What is the effect of Baffle Step on the Phase?

Bricolo · 25th July 2007, 03:13 PM

Hi all,

Here's a question that just came to my mind.
We all know that the baffle step effect reduces the amplitude of the acoustical for the frequencies below the baffle width.

That can be compensated for, actively or passively.

But if the Baffle Step lowers the signal by 6dB in the lows, how is the phase affected? I haven't seen any information about that.

Cheers,
Alex

phase_accurate · 25th July 2007, 03:22 PM

The behaviour of the baffle-step is minimum-phase. Beacuse of that it has the same phase-response as a so called lead filter. The ususal lag filter that is used to EQ it has a phase and amplitude response that is the mirror image of the lead filter.

Regards

Charles

Bricolo · 25th July 2007, 03:32 PM

Good news.

Is there any non-minimum phase behaviors in "natural" things anyway? (by natural I mean physical effects you can observe, not a filter function created by humans)

sreten · 25th July 2007, 05:29 PM

Hi,

The phase is affected the inverse of the correcting circuit.
i.e. : BSC puts the theorectical phase back where it should be.

/sreten.

Svante · 25th July 2007, 05:58 PM

Quote:

Originally posted by sreten
Hi,

The phase is affected the inverse of the correcting circuit.
i.e. : BSC puts the theorectical phase back where it should be.

/sreten.

Yes, indeed.

A simulated case can look like this. It can be seen that the baffle step (green curve) has a positive phase shift around 300 Hz, and that the compensation circuit has a negative phase shift of approximately the same magnitude. This results in the red curve, which is near zero.

25th July 2007, 03:13 PM	#1
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	What is the effect of Baffle Step on the Phase? Hi all, Here's a question that just came to my mind. We all know that the baffle step effect reduces the amplitude of the acoustical for the frequencies below the baffle width. That can be compensated for, actively or passively. But if the Baffle Step lowers the signal by 6dB in the lows, how is the phase affected? I haven't seen any information about that. Cheers, Alex __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

25th July 2007, 03:32 PM	#3
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	Good news. Is there any non-minimum phase behaviors in "natural" things anyway? (by natural I mean physical effects you can observe, not a filter function created by humans) __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

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25th July 2007, 03:22 PM	#2
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	The behaviour of the baffle-step is minimum-phase. Beacuse of that it has the same phase-response as a so called lead filter. The ususal lag filter that is used to EQ it has a phase and amplitude response that is the mirror image of the lead filter. Regards Charles

25th July 2007, 05:29 PM	#4
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, The phase is affected the inverse of the correcting circuit. i.e. : BSC puts the theorectical phase back where it should be. /sreten.

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