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EPDRNotes<br><br>

Phase - the relationship between two waves:

0-120 = additions
12-240 = subtractions
240-360 = additions

0 = +6dB
90= +3dB
180= Cancellation
270= +3dB

wavelength (m)= velocity/frequency
wl=v/f
wl=340/f

100hz wl= 340/100 = 17m

period (for one complete cycle)
t(sec)=1/f
x1000 for m/s

phase relationship for two sources, different arrivals, offsets etc in m

phase= (distance (m) x frequency (Hz) x 360) / 340 m/s

p= (m.f.360) / 340

phase as a time offset

p = (time (m/s) x frequency x 360) / 1000ms

p = (t x f x 360) /1000

comb filter response

periodicity (distance between cancellation or sums)

pr = 1/time offset
pr= 1/o

filters   butterworth and linkwitz reiley 

butterworth is -3dB at crossover point, with 1, 2, 3 etc order filters
lr is -6db at xover point with 2, 4, 6 etc order filters

filters  effects
1st  -6dB /oct      - 45degress phase
2     -12dB         - 90 deg
3 -    -18db     -  135 deg
4-      - 24dB      - 180deg

I must be taking care with the crossover filters I use, especially as the higher order ones have  extreme transiet response characteristics, with ms delays in response. The issue of crossover choice wil take a bit more thinking about but in the case of a dancefloor system, best sound quality will be achieved with farily moderate slopes I think. The ringing effects arent as bad and the cancellation is not so much of an issue with non acoustic information. Its more to do with the tailing off of the slope on top box, and checking polarity as a response to this - mabye not an issue but needs more exploration.

EPStandingwaves