Phase. Polarity. Balance

[James Bang 5,000+ posts]

For those that are running passives, do you all just plug them in and play.

+ to +

- to -

on both tweeter and mid? Exactly how the owners' manual says to do?

Live on the edge and try to disobey the owners'/installation manual //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Click to read more...

 

[James Bang 5,000+ posts]

folks with component sets wanna chime in? //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[mcsoul 10+ year member]

I spoke with ARC support on a pair of passives i purchased and they flip the polarity on the tweeter already. So if you flip it, your flipping it back //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif.

 

[Beerdrnkr 5,000+ posts]

What's a passive xover?

Not many people adjust the passives because they're usually mounted somewhere that's not that easy to get to.

 

[James Bang 5,000+ posts]

I spoke with ARC support on a pair of passives i purchased and they flip the polarity on the tweeter already. So if you flip it, your flipping it back //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif.

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Well, i'm not sure why they would have done that. Not all cars/speakers location/aiming are the same.

Good thing for phase verification tracks. tools. use 'em

 

[mcsoul 10+ year member]

I was ready some **** somewhere that said you get a 180' phase shift for each 24db of crossover slope. I can't remember if it applied to only passive, active or both, or if I was just reading wrong. I try to give myself credit for reading though, but deep down inside I know the remembering part makes all the difference.

 

[7ender 10+ year member]

I used this. Found it on the forum awhile back and saved it to my computer.

1. Set all bands flat, as well as the head unit bass and treble.

2. Turn off the subs. Using music with a good bass line, run the highpass crossover up and down until the midbasses can play as low as possible without any distortion or excessive door panel vibrations.

3. Unhook the mids and tweeters, allowing only the midbasses to play. Listen to mono pink noise or a well-recorded song with a centered vocalist. Test CDs such as the IASCA test CD or Autosound 2000 Test CD 102 or 103 will work great. Listen to where the centered sounds are coming from. Then reverse the polarity of one midbass (Reverse the speaker wires coming from the passive crossover and going to the speaker, just flip the positive and negative wires. I usually flip the driver’s side speaker.) and re-listen to the test CD. If the sounds are more centered then keep it as is. If the centered sounds are more diffuse and un-locatable, then flip the polarity back to where it was originally.

4. Then unhook the midbasses and play the mids only and follow the same polarity and listening tests as before. Mark your best settings.

5. Do the same procedure for the tweeters.

6. When you have tested for the proper polarity from all three ranges of speakers, hook all of them back up with respect to each set of speaker’s best polarity. You can have any combination of polarity, such as all the midbass and tweeters straight and one midrange reversed.

7. Now you should have the correct “acoustic” polarity set within each set of speakers. Next is to set the acoustic polarity between the sets of speakers.

8. Listen to some very familiar music with a good range of sounds. Then flip both midbass’ polarity and listen again. Before you only flipped one midbass, now you are doing both at the same time. For example if the left midbass was reversed and the right was not before, now the left will be not reversed and the right will be. Listen to the music again. If the midbass is more powerful and full then leave the wiring as is. If the midbass sounds weaker and wrong then restore the wiring as before.

9. Perform the same listening tests while flipping the mids and tweeters, and use the wiring configuration that sounds the best.

10. If you have went though all these steps adjusting the polarity of the speakers then the system should sound really good without any eq adjustments. You might want to play with the gain adjustments on the crossover and/or amp to better blend all the speakers together.

obviously, desiregard the mid if you're using two ways.

 

[thch 10+ year member]

this is of use --

a rule of thumb is that for every 12dB/oct of difference between the HPF and the LPF, the phase of one should be inverted to correct for that phase shift difference. the higher slope filters will introduce more phase shift than the lower slope filters.

the acoustic phase of the speaker isn't accounted for in this. thus a speaker that experiences a -12dB/oct slope of its own, and whose phase response is reasonably similar to a what the T/S model predicts wouldn't need that phase inversion.

The phase difference of the speakers are not gaurunteed to be well matched. it is possible for the tweeter to be mounted far from the mid, and at ~3khz, the wavelengths are fairly short to the point that inches can become significant in terms of phase shift.

A car environment also allows for significant reflections from windows, plastics, ect, which can affect the response of the system.

so from the drawing board, where everything is clean, significant unknowns are added. as such the original choice to invert or not invert the tweeter may end up being wrong.

 

[Ctesibius 10+ year member]

I was ready some **** somewhere that said you get a 180' phase shift for each 24db of crossover slope. I can't remember if it applied to only passive, active or both, or if I was just reading wrong. I try to give myself credit for reading though, but deep down inside I know the remembering part makes all the difference.

There is a 90 degree phase shift for every 6db/oct.

A 180 degree phase shift would occur w/ a 12db/oct slope.

24db/oct would have a 360 degree phase shift......

Also keep in mind that some passive crossovers may state their "slope" as an acoustical roll-off rather than an electrical roll-off. They may only need to apply 12db/oct of electrical filtering to achieve a targeted 24db/oct acoustic roll-off, and call it a "24db/oct slope". This probably occurs moreso in home audio than car audio though.

 

[ramos 5,000+ posts]

For those that are running passives, do you all just plug them in and play.
+ to +

- to -

on both tweeter and mid? Exactly how the owners' manual says to do?

Live on the edge and try to disobey the owners'/installation manual //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Actually I do start with everything in mechanical phase, then make adjustments to bring everything into acoustical phase //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif