Audio Signal Phase 101

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Tutorial Breakdown:

Signal Phase
- What's the deal?
- Why does it matter?
- What tools are available?

- In-phase vs. Out-of-phase?
- "Kind of" In-phase?
- "Sort of" Out-of-phase?

Phase is complicated
— Not just In-phase or Out-of-phase
Signal processors can effect phase
— Phase distortion
Good news: humans cannot perceive signal phase differences in some cases
Bad news: other cases...

Signal phase is complicated
— Phase is frequency dependent
Are signal processors going to screw up my mix?
— Linear phase processors

Linear phase
— What's with the name?
Non-linear phase
— Are there any drawbacks or trade-offs?

Is a signal phase shift the equivalent of a time shift, just without the shift in time?
— That doesn't seem so bad
It is more complicated than that
— Phase is frequency dependent

Linear phase
— What's with the name?
— Non-linear phase
Are there any drawbacks or trade-offs?

Linear Phase
— Processing results in a constant time shift for all frequencies
— Relationship between frequencies is not distorted
Trade-off
— Time delay (Latency)

When are linear phase processors useful?
— When you don't want the phase relationship between different frequencies to be distorted
— When a little latency doesn't hurt anything
— Master Bus
— Compensate for latency

[hectorguitar]

Awesome explanation. As an electrical engineer, I am familiar with the topic of distortionless channels and linearity of phase, but you did a very good job at summarizing how this affects your decision making process when mixing and mastering audio.

[mjkirk]

How about including some real life audio examples to reinforce these concepts?

[williameden]

Love Eric Tarr, however i feel David Dorrans explanation makes more sense to me.. My muddled explanation would be.. if in relation to each other all frequencies are delayed by the same amount, ie having a constant group delay, (for linear phase thats half a sample). The output signal will retain all sinusoidal frequencies in their exact same sinusoidal state with a time shift of half the filter length (n/2). .

[sergeyche]

thank u..loved the slow simple speaking

[Amarnamusick]

is their fhase issuing when i only mix solely one wave alone?

or phase issues arise when there are many woves?


thanks again, i remembered to ask another question, please...


u said avoiding frequency distortion, so i may understand from this that phase issues only arise when there are multi tracks not only a one track, ??... like if i' m equing my guitar line alone, as the song have only one guitar recorded in it
? so in this example of a one track do i will face phase issues with it, or no because it isn't playing with any other tracks... sorry i cant translate well but i hope u understand my question...


thanks again
from Alexandria/ Egypt
Foxidoband
Myzzym.

[sikor]

So in general, nonlinear filters (when it comes to phase) shouldn't mess anything up? I mean - you cannot hear the difference?

[chefrabih]

hello pro audio, got an issue with the lack of bass in my hi fi system, it was like ( no 35 hz - 40 hz - even 45 hz were heard ) so i tried to push a bottom called " absolute phase 180 " on my carver preamp panel, the quantity and quality of the bass has changed, but not quite sure if other sounds were affected like MIDS OR HIGHS ! mmm what do you say ?

[marxmenmusicnyc]

to the maker of this video record an audio signal thats audible then worry about phase