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3 ways active crossover

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Thanks, Mashaffer,

I built an op-amp based XO with 3-way outputs but was not happy with what it brought to my tube-based systems, then came the reasons for the searching...

Could you help explain a little more how I can make the 2-way version given a 3-way one?

Thanks,
 
In the schematic listed you will see a chart of R and C values for various crossovers. You can kind of work out ratios for other cut off frequencies from studying that chart. Using a spice simulator like LTspice can help you to confirm/tweak the values. Use the HP section at a suitable crossover for the top, use the LP section also at a suitable (different) crossover.

The middle will be a cascade of a HP and a LP at the above crossover frequencies to create a bandpass. So if the upper crossover was at 7kHz and the lower at 150Hz then your mid band would have a HP at 150Hz and a LP at 7kHz.

As an example my woofer output in this simulation is a band pass. Note I tweaked the values somewhat to get an over all slope that would compensate for open baffle losses but the topology is essentially the same.

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This will get you started.

http://greygum.net/sbench/sbench101/Crossover/xover.gif

It is two way but cascading a HP and a LP will give you the third BP filter that you need.

I am thinking of going active for my ATC SCM20SL Pro.The built-in passive cross-over is a simple 12dB/octave LC filter with the cross-over frequency at 2.8khz.
Using the aboved tube cross-over to start with,what are the components` values should I changed so that it could be used?
 
Here is an SMD version of the LR 24 db/oct. I layed out.
If there is demand I can try and convert it to through hole.

I add the 2 way version I made in through hole as example too.

Of coarse its not tubes, but it shows you just how complex these little buggers can get, 12 opamps per channel in the 3 way...
 

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