Help with active XO

I just 'upgraded' my system with Rod Elliot's design, the 'P09' which is 24db/octave rolloff. It's using TL072 op-amps which sounded great - no noticable signal degradation.

for my 3.5kHz cutoff the calculator returned 39nF and 820ohms.

http://gainphile.blogspot.com/2007/12/bi-amp-active-crossover-using-gainclone.html

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