[[email protected]]

http://www.youtube.com/watch?v=9ZbME...elated&search=

Any comments?

[Arny Krueger]

"Mike Rivers" wrote in message
oups.com...

I would expect that a D/A converter challenge would involve listening,
and that in order for any listening to be valid, it would have to be
through a D/A converter better than any involved in the challenge.

If you do a straight wire bypass test of a D/A converter with analog in,
analog out, then you need only the converter under test. However you will
need a suitable analog source and analog-input monitoring system.

[Scott Dorsey]

In article .com,
wrote:
http://www.youtube.com/watch?v=9ZbME...elated&search=

Any comments?

I'm not sure I understand what the "challenge" is. I see some of the
worst camerwork ever, with a fellow looking at clock waveforms on a
dated but serviceable Tek 7804. No audio, and the camera operator
seems to be having some kind of epileptic seizure.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mike Rivers]

On Oct 19, 10:36 am, (Scott Dorsey) wrote:

I'm not sure I understand what the "challenge" is. I see some of the
worst camerwork ever, with a fellow looking at clock waveforms on a
dated but serviceable Tek 7804. No audio, and the camera operator
seems to be having some kind of epileptic seizure.

Maybe the challenge is to make some sense out of that. People have a
lot of strange ideas about what's wrong with digital devices, mostly
based on the concept that digital audio has steps.

There's someone on the Mackie forum who's looking at the spectrum
analysis display of a Mackie audio interface using one of those
"loopback" test programs, seeing a third harmonic at about -96 dBFS
and claiming that it has "16-bit" distortion. He started his
explanation of how he got to the 16-bit number by extrapolating from a
"2-bit square wave" that had the requisite full set of harmonics. Of
course he'd get the same thing from a 24-bit square wave.

Then I saw his web site selling a high resolution clock generator that
makes anything sound better.

[Richard Crowley]

wrote ...
http://www.youtube.com/watch?v=9ZbME...elated&search=

Any comments?

In the absence of any context, the content is useless.

Perhaps this is just a social experiment to see how many
people can be duped into watching a pointless 2-minute
YouTube video. (Acknowledging the risk of using the words
"pointless" and "YouTube" as being possibly redundant. :-)

[hank alrich]

Mike Rivers wrote:

On Oct 19, 10:36 am, (Scott Dorsey) wrote:

I'm not sure I understand what the "challenge" is. I see some of the
worst camerwork ever, with a fellow looking at clock waveforms on a
dated but serviceable Tek 7804. No audio, and the camera operator
seems to be having some kind of epileptic seizure.

Maybe the challenge is to make some sense out of that. People have a
lot of strange ideas about what's wrong with digital devices, mostly
based on the concept that digital audio has steps.

There's someone on the Mackie forum who's looking at the spectrum
analysis display of a Mackie audio interface using one of those
"loopback" test programs, seeing a third harmonic at about -96 dBFS
and claiming that it has "16-bit" distortion. He started his
explanation of how he got to the 16-bit number by extrapolating from a
"2-bit square wave" that had the requisite full set of harmonics. Of
course he'd get the same thing from a 24-bit square wave.

Then I saw his web site selling a high resolution clock generator that
makes anything sound better.

This might help:

http://www.bswatch.com/

--
ha
Iraq is Arabic for Vietnam

[[email protected]]

You guys apparantly missed the text that unfurls when you click 'more'
on the descriptor. Remember, I'm just pointing this out, I didn't
originate it. I have a Lavry DAC, and I think it sounds quite good.
This dude is claiming something about how the sample rate delivered to
the DAC chip doesn't change at all when changing from 'wide' lock mode
to 'crystal lock', indicating asynchronous sample rate conversion is
taking place. How this results in "operation contrary to the
manufacturer's claims" I don't get. I was hoping one of you could
shed some light. A scope certainly isn't the best device to make very
precise frequency measurements.

Sean B

[Mike Rivers]

On Oct 20, 2:38 am, wrote:

This dude is claiming something about how the sample rate delivered to
the DAC chip doesn't change at all when changing from 'wide' lock mode
to 'crystal lock', indicating asynchronous sample rate conversion is
taking place. How this results in "operation contrary to the
manufacturer's claims" I don't get.

People who don't understand how equipment is designed make all sorts
of nutty claims. How does he know what the sample rate delivered to
the DAC chip is? And why should it change? I believe that the
difference between the two PLL lock modes isn't about sample rate
conversion, it's about jitter. He should sit down and talk with Dan
Lavry at the next AES show.

[Richard Crowley]

wrote ...
You guys apparantly missed the text that unfurls when you click 'more'
on the descriptor.

It would have been helpful to mention that in you original
posting. There are actually some of us who have better things
to do with our time than hang around on YouTube.

Remember, I'm just pointing this out, I didn't
originate it. I have a Lavry DAC, and I think it sounds quite good.
This dude is claiming something about how the sample rate delivered to
the DAC chip doesn't change at all when changing from 'wide' lock mode
to 'crystal lock', indicating asynchronous sample rate conversion is
taking place. How this results in "operation contrary to the
manufacturer's claims" I don't get. I was hoping one of you could
shed some light. A scope certainly isn't the best device to make very
precise frequency measurements.

The scope is likely no worse than any other ordinary bench
method of measuring frequency. There is certinaly better
equipment available in a calibration lab, but not clear that
that is the point? Also not clear that "precise frequency
measurements" is even what is needed here or what may be
"important" to their "argument". Also not clear that they are
even observing or measuring the correct point in the circuit.

The whole exercise seemes of dubious importance, questionable
practice, and unworthy of further discussion, IMHO.

[hank alrich]

Mike Rivers wrote:

On Oct 20, 2:38 am, wrote:

This dude is claiming something about how the sample rate delivered to
the DAC chip doesn't change at all when changing from 'wide' lock mode
to 'crystal lock', indicating asynchronous sample rate conversion is
taking place. How this results in "operation contrary to the
manufacturer's claims" I don't get.

People who don't understand how equipment is designed make all sorts
of nutty claims. How does he know what the sample rate delivered to
the DAC chip is? And why should it change? I believe that the
difference between the two PLL lock modes isn't about sample rate
conversion, it's about jitter. He should sit down and talk with Dan
Lavry at the next AES show.

Please, spare Dan that conversation! G

--
ha
Iraq is Arabic for Vietnam

[[email protected]]

Wow, I was hoping some to stimulate some interesting conversation and
gain a little insight, not stumble on a crab convention. Never mind.

SB

[Scott Dorsey]

wrote:
You guys apparantly missed the text that unfurls when you click 'more'
on the descriptor. Remember, I'm just pointing this out, I didn't
originate it.

Ahh! Okay, that's the last thing I would have done....

I have a Lavry DAC, and I think it sounds quite good.
This dude is claiming something about how the sample rate delivered to
the DAC chip doesn't change at all when changing from 'wide' lock mode
to 'crystal lock', indicating asynchronous sample rate conversion is
taking place. How this results in "operation contrary to the
manufacturer's claims" I don't get.

It doesn't.

If you're locked from a reference clock, the rate may be SLIGHTLY different
than if you're locked from the incoming data clock, but it will only need to
be a few parts per million off to cause clocking errors.

You are not going to see any difference whatsoever on a 7804. You will
probably see a difference on a rubidium-standard frequency counter, though.

I was hoping one of you could
shed some light. A scope certainly isn't the best device to make very
precise frequency measurements.

A scope is a wonderful tool for making gross qualitative measurements,
but if you are looking for miniscule differences in clock rates you
are probably not going to find it with a scope.

And if you ARE going to find it with a scope, you'll find it by creating
a lissajous pattern with the two clocks, not making swept-horizontal
measurements.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Richard Crowley]

wrote ...
Wow, I was hoping some to stimulate some interesting conversation and
gain a little insight, not stumble on a crab convention. Never mind.

If you just want useless discussion about a silly premise,
suggest trying over at news:rec.audio.opinion
But don't get your hopes up for any "insight".

[Arny Krueger]

wrote in message
oups.com...

You guys apparantly missed the text that unfurls when you click 'more'
on the descriptor.

Can we just buy him a cheap microphone and let him make the video over
again, this time in a sensible way?

Of course he's probably using a camcorder which has a mic.

So what's his point - that he's figured out how to post video without audio?

Pretty cool, an audio demo with no audio when there easily can be and should
be.

Are we in the Twilight Zone? ;-)

Remember, I'm just pointing this out, I didn't
originate it.

Well, that improves my opinion of you! ;-)

I have a Lavry DAC, and I think it sounds quite good.

Well, yeah! ;-)

This dude is claiming something about how the sample rate delivered to
the DAC chip doesn't change at all when changing from 'wide' lock mode
to 'crystal lock', indicating asynchronous sample rate conversion is
taking place.

His alleged test is full of holes.

What I get is that may be using one of them new-age fancy o'scopes that has
an on-screen frequency counter display.

It says 117.181 regardless of some switch setting.

Or maybe the photography is so bad that I can't really read the counter
reading off the screen accurately enough to be useful.

I'd like a few more digits displayed, but as I point out below, his method
is unecessarily complex.

How this results in "operation contrary to the manufacturer's claims"

There is no guarantee that he's probing something that is ever at exactly
the word clock frequency. After all, if he's as good of a technican as he
is a commercial maker... ;-)

Besides, when a DAC is processing a SPDIF signal, the DAC's clock should be
exactly the same frequency in any mode that results in an output signal. The
DAC clock frequency should exactly correspond to the clock frequency implied
by the SPDIF signal.

If there is a question about the clock frequency of an ADC, just convert a
test signal with a very precisely known frequency that is within the range
of the ADC. If the ADC clock is wrong, then you can determine it by
analyzing the digitized signal using standard DAW software.

No test equipment is required other than the signal source, which can be as
simple as a CD player playing a test CD you made with standard DAW software.
OK, there will be some slight ambiguity because of slight variations in the
clock in the CD player, but it will be well within the range of variations
that make no audible difference.

So his whole demo is unecessarily complex, in addition to being impossibly
badly made.

Is he trying to sell something? If so, I wouldn't buy it on a dare because
he isn't even a competent technical sales guy, let alone a competent design
engineer.

I don't get.

There may be nothing of merit to get! ;-)

I was hoping one of you could
shed some light. A scope certainly isn't the best device to make very
precise frequency measurements.

I think he used a scope with a frequency counter plug-in. If the video were
worth squat, we might be able to figure that out from what we could make out
from the video.

[hank alrich]

wrote:

Wow, I was hoping some to stimulate some interesting conversation and
gain a little insight, not stumble on a crab convention. Never mind.

SB

We're not here to talk about ghosts. Try something real.

Idiots abound; you found on online talking about Lavry. What is the
sound of a ghost talking out its ass? Oh, wait, there's no audio...

--
ha
Iraq is Arabic for Vietnam