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Phase shift

DonH56

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#61
It is what I have been saying from the beginning. That is fixed, constant ... that phase does not vary with the frequency -> linear, FLAT, ideally 0º in ALL audio band.

It has always been that way and a new amplification technology should respect it.

Imagine an audio chain in which the source, the preamp and the amplifier each vary the phase with the frequency ... We have to eliminate variables from the equation and not to add a new one.
It is impossible to achieve 0 degrees of phase shift in (through) a real system -- there is always some delay unless you have infinite bandwidth. If you delay each and every frequency equally, the signal will arrive all nicely lined up in time, but that requires linear phase.
 
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maty

maty

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Thread Starter #62
Yes, but let us minimize the possible causes of phase shift in ALL electronic components, class D amps included. A wave has three parameters: amplitude, frequency and phase. An ideal audio system should modify only the amplitude of the input signal. Unless it is so throughout the electronic part!

Other thing is a constant, fixed time delay. A few weeks ago I am playing with it from JRiver MC 64-bits, DSP. One of the reasons why I am interested in the dominant H2 profile is to have greater depth in my second system, limited by listening in the near field. Playing with the delays I have achieved greater depth, playing with values from 1 ms to 5 ms. I am even able to fine tune a little more, for example 4.2 ms, thanks to which the piano concerts I have heard these days sounded better than with 5 ms (orchestral music).
 
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Julf

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#63
Yes, but let us minimize the possible causes of phase shift in ALL electronic components, class D amps included. A wave has three parameters: amplitude, frequency and phase. An ideal audio system should modify only the amplitude of the input signal. Unless it is so throughout the electronic part!
Any audio system modifies the phase of the signal.

Other thing is a constant, fixed timne delay. A few weeks ago I am playing with it from JRiver MC 64-bits, DSP. One of the reasons why I am interested in the dominant H2 profile is to have greater depth in my second system, limited by listening in the near field. Playing with the delays I have achieved greater depth, playing with values from 1 ms to 5 ms. I am even able to fine tune a little more, for example 4.2 ms, thanks to which the piano concerts I have heard these days sounded better than with 5 ms (orchestral music).
So what are you delaying in relation to what?
 

Soniclife

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#64
Any audio system modifies the phase of the signal.



So what are you delaying in relation to what?
I believe thinks that different delay settings sound different. When applied to the whole signal, not frequency dependent. Just a simple delay.
 

Julf

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#65
I believe thinks that different delay settings sound different. When applied to the whole signal, not frequency dependent. Just a simple delay.
To a single pair of speakers? If a 5 ms delay brings benefits, think about the hundreds of megaseconds between recording the album and staring playback? :)
 

Julf

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#67
That's how I've been reading it yes.
I just couldn't believe that is what he meant. The easiest way to generate a 5 ms delay is to push "play" 5 ms later than intended...
 

Julf

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#69

Matias

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#70
In my understanding this is a no issue. Bruno already explained this, but again. The delay is constant in time for all frequencies. Only when you plot that constant time as a phase degree x frequency that it shows as a curve. But again these are constant delay in time for all frequencies. No problem.
 
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Cosmik

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#71
Any audio system modifies the phase of the signal.
What does that mean? An audio system can certainly be designed to give no phase modification (it might need to add some latency, however). It will, always be true, of course, that a 1mm length of cable is causing some phase shift. Just not very much. So your statement is literally true, but not very useful :)
 

Julf

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#72
What does that mean? An audio system can certainly be designed to give no phase modification (it might need to add some latency, however). It will, always be true, of course, that a 1mm length of cable is causing some phase shift. Just not very much. So your statement is literally true, but not very useful :)
As useful as the phase mania of @maty, but I was really talking about delay (as it seems that is what maty also talks about).
 

RayDunzl

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#73
My DSP twists phase based on what it "hears" at the listening position, overruling anything else in the chain (except itself).

1572731139833.png


The MartinLogan EQ must have been set for "sharper" automated correction than the JBL trace - more squiggles... this example was two years ago
 
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RayDunzl

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#74
At the listening position...

The MartinLogans throw a measureable "flat" phase over most of the range to the listening position, regular speakers don't, I think, due to their wider dispersion and wall/ceiling/floor reflections.

Here's the listening position phase measurement of my ML in my room vs @dallasjustice M2 setup in his room.

1572732692251.png


Brian Ding (Rythmik Audio) looked at one of my posts and said "That's impossible!"

My cone/dome speakers measure like the M2 above at the listening position. Nearfield, their phase measurement is much flatter (if not entirely flat).
 
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KSTR

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#75
Ray,
switch to linear frequency scale and then note the basically linear slope of the red curve... an underlying pure time delay, point-of-reference type of measurement error. You have to de-embed this for the real phase and then you'll also get a resonable Y-axis scaling (now it's a full 360 degrees per grid line!). The reference point must be set to the top of the first peak of the impulse reponse, for both data sets.
Phase measurements are tricky ;-)
 

RayDunzl

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#76
switch to linear frequency scale and then note the basically linear slope of the black curve...
Do you mean the red curve? (M2 in this case)

1572736406438.png


Makes the 'stats look even better.

an underlying pure time delay, point-of-reference type of measurement error. You have to de-embed this for the real phase and then you'll also get a resonable Y-axis scaling (now it's a full 360 degrees per grid line!). The reference point must be set to the top of the first peak of the impulse reponse, for both data sets.
Phase measurements are tricky ;-)
And what do I have to do to adjust the black line (electrostats)?
 
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ernestcarl

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#77
Ray, that looks like a much older version of REW... I was looking for a Phase only tab but couldn't find it!

I don't exactly understand Maty's obsession with having perfect phase.

Mucked around with the options and here's what I've got:
1572738883417.jpeg
 

ernestcarl

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#78
Just a question:

As for the group delay view in REW, which is more important to look at for reference? The "Min Group Delay"?

1572740500004.jpeg
 

RayDunzl

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#79
Ray, that looks like a much older version of REW... I was looking for a Phase only tab but couldn't find it!
REW V5.20 Beta 24, Overlays window

1572741053737.png
 

March Audio

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#80
Only some words about phase shift, some designers do care, just now: https://www.diyaudio.com/forums/solid-state/344540-alpha-nirvana-39w-8ohm-class-amp.html



Updated with image:

View attachment 37252

- End off topic -
Maty why are you still banging on about this?

Phase shift has importance. The bit you haven't grasped with reference to the Bruno Putzeys comments and his class d designs is this.

If the phase shifts linearly with frequency ie x deg per Hz then it is just a time delay across the whole frequency range which is of no importance at all. When phase shifts non linearly then different frequencies get delayed different amounts from each other. This could be an issue.

Please try and understand the difference between the two situations and stop misrepresenting this as an issue with his class d designs. This is just your lack of understanding of the subject which has been endlessly explained. Its tedious to keep having to correct your lack of understanding.

Also, having said this please take a look at how much passive speakers usually mangle phase and you might come to a different conclusion regarding how important minor shifts are in amplifiers.
 
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