VBIGC T-net with active x-over ?

How do I/ or is it possible to incorporate a 2nd order x-over (300hz) filter between the buffer section and the op-amp ? This would simplify things as I already have 2 of these amps and I would like to run my 3 way speaker actively crossing at 300hz between the woofer and mid-tweet.



  • vbtigc - xover.jpg
    vbtigc - xover.jpg
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Yes, you can do what you want!

The low pass filter is consisting of the 3K9 resistor and the 1n5 cap, in the showed schematics.

But be aware: should you change the value of the 3K9 resistor, you change the input-z and therefore in conjunction with the t-net the overall gain. The input-z in your schematic is 3K9+18K.

So, I recommend to calculate the gain with the excel sheet, available here:


Kind regards

/Edit: be aware of the high pass filter, consisting of 3u3 coupling cap and 3K9+18K.

/second Edit: Sorry, I wrote about 1st order filters...