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if higher sample rate doesnt matter then why .... Effects Pedals, Units & Accessories
Old 18th September 2011
  #301
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Quote:
Originally Posted by dcollins View Post
Are you for real? I'm beginning to doubt you're for real.

Any value, and I mean any value, can be assigned to relate analog levels to digital ones. +4dBu = -20dBFS is a popular one, but it could be anything.

Like your 10,000V A/D converter, for instance. Maybe you set 5,000V to -20dBFS. You might consider gloves for that, though. Electric shock is no joking matter.

DC
exactly
any value can be assigned
so there is NO relation between dBFS and analog voltages
it is all up to the d/a circuit

so there are NO INTERSAMPLE PEAKS unless the d/a is badly designed
Old 18th September 2011
  #302
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... once you (the designer) have defined the relationship between dBFS and dBu in your circuit, the concept of intersample peaks makes perfect sense because every sample value will equate to a particular voltage ... exactly as bogosort said already in your new thread. Once this relationship has been defined, then it can be referred to as a relationship within that circuit!

You're right, any value can be assigned ... in other words, the relationship is up to each designer ... it's not nonexistent, nor is it a confusion of the two domains.

The above is actually superfluous at this point, because psychomonkey already explained it much more concisely in post #291 ... I fail to understand how you rationalise a disagreement with this.

And once again (am I the only one who thinks this?), it seems that you're using the word "peak" colloquially which is adding to the miscommunication in all three threads. I apologise if this is my misunderstanding of what you're posting.
Old 18th September 2011
  #303
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Quote:
Originally Posted by DaveUK View Post
What is really going on here ? Sausages ? Turtles? MRI ? Over saturation? Tape shed? Isopropyl?

Is OAG Really MandyC or Lisasmile?
Mezed or or kfthth or however you say (when your phone doesn't do smilies )

who's OAG...and no I'm not Lisa...who seems to have dissapeared...anyway

my point about Dan Lavry is that he has been elevayed to sainthood here. He designs good gear. Big deal. He doesnt know everything. A lot of what you guys speak is also just theory...perhaps the OP is talking strictly reality. There is a big difference in what any component of any piece of gear is SUPPOSED to do and what it ACTUALLY does. Myself, I really cant argue the theory or the science, so I wont, but Ive seen this witch hunt before and it usually isn't warranted and in fact it ends up that folks burnt at the stake were actually making sense.
Old 18th September 2011
  #304
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Quote:
Originally Posted by MandyC View Post
who's OAG...and no I'm not Lisa...who seems to have dissapeared...anyway

my point about Dan Lavry is that he has been elevayed to sainthood here. He designs good gear. Big deal. He doesnt know everything. A lot of what you guys speak is also just theory...perhaps the OP is talking strictly reality. There is a big difference in what any component of any piece of gear is SUPPOSED to do and what it ACTUALLY does. Myself, I really cant argue the theory or the science, so I wont, but Ive seen this witch hunt before and it usually isn't warranted and in fact it ends up that folks burnt at the stake were actually making sense.
OAG is our antagonist in this drama

You're right on the theory vs practice point. Lavry's most referenced paper explaining sampling theory and his others deal with both though, so they are relevant. You can think what you like about the general opinion of his published papers around here, the fact is that they're absolutely correct and tend to be quite useful references.

Also, this whole discussion isn't really one of theory vs practice ... it's actually been pretty straight forward since it derailed away from the OP. I think it's one of miscommunication and misunderstanding.
Old 18th September 2011
  #305
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Quote:
Originally Posted by oldeanalogueguy View Post
crikey yourself if you think that dBFS has any relation to dBu or dBV or dBSPL or dBm or anything else that is not in the digital domain.
no, your anti Lavry stance amuses me.
Old 18th September 2011
  #306
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Quote:
Originally Posted by oldeanalogueguy View Post
cant say for sure about dan
never found his alleged paper
but narcoman in this thread and many others
seem to think that dBFS can be compared/related to dBu
get the fawck out of here heh

Never said it!! Never. Ever.

You're funny.

Anyway - read this: http://www.lavryengineering.com/docu...ing_Theory.pdf


It's a good introduction to some of the issues in digital and a better resource than wiki .

Dan is also a very very nice chap and thoroughly undeserving of some of the flack and disrespect/disregard he's had on this thread (it certainly makes those of us who work in the biz view posts from those members with a great deal of suspicion). He's contributed so much to the modern tech recording community, so it's quite a shock to read a couple of people doubting his credibility. He's the kind of chap that will get lifetime achievement awards in years to come - he's been THAT influential.

After that you can read my PhD (you naughty man you) if you're very nice.......heh
Old 18th September 2011
  #307
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Quote:
Originally Posted by MandyC View Post
A lot of what you guys speak is also just theory...

Actually it's theorem. Not theory. Quite a difference.
Old 18th September 2011
  #308
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I mixe those up too often ... shame on me.
Old 18th September 2011
  #309
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narcoman's Avatar
 

ach. I was just being a bit pedantic!!
Old 18th September 2011
  #310
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Quote:
Originally Posted by oldeanalogueguy View Post
so there are NO INTERSAMPLE PEAKS unless the d/a is badly designed
Let's put it another way. When a DA converts the stream of data into a smooth voltage variation WRT time some of those voltages will be higher than the preceding and following samples. If they weren't then you'd be implying that every single sample was at or above the peak of every waveform element at digitisation - which would be impossible as it would need an infinite sample rate. Not that I'm saying they join up (that'd be stupid), not that I'm saying they are a problem (might be if you decide to calibrate against VU from a poorly reported digital value); but those peaks MAY not get reported in digital meters and WILL be above the equivalent converted reference level.

Those voltages above your particular sample points are what everyone else (us, most of GS, all DSP books, Shannon et al) in the biz refer to as inter-sample peaks. Those same peaks in the digital domain are the very peaks that many meters do not report. How much of an issue these things are depend very much on DA design, DAW design and any hardware you interface in the analogue stage (although it'd have to be a stupidly designed piece of equipment that couldn't deal with the sort of peaks we're discussing).

If you choose not to accept that then that's okay. You RIGHTLY say that they would only be a problem with a poorly designed DA or 0dB(VU) references with NO headroom. Read that last bit carefully - wouldn't want you to think I was putting VU into the digital realm.

Is that any better for you? Or are we done here in an exhaustive "one man against the masses" sort of way? Doesn't matter to me either way!

Right - I've given what I hope is an explanation of what people are referring to. I'm no longer going to argue with you. Any other readers of this particular part - go read the textbooks yourself. Go read Shannon et al. Go read Dans paper.
Old 18th September 2011
  #311
Quote:
Originally Posted by oldeanalogueguy View Post
rotflamo

an = sign does not equate those things
that is just a typo
a humongous mistake
total bullbleep

there is NO relation between dBFS and dBu other than random
It's called calibration. Once you've calibrated, which is what the = sign represents here, there is a fixed relationship between dBFs and dBu, until the engineer changes it. We both know it's not random, you're just being argumentative. It IS arbitary until defined, then it's fixed.

I don't know why you're banging on about intersample peaks, this is nothing to do with that!
Old 18th September 2011
  #312
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Quote:
Originally Posted by timlloyd View Post
I mixe those up too often ... shame on me.
You in Oxford anytime soon? Grab a coffee?
Old 18th September 2011
  #313
Quote:
Originally Posted by MandyC View Post
who's OAG...and no I'm not Lisa...who seems to have dissapeared...anyway

my point about Dan Lavry is that he has been elevayed to sainthood here. He designs good gear. Big deal. He doesnt know everything. A lot of what you guys speak is also just theory...perhaps the OP is talking strictly reality. There is a big difference in what any component of any piece of gear is SUPPOSED to do and what it ACTUALLY does. Myself, I really cant argue the theory or the science, so I wont, but Ive seen this witch hunt before and it usually isn't warranted and in fact it ends up that folks burnt at the stake were actually making sense.
If you're not going to take the due diligence to educate yourself, maybe you ought to stay out of technical discussions and not attempt to dismiss the scientific paradigm as 'just' theory.
Old 18th September 2011
  #314
Quote:
Originally Posted by narcoman View Post
get the fawck out of here heh

Never said it!! Never. Ever.

You're funny.

Anyway - read this: www.lavryengineering.com/documents/Sampling_Theory.pdf


It's a good introduction to some of the issues in digital and a better resource than wiki .

Dan is also a very very nice chap and thoroughly undeserving of some of the flack and disrespect/disregard he's had on this thread (it certainly makes those of us who work in the biz view posts from those members with a great deal of suspicion). He's contributed so much to the modern tech recording community, so it's quite a shock to read a couple of people doubting his credibility. He's the kind of chap that will get lifetime achievement awards in years to come - he's been THAT influential.

After that you can read my PhD (you naughty man you) if you're very nice.......heh
We see this happen again and again.

Someone with a real body of innovative work and/or insight into the technical and/or artistic realms is generous enough to give his time to explaining that work or the technical background for it, and people with crackpot theories or other axes to grind come out of seemingly nowhere and engage them in illogical, irrational arguments.

Whether it's someone attacking Bruce Swedien for things that have nothing to do with him or people attacking Dan Lavry over their own misunderstandings of digital audio, it pushes away good people who have a lot to give and who have previously shown a willingness to share their knowledge and experience.

It's a shame.
Old 18th September 2011
  #315
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narcoman's Avatar
 

And poor old Bob Katz. A super nice guy berated by plebs with no knowledge or track record. !!

Moderation needs to get brutal round here !! Brutal moderation - surely a great oxymoron!! heh
Old 18th September 2011
  #316
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Quote:
Originally Posted by psycho_monkey View Post
It's called calibration. Once you've calibrated, which is what the = sign represents here, there is a fixed relationship between dBFs and dBu, until the engineer changes it. We both know it's not random, you're just being argumentative. It IS arbitary until defined, then it's fixed.

I don't know why you're banging on about intersample peaks, this is nothing to do with that!
if even 2 people let alone everybody calibrates to their own number then it is totally meaningless

the fact is that there is no logical, physical, meaningful way to change dBFS to dBu or dBv so that you always get the same number
Old 18th September 2011
  #317
Quote:
Originally Posted by narcoman View Post
And poor old Bob Katz. A super nice guy berated by plebs with no knowledge or track record. !!

Moderation needs to get brutal round here !! Brutal moderation - surely a great oxymoron!! heh
Man. I'm glad I apparently missed that. It's hard to think of anyone much more low key, reasonable, and, of course, extremely knowledgeable.
Old 18th September 2011
  #318
Quote:
Originally Posted by oldeanalogueguy View Post
if even 2 people let alone everybody calibrates to their own number then it is totally meaningless

the fact is that there is no logical, physical, meaningful way to change dBFS to dBu or dBv so that you always get the same number
You seem to be perennially surprised and outraged by the basic facts of audio and technical life.
Old 18th September 2011
  #319
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Quote:
Originally Posted by narcoman View Post
Let's put it another way. When a DA converts the stream of data into a smooth voltage variation WRT time some of those voltages will be higher than the preceding and following samples. If they weren't then you'd be implying that every single sample was at or above the peak of every waveform element at digitisation - which would be impossible as it would need an infinite sample rate. Not that I'm saying they join up (that'd be stupid), not that I'm saying they are a problem (might be if you decide to calibrate against VU from a poorly reported digital value); but those peaks MAY not get reported in digital meters and WILL be above the equivalent converted reference level.

Those voltages above your particular sample points are what everyone else (us, most of GS, all DSP books, Shannon et al) in the biz refer to as inter-sample peaks. Those same peaks in the digital domain are the very peaks that many meters do not report. How much of an issue these things are depend very much on DA design, DAW design and any hardware you interface in the analogue stage (although it'd have to be a stupidly designed piece of equipment that couldn't deal with the sort of peaks we're discussing).

If you choose not to accept that then that's okay. You RIGHTLY say that they would only be a problem with a poorly designed DA or 0dB(VU) references with NO headroom. Read that last bit carefully - wouldn't want you to think I was putting VU into the digital realm.

Is that any better for you? Or are we done here in an exhaustive "one man against the masses" sort of way? Doesn't matter to me either way!

Right - I've given what I hope is an explanation of what people are referring to. I'm no longer going to argue with you. Any other readers of this particular part - go read the textbooks yourself. Go read Shannon et al. Go read Dans paper.
nonsense!!

the voltages wil be whatever the d/a designer said they will be

digital samples have no voltages
they are just numbers

you want voltage go to the analog domain
and the d/a will tell you how big the voltage will be

no, i said that almost every sample was below peak when the a/d did its job. the voltage after the d/a can make the analog below as many of the original sampled values as desired.

there are no intersamples in the digital domain just the samples hence no intersample peaks

there are no samples at all in the analog domain
hence no intersample peaks

the only way to claim there are intersample peaks is to confuse the digital and analog domain

there is no way to change dBFS to dBu or dBV or dBSPL etc
as they have no common reference which dB's require
Old 18th September 2011
  #320
Lives for gear
 

Quote:
Originally Posted by narcoman View Post
get the fawck out of here heh

Never said it!! Never. Ever.

You're funny.

Anyway - read this: www.lavryengineering.com/documents/Sampling_Theory.pdf


It's a good introduction to some of the issues in digital and a better resource than wiki .

Dan is also a very very nice chap and thoroughly undeserving of some of the flack and disrespect/disregard he's had on this thread (it certainly makes those of us who work in the biz view posts from those members with a great deal of suspicion). He's contributed so much to the modern tech recording community, so it's quite a shock to read a couple of people doubting his credibility. He's the kind of chap that will get lifetime achievement awards in years to come - he's been THAT influential.

After that you can read my PhD (you naughty man you) if you're very nice.......heh
thanks
i will read it
and guarantee that he played loose with english and confused the digital vs analog domains if he ever says intersample peak
Old 18th September 2011
  #321
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Quote:
Originally Posted by narcoman View Post
no, your anti Lavry stance amuses me.
not anti labry at all
just anti bullbleep and erroneous english that makes no sense
Old 18th September 2011
  #322
Gear Nut
 

Quote:
Originally Posted by oldeanalogueguy View Post
rotflamo
there is NO relation between dBFS and dBu other than random
So, if the only relationship is "random", shouldn't all DAC's turn my samples into noise? Would that be white noise or pink noise?
Old 18th September 2011
  #323
Gear Nut
 

Quote:
Originally Posted by oldeanalogueguy View Post
thanks
i will read it
and guarantee that he played loose with english and confused the digital vs analog domains if he ever says intersample peak
After ALL this you still haven't even read that paper? Dude - he does the math.
Old 18th September 2011
  #324
Quote:
Originally Posted by narcoman View Post
Let's put it another way. When a DA converts the stream of data into a smooth voltage variation WRT time some of those voltages will be higher than the preceding and following samples. If they weren't then you'd be implying that every single sample was at or above the peak of every waveform element at digitisation - which would be impossible as it would need an infinite sample rate. Not that I'm saying they join up (that'd be stupid), not that I'm saying they are a problem (might be if you decide to calibrate against VU from a poorly reported digital value); but those peaks MAY not get reported in digital meters and WILL be above the equivalent converted reference level.

Those voltages above your particular sample points are what everyone else (us, most of GS, all DSP books, Shannon et al) in the biz refer to as inter-sample peaks. Those same peaks in the digital domain are the very peaks that many meters do not report. How much of an issue these things are depend very much on DA design, DAW design and any hardware you interface in the analogue stage (although it'd have to be a stupidly designed piece of equipment that couldn't deal with the sort of peaks we're discussing).

If you choose not to accept that then that's okay. You RIGHTLY say that they would only be a problem with a poorly designed DA or 0dB(VU) references with NO headroom. Read that last bit carefully - wouldn't want you to think I was putting VU into the digital realm.

Is that any better for you? Or are we done here in an exhaustive "one man against the masses" sort of way? Doesn't matter to me either way!

Right - I've given what I hope is an explanation of what people are referring to. I'm no longer going to argue with you. Any other readers of this particular part - go read the textbooks yourself. Go read Shannon et al. Go read Dans paper.
[bold added to reflect the bolding that OAG did when he quoted this in his post below]

Quote:
Originally Posted by oldeanalogueguy View Post
nonsense!!

the voltages wil be whatever the d/a designer said they will be

digital samples have no voltages
they are just numbers

you want voltage go to the analog domain
and the d/a will tell you how big the voltage will be

no, i said that almost every sample was below peak when the a/d did its job. the voltage after the d/a can make the analog below as many of the original sampled values as desired.

there are no intersamples in the digital domain just the samples hence no intersample peaks

there are no samples at all in the analog domain
hence no intersample peaks

the only way to claim there are intersample peaks is to confuse the digital and analog domain

there is no way to change dBFS to dBu or dBV or dBSPL etc
as they have no common reference which dB's require
Would it have made you feel better if the bolded bit had instead read, When a DA converts the stream of data into a smooth voltage variation WRT time some of those voltages will be higher than the [voltages generated from] preceding and following samples... ?


You know, I've read a lot of your writing on this issue and I'm still not entirely sure -- do you acknowledge the phenomenon but are quarreling with the descriptive terms of art used? Or are you suggesting that the scientists and design engineers describing this phenomenon are imagining it?
Old 18th September 2011
  #325
Gear Nut
 

Quote:
Originally Posted by theblue1 View Post
[bold added to reflect the bolding that OAG did when he quoted this in his post below]


Would it have made you feel better if the bolded bit had instead read, When a DA converts the stream of data into a smooth voltage variation WRT time some of those voltages will be higher than the [voltages generated from] preceding and following samples... ?
NO NO NO - you're making the samples and the voltages CONFUSED! The relationship between dbFS nad DBu is RANDOM! heh

Seriously - a good question - I was thinking of posing the same, but I do, perhaps wrongly, believe that oldanalogueguy's answer we more closely resemble my friendly mocking above than anything else.

It is interesting that in all these pages we've only been discussing LPCM based encoding and delta-sigma conversion. (At least, that's what I've assumed.). I'm no EE and I'm no audio pro, but I'm curious if there are other converter and encoding technologies that don't have the issues that we're discussing here. Can anyone comment on intersample peaks in the DSD conversion process?

I started reading up on wikipedia, and there sure is a lot to the subject! More study time...
Old 18th September 2011
  #326
Quote:
Originally Posted by DaveDaveDave View Post
NO NO NO - you're making the samples and the voltages CONFUSED! [...]
Old 18th September 2011
  #327
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dcollins's Avatar
Quote:
Originally Posted by theblue1 View Post
You know, I've read a lot of your writing on this issue and I'm still not entirely sure -- do you acknowledge the phenomenon but are quarreling with the descriptive terms of art used? Or are you suggesting that the scientists and design engineers describing this phenomenon are imagining it?
The existence of inter-sample peaking is not even remotely controversial, so I have no idea what OAG is on about. It's also trivial to demonstrate in D/A (or async. SRC for that matter).

Also, there are many D/A converter chips that have no internal headroom, so the claim that it's just a matter of proper design is also questionable. One would have to digitally attenuate the input to the chip by some number of dB to allow for peaking at the conversion stage................


DC
Old 18th September 2011
  #328
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narcoman's Avatar
 

Quote:
Originally Posted by oldeanalogueguy View Post
nonsense!!

the voltages wil be whatever the d/a designer said they will be

digital samples have no voltages
they are just numbers
Well - for one thing , you can't just design output voltages against reference willy nilly. There are standards to adhere to.....

PROPORTIONALLY, the reference voltage at any given value will be over the nominal value. Read on and see why.....

Quote:
Originally Posted by oldeanalogueguy View Post
you want voltage go to the analog domain
and the d/a will tell you how big the voltage will be

no, i said that almost every sample was below peak when the a/d did its job. the voltage after the d/a can make the analog below as many of the original sampled values as desired.
That isn't what's being discussed!! The only thing that is being discussed is a sample doesn't represent peak code. THAT is all intersample peak means!!

The inter sample peak refers to any reconstruction value over the integral curve being higher than a sample value.

That is all it means. If you can't understand that then I've no idea what to say! It's unbelievable that you'd argue this. What else can anyone say? heh!!
Quote:
Originally Posted by oldeanalogueguy View Post
there are no intersamples in the digital domain just the samples hence no intersample peaks
What happens if you SRC a 44.1 set into a 96 set? What happens then?
You got it - some of the reconstructed and NEW samples will be above pairwise 44.1 samples. In other words there will be inter sample peaks with respect to the original 44.1 sample set. Now - the re-coinstruced analogue waveforms will be the same - but that isn't the point.


Quote:
Originally Posted by oldeanalogueguy View Post
there are no samples at all in the analog domain
hence no intersample peaks
And nobody has said there are. What they have said is that the peaks in the analogue reconstructed waveform don't necessarily line up with the highest samples in sample code. How could they? We don't join dots!

HOWEVER - the respective sample points do not occur (most of the time) when the voltage is at a locally maximum point.


Quote:
Originally Posted by oldeanalogueguy View Post
the only way to claim there are intersample peaks is to confuse the digital and analog domain
Once you set a reference - for example

-18dB(FS) = 0dB(VU)

in a 24bit sample set then the number 000111111111111111111111 (actually it won't be exactly that as 6dB is not 1 bit - but it's close enough for getting the point across) is equatable to 0dB(VU). That is core to the idea of calibration.

Quote:
Originally Posted by oldeanalogueguy View Post
there is no way to change dBFS to dBu or dBV or dBSPL etc
as they have no common reference which dB's require
That is why those of us who do this for a living set standards either locally (on your own) or you obey international convention;

There are several. ITU, AES, EBV, BBC and quite a few more. We set standards and STICK to them year in year out.

Even within hardware there are accepted standards of what 0dB(VU) equates to in terms of voltage! For MOST hardware 0dB(VU) is +4 dBU (not all ).

+4dBU is nominally accepted internationally and across equipment asset at 1.23Vrms.

Now - there are a couple of points to your argument all based around corrupting the central point. It is important when discussing AD and DA that an equivalence is set. However, for ANY digital argument ALL of the points about reference level no matter what value is set as 0dBVU equivalent.

The AES define -18 (or -20 for some use). EBU define -20. The BBC have defined -17, -18 and -20 at various times......

Nobody is confusing analogue and digital because most of us in this discussion are savvy and well versed enough to understand that we all refer to analogue/digital comparisons with a defined reference. The point is - the arguments stand no matter what the reference is; the only thing that changes is the absolute value behind the argument, not the semantics themselves.


Okay - I've absolutely explained this enough and we're going round in circles. Take it easy.....
Old 18th September 2011
  #329
Quote:
Originally Posted by oldeanalogueguy View Post
if even 2 people let alone everybody calibrates to their own number then it is totally meaningless

the fact is that there is no logical, physical, meaningful way to change dBFS to dBu or dBv so that you always get the same number
Well of course there is. You agree a standard! Same way we all drive on one side of the road in a given country...I can take my session from one studio to another, and provided the converters are lined up the same, my gain staging will be the same.

You really are trolling now aren't you? It can't possibly be that you don't grasp this basic concept.
Old 18th September 2011
  #330
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doug hazelrigg's Avatar
Quote:
Originally Posted by oldeanalogueguy View Post
if even 2 people let alone everybody calibrates to their own number then it is totally meaningless

the fact is that there is no logical, physical, meaningful way to change dBFS to dBu or dBv so that you always get the same number
Only partly true... in both Europe and the USA, there are standard methods of calibration. Of course, it's not mandatory that anyone follow them

(but it would be nice if more people were aware of them)
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