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Multi-Way Conventional loudspeakers with crossovers

rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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Old 8th June 2016, 12:58 PM   #1101
pos is offline pos  Europe
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Originally Posted by phantom4 View Post
my subw's design is isobaric, working bandpass. inside the band, there is a huge dip around 54Hz (central freq). same dip exists in main speakers. subw signal is being cut on my subw amp (LPF ~100Hz).

same dip exists in the measurement of main speakers.

after having computed excess group delay, GD chart of REW indicates a peak in group delay as ~90ms right at 68Hz (central freq).

i would like to deploy rePhase, however does not have enough knowledge. i cannot determine the cause of the problem; is it due room mode, is it just a simple magnitude problem that can be smoothed out with EQ? actually, i am confused.

that is why i am asking for solid books to gain a solid understanding of hifi system - environment relationship.
I don't have good book references to give you specifically on measurement techniques (and then loudspeaker and room measurement are also two different subjects, albeit closely related...).

One thing for sure: you should get a proper integration first before even trying to add phase linearization into the mix (that is, unless you are using a FIR crossover).
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Last edited by pos; 8th June 2016 at 01:01 PM.
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Old 8th June 2016, 01:25 PM   #1102
keyser is offline keyser  Netherlands
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Originally Posted by pos View Post
If your target is a minimum phase response (ie you don't linearize the phase of the system's high/low pass) and your crossover are summing properly in a large enough angle, then you should not get any pre ringing.
Pos, I'm not sure I fully understand what you mean by what I marked with bold. Do you mean in-phase crossovers don't work? If you know of a good example of a speaker for which rephase was used to correct phase distortion caused by the crossover, I'd love a link.
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Old 8th June 2016, 01:36 PM   #1103
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I mean a proper in-phase summation over a large enough angle is what one should be looking for.
That implies time aligned drivers (preferably geometrically), directivity matching, and not-to-sharp slopes.

The perfect text book example (albeit not done with rephase) is the one in the Grimm Audio LS12 loudspeaker.
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Last edited by pos; 8th June 2016 at 01:59 PM.
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Old 8th June 2016, 03:35 PM   #1104
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Grimm Audio LS12 loudspeaker.
Err, I meant LS1 : http://www.grimmaudio.com/site/asset...8/speakers.pdf

Keyser, I reread the conversation and I think there must be a misunderstanding somewhere, probably because I was not clear enough.
I totally agree with the principle of in-phase crossover summation, as advocated by Linkwitz
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Old 8th June 2016, 04:22 PM   #1105
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I've worked with rephase to correct the phase distortion of a 2-way LR8 filter on a speaker with drivers that have a very well-behaved response and dispersion and of which the drivers are acoustically aligned. No matter what I do, I always seem to be getting some pre-ringing. Going with less steep crossovers helps, but does not eliminate the issue.

I've looked at the LS1 (which seems to be a very well-designed speaker by the way) and their step response actually does show some minor pre-ringing (see page 6: http://www.grimmaudio.com/site/asset...8/speakers.pdf). Probably inconsequential, but it is there. I have always thought that pre-ringing was an inevitable result of correcting crossover phase and that its inevitability could be proven mathematically. Are you sure that is not the case? Intuitively to me it makes sense there has to be some pre-ringing, because when you visually inspect the filter it appears to be doing things well before the actual peak. But I guess I need to educate myself on the matter .
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Old 8th June 2016, 04:37 PM   #1106
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Quote:
Originally Posted by keyser View Post
I've worked with rephase to correct the phase distortion of a 2-way LR8 filter on a speaker with drivers that have a very well-behaved response and dispersion and of which the drivers are acoustically aligned. No matter what I do, I always seem to be getting some pre-ringing.
What was the frequence of this pre-ringing? A part of it, as seen in Grimm pdf, may come from the dac:


https://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf
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Old 8th June 2016, 07:34 PM   #1107
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Agreed, the preringing probably comes from the DAC's antialiasing filter.

A linear phase filter will have pre (and post) ringing, but the ringing of complementary high and low pass linear phase filters will cancel.
But this cancellation requires the filters to be complementary, which in turn calls for a well matched directivity behavior if you want this to be the case off axis over a reasonable angle.
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Old 8th June 2016, 09:04 PM   #1108
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Pre ringing? What's that? The latest pickiest audiophile excuse against bit manipulation?

Chassez il revient au naturel le galop, it's like a disease...
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Old 9th June 2016, 04:10 AM   #1109
BYRTT is offline BYRTT  Denmark
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
Quote:
Quote:
Originally Posted by keyser View Post
I've worked with rephase to correct the phase distortion of a 2-way LR8 filter on a speaker with drivers that have a very well-behaved response and dispersion and of which the drivers are acoustically aligned. No matter what I do, I always seem to be getting some pre-ringing. Going with less steep crossovers helps, but does not eliminate the issue.

I've looked at the LS1 (which seems to be a very well-designed speaker by the way) and their step response actually does show some minor pre-ringing (see page 6: http://www.grimmaudio.com/site/asset...8/speakers.pdf). Probably inconsequential, but it is there. I have always thought that pre-ringing was an inevitable result of correcting crossover phase and that its inevitability could be proven mathematically. Are you sure that is not the case? Intuitively to me it makes sense there has to be some pre-ringing, because when you visually inspect the filter it appears to be doing things well before the actual peak. But I guess I need to educate myself on the matter .
Quote:
Originally Posted by jmbee View Post
What was the frequence of this pre-ringing? A part of it, as seen in Grimm pdf, may come from the dac:


https://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf
Quote:
Originally Posted by pos View Post
Agreed, the preringing probably comes from the DAC's antialiasing filter.

A linear phase filter will have pre (and post) ringing, but the ringing of complementary high and low pass linear phase filters will cancel.
But this cancellation requires the filters to be complementary, which in turn calls for a well matched directivity behavior if you want this to be the case off axis over a reasonable angle.
keyser,
Beside jmbee and pos good answers pointing to ADC/DAC's, one also can add more excess pre ringing if in measurement setup combination of software verse hardware verse OS is not in sync, below is example of that see more detail in post 1047.
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Old 9th June 2016, 05:59 AM   #1110
BYRTT is offline BYRTT  Denmark
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
Quote:
Originally Posted by keyser View Post
.....I've looked at the LS1 (which seems to be a very well-designed speaker by the way) and their step response actually does show some minor pre-ringing (see page 6: http://www.grimmaudio.com/site/asset...8/speakers.pdf). Probably inconsequential, but it is there. I have always thought that pre-ringing was an inevitable result of correcting crossover phase and that its inevitability could be proven mathematically. Are you sure that is not the case? Intuitively to me it makes sense there has to be some pre-ringing, because when you visually inspect the filter it appears to be doing things well before the actual peak. But I guess I need to educate myself on the matter .
Guess whatever small pre ringing in LS1 paper is their ADC/DAC's or sample rate conversion, about math behind myself got curious and did a small live study. IR in third plot is pretty clean so filters math seems okay and think if reality show other it must be other components in chain or use of wrong filters. In live study use SPDIF loop to rule out distortion from ADC/DAC chain.
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Last edited by BYRTT; 9th June 2016 at 06:04 AM.
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