user   DVD-Video: Theoretical PCM possibilities for DV...   Sep 11 2002, 14:55
- - ChristianHJW   QUOTE (Frank Klemm @ Sep 11 2002 - 01:54 PM)I...   Sep 11 2002, 15:11
- - Joe Bloggs   OK, so non-oversampling DACs use analog filtering ...   Sep 11 2002, 15:29
- - ChristianHJW   .. arent most modern DACs using a combination of d...   Sep 11 2002, 15:37
- - Kim_C   QUOTE (Pio2001 @ Sep 11 2002 - 01:46 PM)For w...   Sep 11 2002, 16:43
- - Joe Bloggs   What troubles me is that I don't even know wha...   Sep 11 2002, 16:51
- - Pio2001   QUOTE (Joe Bloggs @ Sep 11 2002 - 05:29 PM)Ca...   Sep 11 2002, 20:12
- - Frank Klemm   QUOTE (Joe Bloggs @ Sep 11 2002 - 06:42 AM)Hu...   Sep 11 2002, 20:49
- - KikeG   About non-oversampling filters, I have to say that...   Sep 12 2002, 00:45
- - Kim_C   QUOTE (KikeG @ Sep 12 2002 - 02:45 AM)About n...   Sep 12 2002, 13:53
- - 2Bdecided   I've heard David Chesky's 6 channel 24/96 ...   Sep 12 2002, 14:33
- - KikeG   In reply to Kim_C: It is true that human ear cann...   Sep 12 2002, 14:49
- - Kim_C   QUOTE (KikeG @ Sep 12 2002 - 04:49 PM)This do...   Sep 12 2002, 15:20
- - Kim_C   QUOTE (2Bdecided @ Sep 12 2002 - 04:33 PM)P.S...   Sep 12 2002, 15:52
- - Joe Bloggs   QUOTE (2Bdecided @ Sep 12 2002 - 09:33 PM)P.S...   Sep 12 2002, 16:20
- - KikeG   QUOTE (Kim_C @ Sep 12 2002 - 03:52 PM)"b...   Sep 12 2002, 16:51
- - ChristianHJW   QUOTE (KikeG @ Sep 12 2002 - 01:49 PM)In repl...   Sep 16 2002, 12:41
- - Joe Bloggs   I would also think that you're most likely to ...   Sep 16 2002, 13:03
- - KikeG   QUOTE (ChristianHJW @ Sep 16 2002 - 12:41 PM)...   Sep 16 2002, 18:56
- - Pio2001   QUOTE (ChristianHJW @ Sep 16 2002 - 02:41 PM)...   Sep 16 2002, 23:25
- - ChristianHJW   it was an analog filter i had done using a few op-...   Sep 17 2002, 10:39
- - fewtch   Sheesh... all of this started from an original que...   Sep 17 2002, 10:49
- - Pio2001   QUOTE (ChristianHJW @ Sep 17 2002 - 12:39 PM)...   Sep 17 2002, 11:32
- - fewtch   bleep   Sep 17 2002, 12:12
- - KikeG   QUOTE (ChristianHJW @ Sep 17 2002 - 10:39 AM)...   Sep 17 2002, 12:32
- - ChristianHJW   QUOTE (KikeG @ Sep 17 2002 - 11:32 AM)In the ...   Sep 17 2002, 13:31
- - Joe Bloggs   He said analog filter. The most likely explanation...   Sep 17 2002, 16:01
- - KikeG   QUOTE (ChristianHJW @ Sep 17 2002 - 01:31 PM)...   Sep 17 2002, 17:17
- - Pio2001   QUOTE (KikeG @ Sep 17 2002 - 02:32 PM)You can...   Sep 17 2002, 22:40
- - ChristianHJW   QUOTE (KikeG @ Sep 17 2002 - 04:17 PM)It is a...   Sep 19 2002, 13:56
- - KikeG   Well, I was just intending to explain that this ...   Sep 19 2002, 22:18
- - DickD   Regarding the airy sensation, I concur with KikeG....   Feb 11 2003, 14:41
- - robUx4   QUOTE (KikeG @ Sep 19 2002 - 10:18 PM)About f...   Mar 3 2003, 15:00
- - ChristianHJW   QUOTE (robUx4 @ Mar 3 2003 - 02:00 PM)We basi...   Mar 3 2003, 15:35
- - 2Bdecided   Most of the ideas that are being kicked around her...   Mar 3 2003, 16:02
- - user   http://www.hfm-detmold.de/texts/de/hfm/eti...ten/s...   Mar 3 2003, 16:04
- - ChristianHJW   QUOTE (user @ Mar 3 2003 - 03:04 PM)So, they ...   Mar 3 2003, 16:28
- - Frank Klemm   QUOTE (2Bdecided @ Mar 3 2003 - 05:02 PM)Most...   Mar 3 2003, 19:25
- - robUx4   That would be a very interresting stuff. How many ...   Mar 4 2003, 00:09
- - Pio2001   I've got a 24/96 soundcard, and HD 600 Headpho...   Mar 4 2003, 01:06
- - KikeG   I agree pretty much with Pio's explanations an...   Mar 4 2003, 09:46
- - KikeG   QUOTE (robUx4 @ Mar 3 2003 - 03:00 PM)... but...   Mar 4 2003, 09:50
- - Canar   This is completely off-topic, but I just wanted to...   Mar 4 2003, 10:15
- - robUx4   I just wanted to add something to my paleonthologi...   Mar 4 2003, 10:41
- - Pio2001   QUOTE (robUx4 @ Mar 3 2003 - 05:00 PM)The hum...   Mar 4 2003, 12:29
|- - user   interesting study and paper about difference betwe...   Mar 24 2006, 15:26
- - Pio2001   I remember having read this. It must have been dis...   Mar 24 2006, 16:27
- - SebastianG   I wonder why they have chosen 176,4 kHz at 24 bits...   Mar 24 2006, 16:58
- - Pio2001   Probably to stay close to real-world applications.   Mar 24 2006, 17:36


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