some answered, but more questions...
Thanks catapult, that makes sense too.
Did he invert the connections to the tweeter terminals, because at both very high and very low frequencies it is inverting overall?
Or does that also depend on the crossover filters?
Thanks catapult, that makes sense too.
Did he invert the connections to the tweeter terminals, because at both very high and very low frequencies it is inverting overall?
Or does that also depend on the crossover filters?
No, the mid and tweet are wired in phase. The XO is LR4 and non-inverting. The allpass stages are -90 + -270 in the midband so they are non-inverting as well. In theory, they are just a simple time delay with no phase shift. In the real world, there is some phase shift at Fc but he optimized the Fo values with acoustical measurements to get good phase tracking through the crossover range.
Phoenix XO
Thanks for the links.
It's good to see how the professionals with years of experience do it. I'll have a go, and see if I can get even 1% of their performance.🙂
It's good to see how the professionals with years of experience do it. I'll have a go, and see if I can get even 1% of their performance.🙂
Don't forget that there's a polarity-inverting level adjusting stage upstream of the all-pass networks in the Phoenix design. It can get a little confusing, but when you add up all the phase shifts, polarity flips, and roll-offs created by the filter sections the correct polarity hookup for the tweeter is the same as midrange.
http://www.woodartistry.com/linkwitzlab/filters.htm#4
Davey.
http://www.woodartistry.com/linkwitzlab/filters.htm#4
Davey.
catapult said:
Hello all
Exhalent observations Catapult, your notes confirmed a couple of things that were not quite clear to me. Here is another link that mite be of interest.
http://www.woodartistry.com/linkwitzlab/phs-dist2.htm
Another point to consider for the defence of an allpass, is phase shift audiable? SL doesn't seem to think so and who am I to argue. This being true, correcting the phase mismatch introduced by the drivers, crossovers and physical position of the two drivers at and around the crossover frequency makes sence. Another way to put it, if you can't hear phase shift from a single driver, but you can hear it where two drivers with different phase meet (crossover), then try to fix it there, and not worry about phase shift elsewhere.
One thing that is not clear to me is SL uses alternates 0 to -180 and -180 to -360 allpass configs, why not just use multiple 0 to 180 allpass?
Exhalent observations Catapult, your notes confirmed a couple of things that were not quite clear to me. Here is another link that mite be of interest.
http://www.woodartistry.com/linkwitzlab/phs-dist2.htm
Another point to consider for the defence of an allpass, is phase shift audiable? SL doesn't seem to think so and who am I to argue. This being true, correcting the phase mismatch introduced by the drivers, crossovers and physical position of the two drivers at and around the crossover frequency makes sence. Another way to put it, if you can't hear phase shift from a single driver, but you can hear it where two drivers with different phase meet (crossover), then try to fix it there, and not worry about phase shift elsewhere.
One thing that is not clear to me is SL uses alternates 0 to -180 and -180 to -360 allpass configs, why not just use multiple 0 to 180 allpass?
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