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ESS claim DAC pushes the boundaries of audio science, They claim results are supported by blind testing
wakibaki
post Jan 23 2013, 04:23
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Apologies if this topic has been posted previously, I did a search but found nothing.

http://www.youtube.com/watch?feature=playe...p;v=1CkyrDIGzOE

The above link shows a youtube video of an ESS presentation at RMAF.

Granted it is a sales presentation, it details advances ESS claim in the design of their sigma-delta DACs.

Foremost in the claims is the fact that some people can evidently hear features well below the noise floor which were previously held by the majority of engineers to be inaudible. This is said to be confirmed in blind testing.

Large changes in the values of variables in the state space are said to contribute to non-periodic steady-state noise normally invisible using conventional measurement techniques. This is visible when instrumentation is used to examine the Noise-vs-DC Offset.

This is said to be minimized in ESS products by techniques designed to control the state-space related noise by rapidly quenching state variable excursions.

ESS also claim that a further artifact of sigma-delta modulators, variable (non-linear) excess phase, which causes oscillation in S-D modulators, has been eliminated by making their devices unconditionally stable, and that this too contributes to greater acceptance of the devices by some listeners, although the reasons for this are apparently not clearly understood.

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pdq
post Jan 23 2013, 18:54
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I haven't watched the video, but if the DBT that you refer to is the claim that we can hear features well below the noise floor, then that is hardly news. Human hearing is like a Fourier transform, allowing us to selectively hear certain frequency ranges in the presence of higher level noise in other frequency regions.

Similarly, if the total noise of a DAC is, say -96 dB, a spectrum analysis will show far lower noise as a function of frequency, depending on the chosen bandwidth. This is true of any modern DAC, including the one from ESS.

I would be much more interested if a third party had done a careful, level matched DBT that showed a difference.
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Dynamic
post Jan 23 2013, 20:10
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pdq, it wasn't all about hearing below -96 dB - he mentioned why that is, and the guy seemed to know his stuff and explain a lot of it pretty well to a lay audience, partly by analogy. He also had a decent enough analogy of noise shaping (error-diffusion type of idea) to get the idea across.

It seemed to be about some type of variation in the quantization noise spectrum and amplitude spikes within it as DC level offset slowly adjusts or as you switch from say a 1kHz tone to a 20kHz tone, which the sigma-delta modulators tended to slowly converge upon with an unstable type of feedback loop. There's something plausible there, and it could well be that they've made it inaudible if it was audible before. It's not clear which components they're comparing and the exact nature of the blind tests, but they claimed that different features in their FPGA could be turned on or off, allowing them to select 5 features to control 5 states (modelling it as a state machine), the last of which apparently made it a match for a linear DAC in the blind testing.

There was a 3D plot of their device pictured as a state machine (they couldn't plot all 5 dimensions they controlled for) which seemed to show it tighly constrained, while the device without their magic had a more unconstrained chaotic pattern in the mysterious parameters, and there were spectral plots showing spikes in the noise floor presumably of their modulator without their FPGA's features enabled (or maybe an unnamed competitor's SDM) and a clean spectrum with it enabled. These were at a plausible level for a 16-bit signal with small amounts of inadequate dither to become potentially audibly degraded by quantization noise in the presence of a -30dB test tone, though they ought to be rather well masked in real music, examples of which included an old Frank Sinatra track, an un-named piece and a modern recording where a shaker is used, which somehow it supposed to reveal the difference. The guy claimed that their measurements would get them in the door at the consumer companies, this 3D plot would really pique interest, and the companies would only decide when their 'golden-ear' audiophile gave it the thumbs up.

It all has a mixture of an air of plausibility and reasonableness in the presenter, and a mix of test & measurement plots and computer modelling plots, combined with the secrecy and lack of detail and transparency that leads one to have enough suspicion that it could all just be a blind-them-with-science marketing approach with some superficially plausible theory behind it.

The best approach to truly demonstrate the truth of their claims to skeptical listeners at a conference like that would probably be to provide a digital sound clip and a digital zero source generated on the same clock, two or more DACs with analogue outputs level-matched in a low-noise summing amplifier sent to a single headphone amplifier and a set of high-grade headphones, and send the non-zero digital signal to one DAC or the other DAC one at a time, while the other DAC receives zero, under computer control to provide A/B/X comparisons (potentially with software very much like the software ABX comparators we use here, allowing the choice of a specific revealing part of the clip, such as this shaker). There might need to be time-alignment of the two channels also if switching is allowed during playback.


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Posts in this topic
- wakibaki   ESS claim DAC pushes the boundaries of audio science   Jan 23 2013, 04:23
- - saratoga   DACs were a solved problem ten years ago so I...   Jan 23 2013, 05:28
- - phofman   The claim would have been much more credible if th...   Jan 23 2013, 08:13
|- - wakibaki   QUOTE (phofman @ Jan 23 2013, 07:13) The ...   Jan 23 2013, 18:36
- - pdq   I haven't watched the video, but if the DBT th...   Jan 23 2013, 18:54
|- - Dynamic   pdq, it wasn't all about hearing below -96 dB ...   Jan 23 2013, 20:10
- - Dynamic   There's some plausible stuff in there, but the...   Jan 23 2013, 19:22
- - Willakan   During the presentation on jitter, the ESS guy als...   Jan 23 2013, 20:40
|- - Banned   QUOTE (Willakan @ Jan 23 2013, 21:40) Dur...   Jan 23 2013, 21:01
- - wakibaki   One of the 'golden ear' claims that has be...   Jan 23 2013, 21:04
|- - db1989   QUOTE (wakibaki @ Jan 23 2013, 20:04) Ult...   Jan 23 2013, 21:25
|- - Dynamic   QUOTE (wakibaki @ Jan 23 2013, 20:04) Ult...   Jan 23 2013, 21:49
|- - Arnold B. Krueger   QUOTE (wakibaki @ Jan 23 2013, 15:04) ESS...   Jan 24 2013, 14:12
- - Dynamic   I think inter-aural timing differences under 1ms c...   Jan 23 2013, 21:13
- - greynol   Until positive DBT results can be repeated by an i...   Jan 23 2013, 21:38
|- - wakibaki   QUOTE (greynol @ Jan 23 2013, 20:38) Unti...   Jan 23 2013, 23:14
|- - greynol   QUOTE (wakibaki @ Jan 23 2013, 14:14) If ...   Jan 23 2013, 23:25
||- - wakibaki   QUOTE (greynol @ Jan 23 2013, 22:25) Fall...   Jan 24 2013, 02:09
||- - pdq   QUOTE (wakibaki @ Jan 23 2013, 20:09) No,...   Jan 24 2013, 03:06
||- - Nessuno   QUOTE (pdq @ Jan 24 2013, 03:06) Last I k...   Jan 24 2013, 18:00
|- - saratoga   QUOTE (wakibaki @ Jan 23 2013, 17:14) If ...   Jan 24 2013, 02:56
- - Willakan   Pretty impressive typo in my earlier post: I meant...   Jan 23 2013, 22:36
- - greynol   Funny how it is you who gets to rely on words like...   Jan 24 2013, 02:46
- - greynol   ...until it is disproved that the Flying Spaghetti...   Jan 24 2013, 03:06
- - Arnold B. Krueger   QUOTE (wakibaki @ Jan 22 2013, 22:23) Apo...   Jan 24 2013, 14:28
|- - 2Bdecided   QUOTE (Arnold B. Krueger @ Jan 24 2013, 13...   Jan 24 2013, 18:50
|- - dhromed   QUOTE (2Bdecided @ Jan 24 2013, 18:50) so...   Jan 25 2013, 11:50
||- - 2Bdecided   QUOTE (dhromed @ Jan 25 2013, 10:50) I...   Jan 25 2013, 13:56
||- - 2Bdecided   QUOTE (2Bdecided @ Jan 25 2013, 12:56) I ...   Jan 25 2013, 17:59
|||- - Arnold B. Krueger   QUOTE (2Bdecided @ Jan 25 2013, 11:59) QU...   Jan 25 2013, 19:28
|||- - 2Bdecided   QUOTE (Arnold B. Krueger @ Jan 25 2013, 18...   Jan 25 2013, 19:49
||- - dhromed   QUOTE (2Bdecided @ Jan 25 2013, 13:56) QU...   Jan 26 2013, 00:19
|- - Arnold B. Krueger   QUOTE (2Bdecided @ Jan 24 2013, 12:50) QU...   Jan 25 2013, 13:15
|- - 2Bdecided   QUOTE (Arnold B. Krueger @ Jan 25 2013, 12...   Jan 25 2013, 13:53
|- - Arnold B. Krueger   QUOTE (2Bdecided @ Jan 25 2013, 07:53) QU...   Jan 25 2013, 16:35
|- - benski   QUOTE (Arnold B. Krueger @ Jan 25 2013, 11...   Jan 25 2013, 17:24
|- - 2Bdecided   QUOTE (benski @ Jan 25 2013, 16:24) What ...   Jan 25 2013, 17:55
||- - benski   QUOTE (2Bdecided @ Jan 25 2013, 12:55) an...   Jan 25 2013, 18:22
||- - Arnold B. Krueger   QUOTE (benski @ Jan 25 2013, 12:22) QUOTE...   Jan 25 2013, 18:27
||- - 2Bdecided   QUOTE (benski @ Jan 25 2013, 17:22) QUOTE...   Jan 25 2013, 19:44
|- - Arnold B. Krueger   QUOTE (benski @ Jan 25 2013, 11:24) QUOTE...   Jan 25 2013, 18:21
- - Willakan   There's certainly no shortage of contentious c...   Jan 24 2013, 22:28
|- - Hotsoup   QUOTE (Willakan @ Jan 24 2013, 14:28) ......   Jan 24 2013, 22:46
- - 2Bdecided   This one is quite interesting... http://www.youtub...   Jan 25 2013, 11:12
- - Woodinville   Digital will not sound like analog until we start ...   Jan 25 2013, 11:13
- - db1989   If he hasnít had his lunch yet, his blood glucose ...   Jan 25 2013, 18:30
- - 2Bdecided   QUOTE (db1989 @ Jan 25 2013, 17:30) If he...   Jan 25 2013, 19:51


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