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A silly magazine filled with misinformation
Old 11th September 2007
  #1
A silly magazine filled with misinformation

I'm not sure how I got on these guys' mail-list: Record-Producer.com


Their latest foray into superficial but fundamentally incorrect information about recording is here:

Why a digital signal is never accurate


I suggest you feel free to write them a comment. They need some wising up.
Old 11th September 2007
  #2
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UnderTow's Avatar
Whoever wrote that article is too chicken to even put their name underneath it. heh

Alistair
Old 11th September 2007
  #3
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dlmorley's Avatar
I guess it is correct if we assume that there is no such thing as infinite resolution. But this applies to ALL recording formats.

I guess they could have just said "NO recording is ever accurate"

There are of course just 2 types of recordings.. good and bad
Old 11th September 2007
  #4
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emkay's Avatar
 

Quote:
Originally Posted by UnderTow View Post
Whoever wrote that article is too chicken to even put their name underneath it. heh

Alistair
I think David Mellor, the editor of the site is the guilty party,,,,,,,,,,,
Old 11th September 2007
  #5
Quote:
Originally Posted by dlmorley View Post
I guess it is correct if we assume that there is no such thing as infinite resolution. But this applies to ALL recording formats.

I guess they could have just said "NO recording is ever accurate"

There are of course just 2 types of recordings.. good and bad
Ditto that.


I was probably a little harsh in my titling of this thread but it's the second or third little mini article I've caught with dubious or misguided information.

It's a good looking publication. Maybe it just needs a little truth-squading.
Old 11th September 2007
  #6
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Ethan Winer's Avatar
 

Lightbulb

Quote:
Originally Posted by theblue1 View Post
superficial but fundamentally incorrect information
No kidding. And not just that article, but most magazine articles and web sites. Bad science is the new conventional wisdom.

--Ethan
Old 24th September 2007
  #7
Here for the gear
 

Response from David Mellor, author of the article

Hi, I'm David Mellor, publisher of Record-Producer.com and author of the article 'Why a digital signal is never accurate'.

I stand by every word of this article. If anyone would like to state clearly where the article is in error, then I would be only too pleased to correct it immediately.

I would however advise that you carefully read Ken C. Pohlman's 'Principles of Digital Audio' and John Watkinson's 'The Art of Digital Audio', or any other reputable tome on digital audio principles first. You will find that they concur with my article in every detail.

I don't plan on commenting further in this thread, so please contact me through the Record-Producer.com website. Your correspondence will receive my full attention.


Record-Producer.com:
Old 24th September 2007
  #8
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Quote:
The web site you are accessing has experienced an unexpected error.
Please contact the website administrator.

The following information is meant for the website developer for debugging purposes. Error Occurred While Processing Request Error Executing Database Query.

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java.sql.SQLException: [Macromedia][SQLServer JDBC Driver][SQLServer]Cannot open database requested in login &apos;davidme_mcdl&apos;. Login fails. at macromedia.jdbc.base.BaseExceptions.createException(Unknown Source) at macromedia.jdbc.base.BaseExceptions.getException(Unknown Source) at macromedia.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source) at macromedia.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source) at macromedia.jdbc.sqlserver.tds.TDSLoginRequest.processReplyToken(Unknown Source) at macromedia.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source) at macromedia.jdbc.sqlserver.SQLServerImplConnection.open(Unknown Source) at macromedia.jdbc.base.BaseConnection.getNewImplConnection(Unknown Source) at macromedia.jdbc.base.BaseConnection.open(Unknown Source) at macromedia.jdbc.base.BaseDriver.connect(Unknown Source) at macromedia.jdbc.MacromediaDriver.connect(Unknown Source) at coldfusion.server.j2ee.sql.pool.JDBCPool.createPhysicalConnection(JDBCPool.java:562) at coldfusion.server.j2ee.sql.pool.ConnectionRunner$RunnableConnection.run(ConnectionRunner.java:67) at java.lang.Thread.run(Unknown Source)



Did someone spit the dummy?
Old 24th September 2007
  #9
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Ethan Winer's Avatar
 

Lightbulb

Quote:
Originally Posted by David Mellor View Post
If anyone would like to state clearly where the article is in error, then I would be only too pleased to correct it immediately.
Actually, I was commenting on magazines and audio advice generally. In fact, I agree with your summary:

Quote:
Having said that, the inaccuracies produced even in CD-quality audio are tiny, and in 24-bit audio they are tinier still. It is worth knowing about, but most people would find it difficult to tell the difference between the raw output of the preamp, and the digitized version.
--Ethan
Old 25th September 2007
  #10
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I can't comment about the rest of the site, but I read the article and I did not see anything that was blatantly wrong (flame suit on).

Then again, I will be the first to admit that I am not an expert in this area.

Can somebody please enlighten me?
Old 25th September 2007
  #11
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Whatever the outcome, David Mellor gets points just for showing up and defending his pub. thumbsup
Old 25th September 2007
  #12
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Quote:
Originally Posted by DAWgEAR View Post
I can't comment about the rest of the site, but I read the article and I did not see anything that was blatantly wrong (flame suit on).

Then again, I will be the first to admit that I am not an expert in this area.

Can somebody please enlighten me?
With a 24 bit converter the errors and noise of the digital conversion is way below the errors and noise introduced by the analog side of the converters.
I'd say it is even below the threshold of human hearing.

The best specs i've ever seen is a dynamic range of 127 dB or so. And the errors of the digital conversion is around -144 dB or so.

So to "blame" the digital conversion is like hooking up an AKG C1000 to a Neve 1084 and blaming the 1084 for the poor quality of the recording.
Old 25th September 2007
  #13
Gear Addict
 

Agree button pushed for KingDaddyO.

David: I find nothing wrong in this article, besides that I can not find what its purpose is:
- If you want to help people improve their digital recording, some more advice would be desirable (I agree on what you wrote about dither though).
- If you want to make a pro-analogue-anti-digital statement, you should clearly state it and face the discussion
- If you (which is most likely and perfectly legitimate) want to advertise for your Audio Masterclass, I'd advise you to get into some more depth to make people really curious.

Anyway, I'll give it a try and read more of your articles.

Generally speaking about audio magazines: I used to be a big fan of them but most recently, I am getting the impression they run out of material. I bought a magazine because they had an article about guitar amp miking, as the headline indicated. When I read the article, I had to find out that they spread information about the function of pickups and amps over several pages (which was well done but not what I expected) and concluded: "And if you want to know how to put a mike in front of the amp, buy the next issue".

Cheers, Thomas
Old 25th September 2007
  #14
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Will's Avatar
 

I know David Mellor, he writes for the European version of Audio Media in the colum (well more like several pages) 'A Sound Persons Guide to Video', or something along those lines.

Never seen the site but always found the articles in Audio Media interesting.
Old 26th September 2007
  #15
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Everybody has an agenda. Magazines want to keep their advertisers happy. David Mellor wants to sell his audio classes. I want to require PT to open AAF and OMF files without charging PT users an extra $500 for the ability to do so. The moderators of this site want to protect religious zealots from posters like me who mock religion with off-color humurous comments (which get deleted.)

Nothing wrong with having an agenda, as long as the agenda isn't being hidden behind some fake pretense.
Old 26th September 2007
  #16
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UnderTow's Avatar
Quote:
Originally Posted by David Mellor View Post
Hi, I'm David Mellor, publisher of Record-Producer.com and author of the article 'Why a digital signal is never accurate'.

I stand by every word of this article. If anyone would like to state clearly where the article is in error, then I would be only too pleased to correct it immediately.
Well you asked so here goes:

Quote:
Originally Posted by www.record-producer.com

Why a digital signal is never accurate
This is a misleading title. Neither analogue nor digital recordings are perfectly accurate. Your title implies that digital recording is less accurate than analogue recording when in reality, the opposite is true.

Even the semantics of the title are incorrect. A digital signal can easily be perfectly accurate. If every 1`and 0 gets transmitted correctly, the signal is accurate. You probably meant "Why is a decoded digital signal never absolutely accurate to the source?". (Or something like that)


Quote:
Originally Posted by www.record-producer.com
The signal that comes from the output of your microphone preamplifier is pure and perfect.
The output of a preamp is never pure nor perfect. There is no such thing as pure and perfect in nature. Starting with this erroneous premise is not a good start for an article.

Quote:
I would however advise that you carefully read Ken C. Pohlman's 'Principles of Digital Audio' and John Watkinson's 'The Art of Digital Audio', or any other reputable tome on digital audio principles first. You will find that they concur with my article in every detail.
I suggest you go and reread those books yourself.

Quote:
Fortunately there are two ways the problem can be lessened.
Your major misunderstanding is that dither is something extra that is added to lessen the flaws of digital sampling. Dither is an integral part of digital sampling. Without it, the system is broken! Your whole article is like saying that cars are flawed because they are so heavy and thus very hard to push around but the problem can be lessened by adding a combustion engine to the car.

Dither linearises the quantae steps of digital sampling thus removing the quantization distortion. In a sense we trade in quantization distortion for noise. But that isn't really accurate either as lack of dither means a broken system.

In practise perfectly random dither is hard to generate so there might be some residual quantization distortion left over. That said, in a good converter, this distortion is many dB below the dither noise let alone below the noise floor of the recording itself (assuming 24 bit converters). In other words, it is a non-issue.

A good 24 bit converter gives you more headroom, less distortion, and a flatter frequency response than any analogue medium. Thus your whole article is misleading and technically flawed.

Quote:
I don't plan on commenting further in this thread, so please contact me through the Record-Producer.com website. Your correspondence will receive my full attention.
People are willing to correct your misunderstandings but we are supposed to come to you?

Alistair
Old 26th September 2007
  #17
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Quote:
Originally Posted by Ethan Winer View Post
Bad science is the new conventional wisdom.

--Ethan

I've no comment on the subject of this thread, but Ethan, as a modern sociological observation, that's a winner. Hilarious, and sadly all too true.





Cheers.

Old 26th September 2007
  #18
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Ethan Winer's Avatar
 

Lightbulb

Quote:
Originally Posted by Empty Planet View Post
I've no comment on the subject of this thread, but Ethan, as a modern sociological observation, that's a winner. Hilarious, and sadly all too true.
One of my favorite stories I love to tell is about my Audio Myths article I wrote in the late 1990s. I had just written an article for one of the major audio mags, which got a lot of good reader feedback, so I proposed writing up my top ten myths. I put together an outline and sent it to the editor. He called me a week later to say the staff had a meeting about my article, and they disputed every one of my points. D'oh!

Fortunately Audio Media had the sense to see the value, and they published it.

--Ethan
Old 26th September 2007
  #19
I agree: props on David for showing up to stick up for his article.

And -- I suppose if we want to get really rabinical with this, sure -- absolutely -- in the real world, no process, analog or digital, will likely ever have absolute perfection.

So, in that sense, sure, there's the fig leaf to hide behind, I guess.


But let's be real, here, huh?

To refresh the institutional memory, here, this is the head of the article:

Quote:
Why a digital signal is never accurate

The signal that comes from the output of your microphone preamplifier is pure and perfect. But as soon as it is converted to digital, something is lost. Why does that happen?
OK...

Let's assume he meant that we've arbitrarily set the output of "our" mic pre as the standard of "pure and perfect" -- elsewise, he's obviously off the mark on square one.

So, we've decided to make the existing output of the pre the standard to which we must hold the digital signal.

The Nyquist-Shannon Theorem is pretty explicit:
Quote:
Exact reconstruction of a continuous-time baseband signal from its samples is possible if the signal is bandlimited and the sampling frequency is greater than twice the signal bandwidth.
As long as we can assure perfect bandlimiting above the so-called Nyquist point (obviously the big gotchya here), we should be able to reproduce that electrical signal. Perfectly.

If David can arbitrarily say the output of the preamp in his example is "perfect," I'd say we should be use "perfect" converters for our example... after all we're talking about "digital" in general -- not a specific set of real world converters.

Just as he was arbitrarily able to create a "perfect" preamp output -- by parallel token, it seems only reasonable that when talking about the capabilities of digital sampling in the abstract to faithfully reproduce this "perfect" preamp signal we should properly be talking about a "perfect" set of converters (with perfect filters and perfect internal timing), as well.

And that is just to say that our imaginary converters simply perform their function without error, fulfilling the functions required of them by Nyquist-Shannon, nothing more or less.

And, per Nyquist-Shannon, those perfect converters should be able to reproduce an input signal with perfect accuracy.


So, what can we conclude?

If we have converters that operate without any error, we should be able to exactly recreate a given signal within the limits imposed by Nyquist-Shannon -- but in the real world, we clearly cannot expect "perfect" devices or processes. So, in that sense, David's presumably-intended-to-be-provocative title is certainly accurate, at least with regard to the world of practical reality. But, if we take that point of view, it's also all but meaningless, as well.


You can't really have it both ways, I don't think, here.
Old 27th September 2007
  #20
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Chrisac's Avatar
 

Quote:
Originally Posted by David Mellor View Post
Hi, I'm David Mellor dfegad
I don't plan on commenting further in this thread, so please contact me through the Record-Producer.com website. Your correspondence will receive my full attention.

Record-Producer.com:

Will I get my secretary to call your one?

Last edited by Chrisac; 27th September 2007 at 08:27 PM.. Reason: spelling
Old 27th September 2007
  #21
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I will probably be banned but it will have been worth it
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