sebackman
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- Jan 24, 2020
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Hi all,
Frequency measurements are well covered in this thread.
But I do from time-to-time struggle with finding a good repeatable practice to determine time alignment and phase correction to correct in the DSP. And the order thereof.
Genelec often receive good reviews and I think this not only their very nice FR but also that phase and time alignment is excellent. I use a pair of 8340 as reference when building, which is humbling.
I typically use 2-channel time-windowed MLS pulses (reasonable noise resistant) to measure and more or less follow the description in the @napilopez description to find & correct the FR. So far, all good.
When happy with FR and correction on each driver I would like to find a “best practice” for finding the flight time correction and phase correction needed for a 2- or multi-way system.
I guess flight time correction, ie drivers not being in a vertical plane can be done by “ruler”, ie measuring the physical distance, or by SW, ie measuring the difference in flight time at one spot with a certain distance from the speaker baffle.
When using the “ruler” method how do you determine the measuring point on a cone speaker? Or on a larger dome for that matter? Or driver /wave guide?
If you use SW (REW/ARTA or other?), at what distance do you measure and do you focus the mic on the tweeter or “in-between”?
How do you go about this?
In a DSP (non-FIR) all EQ’s, PEQ’s, crossovers and potential passive components after the amp will alter the phase for each driver. A way of finding the phase at XO can be to track phase for the woofer and tweeter when measuring and then apply phase shift on either to “catch-up” to the other. Not easy. This will create different outcome dependent on distance and position of the mic.
How do you go about this? What is your procedure and what settings do you use?
Maybe this is described i practical manors somewhere and if so a link would be appreciated.
Kind regards
//Rob
Frequency measurements are well covered in this thread.
But I do from time-to-time struggle with finding a good repeatable practice to determine time alignment and phase correction to correct in the DSP. And the order thereof.
Genelec often receive good reviews and I think this not only their very nice FR but also that phase and time alignment is excellent. I use a pair of 8340 as reference when building, which is humbling.
I typically use 2-channel time-windowed MLS pulses (reasonable noise resistant) to measure and more or less follow the description in the @napilopez description to find & correct the FR. So far, all good.
When happy with FR and correction on each driver I would like to find a “best practice” for finding the flight time correction and phase correction needed for a 2- or multi-way system.
I guess flight time correction, ie drivers not being in a vertical plane can be done by “ruler”, ie measuring the physical distance, or by SW, ie measuring the difference in flight time at one spot with a certain distance from the speaker baffle.
When using the “ruler” method how do you determine the measuring point on a cone speaker? Or on a larger dome for that matter? Or driver /wave guide?
If you use SW (REW/ARTA or other?), at what distance do you measure and do you focus the mic on the tweeter or “in-between”?
How do you go about this?
In a DSP (non-FIR) all EQ’s, PEQ’s, crossovers and potential passive components after the amp will alter the phase for each driver. A way of finding the phase at XO can be to track phase for the woofer and tweeter when measuring and then apply phase shift on either to “catch-up” to the other. Not easy. This will create different outcome dependent on distance and position of the mic.
How do you go about this? What is your procedure and what settings do you use?
Maybe this is described i practical manors somewhere and if so a link would be appreciated.
Kind regards
//Rob
