I did google for this. When a 2nd order crossover is used, tweeters are often wired out of phase to keep them in phase with the mid( or mid/woofer in 2 way spk). But in a 3 way system, where the tweeter is wired out of phase with the mids, I have not seen the woofer also wired out of phase.
Why is that?
Why is that?
Yes, the woofer should always be wired in positive polarity (cone goes out of the cabinet for a positive input voltage
applied to the positive input terminal), and then the other drivers are connected in polarities relative to the woofer.
applied to the positive input terminal), and then the other drivers are connected in polarities relative to the woofer.
If you are using 2nd order on a three way, the standard I have followed is you only wire the mid in reverse polarity.
That makes sense to me, but I hadn't noticed it in practice. Maybe I just wasn't looking well enough.
That said, this is the crossover from mine and a friend's Moabs. The tweeter (Blue) is out of phase from the mids (Green), but the woofers (Red) don't appear to be. Does that make sense? (Not relevant to my question, but the right green runs 12 of the 14 "tweeter" drivers in 4 sets of 3, the left green the other 2 - they function as 2 midrange drivers)
Brad,
if your 3 way system has perfect "textbook" 2nd order acoustic crossover slopes, the mid would be out of phase with the other drivers but realize that 2nd order topology refers to the electrical response of the filter, and does not account for the the acoustic response of the driver + filter combo. You have to take into account the acoustic roll off of each driver. Example: if the tweeter naturally rolls off at -12dB/oct at 2.5Khz and you apply a -12db high pass filter at 2.5khz, you now have a -24dB roll off at 2.5KHz and the drivers would want to sum flat while being in phase with each other, no reversal needed. If things aren't exact, You may also get an 18db /oct roll off , the phase response will be off by 90 deg and the tweeter may work in or out of phase. You could end up with anything in between, To sum it up (pun intended) there is no simple way to tell the correct phase of a driver in a system by filter topology alone, you really need to measure the system or listen really closely and the connection that sounds "sucked out" is probably incorrect. Hope this all make sense. Happy to clarify if not.
Geo
