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Best crossover point between 400hz and 1000hz?

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  • #16
    Originally posted by billfitzmaurice View Post
    Time align is most critical in the 300-700Hz range, to the extent that it can be very audible when it's off, so if you lack the ability to time align either by physical placement or electronic means you're better off not crossing over there, choosing your drivers accordingly.
    Got it, thanks.

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    • #17
      Originally posted by billfitzmaurice View Post
      Anything below 800Hz can be an issue, so it's an area to be avoided.
      Say what???????

      I guess that means most 3way designs have no chance of working properly. Good grief!
      https://www.facebook.com/Mosaic-Audi...7373763888294/

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      • #18
        Originally posted by billfitzmaurice View Post
        That's where our ears are most sensitive to the effects of delays between multiple sources.
        Group delay audibility threshold (headphones) is 1ms worst case at 400Hz to 5 kHz, and 2ms at 200Hz, but the 1 ms difference is a foot of air path difference. No way you'll hear a fraction of that difference especially in a room with reflections.

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        • #19
          I said nothing about group delay. The problems that can arise with a crossover in the 300-700Hz range have been well known since the 1930s. Check your back issues of the JAES.
          www.billfitzmaurice.com
          www.billfitzmaurice.info/forum

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          • #20
            Originally posted by billfitzmaurice View Post
            I said nothing about group delay. The problems that can arise with a crossover in the 300-700Hz range have been well known since the 1930s. Check your back issues of the JAES.

            Are you referring to those tests they did in the 30s with the big horn cabinets in movie theaters, moving the cells back and forth and listening? I remember those but nothing else that would qualify as 'well known". Those test were particular to a really different set of radiation patterns, box sizes and listening venue than a set of home speakers.

            If you're referring to something else, I'm not aware of it but would love to hear about it.

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            • #21
              Originally posted by DDF View Post

              Group delay audibility threshold (headphones) is 1ms worst case at 400Hz to 5 kHz, and 2ms at 200Hz, but the 1 ms difference is a foot of air path difference. No way you'll hear a fraction of that difference especially in a room with reflections.
              I'm not clear on what you're saying here, I think the "(headphones)" is throwing me off.

              Are you saying that at 400-Hz (for example), a 1ms difference (or a foot path of air) between drivers (like a woofer and a midrange) is unrecognizable?

              Is there a table or a way to derive the time from the frequency?

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              • #22
                Originally posted by DDF View Post


                Are you referring to those tests they did in the 30s with the big horn cabinets in movie theaters, moving the cells back and forth and listening? I remember those but nothing else that would qualify as 'well known". Those test were particular to a really different set of radiation patterns, box sizes and listening venue than a set of home speakers.

                If you're referring to something else, I'm not aware of it but would love to hear about it.

                Bill, PS not trying to play gotcha, sincerely curious. Are you referring to the fact that 300-700 Hz is the meat of the vocal range? I agree getting the xover wrong in this range is the worst range to get it wrong, but I think a properly designed xover and driver compliment would work fine in this range.

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                • #23
                  Originally posted by philthien View Post

                  I'm not clear on what you're saying here, I think the "(headphones)" is throwing me off.

                  Are you saying that at 400-Hz (for example), a 1ms difference (or a foot path of air) between drivers (like a woofer and a midrange) is unrecognizable?

                  Is there a table or a way to derive the time from the frequency?

                  Easiest way to remember is 1kHz wavelength ~ foot, and it all scales off that (500Hz = 2 ft, 2 khz = .5 ft...). I thought Bill was saying that group delay distortion (ie different frequencies having different delays to your ears) was most audible 300-700Hz, but its not what he was saying.

                  No, I wan't saying moving the driver a foot is unrecognizable. It will change the off axis radiation pattern which changes total power response, response at reflection points etc and that's audible. What wouldn't be audible is the effect on group delay, the limits of audibility of which was studied using headphones

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