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Review and Measurements of Empirical Audio Synchro-Mesh

Empirical Audio

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I also want to talk about J-Test here. I'm not a fan. The reason? It's a signal only, not a jittery source. It was designed to "stimulate" jitter in the source device or the receiving device.

In the other thread, a test was cited where they used a transport to play the J-Test file. If the track stimulates jitter, how do we know how much jitter is created? Every source that plays the J-test track will "stimulate" different levels of actual jitter in that source device. Different amplitudes and different spectra. The jitter source will be different every time.

What we need instead is a jitter STANDARD. A device that outputs a signal with a fixed set of jitter characteristics or maybe even more than one: low frequencies, high-frequencies, correlated, non-correlated etc.. Each of these selectable. With this tool, one could actually determine what jitter rejection a device exhibits.
 

SIY

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I also want to talk about J-Test here. I'm not a fan. The reason? It's a signal only...

Everything is a "signal only." Perhaps you could give a technical critique of Julian Dunn's peer-reviewed paper instead of a hand-wave? Preferably including experimental data? I'd be interested in an analysis to see if what you're claiming has any merit.
 
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amirm

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I also want to talk about J-Test here. I'm not a fan. The reason? It's a signal only, not a jittery source. It was designed to "stimulate" jitter in the source device or the receiving device.
No digital source file ever can have jitter added to it as jitter is an analog thing that can't exit in the file. J-test however, was designed to a) have no dither so that the noise floor is exceptionally low as shown in my measurement and b) toggles all the bits on and off on frequent basis. The latter for S/PDIF can show jitter induced on the cable more than other test signals. Indirectly, the toggling of the bits causes more correlated noise on the power supply so can show internally generated noise and jitter.

Regardless, for my tests of Synchro-Mesh I also added jitter in the analyzer so we had both.
 

PierreV

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The thing that we both noticed is that in at least 2 of the tracks, the 8X version sounded more focused. This made it difficult, because the altered track actually sounded better than the original

(...)

I have a theory about this improvement in focus in the 8X tracks:

There you go. If @Blumlein 88 has not patented the process, you have just stumbled upon a new product idea...
 

SIY

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Forensics is all about gathering evidence to get to the facts.

Until then, it might be best in the interests of accuracy not to state "sounds different" as a fact. It is merely an extraordinary claim without any evidentiary support.
 

Empirical Audio

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No digital source file ever can have jitter added to it as jitter is an analog thing that can't exit in the file. J-test however, was designed to a) have no dither so that the noise floor is exceptionally low as shown in my measurement and b) toggles all the bits on and off on frequent basis. The latter for S/PDIF can show jitter induced on the cable more than other test signals. Indirectly, the toggling of the bits causes more correlated noise on the power supply so can show internally generated noise and jitter.

Regardless, for my tests of Synchro-Mesh I also added jitter in the analyzer so we had both.

If you can add this jitter generated by the analyzer to any signal, then this is good, albeit expensive for most of us. What are the characteristics of this added jitter and can you change them?
 

Empirical Audio

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Ok it's snarky. However if judgement by ear in some cases chooses a known lower Fidelity file what's that mean for ear based judgement? A minimum it means ears are inadequate for technical accuracy.

I agree. One needs both trained ears using a resolving system and measurements. I would argue that "technical accuracy" is not yet properly defined, being based on actual human hearing correlation. This is the real definition of "lower fidelity". Only the human ear can make that judgement. If jitter is much more significant to the human ear than the effects of this A/D-D/A, then this changes the definition of fidelity and it should change the definition of technical accuracy, Accuracy for the sake of accuracy only and not correlating to hearing is tilting at windmills.
 
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svart-hvitt

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I think the only hope for super clocks to survive as a means of improving sound (different and/or better/worse) is competently arranged DBTs.

Otherwise, in absence of any technical evidence, ASR should take a clear stance with regard to Empirical, Mutec, Grimm, Antelope and other producers of super clocks.
 

Empirical Audio

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Those are valid points. Though, if you can argue (correctly) that the higher noise is too low to be audible, I can argue (presumably correctly), that at below -110dB, the widening of the tone at the base is also inaudible, as are the sideband tones “hugging” the main tone.

I wanted to clarify my response to this. I think one thing that would have been valuable (maybe it still can be done by Amir), is to zoom in on the lower part of the tone spike in the plots to see if the Synchro-Mesh spike is thinner than the Gustard spike. I suspect that this will be the case at much higher levels than -110dB.
 

Empirical Audio

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I think the only hope for super clocks to survive as a means of improving sound (different and/or better/worse) is competently arranged DBTs.

Otherwise, in absence of any technical evidence, ASR should take a clear stance with regard to Empirical, Mutec, Grimm, Antelope and other producers of super clocks.

These same jitter-lowering circuits are often now used inside the DAC, so this technology needs to improve over time.

The main heartburn that I have with using jitter-reduction inside the DAC is that the benefits of lower and lower jitter sources will not be realized. All DAC manufacturers are not equal when it comes to jitter reduction, so you are stuck with the sound of that DAC and it's jitter and nothing you can do to improve it, short of mod it.
 

sergeauckland

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I think the only hope for super clocks to survive as a means of improving sound (different and/or better/worse) is competently arranged DBTs.

Otherwise, in absence of any technical evidence, ASR should take a clear stance with regard to Empirical, Mutec, Grimm, Antelope and other producers of super clocks.
Or note that in engineered DACs, the analog output doesn't show any issues with jitter at any level even vaguely near audible.

Not good for FUD, but great for consumers.
Exactly. There's no evidence whatsoever (only anecdote) that any of this is audible, or has been for a long time. What happens at -110dB is of zero interest audibly. I can understand chip manufacturers, and therefore equipment manufacturers, being interested in better and better numbers, but that's all they are, numbers that have no relevance to anything audible, however 'revealing' one's system is.


S.
 
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amirm

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If you can add this jitter generated by the analyzer to any signal, then this is good, albeit expensive for most of us. What are the characteristics of this added jitter and can you change them?
I added sinusoidal jitter to my measurements in the review. You can set the frequency of that jitter sine wave up to 200 kHz (again, I showed that in the measurements). Amplitude can be up to 1.6 microseconds.

In addition to sine wave, the jitter spectrum can be square wave and noise.
 
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amirm

amirm

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There could be a case for his synchro-mesh unit, one where audiophiles own older, previously high performing, expensive 32-48KHz standalone 16-18 bit D/As from the RBCD transport/dac era.
This device has a fixed 96 kHz output so you can't use it with such DACs.
 

restorer-john

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That was not their very first separate converter, though the first was paired with a complete CD player with a digital output as the transport.
I bought one and used it for years.

Ah the cool DAS-702es or the 703es? I'd forgotten about that. They were interesting alright. Sony pairing D/A equipped CD players with a matching but separate D/As. Didn't makea lot of sense to me. The later 703 used the Philips TDA-1541. Strange period where Sony was using Philips' D/As while they waited for the BB PCM-58 and their own PWM converters.

What happened to the transport? I hope you still have it- it can be resurrected.
 
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