Passive crossover design

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Helge A. Bentsen

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Jan 19, 2011
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Is there a good guide and software package available on the web for designing passive crossovers?

I gave up on this years ago when I discovered the capability of DSP and Smaart, but I've been more and more curious about this lately.
My previous attempts was nothing to write home about, I just pulled components from a table and soldered them together. Didn't sound that great to be honest.
 
There's quite a bit of information on the fundamentals freely available online (RLC filters are covered in most electrical engineering degree programs), although many of the calculators for passive filters are targeted at RF applications (where active options are far fewer, and the component values for passive filters are a bit more tractable than for audio frequencies).

If a bit of math doesn't scare you, http://alignment.hep.brandeis.edu/Lab/Filter/Filter.html looks to be a reasonable place to start for the theory and a bit of discussion on practical applications.
 
Free software for passive crossover design has come on a lot recently, XSim and VituixCAD being the 2 most popular options currently.
As you found in the past, using standardised values only gets you a madiocre result because those standard values cannot account for the real world variation in amplitude and impedance responses with frequency.
Modern software gets past that by importing frequency and impedance responses of the actual drivers in the prototype cab as the starting point so you have a much better chance of a good end result.
There are a couple of good crossover design threads sticked over at diyaudio.com in hthe Multiway subforum that may be a better introduction than I'm giving here.
Cheers
David.
 
So, what's the procedure for generating your own FRD and ZMA files?

Looks like this package could do it.
www.parts-express.com

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OmniMic V2 and DATS V3 Dayton Audio Speaker Measurement BundleAccurate measurements and specs are essential when designing and building speaker systems and Dayton Audio's OmniMic V2 and DATS V3 can help you with each step in the process. Whether you are verifying the T/S parameters of a woofer...
www.parts-express.com
 
If you want an all in one solution then yes, the DATS system is popular.
You can do it without that though - FRD and ZMA are really just tab delimited text files, I'd imagine you could get SMAART etc to export frequency response curves that way if you already have that.
Freeware such as Room EQ Wizard and Holm Response are also capable of doing it.
You can measure impedance with a fairly simple resistor based jig in most programs that can do frequency responses too; the guide for how to make REW do it is here: link.
HTH,
David.
 
Thanks everybody. I have played around with XSim and watched a few videos/read some forum stuff.
Looks interesting, now I have a idea for a dual 10" with passive XO.

Going to try to start this project in january.


(having too much free time isn't good when you're used to working production, spent a couple of days on research now when I was supposed to do nothing)
 
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