Speaker phase confusion

Upon opening the crossover in this person's loudspeaker it was discovered the midrange driver is wired in opposite phase. Is that right or a mistake?

[alt]

Loved this video! Short, sweet and 100% to the point with no fluff.

[rigorhead]

Pretty darn good explanation for the layman. Great video!

[hugobloemers]

Talking about Chris, the lunch talks with Chris where among the best videos of this channel. It would be nice to have some more of that.

[richardhernandez]

Making sense from confusion, thanks, Paul.

[OG-gx]

Great explanation! The beauty of digital FIR filter in the crossover is that the stay linear.

[samueldewit]

It's almost like your painting a nyquist diagram in the air. Seeing someone explaining phases, filters and phase shifts like that makes you smile 😀 Great video.👍

[retiredjedi]

Besides the wiring phase there is also phase shift from driver coil not on same plane. Then wire reverse can correct. When determining needed phase, only do one speaker. When you close your eyes and listen. You want all drives to sound as one. Out of phase with each other accusticly will sound like separate speakers. Swap the midrange wires and listen again you will hear the difference. You always want the bass cone to move forward on positive signals. Use a 'D' cell battery for cone direction test

[Stronz_music]

Very very nice explained, simple and should be easy to understand for all people .

I think the problem with this is that most people can not wrap around in their head
what is really going on when polarity is flipped .

- Example -
3 ways system, bass, mid and tweeter with mid flipped polarity -

- - Most misunderstandings is that they think - -

'''' When the mid is flipped then it play opposite ''''
When the bass and tweeter '' push out, then they think the mid is
still pull in '' .
This is because they doesn't get what the phase means .
When the phase is reversed that mean the electrical polarity is reversed so
what was the '' plus side '' now become the '' minus side ''

Sound waves is made of waves going from plus to minus voltage and the time
in between two cycles ( a plus and minus ) determines the frequency .
( the wave lenght in between two )
That is why two equally signals but 180 degree out of phase wll cancel
each other out .
There is a voltage cycle at 360 degree in a full cycle and at 270 degree it is
fully reversed so what was max positive voltage is now max negative voltage .
( fully reversed when there is 180 degree in between them )
That mean a signal at 10 volt max positive at 90 degree
and 10 volt max negative 270 degree will result in 0 voltage .
If the two signals is 180 degree out of phase so the max positive and max
negative is at exact same time .
( Thus in between the 90 degree and 270 degree is 180 degree difference )

The cycle start at 0 degree at 0 voltage and rice up to max voltage at 90 degree then it
decrease to 0 at 180 degree and further decrease into negative voltage to
max negative at 270 degree and rise up to 0 voltage at 360 degree .
( also zerro degree . 0 degree is start of cycle and 360 is end and start of new so also 0 )

This is for a normal symetrical sine wave there is waves with other characteristics .

It is the same with Air preasure from moving speakers .
When two equally speakers is placed front to front and phase is flipped 180 degree
on one of them they will cancel each other out .
When one push the other will pull and result is '' nothing '' .

This is the principle used in noise cancelation systems ( eg headsets or in cars ect )
You take the noise and flip the phase and send it back out to calcel it out .

You have to explain it like the red and black terminals on the speaker '' plus, minus ''
so they can get the physical picture of what is going on .
Even when say ' It is to get the phase right at listning position, they wont get
what it means and still think '' the mid is kind of reversed ''
But the mid is NOT reversed at all .
( Even if it look reversed )
When the phase is shifted then the electrical plus point of the sine wave is
now become the minus side and vise versa .
So to wire it up correctly with respect to '' plus and minus '' on the mid speaker
terminals, you then have to reverse them .

This simply mean that in the end all 3 speakers, Bass, mid and tweeter
they Push and pull at the same time as if one speaker .
They are all in phase as we say and the acoustical push / pull of the
air in the room is also in phase
( They move the air in same direction at same time )

Another typically misunderstandings is that many people claim,
'' when the speaker is reversed then you loose the tight transient's
because the sound doesn't exactely start at once blah blah ''
Yes believe or not, there is still many there claim that .

It is simply NOT true at all, the phase ( voltage ) is reversed in the
cross over filter and '' timing '' is still the same .
so in the case of a 3 way speaker with mid reversed then the electrical
'' polarity '' is just reversed and the mid still play at same timing .
This is simply just a myth .
There are other factors in play when it comes to transient response .
One imortant factor is the acclerationof the speaker itself .
A heavier cone is a bit slower to start and stop than a lighter one .
Also the ' spider's ' construction tribute to how fast it can acclerate
and the accleration is what determine how effective it is to replicate
transients with good or bad response .

The place ment of the speakers themself in the cabinet can also tribute
to how well the speakers is ' lined up ' in phase with each other .
A good rule of thumb is -
When you look at the speaker cabinet from the side, then the speakers
should NOT be lined up on a front baffle in one line .
The mid and tweeter should be moved back so the voice coils are in line
with each other .
This to make shure that the wave lenghts ' line up ' so all the frequencies
reach you at the same time .
This will increase the ' transient's ' so it sound more ' fast ' .
If they arrive a little out of phase ( Yes this is phase again ) then it will
sound ' more muddy ' and '' clarity '' be less accurate .
( so to use HiFi words )

That is why you see speakers where the mid and tweeter is lined up longer
to the back than the bass when look at the front of the speaker cabinet .
Simply to get the wave lenght's lined up in phase .

Reflections and the room itself is also a major player, tributing to change
the acoustical phase .
When a wave is hitting a wall and reflected back it get delayed and the delay
itself when arrive at listning position can be out of phase too .
A good example is a bass wave when it hit a back wall and reflect ( bounce back )
at certain frequencies depending of the room size, some frequencies will
hit each other and cancel out when arrive and phase is going through negative .
But other frequencies will hit when top of wave meet each other and ' amplify '
each other .
If top of one half of wave with same polarity meet at same time the result is
now a double size wave and this is what caused STANDING waves in the room .
So you end up with some bass that simply is gone and you lack bass in certain
frequencies while in others you end with way too much, resulting in this
typically '' Boomy '' bass sound .

On the other hand the higher frequencies they do the same and the result end up
with ' harsh ' sound and too much and / or too little in those frequencies .
But the higher frequencies also produce ' echo / delay ' too ...

You can combat this by using bass absorbers in the corners and acoustic
damping of the walls ect .
But you can NEVER remove it 100 percent .
You can only ' tame ' the problem so it be less ' visible to your ears '
A perfect room doesn't exist but you can get close enough that it will sound
near perfect and really good ( even on a very cheap budget )

Yes there is many factors in play that can change the phase of the
acoustical signal ( the air moved )
Being an Audiophile / musician can be a really challenge when it comes to
get '' The Perfect Sound '' .

Thanks making this video Paul .
Short but very informative and easy to understand explanation .
Im shure many people will understand it .

Edit - Sorry for my typos, it is very late now here in the philippines and im
sitting with my coffe .

[nisabelle]

Great as always. Thanks Paul, we are lucky to have you here!

[txmike]

Good explanation. That happened to me with a 2-way I designed, using a 1st order filter (plus Zobel) for the woofer and a 2nd order for the tweeter. Assembled, my frequency test showed a big dip at the crossover point. So I reversed the polarity on the tweeter and the result was a beautiful, flat response curve. That was a learning point for me.

[MrDoneboy]

Tnank's Paul, for your no nonsense approach, to explaining the madness of electronics!

[anaussieaudiophile]

Very interesting Paul enjoyed the explanation about how a crossover works and the phase shifting that occurs.

[janinapalmer]

That crossover point is SO critical ... you can get a huge peak or an equally big suck out ...

[graxjpg]

I know that filtering shifts phase. The midrange driver being the most filtered, it makes sense to flip its phase. Thanks Paul for making ideas like this easier to understand

[doowopper]

It could also be that the midrange has an odd order crossover and the woofer and tweeter use even order crossover (or vice versa). Just as each stage of an amplifier inverts phase, so does each order of a crossover.

[Rene_Christensen]

It is not that you want all drivers to be in phase, as only a few cross-overs have that aim (such as Linkwitz-Riley), and you have to try to achieve that even as the drivers have their own phase. It is that you want a flat magnitude! And then there is a natural way to wire the drivers as parts of the transfer function may have negative sign in its numerator.

[budgetaudiophilelife-long]

🤔 MAKES SENSE ….THANKS PAUL FOR EXPLAINING IT IN A WAY WE CAN UNDERSTAND 🤗🤗🤗😍😍😍

[preddy]

Thought I'd add that the phase and polarity stuff (outer box or inner crossovers) for a single speaker box doesn't matter until a stereo setup is needed. Then placement, polarity/phase becomes important.

[TheMirolab]

Paul stresses that the goal is acoustic summation at the crossover point, but I'd argue that it's electrical too. A 2nd order LP on the woofer will usually rotate the phase by around 90 deg at the -3dB point (depending greatly on the filter alignment). A 2nd order HP on the tweeter will ALSO rotate the phase 90 deg in the other direction. That puts the 2 drivers 180 deg out of phase at the crossover point... both acoustically AND electrically. Forget about 3-ways.... even on 2-ways you will often find the tweeter wired in reverse.... It also depends on the physical time-alignment of the drivers, the baffle angle, and the intended listening angle. There's a LOT of variables, even for just a 2-way speaker.

[ScottGrammer]

Excellent explanation, and spot on the money.