Very confused, crossover help

[Jakerrr 10+ year member]

Ok, so I've been researching a lot about crossovers. It seems like there are 2 schools of thought, the 1st one being less popular, but it was "keep hope alive" who said it:

1) Each order (6dB) adds 60 degrees to the phase.

2) 1st order (-6dB/octave) does not change phase, 2nd order (-12dB/octave) flips phase 180 degrees, and 3rd and 4th change phase minimally.

Also I've read contradicting information as to whether electronic/active crossovers switch phase just like passives. The only thing that seems universal is that 2nd order (-12dB/oct) flips phase 180 degrees.

Can anyone help clear some of this up for me? The main thing I'm most concerned with, is this:

If my passive crossover for my mid and tweet is low/high pass 12/12 dB octave, ignoring other variables, my tweet and midbass will be in phase because they've BOTH been flipped 180 degrees out of phase by the crossover, right? Because a lot of people say you need to reverse the polarity on either the tweets or the mids, not both, in order to have them in phase. I'm so confused...

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[honkyg 10+ year member]

from everything ive learned over the years concerning crossover, i was certain just about everything ive read depicts each order as a 90* shift, i.e.; 1st order=90*, 2nd=180*, 3rd=270*, and 4th=360*

(5th [30db/octave] and 6th [36db/octave] orders too, but not practical for a cabin environment).

as i understand it from experience, if the tweet and mid are very close to each other or on a coaxial/braxial alignment, they should be relatively in phase, as well as most mass produced crossovers i know of have each crossover section built in the same order.

the easiest way to shift 180* is to wire the driver/s in opposite polarity.

i believe the case of shifting phase 180* is necessary for only one side of the vehicle if you're running into discernible differences in l/r stage imaging at given frequencies.

active crossovers by nature do not shift phase thanks to the advent of the 24db/octave linkwitz-riley design. some active crossovers, active capable head units, and most dsp's have options to change the roll-off (decay)/roll-in (attack) slope (db/octave), but the response is consistently in phase and then can be fine tuned with time alignment dependent on axis placement between drivers.

i tend to steer away from passive setups if i can due to the difficulty of dialing each band in properly or building a lattice delay into the passive filter.

kha will need to weigh in on this.

 

[Jakerrr 10+ year member]

from everything ive learned over the years concerning crossover, i was certain just about everything ive read depicts each order as a 90* shift, i.e.; 1st order=90*, 2nd=180*, 3rd=270*, and 4th=360* (5th [30db/octave] and 6th [36db/octave] orders too, but not practical for a cabin environment).

as i understand it from experience, if the tweet and mid are very close to each other or on a coaxial/braxial alignment, they should be relatively in phase, as well as most mass produced crossovers i know of have each crossover section built in the same order.

the easiest way to shift 180* is to wire the driver/s in opposite polarity.

i believe the case of shifting phase 180* is necessary for only one side of the vehicle if you're running into discernible differences in l/r stage imaging at given frequencies.

active crossovers by nature do not shift phase thanks to the advent of the 24db/octave linkwitz-riley design. some active crossovers, active capable head units, and most dsp's have options to change the roll-off (decay)/roll-in (attack) slope (db/octave), but the response is consistently in phase and then can be fine tuned with time alignment dependent on axis placement between drivers.

i tend to steer away from passive setups if i can due to the difficulty of dialing each band in properly or building a lattice delay into the passive filter.

kha will need to weigh in on this.

So a 12dB/oct active x-over would not affect phase? Everything I've read says it does. My mid and tweeter are both equidistant from listening position.

I researched a little more and it is universally understood that the tweeter and woofer will be 180 degrees out of phase (one section is -90 degrees, the other is +90, = 180) in a 12 db/oct hi/lo pass, passive crossover. So now my question is:

do component sets come with the negative terminal output for the tweeter labelled "+" and vice versa? Or do you have to reverse the polarity yourself and wire backwards at the tweeter manually?

 

[honkyg 10+ year member]

So a 12dB/oct active x-over would not affect phase? Everything I've read says it does. My mid and tweeter are both equidistant from listening position.
I researched a little more and it is universally understood that the tweeter and woofer will be 180 degrees out of phase (one section is -90 degrees, the other is +90, = 180) in a 12 db/oct hi/lo pass, passive crossover. So now my question is:

do component sets come with the negative terminal output for the tweeter labelled "+" and vice versa? Or do you have to reverse the polarity yourself and wire backwards at the tweeter manually?

ok, i need to see what youre reading, because something does not sound right and im halfway tempted to say you getting confused.

heres a link to understanding linkwitz-riley and butterworth Linkwitz-Riley Crossovers: A Primer

edit, maybe im the one getting confused, lmao.

 

[Jakerrr 10+ year member]

ok, i need to see what youre reading, because something does not sound right and im halfway tempted to say youre getting confused.
heres a link to understanding linkwitz-riley and butterworth Linkwitz-Riley Crossovers: A Primer

All I am saying is the tweeter and woofer connected to the same crossover will be 180 degrees out of phase with respect to each other, so one of them must be wired in reverse polarity. Practically every single audio site explains it like that.

"If the speakers are wired with the same polarity (the positive speaker wire connected to the positive terminal of each speaker) the connection is in-phase. For 12dB/octave crossovers, this connection will result in a deep dip in the output response at the crossover point. To get a flat response (or close to flat for alignments other than Linkwitz-Riley), you must wire one speaker out of phase (typically, the tweeter is wired out of phase)."

Passive Crossover Slopes

I'm not sure what you thought I was confused about, but wiring the tweeter in reverse in 2nd order x-overs is universally explained through every audio website. I'm just wondering if the company who manufactures a component speaker system takes this into account and labels their tweeter terminals in reverse, or if they expect the customer to take care of the problem themselves or ignore it

 

[Jakerrr 10+ year member]

ok, i need to see what youre reading, because something does not sound right and im halfway tempted to say you getting confused.
heres a link to understanding linkwitz-riley and butterworth Linkwitz-Riley Crossovers: A Primer

edit, maybe im the one getting confused, lmao.

Even the site you gave me says it in several places...

"We now have a 2nd-order Linkwitz-Riley crossover. The new vector diagram looks like Figure 14a. Each vector is .5 long (from the fact that each 1st-order reduces by 0.707, and .707 x .707 = .5) with phase angles of ±90°. Since the phase difference equals 180°, we invert one before adding and wind up with a unity vector 90° out of phase with the original."

"The summed response is perfectly flat. Figure 16 shows the phase response. At the crossover frequency we see the HF output (upper trace) has +90° phase shift, while the LF output (lower trace) has -90° phase shift, for a total phase difference of 180°. Invert one before summing and the result is identical to the LF output."

 

[honkyg 10+ year member]

Even the site you gave me says it in several places...
"We now have a 2nd-order Linkwitz-Riley crossover. The new vector diagram looks like Figure 14a. Each vector is .5 long (from the fact that each 1st-order reduces by 0.707, and .707 x .707 = .5) with phase angles of ±90°. Since the phase difference equals 180°, we invert one before adding and wind up with a unity vector 90° out of phase with the original."

"The summed response is perfectly flat. Figure 16 shows the phase response. At the crossover frequency we see the HF output (upper trace) has +90° phase shift, while the LF output (lower trace) has -90° phase shift, for a total phase difference of 180°. Invert one before summing and the result is identical to the LF output."

i get what youre saying now,.. and tbh, i was the one being confused,.. in fact, i was confusing myself, lol, not you.

yes, the high and low passes are 180 degrees out of phase in a 12db/octave passive crossover, but if you look at the construction of the passive crossover, its fairly clear that manufacturers do not account for that in terms of wiring the tweeter in opposite polarity,.. least thats what i see from the hundreds i have downstairs.

ill get back to this when i have more time. im currently trying to put my home theater together.

 

[Jakerrr 10+ year member]

i get what youre saying now,.. and tbh, i was the one being confused,.. in fact, i was confusing myself, lol, not you.
yes, the high and low passes are 180 degrees out of phase in a 12db/octave passive crossover, but if you look at the construction of the passive crossover, its fairly clear that manufacturers do not account for that in terms of wiring the tweeter in opposite polarity,.. least thats what i see from the hundreds i have downstairs.

ill get back to this when i have more time. im currently trying to put my home theater together.

Thanks man. ill just play a 3.2 Hz tone with the tweeters how they are and reversed. The louder one will be correct