Stereo to mono low pass x-over

[90scaraudio]

I've been reading all I could about op-amps and active crossovers from many sources and I've come up with this....
Please, anyone, any input as to design or if something will not work, please give feedback. You can be harsh😀. I want to take the stereo, (yes it's stereo) subwoofer output of my headunit, (it does not have a crossover built in), sucks!!! and go through this device, then into an amp that uses only one channel input when bridged...again, the amp has no crossover.
I have all the components and op-amps...
Any advice.

 

[Perry Babin]

Most of it looks like it will work but I can't comment on the crossover stage. I generally use state-variable crossovers which are different.

What are you using for a power supply to feed the op-amps?

 

[90scaraudio]

I revised it a little.
I'm borrowing a small dc to dc PS out of an old electronic crossover for the +/- 15v.
My biggest worry is the stereo to mono section with the inverting amps😕. Do I need to put the 680pf caps to ground on the line in or can they be a different value or eliminated completely?
Will it work OK😕

Thanks All

 

[Perry Babin]

The 680pf caps don't need to be there but I'd probably leave them in the circuit.

Does the power supply have an isolated secondary or is the secondary ground directly connected to chassis ground?

 

[90scaraudio]

The secondary is isolated from chassis. I'll give it a whirl and see what happens.
Thanks for taking a look at it.

Now back to repairing another amp on my bench😀