What exactly is GLM doing to set phase?

[Mort]

I am tempted to video this but maybe I can describe.

GLM has two phases, the first one that resembles all other DSP I've done (Wiim, Dirac live, audyssey )

You hit the button, sweep one monitor, maybe a timing chirp, sweep second and done. Right? We've all done that a million times.

GLM has a second 'phase' configuration where it will repeatedly (about 5 minutes) play a tone very near the selected crossover. The tone will repeat, get louder and softer, alternate phase and then the other speaker goes. It's quite slow compared to the first stage.

My question is about the second stage. What is happening in GLM that the other DSPs skip? Is it important? Why would they not do the same thing? By what mechanism does this work? What exactly is being accomplished?

I may have misunderstood or framed something wrong. Feel free to correct.



One thing I will say, the automatic subwoofer integration of GLM is amazing.

 

[dagfinn]

GLM has crossover and control DSP in each of your monitors too, and can manipulate phase/EQ for each driver separate. Extended Phase Linearity? I'm guessing, I have no Ones nor GLM.

 

[Mort]

Extended Phase Linearity? I'm guessing,

That's a good guess.

 

[darkinners]

I believe you mean Auto Cal and Auto Phase Alignment, the chirp/sweep you hear in "first stage" is for frequency calibration to your room, not calibrating the phase.
The "2nd stage" I think you mean the phase alignment, that only available when you have SAM enabled Genelec subwoofer. I am guess it keep playing a tone at the set crossover frequency at different degree of phase (per 15° interval), the GLM microphone pickup the level of different degree of phase alignment and set the loudest one as the closest phase alignment.

 

[Mort]

I believe you mean Auto Cal and Auto Phase Alignment, the chirp/sweep you hear in "first stage" is for frequency calibration to your room, not calibrating the phase.
The "2nd stage" I think you mean the phase alignment, that only available when you have SAM enabled Genelec subwoofer. I am guess it keep playing a tone at the set crossover frequency at different degree of phase (per 15° interval), the GLM microphone pickup the level of different degree of phase alignment and set the loudest one as the closest phase alignment.

Yeah that sounds about right.

Why don't other DSPs use this approach?

 

[TheKoC]

Yeah that sounds about right.

Why don't other DSPs use this approach?

GLM is specific für the SAM-Monitors, so it can change the active crossovers between drivers directly. I assume that is what this is for (just a guess, I don't have Genelecs). It knows the capability of each speaker exactly.
Other DSPs have the "disadvantage" of having to work with all kinds of active/passive speakers, and can't do that.