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Old 12th April 2012, 05:40 AM   #291
jitter is offline jitter  Netherlands
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Quote:
Originally Posted by abraxalito View Post
I can think of another interesting experiment - find out if any recordings use NOS ADC.
I found out that with Cool Edit you can edit individual samples, so I should be able to eliminate the ringing that occurred during the recording-stage. Cool indeed. Later today I will give it a go...

No doubt the Octave will show the difference, but I'm curious it if has any effect on the OS DAC. Will ringing be less? Anyone care to speculate?

Last edited by jitter; 12th April 2012 at 05:50 AM.
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Old 12th April 2012, 05:42 AM   #292
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Well if you can see the ringing why do it by hand? Why not design a very narrow band notch filter at the ringing frequency?
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Old 12th April 2012, 05:53 AM   #293
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Doing it by hand is in this case the quickest thing to do. The impulse is so short that it's only a very limited amount of samples that need to be edited. I'll post the results later today.
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Old 12th April 2012, 09:08 AM   #294
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Originally Posted by ThorstenL View Post

SACD is basically the DS Modulator output from a generic ADC originally meant for transferring analogue recordings for later release on CD. On a fundamental level the principle is flawed, both due to the DS nature and the fact that for the claimed dynamic range and bandwidth the required dither would overload the modulator.

This is generally shown by the simple observation that most (all? - but I have not measured all) SACD Players have a rising noisefloor in the audio range and by 20KHz have only comparable SNR to CD. While I am not in general a fan of adding dither, in principle CD can achieve a similar result using suitably noiseshaped dither during the mastering.

I suspect "pure" SACD primarily sound better than their PCM counterparts because editing and applying effects to DSD is even now not well and widely supported, compared to the proliferation of such tools in the "PCM Universe", where so many dynamic range and other effects are now routinely applied that to my "old skool analogue minimalist recording" ears even recordings that are by todays standards nearly untouched sound sound over-produced and overcooked.
SACD has the fame of being airy and sweet, which i correlate to lots of HF material (and a great deal of distortion up there), plus the typical "sweetness" of S-D.
BUT often the SACD recordings are mastered much better than the equivalent CD layer -another important factor why many audiophiles says that it sounds better

Quote:
THAT SAID, really good CD-Recordings using really high grade CD-Replay, to my ears at least (and as I demonstrated in the early 2K's at a few London HiFi Shows to many others) can achieve the same or greater subjective sound quality as that offered by SACD.
JVC "24 bit" ones for instance are amazing.
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Old 12th April 2012, 03:16 PM   #295
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Below, is the link to a rather interesting hobbyist review comparing the Lamipzator DAC level-4 to the Metrum Octave.

The Audio Eagle - DAC_Comparison / Does Digital Finally Rock?
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Old 12th April 2012, 04:31 PM   #296
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You are talking smak about SACD just to feel good about yourself? "Lots of HF noise"? Did you ever listen to a SACD? There is no audible noise present in audio band, the sounds come from a dark background, the noise at 20kHz is some -110dB. If you average the noise with "A" curve you get something lower than that. CD can only dream of -96dB at digital zero (not using "mute").
Sure, some SACD are not native DSD recordings and I can easily spot the ones that are PCM-based. Usuall are releases of old albums or live concerts.
This is a real-live (Sony SCD-1) SACD player noise spectrum:
Click the image to open in full size.

Last edited by SoNic_real_one; 12th April 2012 at 04:44 PM.
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Old 12th April 2012, 05:01 PM   #297
jitter is offline jitter  Netherlands
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Quote:
Originally Posted by jitter View Post
I found out that with Cool Edit you can edit individual samples, so I should be able to eliminate the ringing that occurred during the recording-stage. Cool indeed. Later today I will give it a go...

No doubt the Octave will show the difference, but I'm curious it if has any effect on the OS DAC. Will ringing be less? Anyone care to speculate?
Here are the measurements with the ringing removed from the impulse.

While I was editing the samples, Cool Edit already "predicted" what the impulse would look like on a traditional DAC. As you can see in the first pic, the ringing is shorter in length (time) but higher in amplitude. This, shorter but stronger ringing shows in the measurements from the PDR-555RW, but not from the DAC1. The signal from the Octave confirms that the ringing was indeed removed from the recording.

@Ken Newton, comparing these measurements with my previous impulse measurements with the ADC ringing still present (post 282), I'm beginning to think that those formed during the DA-conversion overshadow those from the AD-conversion. I'm even thinking that, with the ones from the AD-conversion still present, ringing is actually slightly less severe. Wether they interact or not is hard to tell from the measurements.

From left to right:
-Waveform in Cool Edit predicts ringing analogue domain after OS DA-conversion despite removal of ringing from AD-conversion;
- Octave, 44.1 kHz, confirms removal of ringing;
- DAC1, 44.1 kHz, only DAC-ringing;
- PDR-555RW, 44.1 kHz, only DAC-ringing.
Attached Images
File Type: gif Image1.gif (16.8 KB, 169 views)
File Type: gif oct_editedimp_44k..gif (4.5 KB, 167 views)
File Type: gif dac1_editedimp_44k..gif (4.8 KB, 166 views)
File Type: gif 555_editedimp_44k..gif (4.9 KB, 164 views)

Last edited by jitter; 12th April 2012 at 05:11 PM.
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Old 12th April 2012, 05:58 PM   #298
qusp is offline qusp  Australia
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yes I do realise its a compounding effect, I presume due to some equivalent of a moire pattern in the time domain
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Old 12th April 2012, 08:03 PM   #299
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Quote:
Originally Posted by jitter View Post
Here are the measurements with the ringing removed from the impulse.

@Ken Newton, comparing these measurements with my previous impulse measurements with the ADC ringing still present (post 282), I'm beginning to think that those formed during the DA-conversion overshadow those from the AD-conversion. I'm even thinking that, with the ones from the AD-conversion still present, ringing is actually slightly less severe. Wether they interact or not is hard to tell from the measurements.
Thanks, for taking the time to conduct and show these graphs. I can see what you are suggesting about the ADC sinc response maybe not being nearly as important as the DAC filter. However, it appears that a proper DAC apodising filter produces a subjective sound quality which is very similar to what one hears via NOS. Keep in mind that a 'brick wall' apodising DAC filter produces the same amount of impulse repsonse ringing during playback as any other 'brick wall' filter. The only difference is where the stop-band rejection begins. This is intriuguing. It probably should be said that a filter doen't HAVE to be minimum phase in order to remove the ADC sinc filter response. It could just as well be a linear phase apodising filter.
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Old 12th April 2012, 08:25 PM   #300
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Hi,

Quote:
Originally Posted by SoNic_real_one View Post
You are talking smak about SACD just to feel good about yourself?
Whoever you directed this remark at aside, it is seriously out of order. Not that it matters though, but please refer to the forum rules.

Now let's get on with facts instead of discussing rude boyz lingo.

Quote:
Originally Posted by SoNic_real_one View Post
"Lots of HF noise"? Did you ever listen to a SACD? There is no audible noise present in audio band, the sounds come from a dark background, the noise at 20kHz is some -110dB. If you average the noise with "A" curve you get something lower than that. CD can only dream of -96dB at digital zero (not using "mute").
Well, well well.

Incidentally, CD does not have to dream 'of -96dB at digital zero (not using "mute")' (BTW, hint, the correct technical term to use is digital silence). It actually easily exceeds this, if DAC's with 16 Bit equivalent performance (such as the TDA1541A and other similar ones) are used. For example the TDA1541 is rated as -110dB noise with digital silence. The noisefloor is much increased by the 16-Bit quantisation noise if for example a -90dBFS signal is applied.

But, how about we instead compare SACD and CD with some signal, shall we (after all, no-one listens to digital silence, well, no-one I know anyway)?

Here the graph from the same test set at stereophile you appropriated yours from:

Click the image to open in full size.

I do not wish to to be rude, but looking at this I though to myself: "W. T. F. is THAT!?"

The first thing we observe is that there is actually more HF-Noise (HF here used in the technical sense of "High Frequency" as compared to AF which means "Audio Frequency") than there is signal. At least I personally would call that "Lots of HF noise"...

What you should really see is the same plot at 0dBfs. A beaut, 10dB more HF-Noise than actual signal! I know a fair few Amplifiers that will not be very comfortable with such a signal. In fact almost any Solid State Class AB Amplifier is going to have a hissy fit if you feed it THAT kind of signal. My own Amp's actually would not mind, but that is another story.

Another way would be to call all this HF stuff "200% added HF distortion". Of course, added HF distortion of as much as 30% is the very crime that "Non-OS" DAC's are routinely charged with...

The second thing we observe is the shape of the -60dB Peak, which is smeared all over so that -100dB it already covers well over two octaves. I like to call the cause of what this this graph shows "Fuzzy Distortion" (as opposed to the distinctly separate phenomena of jitter) and it is indeed inherent to the use of a 128 Level at 44.1KHz (that is a system that without noise-shaping is equivalent to 7 Bits sampled at 44.1KHz).

To be honest, any PCM System that measured like what is shown above I would consider "defective by design". Of course, it is not "revoltingly bad PCM" but instead "Super Audio CD", so it has to be good, after all it SO SUPER compared to CD with it's 16-Bit's at 44.1KHz and anyway, what is a 9dB shortfall among friends?

Let us compare this with a "State Of The Art" result for CD standard PCM, that is state of the art in 1989, in the form of the TDA1541 equipped Philips LHH-1000 (which is incidentally one of my references):

Click the image to open in full size.

While this shows -90dBFs, the noisefloor of this system does not change with signal levels above 1LSB, we can see it offers around 6dB improvement over SACD at 20KHz. Moreover, we would find a much, much narrower peak at -60dB than with SACD,

This should actually not surprise anyone who understand a minimum about digital audio.

As for why do some people prefer the sound of SACD? No idea*.

Ciao T

* If one was rude and witty, one may, hypothetically speaking, be tempted to suggest that they have not been talking, what was mentioned earlier, but instead have been taking it. But that would be rude and against the rules.
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