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John Williamson John Williamson is offline
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Default Compensating for phase shift when bussing things out in digital?

On 06/09/2017 13:00, Scott Dorsey wrote:
James Price wrote:

That said, comb filtering also applies to the reflection from the floor
back into the mic(instant comb filtering), though I think it keeps stuff
cleaner than multi mics.


Yes, that's comb filtering caused by phase shift. The signal is delayed by
the additional distance of the reflection. It takes about a millisecond for
sound to travel a foot in free air. Move the mike five feet, you have a
uniform phase shift of 5ms at all frequencies.

A point of order. What you have is a uniform time delay of 5ms, which
causes a different number of degrees of phase shift, depending on the
frequency. The time delay will cause phase shift at all frequencies, but
the angle of that shift will vary at different frequencies, so giving
rise to comb filtering as some frequencies add and others subtract

A phase shift of x degrees for multiple frequencies an be obtained at
any frequency, but not by using a fixed delay in the signal path.

Sloppy phrasing is what's causing a lot of the confusion in this thread.


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Mike Rivers Mike Rivers is offline
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Default Compensating for phase shift when bussing things out in digital?

On 9/5/2017 9:20 PM, James Price wrote:
You're assuming only harmonic overtones are present, which isn't the case,
in my opinion.


Your opinion? Oh.

Overtones, by definition, are harmonically related. Of course you can mix a piano playing in C with a trumpet playing in B-flat and you'll have frequencies that aren't harmonically related. Then, you can have intermodulation distortion where two unrelated frequencies add or subtract to form another frequency that's not a harmonic of either frequency.




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James Price[_5_] James Price[_5_] is offline
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Default Compensating for phase shift when bussing things out in digital?

On Wednesday, September 6, 2017 at 7:00:39 AM UTC-5, Scott Dorsey wrote:
James Price wrote:

That said, comb filtering also applies to the reflection from the floor
back into the mic(instant comb filtering), though I think it keeps stuff
cleaner than multi mics.


Yes, that's comb filtering caused by phase shift. The signal is delayed by
the additional distance of the reflection. It takes about a millisecond for
sound to travel a foot in free air. Move the mike five feet, you have a
uniform phase shift of 5ms at all frequencies.

Same thing when you sum two microphones at different places in the room
and leakage between them gets comb filtering. That is comb filtering
caused by phase shift.

I don't why you are getting so far afield talking about crazy unrelated
stuff like beat notes.


To paraphrase one of my earlier posts, delay a sound by .5 ms and 1K, 3K, 5K and 7K components will be 180 degrees out of phase and 2K, 4K, 6K and 8K components will be in phase.
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James Price[_5_] James Price[_5_] is offline
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Default Compensating for phase shift when bussing things out in digital?

On Wednesday, September 6, 2017 at 8:03:26 AM UTC-5, Mike Rivers wrote:
On 9/5/2017 9:20 PM, James Price wrote:
You're assuming only harmonic overtones are present, which isn't the case,
in my opinion.


Your opinion? Oh.

Overtones, by definition, are harmonically related. Of course you can mix a piano playing in C with a trumpet playing in B-flat and you'll have frequencies that aren't harmonically related. Then, you can have intermodulation distortion where two unrelated frequencies add or subtract to form another frequency that's not a harmonic of either frequency.


Incorrect. Harmonics are not just created the way we expect from
pure sounds. Those are still created. I'm not going to go any further
in this physics exercise but you're missing a step as to where and how
partials are created and what makes them harmonic and inharmonic.
Intermodulation distortion is nothing more than difference tones.
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Scott Dorsey Scott Dorsey is offline
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Default Compensating for phase shift when bussing things out in digital?

James Price wrote:
On Wednesday, September 6, 2017 at 7:00:39 AM UTC-5, Scott Dorsey wrote:
James Price wrote:

That said, comb filtering also applies to the reflection from the floor
back into the mic(instant comb filtering), though I think it keeps stuff
cleaner than multi mics.


Yes, that's comb filtering caused by phase shift. The signal is delayed by
the additional distance of the reflection. It takes about a millisecond for
sound to travel a foot in free air. Move the mike five feet, you have a
uniform phase shift of 5ms at all frequencies.

Same thing when you sum two microphones at different places in the room
and leakage between them gets comb filtering. That is comb filtering
caused by phase shift.

I don't why you are getting so far afield talking about crazy unrelated
stuff like beat notes.


To paraphrase one of my earlier posts, delay a sound by .5 ms and 1K, 3K, 5K and 7K components will be 180 degrees out of phase and 2K, 4K, 6K and 8K components will be in phase.


You can't be "in phase" or "out of phase." You can only be in phase _with_
something else, or out of phase _with_ something else.

Yes, if you delay a sound by 0.5ms, then some components will be in phase
with those of the original signal, and some will be out of phase with those
of the original signal. This is why we get comb filtering when we mix that
delayed signal with the original signal.

But the phase relationship between the original components does not change.
So if you had a 1K and 3K component that started out in phase with one another,
they will remain in phase with one another after the delay.

Phase shift is a relative thing, you have to specify what it's relative to.

Still, this has absolutely nothing to do with beat notes or nonlinearity.
--scott
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Scott Dorsey Scott Dorsey is offline
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Default Compensating for phase shift when bussing things out in digital?

James Price wrote:
On Wednesday, September 6, 2017 at 8:03:26 AM UTC-5, Mike Rivers wrote:
On 9/5/2017 9:20 PM, James Price wrote:
You're assuming only harmonic overtones are present, which isn't the ca=

se,
in my opinion.

=20
Your opinion? Oh.=20
=20
Overtones, by definition, are harmonically related. Of course you can mix=

a piano playing in C with a trumpet playing in B-flat and you'll have freq=
uencies that aren't harmonically related. Then, you can have intermodulatio=
n distortion where two unrelated frequencies add or subtract to form anothe=
r frequency that's not a harmonic of either frequency.=20

Incorrect. Harmonics are not just created the way we expect from
pure sounds. Those are still created. I'm not going to go any further
in this physics exercise but you're missing a step as to where and how
partials are created and what makes them harmonic and inharmonic.


Inharmonic partials are not harmonics. That's why we call the inharmonic.
Harmonics are integral multiples of the original signal caused by nonlinearity.
Other partials are mixing products, not harmonics.

Intermodulation distortion is nothing more than difference tones.


Yes, and IMD products are not harmonics. You are seeming to want to use the
word harmonics differently than physicists use it.

In any event, none of this has the slightest connection with phase shift and
group delay.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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[email protected] makolber@yahoo.com is offline
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Default Compensating for phase shift when bussing things out in digital?



Incorrect. Harmonics are not just created the way we expect from
pure sounds. Those are still created. I'm not going to go any further
in this physics exercise.....




well this is another semantics problem regarding the verb to "mix"

in audio parlance, "mixing" is just adding and this is a linear process and no new frequencies, intermod or harmonics are created (ideally).

in RF land "mixing" is multiplying and this is non-linear and new frequencies are creating including harmonics and sum and difference intermods.

m


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Mike Rivers Mike Rivers is offline
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On Wednesday, 6 September 2017 11:43:40 UTC-4, James Price wrote:

Incorrect. Harmonics are not just created the way we expect from
pure sounds. Those are still created. I'm not going to go any further
in this physics exercise but you're missing a step as to where and how
partials are created and what makes them harmonic and inharmonic.


Harmonics are multiples of the fundamental frequency. Nothing else. Partials can be harmonic or inharmonic. It's OK if you want to call the harmonically related partials "harmonics," but the inharmonic ones are, er. . . , inharmonic and therefore are not harmonics.

Intermodulation distortion is nothing more than difference tones.


Music theorists don't use the term "intermodulation distortion" but often refer to "beats."
Mix 440 Hz with 442 Hz and you get a 2 Hz component. When that 2 Hz component mixes with the 440 Hz and 442 Hz tones, that's when you get intermodulation distortion.



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Default Compensating for phase shift when bussing things out in digital?

"Mike Rivers" wrote in message
...

On 9/5/2017 9:20 PM, James Price wrote:
You're assuming only harmonic overtones are present, which isn't the
case,
in my opinion.


Your opinion? Oh.

Overtones, by definition, are harmonically related. Of course you can mix
a piano playing in C
with a trumpet playing in B-flat and you'll have frequencies that aren't
harmonically related.
Then, you can have intermodulation distortion where two unrelated
frequencies add or subtract
to form another frequency that's not a harmonic of either frequency.


No, overtones are not necessarily harmonics, by definition. Overtones at
frequencies that are integer multiples of the fundamental are harmonics. In
the real world of musical instruments, overtone frequencies may be nearly
exact integer multiples of the fundamental frequency; so close as to be,
practically, harmonics. But in some instruments, the deviation from exact
integer frequencies, or "inharmonicity" is significant, as any competent
piano tuner knows. And in some cases, the overtones have no apparent
relationship to the integer multiples, as in many percussion instruments.
The overtones at integer multiples are harmonics, but many overtones are not
harmonics.

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Default Compensating for phase shift when bussing things out in digital?

"Mike Rivers" wrote in message
...
Incorrect. Harmonics are not just created the way we expect from
pure sounds. Those are still created. I'm not going to go any further
in this physics exercise but you're missing a step as to where and how
partials are created and what makes them harmonic and inharmonic.


Harmonics are multiples of the fundamental frequency. Nothing else.
Partials can be
harmonic or inharmonic. It's OK if you want to call the harmonically
related partials
"harmonics," but the inharmonic ones are, er. . . , inharmonic and
therefore are not harmonics.


But that wasn't your claim. You didn't say that all harmonics are harmonics,
you claimed
that all overtones are harmonics. Big difference. Not all overtones are
harmonics, and he
didnt say that inharmonic overtones were harmonics. Your statement above is
correct,
but it doesn't prove your previous, different, claim.

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wrote:

in RF "mixing" means multiplying or modulating

in RF "combining" means adding which is what audio folks call mixing

yeah its confusing


Which is why the only safe way of describing what is going on is to show
the sin(ft+theta)+.... math....
--scott
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Mike Rivers Mike Rivers is offline
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On Wednesday, 6 September 2017 20:01:18 UTC-4, None wrote:

No, overtones are not necessarily harmonics, by definition. Overtones at
frequencies that are integer multiples of the fundamental are harmonics. In
the real world of musical instruments, overtone frequencies may be nearly
exact integer multiples of the fundamental frequency; so close as to be,
practically, harmonics. But in some instruments, the deviation from exact
integer frequencies, or "inharmonicity" is significant, as any competent
piano tuner knows. And in some cases, the overtones have no apparent
relationship to the integer multiples, as in many percussion instruments.
The overtones at integer multiples are harmonics, but many overtones are not
harmonics.


Quit being an asshole, will you? Musicicians deal in overtones. Scientists deal in harmonics. Musicial instruments are physical things, and they aren't perfect. That's why some overtones are slightly off being integer multiples of the fundamental. It's what makes musical instruments more interesting than sine wave generators.

When it comes to percussion instruments, they make noise, and noise can be composed of many unrelated frequencies. If a musician chooses to call them overtones, so be it.


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"Mike Rivers" wrote in message
...
Quit being an asshole, will you? Musicicians deal in overtones. Scientists
deal in harmonics.


Plenty of scientists deal with overtones which are not harmonics, especially
in the science of acoustics, even in non-musical contexts. Plenty of
musicians as well. The two words usually mean two different (but obviously
related) things. Are you continuing to deny that, as you apparently did in a
recent post?

Gee, anyone who reads this group knows that I actually can be a real asshole
when I feel like it, but in this case, I was simply disputing your claim:
"Overtones, by definition, are harmonically related." That's an
unnecessarily narrow definition. Most of the scientists and engineers that
I've worked with over the last 45 years, in the fields of acoustics, audio,
and music, have used a definition of "overtone" that includes overtones that
are not harmonics, such as the definition in the first dictionary that comes
to hand, Merriam-Webster. Yes, I've seen your definition as well (I think
Tremaine uses it), but there is whole wide world outside that limited
definition.

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On 9/6/2017 10:23 PM, None wrote:
your claim: "Overtones, by definition, are harmonically related." That's
an unnecessarily narrow definition.


It's good enough for me. I'm done arguing with you about this. If you
want to argue about something significant and related to the subject at
hand (see above "Subject"), then bring it on.

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"Mike Rivers" wrote in message news
It's good enough for me. I'm done arguing with you about this.
If you want to argue about something significant and related to
the subject at hand (see above "Subject"), then bring it on.


Quit being an asshole, will you? If someone's using their own
personal definition, rather than the one that most everyone
else uses (just to be an asshole, apparently), it's useful to
point that out, as it's significant and related to the subject
at hand. Sure, you can use your own definition, but when
you try (and fail) to foist your narrow definition on everyone
else with a self-important condescending edict, it's worth
calling you out.
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On Wednesday, September 6, 2017 at 11:09:59 PM UTC-4, None wrote:
"Mike Rivers" wrote in message news
It's good enough for me. I'm done arguing with you about this.
If you want to argue about something significant and related to
the subject at hand (see above "Subject"), then bring it on.


Quit being an asshole, will you? If someone's using their own
personal definition, rather than the one that most everyone
else uses (just to be an asshole, apparently), it's useful to
point that out, as it's significant and related to the subject
at hand. Sure, you can use your own definition, but when
you try (and fail) to foist your narrow definition on everyone
else with a self-important condescending edict, it's worth
calling you out.


DAW = No!
DAS = Yes!

Jack
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