# Crossovers



## jwhite8086 (Feb 4, 2007)

I am thinking about designing me some new speakers to build.
What are the options for the crosovers, do I build them for best quality ,passive, active or does everyone just buy them?


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## Geoff St. Germain (Dec 18, 2006)

The crossover should be specifically designed and built for the drivers you are using in the specific cabinet you are using. Most people do not buy generic crossovers because they will rarely integrate the drivers in anything close to an ideal manner. 

Most people tend to go passive, though some people do go active. In the end it's up to you. Active will require additional amplification compared with a passive crossover, but avoids some things such as insertion loss. In the end it's what you're comfortable with.


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## BoomieMCT (Dec 11, 2006)

Geoff St. Germain said:


> The crossover should be specifically designed and built for the drivers you are using in the specific cabinet you are using. Most people do not buy generic crossovers because they will rarely integrate the drivers in anything close to an ideal manner.
> 
> Most people tend to go passive, though some people do go active. In the end it's up to you. Active will require additional amplification compared with a passive crossover, but avoids some things such as insertion loss. In the end it's what you're comfortable with.


. . . yeah, What he said! That's a pretty good summary of the situation. A DIY passive x-over will better fit the drivers and enclosure (and often be cheaper) than a pre-made one. Active x-overs are more efficient as you don't need any padding (resistors) to make the driver's levels match. They usually (but not always) cost more as you need more amps.

If you are interested in crossover design my personal favorite freeware to use is the FRD Consortium's Passive Crossover Designer. If you put good driver / enclosure data into it the results are pretty accurate. It is also quite flexible and allows you to add additional componants to the x-overs as you like.


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## jwhite8086 (Feb 4, 2007)

Thanks were do you buy the parts and are there high quality parts that make the crossover better or will they all be the same if made properly.


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## BoomieMCT (Dec 11, 2006)

jwhite8086 said:


> Thanks were do you buy the parts and are there high quality parts that make the crossover better or will they all be the same if made properly.


I think the four main places people go is Parts Express, Madisound, MCM and Zalytron. There is a difference in quality. Higher quality means the listed values are more likely to be what the part actually is. There are also noise differences. Like most things I think it follows the laws of diminishing returns - the more money you spend the margin of improvement gets smaller.


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## jwhite8086 (Feb 4, 2007)

are their any good tutorials on building crossovers


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## JCD (Apr 20, 2006)

jwhite8086 said:


> are their any good tutorials on building crossovers


I haven't seen one yet.. even the DIY bible, Vance Dickason's "Loudspeaker Design Cookbook" pretty much skims the subject just due to the complexity. 

I think the Passive Crossover Designer from FRD is a great starting point. From there, you deviate to get the results you're looking for.

I've chickened out in this aspect -- the speakers I've built had crossover already designed, and the crossover for my current project is going to be active. 

JCD


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## BoomieMCT (Dec 11, 2006)

LDC is a good place to go first. Vance talks about the basics. LDC comes with some software (and Excel sheet) that will autocalculate basic crossovers for you. When you get comfortable with that you can learn when to use zobels, BSC's, notch filters, etc. My advice is to start building some cheaper speakers to learn on a work your way up to your master work. When you understand the basic concepts PCD is a great place to test out ideas.

BTW here are the other network pieces I mentioned;

Zobel: A seres capacitor and resisitor in parallel with a driver. I use these if I'm crossing over a driver at a point where it's impedence curve takes a big upswing thereby throwing off the crossover point. 

BSC: A parallel inductor and resistor in series with a driver or at the start of a network. This is used to supress high frequencies to give bass a boost. This is used to compensate for the baffle step. 

Notch filter: A parallel inductor, capacitor and resistor. Used to supress a narrow frequency range. I mainly use this with metal cone wide range drivers that play over a breakup node.

As a final note, I encourage experimentation. I also encourage buying spare parts just in case you want to change some values. I make a habit of ordering a few extra crossover parts every time I put in a parts order. Don't get discouraged if things don't work out perfectly on the first try. As you do this more you will find you can build good sounding networks faster with experience.


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## jwhite8086 (Feb 4, 2007)

Man I have to learn a new language "Crossover american" I think starting small is a good idea


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## BoomieMCT (Dec 11, 2006)

Don't be intimidated! The nice thing about crossovers is you can build them a piece at a time. I have many crossovers that I added on to after "finishing" to improve / alter one thing or another.


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## groundie (Feb 7, 2008)

just my 2c from a beginner...
having done some reading about the passive vs active crossover discussion, i was super curious about the so-called true bi-amping using an active crossover.
i have just recently done that using Behringer DCX2496 and a pair of ready-made diy speakers (first time for me), i'm quite impressed with the sound improvement over my previous setup with B&W DM640s.
actually, my current setup is tri-amping including the subwoofer.

yes, this does involve multiple amps and that could be a deterent for some, but for me, i'm hooked to the sound and already salivating for better drivers.


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