Lavry Engineering Paper on Hi-Res

[Mark Powell]

One of his basic points, near the beginning, is that you don't get anywhere near a 24-bit word length due to inherent inaccuracies until you have a sample rate as low as 50-60 Hz.

 

But several people here are totally ignoring this and talking abou 24/192.

 

So do you think he is just plain wrong on this?

 

[Mark Powell]

Your quoted 'consumer sound card' may well claim 24/192. But it is the accuracy that it important, surely? Encoding inaccurately at 24/192 really means that some, we don't know how many, of the least significant bita are inaccurate. From Lavry's "24 bit when we approach 50-60Hz" I would make a guess, and say half of them. So we have 12 bit accuracy at 192K. Whatever, it wil be a lot less than 24 accurate bits.

 

Re his other figures, ignore his 100MHz figure, that's too high to concern us. But 24 bit at 50Hz, and whatever he said (can't remember, say 12) at 1MHz still leaves us with way less than 24 bit accuracy at 192K.

 

Manufactures, and studio people, can say what they like, such as 24/192, and the manufacturers may be correct. I have no doubt they do sample at 192K at take measurements at a depth of 24 bits, but without telling us how many of those bits are accurate it is meaningless. The 'studio' guys just read the manufacturers numbers, same as we do.

 

And yes, of course, as time moves on these things will become more accurate. But as no one discloses how accurate they are now, we are left with 'more accurate than what?'

 

Just some thoughts, I am not disagreeing with what you or anyone says.

 

[Mark Powell]

The two, quite expensive, ones I have heard sound bl**dy awful! One was an Arcam FM tuner, can't remember who made the other.

 

[Mark Powell]

I'm sorry, but I must come back on this.

 

"20 bit accuracy at 50-60Hz" is clear enough. "Near 16 bit accuracy at 1MHz" is also clear.

 

So let's accept, say, 17 or 18 at 192K. Whatever, it aint 24, like many manufacturers claim. Sure they measure it, but their last 6 or 7 bits are worthless. Assuming Lavry is right, of course.

 

Maybe they know they are worthless, and that lets them 'justify' their digital volume controls

 

[Mark Powell]

Listening is what counts. But too many people are just number chasing, without even considering what it actually means. They read 24/192 in the advertisement or on the box and just believe it, despite Lavry's paper saying the two together are currently impossible. Sample as deep as you like and as fast as you like, but don't necessarily believe the values you get.

 

It is like a digital clock. It says 10:24. But I bet it is not accurate to four digits. It might well actually be 10:19, and making it read 10:24:46 does not make it any more accurate.

 

[Mark Powell]

And if that suddenly reads wrong we have got a whole lot more to worry about than sample rates

 

[Mark Powell]

I don't think it is negative at all. It is just true. Of course, that is assuming Lavry is right (which he may not be) in saying you can't have a bit depth of 24, with true 24-bit accuracy, and 192K sample rate at the same time.

 

You tell us whether he is right or wrong. You should know, you make a DAC. Can you have 24-bit accuracy at 192K or not? Or is it like my clock analogy, reading 10:24:46 when it is actually 10:19?

 

Or are we all to just nod our heads in agreement with all these DAC claims and just give them our money? Is that what 'being positive' has to be?

 

[Mark Powell]

Here in the UK a Naim preamp with a tube power amp is a quite favoured combination, if a little unusual. There seems to be some kind of synergy. You may have some doubts about the McIntosh (which replaced a Naim NAP250) but Naim gear is the equal of anything on the market, though my preamp is not their top one by any means.

 

Tube amps are not all blurry, you know.

 

[Mark Powell]

Lavry talks of 'near 24-bit at 50-60Hz' So it will be lower at 192K.

 

I have already asked PeterSt, who makes DACs, whether it is possible today or not.

 

[Mark Powell]

So you like tubes after all, 'low rssolution' included

 

Not that this 'resolution' means anything. To misquote Jud, "Who ever comes out of a live concert praising the 'resolution'?"

 

[Mark Powell]

67 years have made me think the worst of many things. Like our local member of parliament, who has just been caught for telling the police that his ex-wife was driving when he had an accident. Not even a serious accident, but lying to the court is very serious. And he was a government minister. Now he is a government ex-minister

 

And the cheap binoculars, advertised as 'See fifteen miles'. I can see the Andromeda Galaxy, two and a half million light years away, without any binoculars at all. Not during the daytime of course

 

So I'm cynical.

 

[Mark Powell]

Where do I apply?

 

You can put the secretary in the car, then the car in the garage. That will not need so much space as keeping them separate

 

[Mark Powell]

28000 miles

 

Thank you for giving me the biggrst laugh I have had all day!