Why the preoccupation with jitter? - Page 9

sam9 · 19th February 2005, 09:50 PM

I'm sort of dumb about this but wouldn't the expedient of reclocking the data stream at the the DAC rather than deriving the clocking from upstream resolve the issue. Hence, within reason all manner of indignities can be suiffered by the data stream. How expensive would this be relative to some of the cosmetic features a lot gear have.

Actually, I was told (but can't verify) that some of the mass market (and modestly prices) AVRs do just that. In the quantitiies they build the cost is not great. I assume there can be something audibly amiss at the very low end of the quality spectrum -- why make a perfect DA conversion for something that's going to played through B_ _ _ system.

Of more interest to me is the question of what is the relative performance quality in the middle to higher end products. For instance, my current multi-format disc player costs about US$200 but have be reviewed very (and I mean VERY) highly by several noted "golden-ear" type who are normally unable to recomend anything that isn't priced in round thousands. Yet, nearly all the "fixes" on the market cost more than the unit being fixed.

Jocko Homo · 19th February 2005, 10:03 PM

I can't address that market and what it does, but..........

In the old days of CD players, the clock was part of the filter chip. It was cheaper to add a few extra doo-hickies in the silicon that it would be to stick a separate clock in. It worked, sounded good enough for mass market, and since it was mass market, good enough was more than good enough.

With external D/A boxes, it is another, more nasty, problem. I seriously do not think that they ever expected anyone to use SPDIF, because if they did, why did they conjure up TOSLINK? But, it worked, and good enough is good enough. Discussions of jitter problems here are a different matter than in system that does not have a PLL recovered clock.

Only a relatively small number of consumers care about this stuff, so there is no incentive for them to do better than "good enough".

We could argue for weeks on whether or not the manufacturers care, how low jitter needs to be, and resolve nothing.

Jocko

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19th February 2005, 09:50 PM	#81
sam9 diyAudio Member Join Date: Jun 2002 Location: Left Coast	I'm sort of dumb about this but wouldn't the expedient of reclocking the data stream at the the DAC rather than deriving the clocking from upstream resolve the issue. Hence, within reason all manner of indignities can be suiffered by the data stream. How expensive would this be relative to some of the cosmetic features a lot gear have. Actually, I was told (but can't verify) that some of the mass market (and modestly prices) AVRs do just that. In the quantitiies they build the cost is not great. I assume there can be something audibly amiss at the very low end of the quality spectrum -- why make a perfect DA conversion for something that's going to played through B_ _ _ system. Of more interest to me is the question of what is the relative performance quality in the middle to higher end products. For instance, my current multi-format disc player costs about US$200 but have be reviewed very (and I mean VERY) highly by several noted "golden-ear" type who are normally unable to recomend anything that isn't priced in round thousands. Yet, nearly all the "fixes" on the market cost more than the unit being fixed.

19th February 2005, 10:03 PM	#82
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	I can't address that market and what it does, but.......... In the old days of CD players, the clock was part of the filter chip. It was cheaper to add a few extra doo-hickies in the silicon that it would be to stick a separate clock in. It worked, sounded good enough for mass market, and since it was mass market, good enough was more than good enough. With external D/A boxes, it is another, more nasty, problem. I seriously do not think that they ever expected anyone to use SPDIF, because if they did, why did they conjure up TOSLINK? But, it worked, and good enough is good enough. Discussions of jitter problems here are a different matter than in system that does not have a PLL recovered clock. Only a relatively small number of consumers care about this stuff, so there is no incentive for them to do better than "good enough". We could argue for weeks on whether or not the manufacturers care, how low jitter needs to be, and resolve nothing. Jocko

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