Q: Flipping Phase

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I am reading a book on studio tricks used to create bigger sounds in home
recording. One term mentioned is to dupe a track, and "flip the phase" of
the track. While I know what this meas technically, what does one do to
"flip the phase" on a digital recording? Is there a piece of hardware to
use, or should I try software, or what? Thanks.

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EricK <eric@raw-tracks.com> wrote in
news:FECve.6983$B_3.4833@fe05.lga:

> My Last Sigh wrote:
>> I am reading a book on studio tricks used to create bigger
>> sounds in home recording. One term mentioned is to dupe a
>> track, and "flip the phase" of the track. While I know what
>> this meas technically, what does one do to "flip the phase"
>> on a digital recording? Is there a piece of hardware to use,
>> or should I try software, or what? Thanks.
>
> What they meant to say was to flip the "Polarity".

Flipping the polarity results in a 180 degree phase difference
between the two tracks. .

--
Bob Quintal

PA is y I've altered my email address.

Archived from groups: rec.audio.pro (More info?)

this is more commonly done than these posts imply--brief delay/phase
flip. just listen to the horn tracks on any fela record and see how
good it can be. yes, your records will cancel out on mono clock
radios, and yes the spread is unnaturally wide. oh no.

jeff

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My Last Sigh wrote:
> I am reading a book on studio tricks used to create bigger
sounds in
> home recording. One term mentioned is to dupe a track,
and "flip the
> phase" of the track.

A *BAD* choice of words, even though we all know it is quite
customary.

>While I know what this means technically,

It means flipping the polarity of the signal.

> what does one do to "flip the phase" on a digital
recording?

You flip the polarity of the signal. There's usually a
pushbutton or an effect that does this, someplace in the
software, device driver, or whatever.

> Is there a piece of hardware to use, or should I try
software, or what?

The facility for changing polarity of a channel is where you
find it. It's in some device drivers, and its a standard
effect in most DAW software.

Note that flipping the polarity is really quite different
from 180 degrees of phase shift. 180 degrees of phase shift
implies a time delay, while flipping polarity does not.

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On Mon, 27 Jun 2005 03:53:50 -0400, Joe Mama wrote
(in article <42bfb056$0$11692$afc38c87@news.optusnet.com.au> ):

> Bob Quintal wrote:
>> EricK <eric@raw-tracks.com> wrote in
>> news:FECve.6983$B_3.4833@fe05.lga:
>>
>>
>>> My Last Sigh wrote:
>>>
>>>> I am reading a book on studio tricks used to create bigger
>>>> sounds in home recording. One term mentioned is to dupe a
>>>> track, and "flip the phase" of the track. While I know what
>>>> this meas technically, what does one do to "flip the phase"
>>>> on a digital recording? Is there a piece of hardware to use,
>>>> or should I try software, or what? Thanks.
>>>
>>> What they meant to say was to flip the "Polarity".
>>
>>
>> Flipping the polarity results in a 180 degree phase difference
>> between the two tracks. .
>>
> As I understand it, phase isn't a function of amplitude but of time.
> Which makes that only true for repeating waves (sine, square, etc.), and
> not for complex audio waveforms. Yes? No?
>
> Cheers,
> -joe.

If he's copying one to another track and playing both, the two are identical
regardless of their complexity. They will cancel.

Regards,

Ty Ford



-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com

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Scott Dorsey wrote:

> I will warn you that wide panning where you pan a track to
one side
> and an inverted version of the same track to the other
side can give
> you a very diffuse and airy sound, but when you play it
back in mono
> it goes away. Fun trick, but watch mono compatibility.

If a just sorta diffuse sound suffices, phase shifting one
channel by +45 and the other by -45 gives you a nice diffuse
sound, and improved mono compatibility. This is easy enough
to implement in Audition - just bring up the graphic phase
shifter.

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On 6/27/05 3:53 AM, in article
42bfb056$0$11692$afc38c87@news.optusnet.com.au, "Joe Mama"
<bloodywanker@drugsmakemecool.com> wrote:

> Bob Quintal wrote:
>> EricK <eric@raw-tracks.com> wrote in
>> news:FECve.6983$B_3.4833@fe05.lga:
>>
>>
>>> My Last Sigh wrote:
>>>
>>>> I am reading a book on studio tricks used to create bigger
>>>> sounds in home recording. One term mentioned is to dupe a
>>>> track, and "flip the phase" of the track. While I know what
>>>> this meas technically, what does one do to "flip the phase"
>>>> on a digital recording? Is there a piece of hardware to use,
>>>> or should I try software, or what? Thanks.
>>>
>>> What they meant to say was to flip the "Polarity".
>>
>>
>> Flipping the polarity results in a 180 degree phase difference
>> between the two tracks. .

At one specific frequency...

Archived from groups: rec.audio.pro (More info?)

On Mon, 27 Jun 2005 17:53:50 +1000, Joe Mama
<bloodywanker@drugsmakemecool.com> wrote:

>>>>I am reading a book on studio tricks used to create bigger
>>>>sounds in home recording. One term mentioned is to dupe a
>>>>track, and "flip the phase" of the track. While I know what
>>>>this meas technically, what does one do to "flip the phase"
>>>>on a digital recording? Is there a piece of hardware to use,
>>>>or should I try software, or what? Thanks.
>>>
>>>What they meant to say was to flip the "Polarity".
>>
>>
>> Flipping the polarity results in a 180 degree phase difference
>> between the two tracks. .
>>
>As I understand it, phase isn't a function of amplitude but of time.
>Which makes that only true for repeating waves (sine, square, etc.), and
>not for complex audio waveforms. Yes? No?

Y'all just stop it! Right now, or I'm gonna tell your mamas.

Polarity and phase are totally, completely unrelated. Rumors
otherwise are bogus. Just say no.

Don't make me stop this car.

Chris Hornbeck
"I can build you a test that will show either one. Which would you prefer
me to demonstrate?
--scott

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Joe Mama <bloodywanker@drugsmakemecool.com> wrote in
news:42bfb056$0$11692$afc38c87@news.optusnet.com.au:

> Bob Quintal wrote:
>> EricK <eric@raw-tracks.com> wrote in
>> news:FECve.6983$B_3.4833@fe05.lga:
>>
>>
>>>My Last Sigh wrote:
>>>
>>>>I am reading a book on studio tricks used to create bigger
>>>>sounds in home recording. One term mentioned is to dupe a
>>>>track, and "flip the phase" of the track. While I know what
>>>>this meas technically, what does one do to "flip the phase"
>>>>on a digital recording? Is there a piece of hardware to
>>>>use, or should I try software, or what? Thanks.
>>>
>>>What they meant to say was to flip the "Polarity".
>>
>>
>> Flipping the polarity results in a 180 degree phase
>> difference between the two tracks. .
>>
> As I understand it, phase isn't a function of amplitude but of
> time. Which makes that only true for repeating waves (sine,
> square, etc.), and not for complex audio waveforms. Yes? No?
>
First of all, those complex audio waveforms are made up by
adding together multiple sine waves. so are square waves (all
harmonics of the sine), and triangle waves (all odd harmonics).

Now to answer your question, Complex audio waveforms contain
repeating patterns, it's just that the patterns are complex, not
simple like a sine wave, therefore phase (technically phase
time) is applicable to audio.

Also, note that a complex audio wave has two parts, the
repeating waveform, and a much slower envelope. Both have
ampolitude and phase, as defined bi the National Institute of
Science and Technology (NIST). Their definition of phase is .

phase: 1. Of a periodic, varying phenomenon, e.g., an electrical
signal or electromagnetic wave, any distinguishable
instantaneous state of the phenomenon, referred to a fixed
reference or another periodic varying phenomenon.

http://www.its.bldrdoc.gov/fs-1037/dir-027/_3976.htm has further
description and examples.

One could say the positive phase of a wave versus the negative
phase and be correct, in engineering terms.

> Cheers,
> -joe.
>

Cheers.

--
Bob Quintal

PA is y I've altered my email address.

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On Wed, 29 Jun 2005 00:29:55 GMT, Bob Quintal <rquintal@sPAmpatico.ca>
wrote:

>The definition of phase does not require, nor even imply, a
>delay,.
>
>phase: 1. Of a periodic, varying phenomenon, e.g., an electrical
>signal or electromagnetic wave, any distinguishable
>instantaneous state of the phenomenon, referred to a fixed
>reference or another periodic varying phenomenon.
>http://www.its.bldrdoc.gov/fs-1037/dir-027/_3976.htm

It requires a time difference. How do you define "delay"?

Chris Hornbeck
"Untestable does not mean meaningless."
-Joe Sensor

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Mike Rivers wrote:
> In article <42bfb056$0$11692$afc38c87@news.optusnet.com.au> bloodywanker@drugsmakemecool.com writes:
>
>
>>As I understand it, phase isn't a function of amplitude but of time.
>
>
> That's correct.
>
>
>>Which makes that only true for repeating waves (sine, square, etc.), and
>>not for complex audio waveforms. Yes? No?
>
>
> A repetitive, simple waveform make it easy to see and express phase
> shift as a number, but no waveform is immune to phase shift.

Sorry, I don't think I explained myself very well. What I was getting
at was that, as far as I can figure, a polarity inversion is, in
practice, the same as 180° of phase shift for repeating waves. As in:
if you were to duplicate a track with a 'repeating' type of waveform and
zoom in and look at the two, the comparison of the two tracks would look
(and sound) the same (excepting the first 1/2-period of the wave)
regardless of whether you shift the phase 180° or invert the polarity.
With a complex waveform I wouldn't think this to be the case.

> A polarity inversion is a special case, the equivalent of 180 degrees
> of phase shift at all frequencies.
>

I'm not getting this: probably because I'm having trouble not thinking
in terms of a DAW, where if I were to duplicate, say, a kick drum, and
invert the duplicates polarity, it would 'look' (and I dare say, sound)
very different than any type of phase shift I can imagine. In order to
visualize this, would I have to imagine splitting the kick drum up into
all it's composite frequencies, shifting the phase of each one 180°, and
then putting it all back together again? Even still, I can't see how
that could be analogous to polarity inversion, because that doesn't
introduce any kind of delay. Or is it just that it's not really the
same process, but the result is the same?

Aaaaahhhh. My head hurts.

Cheers,
-joe.

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Bob Quintal wrote:

>
> The definition of phase does not require, nor even imply, a
> delay,.
>
> phase: 1. Of a periodic, varying phenomenon, e.g., an electrical
> signal or electromagnetic wave, any distinguishable
> instantaneous state of the phenomenon, referred to a fixed
> reference or another periodic varying phenomenon.
> http://www.its.bldrdoc.gov/fs-1037/dir-027/_3976.htm
>
>

Fair enough, but I think the term 'phase SHIFT' does imply, and even
requires, delay.

That definition would allow for use of the term 'phase invert' though,
wouldn't it? I was always taught that was erroneous.

You learn something new every day.

Cheers,
-joe.

Archived from groups: rec.audio.pro (More info?)

In article <42c261f1$0$16492$afc38c87@news.optusnet.com.au> bloodywanker@drugsmakemecool.com writes:

> What I was getting
> at was that, as far as I can figure, a polarity inversion is, in
> practice, the same as 180° of phase shift for repeating waves. As in:
> if you were to duplicate a track with a 'repeating' type of waveform and
> zoom in and look at the two, the comparison of the two tracks would look
> (and sound) the same (excepting the first 1/2-period of the wave)
> regardless of whether you shift the phase 180° or invert the polarity.
> With a complex waveform I wouldn't think this to be the case.

They would look the same if you picked the right "window" of time for
both. But if you picked the same window of time for both, one would be
going positive at the same time as the other was going negative. And
for a waveform that's symmetrical in time, you won't hear a difference
when listening to one waveform at a time. But sum them and they'll
cancel (you'll certainly hear that).

However if you have non-symmetrical waveforms, not only can you see a
difference in the appearance of the waveform, but there are cases
where the difference is quite audible. If you have a DAw program that
can generate a waveform, try generating a minute or so of a 20 Hz
sawtooth. Import that into your DAW and listen to it. Then invert the
polarity and listen again. You'll hear a difference. If you don't have
a convenient way to generate a waveform, you can download a short
demonstration file that has a few seconds of such a sawtooth, then the
polarity inverts. You'll be able to hear the change on just about any
speakers.

http://www.recordingmag.com/downlo [...] arity.html

> > A polarity inversion is a special case, the equivalent of 180 degrees
> > of phase shift at all frequencies.
>
> I'm not getting this: probably because I'm having trouble not thinking
> in terms of a DAW, where if I were to duplicate, say, a kick drum, and
> invert the duplicates polarity, it would 'look' (and I dare say, sound)
> very different than any type of phase shift I can imagine.

This is true, but if you were to duplicate a simple waveform and
invert the polarity, it would look exactly like a 180 degree phase
shift. It's really difficult to visualize phase shift on a complex
waveform because, other than for special cases, the phase shift of
each frequency that makes up that complex waveform will be different.
However, a polarity inversion is absolute. At any given time, what was
going positive, becomes negative by the same amount. This is what will
happen if in invert the polarity or shift the phase of a single
frequency (which is a sine wave, and only a sine wave) by 180 degrees.

As far as the sound of an inverted kick drum, you can certainly
try that and listen for yourself. A kick drum is a good example of the
kind of waveform that can sound different in opposite polarity, and in
fact, it's often a good idea to try inverting the polarity of the kick
drum to see which way it sounds best in the context of the mix. In
real life, when you have leakage between mics on a drum kit, inverting
the polarity also changes the phase relationship of leakage, which can
have its own effect on the sound of the drum kit.

But that's a digression.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

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Chris Hornbeck <chrishornbeckremovethis@att.net> wrote in
news:7us3c1104imcre44tbqdk1eftd8745llf7@4ax.com:

> On Wed, 29 Jun 2005 00:29:55 GMT, Bob Quintal
> <rquintal@sPAmpatico.ca> wrote:
>
>>The definition of phase does not require, nor even imply, a
>>delay,.
>>
>>phase: 1. Of a periodic, varying phenomenon, e.g., an
>>electrical signal or electromagnetic wave, any distinguishable
>>instantaneous state of the phenomenon, referred to a fixed
>>reference or another periodic varying phenomenon.
>>http://www.its.bldrdoc.gov/fs-1037/dir-027/_3976.htm
>
> It requires a time difference. How do you define "delay"?
>
> Chris Hornbeck
> "Untestable does not mean meaningless."
> -Joe Sensor

Read the definition above. instantaneous figures in the
definition, to either a different (fixed) reference OR to
another periodic varying waveform.

I'll give you another example to chew on, take two different
sine waves, one of 50 Hz the second 55Hz. at some instantaneous
time, the two frequencies will be in phase, and add, at other
instants, they'll be out of phase, and cancel. There is no delay
involved in that example.


--
Bob Quintal

PA is y I've altered my email address.

Archived from groups: rec.audio.pro (More info?)

On Wed, 29 Jun 2005 23:36:07 GMT, Bob Quintal <rquintal@sPAmpatico.ca>
wrote:

>> It requires a time difference. How do you define "delay"?
>
>Read the definition above. instantaneous figures in the
>definition, to either a different (fixed) reference OR to
>another periodic varying waveform.

The question was meant rhetorically, to encourage thought.

>I'll give you another example to chew on, take two different
>sine waves, one of 50 Hz the second 55Hz. at some instantaneous
>time, the two frequencies will be in phase, and add, at other
>instants, they'll be out of phase, and cancel. There is no delay
>involved in that example.

There is no "phase" in this example. Perhaps a standard
text would be the better place to start, rather than newsgroup
postings, which (particularly true in this issue) can be
marginal.

Good fortune,

Chris Hornbeck
"Chief Assistant to the Assistant Chief" -F&S

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Chris Hornbeck <chrishornbeckremovethis@att.net> wrote in
news:3ve6c1lp4f00l8nv71k1nj473oo31683qv@4ax.com:

> On Wed, 29 Jun 2005 23:36:07 GMT, Bob Quintal
> <rquintal@sPAmpatico.ca> wrote:

>>I'll give you another example to chew on, take two different
>>sine waves, one of 50 Hz the second 55Hz. at some
>>instantaneous time, the two frequencies will be in phase, and
>>add, at other instants, they'll be out of phase, and cancel.
>>There is no delay involved in that example.
>
> There is no "phase" in this example. Perhaps a standard
> text would be the better place to start, rather than newsgroup
> postings, which (particularly true in this issue) can be
> marginal.

There is phase in that example. That you cannot understand that
is your loss.

> Good fortune,
>
> Chris Hornbeck
> "Chief Assistant to the Assistant Chief" -F&S
>
--
Bob Quintal

PA is y I've altered my email address.

Archived from groups: rec.audio.pro (More info?)

On 6/30/05 7:34 PM, in article
1120174445.e17f546d469f474db5e809897a6b064d@teranews, "Bob Quintal"
<rquintal@sPAmpatico.ca> wrote:

> SSJVCmag <ten@nozirev.gamnocssj.com> wrote in
> news:BEE8A9F1.B34C%ten@nozirev.gamnocssj.com:
>
>> On 6/29/05 7:36 PM, in article
>> 1120088168.1c753c32c5d8d4991ecc87142d33b707@teranews, "Bob
>> Quintal" <rquintal@sPAmpatico.ca> wrote:
>
>>>>> The definition of phase does not require, nor even imply, a
>>>>> delay,.
>>
>> No it doesn't, but the TOPIC at hand, VARYING PHASE, -does-!
>>
> The original poster used the term Flipping phase, not varying
> phase.

Nice Bob. Really nice. As many would easily and correctly predict, a
question about 'flipping phase' will indeed prompt both a conversation to
POLARITY issues, as well as the correct terminology as to when why and how
to use PHASE or POLARITY, which combines the two into describing what PHASE
really is and why it's related to TIME when you vary it.
Thus the topic at hand is indeed varying phase.

Can we move on now?
Thanks