Pre and post ringing in amplitude and phase corrections

[QMuse]

My first thought would be that is what that SAM process is for but weird enough it looks add tons of more phaseshift and while i can imagine it to be audioable i cant imagine it be natural.

Exactly. SAM actually spoiled phase so I can't understand what was the idea behind it.

 

[Soniclife]

In below curves that is traced from over stereophile site i see one error that is system roll off in lows is somehere beteen 2nd and 3rd order slope and that is not in line with a ported tuning will be of 4th order roll off so think for system sum curve they had some room gain into their measured curve

They don't compensate their measurements correctly in the bass, it's explained on their site. Would that affect the roll off?

 

[Soniclife]

In relation to topic for this thread one can in DSP linearize above grey curve excess phase relative to green phase curve that belong to amplitude of system. My first thought would be that is what that SAM process is for but weird enough it looks add tons of more phaseshift and while i can imagine it to be audioable i cant imagine it be natural.

As they are using IIR filters for this I don't think they could fix the phase, and the response at the same time. Their specific claim was they could fix the response, without pre ringing.

 

[BYRTT]

Exactly. SAM actually spoiled phase so I can't understand what was the idea behind it.

Ha ha agree whats the idea, in initial view of those graphs thought no SAM was the processed one.

They don't compensate their measurements correctly in the bass, it's explained on their site. Would that affect the roll off?

Thanks that explain we get some room gain there in lows roll off, it doesn't mean anything for previous textbook simulation exercise because phase was set minimum phase (follow amplitude response), it was just i felt best tell about the roll off was not a real 4th order one as expected for ported design so no one could question simulated model was idiotic or way off reality : )

As they are using IIR filters for this I don't think they could fix the phase, and the response at the same time. Their specific claim was they could fix the response, without pre ringing.

Sounds right then if DSP is 100% IIR filter based, if i'm not too lazy will have a look down the road read their manual, but can say have seen some other brands DSP is configured as dual band so as sample rate in the low band can be set to half or quater of the high band, a feature that improve on time it takes to process stuff so system lag is as low as possible, but that dual band feature cost that huge phase shifting minimum phase filter and there's a chance it is what wee see in your unit.

 

[andreasmaaan]

@Soniclife, thanks for taking those measurements. Oddly, my copy of REW won't open them - this is the error message it gives me:

even though the files are obviously in .mdat format. Anyone have any ideas?

If not, perhaps @Soniclife you wouldn't mind taking screenshots of the phase responses and step responses with SAM engaged and disengaged?

 

[QMuse]

@Soniclife, thanks for taking those measurements. Oddly, my copy of REW won't open them - this is the error message it gives me:

View attachment 54936

even though the files are obviously in .mdat format. Anyone have any ideas?

Upgrading to the latest version is always a good idea with problems like this one.

 

[andreasmaaan]

Upgrading to the latest version is always a good idea with problems like this one.

Need I have mentioned that I'm running the latest version?

 

[QMuse]

Need I have mentioned that I'm running the latest version?

Well, yes - mentioning that is always a good idea.

Try this one (change extension from .txt to .mdat).

 

[Soniclife]

@Soniclife, thanks for taking those measurements. Oddly, my copy of REW won't open them - this is the error message it gives me:

View attachment 54936

even though the files are obviously in .mdat format. Anyone have any ideas?

If not, perhaps @Soniclife you wouldn't mind taking screenshots of the phase responses and step responses with SAM engaged and disengaged?

Odd, as others opened them. Are you on a Mac, they were done with Windows.
I'm on holiday this week, so away from my machine.

 

[QMuse]

If not, perhaps [USER=297]@Soniclife you wouldn't mind taking screenshots of the phase responses and step responses with SAM engaged and disengaged?

I already posted those on the previous page.

 

[andreasmaaan]

Odd, as others opened them. Are you on a Mac, they were done with Windows.
I'm on holiday this week, so away from my machine.

Really strange, yeh I'm also running Windows...

I already posted those on the previous page.

Oops, thanks for that Exactly as you stated @QMuse, SAM processing appears to be having the opposite effect to that claimed, rendering the speaker's time-domain performance far less linear.

Very odd - I have no idea why it would (apparently) be doing that, either intentionally or as a side effect of some other intentional processing. The degree of phase distortion SAM appears to be introducing actually pushes the speaker beyond experimentally derived thresholds of audibility, at least for certain listeners and with certain signals.