crossover design book

[chrisg]

I was wondering if someone has a good practical reference for crossover design. Been dealing with these for a while and would like to gain some more insight. Thanks!

[donradick]

> I was wondering if someone has a good
> practical reference for crossover design.
> Been dealing with these for a while and
> would like to gain some more insight.
> Thanks!

Best noob crossover tutorial:
Speaker Building 201
<A HREF="http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-044">http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-044</A>

Best in depth reference:
Loudspeaker Design Cookbook:
<A HREF="http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-035">http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-035</A>

Guru level reference (John Kreskovsky):
<A HREF="http://www.geocities.com/kreskovs/John1.html">http://www.geocities.com/kreskovs/John1.html</A>

Also, snag copies of (free)
Passive Crossover Designer 6.12
and Speaker Workshop
You can learn a whole lot with the 2 free software tools by loading a driver and looking at different crossovers.

HTH,
-don

[chrisg]

Don - thanks for the excellent recommendations.

Chris

> Best noob crossover tutorial:
> Speaker Building 201
>
> <A HREF="http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-044">http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-044</A>
> Best in depth reference:
> Loudspeaker Design Cookbook:
>
> <A HREF="http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-035">http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-035</A>
> Guru level reference (John Kreskovsky):
>
> <A HREF="http://www.geocities.com/kreskovs/John1.html">http://www.geocities.com/kreskovs/John1.html</A>
> Also, snag copies of (free)
> Passive Crossover Designer 6.12
> and Speaker Workshop
> You can learn a whole lot with the 2 free
> software tools by loading a driver and
> looking at different crossovers.

> HTH,
> -don

[Chris Roemer]

> Don - thanks for the excellent
> recommendations.

> Chris

If you're on a PC, and you don't own Excel/Office, you CAN model XOs using PE's f.txt and z.txt files using the STANDALONE "XOverSim.exe" off the FRD Consortium website.

Textbook calculations (or online calculators) all PRESUME a driver with a FLAT impedance profile. Dynamic drivers (all those with VOICE COILS) are NOT like this. They ALL have a sharp impedance peak at resonance (25 to 60 Hz, say, for a woofer, and from around 500 Hz for a VERY robust tweeter up to 3 kHz or more for a small dia. "lightweight"), AND a continuing RISE the higher up in freq you go, with woofers rising VERY HIGH (4x to 10x NOMINAL is NOT uncommon).

Most books (I have 201 and LDC) can get you to want to create a 4th order Linkwitz/Riley filter, and give you ways to calculate component values, BUT that's NOT what you are really after. You're trying to target a 4th order "acoustic slope" which is the combination of a driver's natural rolloff (like an 8" woofer that "drops off" after 3 kHz) COMBINED with a SECOND ORDER "electrical filter" (whose slope is referred to as the "Filter Transfer Function") which gives you (ultimately) your 4th order slopes. You can NOT accurately calculate the proper component values to obtain these acoutic slopes w/o using frequency AND IMPEDANCE curves.

Furthermore, even if you have modeled a high pass and low pass filter that are both "down" -6dB at 2000 Hz, they'll only "sum flat" (+6dB) IF they are "in phase", so you also need phase data to go along with your freq curves.

ALSO, adding caps and coils to a driver's phase data "rotate" the phase to the point where your drivers can be 180* "out", or 90* out, or 17*, or ANY phase angle, really. Only a simulator can show you how all these interrelated factors combine in a crossover design.

And even that's not the end of it. We haven't even discussed baffle effets yet!

Chris