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Old 24th August 2004, 04:53 AM   #1
Deafboy is offline Deafboy  Canada
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Default Crossover design question

I'm designing a two-way loudspeaker system using Dynaudio drivers. I modeled the impedance and acoustic frequency responses of the drivers using CALSOD from measurements that I've taken. I designed the crossover for each driver in order to get 4th order L-R alignments. So far so good. My question is, since drivers aren't perfect, should I optimize the final -system- response for flattest frequency response or should I try to get as close as possible to the theoretical L-R alignments? If I try get flattest system response then each driver + crossover section deviates quite a bit from the theoretical L-R alignments. I may get very flat frequency response but I lose advantages of the L-R alignments.

Which is the better compromise for getting best subjective results?

Thanks in advance,

Michel
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Old 24th August 2004, 01:23 PM   #2
Jay is offline Jay  Indonesia
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In my opinion, good ear is the most important tool, no matter how advance the technology used in the design.

For expensive drivers like yours, why wouldn't you try both approach and listen??
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Old 24th August 2004, 01:37 PM   #3
Deafboy is offline Deafboy  Canada
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Quote:
Originally posted by Jay
In my opinion, good ear is the most important tool, no matter how advance the technology used in the design.

For expensive drivers like yours, why wouldn't you try both approach and listen??
I guess I could, I just wonder what are the opinions of other people that were in the same position as I am now.
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Old 24th August 2004, 01:43 PM   #4
gary f is offline gary f  Canada
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I don't care so much for perfect textbook crossover. As long as the drivers are in phase at x-over frequency. I guess it's much better to have good frequency response.

F
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Old 24th August 2004, 03:08 PM   #5
Deafboy is offline Deafboy  Canada
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Quote:
Originally posted by gary f
I don't care so much for perfect textbook crossover. As long as the drivers are in phase at x-over frequency. I guess it's much better to have good frequency response.

F
Can you can give me reasons why you think so?
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Old 24th August 2004, 03:18 PM   #6
Svante is offline Svante  Sweden
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Default Re: Crossover design question

Quote:
Originally posted by Deafboy
[B] since drivers aren't perfect, should I optimize the final -system- response for flattest frequency response
No doubt, yes. The overall system response is much more important than the frequency response at the loudspeaker terminals, or some other point in the signal path.
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Old 24th August 2004, 06:17 PM   #7
Salas is offline Salas  Greece
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Personally a have abandoned any simulation aid years ago.
I go the old way, measure-listen-measure-listen, cycle.
Much work, long period...real loudspeaker. Simulation is great to avoid gross errors. Cant suggest the sound when we go to tailor things.
Just my humble experience, I dont claim any justification of my approach.
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Old 24th August 2004, 06:53 PM   #8
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If natural reproduction is your aim, I would go for flattest frequency response any day. And I would use measurement equipment to varify it too, because although the ear-brain system is remarkable in many ways it is notoriously bad at picking out frequency response deviations. Room acoustics will have a big effect on the final response too.

/M
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Old 25th August 2004, 04:16 AM   #9
Jay is offline Jay  Indonesia
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Default Re: Crossover design question

Quote:
Originally posted by Deafboy
My question is, since drivers aren't perfect, should I optimize the final -system- response for flattest frequency response or should I try to get as close as possible to the theoretical L-R alignments?
Quote:
Originally posted by gary f
I don't care so much for perfect textbook crossover. As long as the drivers are in phase at x-over frequency. I guess it's much better to have good frequency response.
Quote:
Originally posted by Deafboy
Can you can give me reasons why you think so?
Flat response is necessary, L-R allignment is not. Text book allignments try to give flat response at cross point (or a few dB bump) with "mirror" superposition. So the flat response is infact the objective, while the technique may vary.

Text book crossovers also assumme a constant resistive load which is not true. Textbook crossover also do not include complete enough parameters (i.e. the characters of individual driver, so we heard something like 1.2Re or crossing at 2 octave above Fs???). Then the accoustic effect of the enclosure. Then the capacitor brand
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Old 25th August 2004, 06:25 AM   #10
Deafboy is offline Deafboy  Canada
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Default Re: Re: Crossover design question

Quote:
Originally posted by Jay






Flat response is necessary, L-R allignment is not. Text book allignments try to give flat response at cross point (or a few dB bump) with "mirror" superposition. So the flat response is infact the objective, while the technique may vary.

Text book crossovers also assumme a constant resistive load which is not true. Textbook crossover also do not include complete enough parameters (i.e. the characters of individual driver, so we heard something like 1.2Re or crossing at 2 octave above Fs???). Then the accoustic effect of the enclosure. Then the capacitor brand
OK, frequency reponse is the desired goal. The advantages of the L-K alignment is the lobing is less severe and less frequency dependant. That in itself is also a frequency response criteria.

BTW, I never mentioned about a using "textbook" crossovers supposing perfect drivers having resistive loads and perfect acoustic response. What I'm talking about is designing the crossover so that each driver (real drivers) matches as close as possible the ideal acoustic response of a 4th order L-R alignment. The sum of the driver responses (system reponse) gives a acoustic frequency which is more or less flat (because the drivers aren't perfect). Further optimization of the frequency response of the whole system with CALSOD can give a flatter result.
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