# Choosing crossover: 12, 18, or 24db slope



## B'dole (Nov 2, 2010)

I'm trying to pick a good crossover setup for the following system:

Fronts: 6.5"/1" components, amp does not have a built-in crossover
Center: DIN-sized center speaker kit, amp has 12db slope crossover, will probably use 400Hz
Rears: 6.5" coaxials, amp has 12db slope crossover, will probably use 100Hz
Sub: 6.5" CVT654, amp has 12db slope crossover, will probably use 100Hz

So the easiest solution would be to just use the head unit crossover setting or a pair of Fmods to hi-pass the front components, 12db slope at either 80, 100, or 120Hz. Does the passive crossover included with most components already hi-pass for the mid-bass or not?

Alternatively, I had thought about going with either the Planet Audio EC20B or the Clarion MCD360 3-way crossover. Those crossovers would let me use an 18db slope over three pairs of speakers, including much more control over the sub. I could use it on the Fronts, Center, and Sub, while letting the Rears remain 12db amp crossover'd.

I have read here that I may have phase issues with a 12 db or an 18db slope. The Planet Audio and Clarion include phase switches for the sub only. My head unit allows time alignment. Not too keen on reversing speaking polarity.

Thoughts and recommendations are much appreciated!


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## kyheng (Jan 31, 2007)

Got steeper slope are always better, but then have to depend to your spekaers location, that's more important.


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## katodevin (Feb 14, 2008)

I would disagree with the "always better" statement. It all depends on your install, so experiment.

In my experience, with closely mounted drivers that are capable of playing a wide range, 12db slopes with phase inversion sound more natural to me than steeper slopes. If you're playing near your speaker's limits, then yes, steeper slopes are better always.


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## Allan74 (Jun 17, 2010)

Butterworth ?, Linkwitz ?


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## quality_sound (Dec 25, 2005)

I like 24dB slopes personally. Well, multiples of 24 really. I don't like dealing with the phase issues of odd-order slopes.


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## sqnut (Dec 24, 2009)

Allan74 said:


> Butterworth ?, Linkwitz ?


Would you hear the difference?


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## kyheng (Jan 31, 2007)

katodevin said:


> I would disagree with the "always better" statement. It all depends on your install, so experiment.
> 
> In my experience, with closely mounted drivers that are capable of playing a wide range, 12db slopes with phase inversion sound more natural to me than steeper slopes. If you're playing near your speaker's limits, then yes, steeper slopes are better always.


I think you got me wrong on that... Period..
What I meant was, got steeper slopes means you have more tuning options. Does not means you have to set steep slopes all the time.


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## B'dole (Nov 2, 2010)

Thanks for the responses. 

Neither the head unit or the amp list their crossover type, other than being 12db/octave. Upon further reading though, I see that the head unit crossover is deactived when playing SACD, which will be one of the primary uses. So the head unit crossover is off the table.

Here are a few choices which differ by slope (and price!):

1a. Pair of 12db/octave Fmods on the non-crossover'd amp. $25
1b. Plus an 18db/octave PFmod on the sub. $40

2. Six channels of 18db/octave crossovers for the fronts, center, and sub. $60

3. Six channels of 24db/octave Linkwitz-Riley crossovers for the fronts, center, and sub (AudioControl 6XS), plus the pleasure (sic) of dealing with the replaceable crossover modules . $200+

Further thoughts?


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## kyheng (Jan 31, 2007)

Depends on how much more you willing to spend, I may consider the latest MS-8 or Audison BitOne.1.
Going passive on car is not the best method, as it is time consuming and a lot of parts(coils and capacitors) to be used to get the "best" crossover point that suits your taste.


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## Arezump (Jan 6, 2010)

kyheng said:


> Depends on how much more you willing to spend, I may consider the latest MS-8 or Audison BitOne.1.
> Going passive on car is not the best method, as it is time consuming and a lot of parts(coils and capacitors) to be used to get the "best" crossover point that suits your taste.


ahh..c'mon man, dont pave the thread by forcing its subjectivity to be debated again..& again....how in the hell u think that passive wouldnt be the best method?

am nodding my head when it comes to those "time consuming" part..but for certain people out there, the climax are just right at the peak of "doing the right thing" by giving all your commitments on choosing various names, values, type of capacitors/coils/resistors as they think that those efforts could be much more rewarding rather than doing it "plug n play..!!"


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## kyheng (Jan 31, 2007)

^You are right... But did I force others to follow? Nope, I don't. I don't mind if you wanted to be a screen dumb and if this will makes you happy, go ahead, I'll let you be the winner.


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## Arezump (Jan 6, 2010)

kyheng said:


> ^You are right... But did I force others to follow? Nope, I don't. I don't mind if you wanted to be a screen dumb and if this will makes you happy, go ahead, I'll let you be the winner.


wow..you're too emotional man.. take it easy..
no one will take the podium today!
btw, watch your words as no one like to be a "screen dumb" or an emotional biatch socializing on her menstrual pain day! ouchh..!!


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## B'dole (Nov 2, 2010)

Um, so if I can interject, I understand a 12 db slope changes the phase 180 degrees and an 18db slope changes it 270 degrees. And the 180 can be fixed by reversing polarity. Can the 270 be fixed, or do 18db slope/270 degree crossovers always sound off? 

18db and 24db seems to be relatively popular for the subwoofer, while 12db and 24db seem more common for the components. What is the reason?


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## brocken (Apr 26, 2010)

To answer a question in the OP - no, most passive crossovers do not have a high pass built in for mids. You would need to set that with your amp or HU.
The passive XO usually has a lowpass for the mids and a highpass for the tweets.


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## B'dole (Nov 2, 2010)

brocken said:


> To answer a question in the OP - no, most passive crossovers do not have a high pass built in for mids. You would need to set that with your amp or HU.
> The passive XO usually has a lowpass for the mids and a highpass for the tweets.


Thanks brocken. I had suspected that might be the case, but the literature never says for components. It would make sense to do it that way so that the installer can blend them with the sub.


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## katodevin (Feb 14, 2008)

Arezump said:


> wow..you're too emotional man.. take it easy..
> no one will take the podium today!
> btw, watch your words as no one like to be a "screen dumb" or an emotional biatch socializing on her menstrual pain day! ouchh..!!


Yah, I'm not sure if its an ESL thing or not (or maybe Maylasia is just rude), but many of Kyheng's posts come off really abrasive and abrupt, if I see him get involved in a thread, that is usually my cue to exit, stage left.


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## kyheng (Jan 31, 2007)

^Well, it is always because you choose not to understand and trying to be a hero.... If a person can't differentiate "set" and "got", it is sad, right?


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## Allan74 (Jun 17, 2010)

sqnut said:


> Would you hear the difference?


Between Butterworth ?, Linkwitz ? Eventually, I am sure, by way of distortion if not careful.....and depending on the setup.

If you are riding the ragged edge of LOW TWEETER Crossover Point (_for example, 1800hz_), it would sure be nice to know if you were -3db, -6db or even flat on the crossover point itself......so atleast you have a better chance of keeping things within your control. Choosing a slope is only half the battle I think.


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## Allan74 (Jun 17, 2010)

I just realized something as well....which turns out to be my fault for not asking more questions about the situations certain statements were made in.

I have always found it quite disturbing that many people here have claimed to run Midbass hipass crossover points of 70hz etc......when in fact I should have confirmed that most were likely running a Linkwitz alignment, which is already -6db down at the crossover point......rather than doubt them entirely.

For some reason, when someone rattles off a crossover value in conversation, My brain is programmed to think Chebychev first, by default (_even though it's an alignment that I would never use_).....looking at the crossover point itself as the actuall beginning of the slope with no attenuation beforehand.....then onto Butterworth as my secondary, which is only -3db down at the crossover point.

EUREKA ! My brain actually does work on occasion......lol


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## kyheng (Jan 31, 2007)

^^Because most systems they have a sub, that's where those value(63, 70, 80Hz come about), also the resonance frequencies of the particular midbass is around that range... So it is like a fail safe value for midbass's HPF.


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## Allan74 (Jun 17, 2010)

kyheng said:


> ^^Because most systems they have a sub, that's where those value(63, 70, 80Hz come about), also the resonance frequencies of the particular midbass is around that range... So it is like a fail safe value for midbass's HPF.


You officially get the 'Captain Obvious' award for the first part of your statement. I am rolling my eyes at the last part......


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## tornaido_3927 (Nov 23, 2009)

B'dole said:


> Um, so if I can interject, I understand a 12 db slope changes the phase 180 degrees and an 18db slope changes it 270 degrees. And the 180 can be fixed by reversing polarity. Can the 270 be fixed, or do 18db slope/270 degree crossovers always sound off?
> 
> 18db and 24db seems to be relatively popular for the subwoofer, while 12db and 24db seem more common for the components. What is the reason?


I think it's because people like to have their sub not play high, so they try and keep it at a steep slope, and for the components I'm pretty sure those are the most common simply because they are the easiest to integrate for most people. Eg. flipping polarity with a 12db x/o.

I'm not sure an 18db (for example) crossover is "fixable" in the sense of phase inversion or similar, but I do know that slopes of 6db, 18db, etc, can be very helpful if you want to get more out of your system. MiniVanMan said once that he is a fan of the odd order slopes for several reasons, most of which I cannot recall. But one was; in a car if a driver has a natural rolloff of 6db per octave, then wouldn't it make more sense to use a 6db crossover so that the actual _real world_ rolloff is 12 db? I thought it was a good idea, so I went out and played with my crossovers for ages..

Food for thought


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## Arezump (Jan 6, 2010)

kyheng said:


> ^Well, it is always because you choose not to understand and trying to be a hero.... If a person can't differentiate "set" and "got", it is sad, right?



But it would be even more sad if one's judgment was actually derived from his own pigheaded behavior & assuming options to be fairly suggested in his own preference - only? 
you may have your own reason to say whats the the "best" but preferences are just made of personal taste, views, likings & opinions and could be differ from what you have or experienced! 
you may not have the intention to force someone for having similar interest or opinions like what you have, but your phrase on stating that "Goin passive on car is not the best method" is like-wow! this man knows everything! & oh..plead me to understand u..will ya?


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