Phase shift

[March Audio]

Why I love my modded KEF Q100 speakers? Thanks to a very good 5.25" coaxial I have time aligned ALL frequencies ->"magical" sound versus traditional 2-ways (KEF 6.5" coaxial has not these "magical"). With acoustic instruments the "magical" is more great.

The problem with the delay is if they are different in woofer versus tweeter, like 2-ways.

https://en.wikipedia.org/wiki/Loudspeaker_time_alignment

[ Loudspeaker time-alignment usually simply referred to as "time-alignment or Time-Align" is a term applied to loudspeaker systems which use multiple drivers (like woofer, mid-range and tweeter) to cover the entire audio range. It is the technique of delaying the sound emanating from one or more drivers (greater than 2-way) to correct the transient response, improve accuracy and, in non-coaxial drivers, improve the directivity or lobe tilting at the crossover frequencies. ]

In class A and AB, the phase is not exceeded by +/- 6º in the audio band, although it is rarely publicized. Why should class D have another criteria?

https://www.audiosciencereview.com/...-of-purifi-1et400a-amplifier.7984/post-254975

Hypex NC400, measured by amirm at my request. The graph shows how the phase varies with frequency, progressively, but varies.

Of course, loudspeakers with a good DSP you can solve the problem -> Kii and many others. But traditional loudspeakers without DSP...

Phase is important for crossovers in speakers. Poor phase alignment causes summation issues and directionality issues as you show. Do not conflate this with unrelated amplifier issues.

 

[ernestcarl]

REW V5.20 Beta 24, Overlays window

Oops... not that much older.

Looks more or less the same

 

[March Audio]

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).

Maty

Don is precisely correct. The phase, so long as it shifts linearly with frequency is of no issue. You do not need it to be zero across the frequency range. Until you understand and accept this point you will continue to mislead yourself and others.

 

[RayDunzl]

please take a look at how much passive speakers usually mangle phase

I measured the JBL 308 up close, and the phase looked flatter. The phase gets mangled after bouncing around the room, so, I guess we're used to it or largely immune. Of interest to me is how the stats extend that flat measured phase on out to the listener.

Red - JBL LSR 308 at a meter or so
Black - MartinLogan at 10 feet

 

[Killingbeans]

Maty why are you still banging on about this?

It's just one of those great mysteries that no man (or woman for that matter) will ever be able to solve.

 

[ahofer]

It’s kind of like Ron Paul bringing up the Gold Standard in every congressional hearing where he could get his hands on the mic.

 

[ernestcarl]

Just a question:

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

View attachment 37712

Reading this from the Neumann website made me wonder about the seemingly high GD in my measurements:

frequency-dependent delay…
The subjective effect of excessive group delay is a “loosening” of the bass or a “less dry” bass quality. Currently there is insufficient psychoacoustic research on the threshold of group delay at low frequencies. One value is known: 2.5 ms at 100 Hz. This happens to be the same as that seen in the KH 310 A and O 410. A vented cabinet with a similar low frequency performance would have about 5 ms of group delay at 100 Hz. At higher frequencies, >1 kHz, group delay should be less than 1.6 ms (55 cm or 2 ft), which it is in most loudspeaker designs.

From the Help Wizard: "If the system being measured was inherently minimum phase (as most crossovers are, for example) the minimum phase response is the same as removing any time delay from the measurement. Room measurements are typically not minimum phase except in some regions, mainly at low frequencies."

Okay, seems to be close enough... that is being outside an ideal measuring environment. The extreme climb below 30Hz likely has to do with my extreme sub cut off and/or room.

 

[Cbdb2]

[QUOTE="maty, post:
PS: Hugh Dean always defends that GNFB must be < 29 dB - 31 dB to obtain better sound.

-> https://www.diyaudio.com/forums/aksa/294346-brand-super-aksa-saksa-85-a-6.html#post4878481

5. Feedback has an effect on the sound quality...[/QUOTE]

Are you sure thats not > 31db? Thats what this well known paper says. It also shows that other feedback has the same effect as GNFB, so people who think local feedback is better than global are wrong.

https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf

I believe the "standard" procedure for amp design is to design for lowest distortions before applying feedback, than add the feedback to linearize the cicuit more.

 

[Julf]

I believe the "standard" procedure for amp design is to design for lowest distortions before applying feedback, than add the feedback to linearize the cicuit more.

Bruno Putzeys: The F-word (or why there is no such thing as too much feedback)

 

[Cbdb2]

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).

Not sure I understand. Your not saying delaying the entire signal has an audible effect? Thats just to easy to prove wrong.

 

[Cbdb2]

I measured the JBL 308 up close, and the phase looked flatter. The phase gets mangled after bouncing around the room, so, I guess we're used to it or largely immune. Of interest to me is how the stats extend that flat measured phase on out to the listener.

the freq. domain doesnt show the right info. Think of a drum hit, its the initial spike that gets mangled, and that hits your ears before any room effects get there. And every time Dr. Toole talks about it he say it "usually" makes no difference, which I take as it sometimes does matter, somwhy not adress it.

 

[NTK]

the freq. domain doesnt show the right info. Think of a drum hit, its the initial spike that gets mangled, and that hits your ears before any room effects get there. And every time Dr. Toole talks about it he say it "usually" makes no difference, which I take as it sometimes does matter, somwhy not adress it.

There was a discussion a couple of months ago on AVS Forum on this topic, and I quote Dr. Toole from one of his posts:

...
As for "monaural" effects, there have been several careful tests over the years, explained in Section 4.8.1 in the 3rd edition, showing that even in anechoic or headphone listening to specially constructed sounds, humans are essentially phase deaf. Why? Because if we were sensitive to phase shift in sounds we would go crazy - virtually everything we hear is randomly corrupted by phase shifts because of reflected sounds. Think about just carrying on a conversation across a table - the voice waveform is corrupted by the strong table reflection, but it is not a perceptual problem.

https://www.avsforum.com/forum/89-s...aker-what-science-shows-155.html#post58503332

 

[RayDunzl]

the freq. domain doesnt show the right info.

True.

I try to look at more than than just the frequency when I'm looking.

The "hash" in the upper frequences of an unsmoothed frequency response shows reflections (cancellations/narrow dips)

Impulse response shows reflections.

Step response gives hints to timing and bass ringing with discontinuities at reflection times.

ETC shows late levels from the room.

An in-room recording shows waveforms/timing for comparison to source wave.

And so on.

There's plenty to see when fooling around. I do that sometimes.

 

[Cbdb2]

There was a discussion a couple of months ago on AVS Forum on this topic, and I quote Dr. Toole from one of his posts:

https://www.avsforum.com/forum/89-s...aker-what-science-shows-155.html#post58503332

Dr Tooles not perfect. If he can explain how a snare drum attack, the first few mllisecs, is effected by reflections that dont arrive till after the attack I might buy it. Im not saying hes wrong about us being phase deaf just not buying the room explanation, besides doesnt he claim the same deafness in anechoic chambers and headphones?

 

[maty]

https://www.audiosciencereview.com/...-dual-mono-stereo-amp-review.9938/post-268273

Corrected results of Hypex NC400 is much worse!!!

https://www.audiosciencereview.com/...ments-of-hypex-nc400-diy-amp.5907/post-132771

First measurements: about 16º at 20 kHz. Corrected: 41º at 20 kHz.

 

[Julf]

Corrected results of Hypex NC400 is much worse!!!

"Larger", not "worse". What's up with the 1990's web colors?

 

[DS23MAN]

Maty,

Give us some rest, tomorrow morning at 9.00 AM you can indulge yourself testing and reviewing build quality, phase respons and mains filters over here:

https://www.mediamarkt.es/mcs/marketinfo/_MediaMarkt-Tarragona-Tarragona,27356,-5.html

 

[maty]

It is not my problem that many are confused about the phase, mixing concepts.

 

[Thomas savage]

It is not my problem that many are confused about the phase, mixing concepts.

You do need to learn when it's best to step off your hobby horse mate.

 

[DS23MAN]

It is not my problem that many are confused about the phase, mixing concepts.

Ok,

Please do a write up for us ( no Google copy/paste) about absolute phase, minimum phase, excess phase and group delay....