Check my work -- PCB for sub controller

[nullspace]

Hi All,

I'm trying to put together a PCB for a stereo open baffle subwoofer controller, but I could really use a couple extra pair of eyes to help pick out my mistakes.

I've attached a schematic & the PCB layout, and the gist of the project is:
1) Volume control + 1st-order low-pass at 28hz (to compensate for dipole roll-off).
2) 2nd-order low-pass, variable via DIP plug-in, planning on between 75hz and 150hz.
3) 2nd-order high-pass at 29hz with variable-Q, to help protect the subs below Fs and provide a bit of low-end eq if needed.
4) 0-180 degree phase adjustment.

Let me say that I'm not a filter expert and the design is 'cookbook', so keep an eye out for errors in both the schematic and PCB layout. I'm planning on using OPA2134s for the opamps, WIMA caps, and Vishay RN55 resistors, plus a +/-15V supply with V+ & V- bypassed by 10uf.

Any and all help with this would be most appreciated. If it's any incentive at all, I'll have extra boards available for a pittance when I get it up and running.

Regards,
John

[Cro maniac]

I think you should consider adding some gain to that thing because of droping sensitivity of woofer in OB so you don't end up with too weak signal for proper balancing the bass with the rest of the system.

On www.linkwitzlab.com/filters.htm you can find some circuits for proper OB equalization

[nullspace]

Thanks for the comments.

I won't need any additional gain, as I'll be tapping the full range signal from the speakers posts of my main amps. That's also why there's no input buffer.

I've seen Linkwitz's page, but I'm using a 1st-order lowpass to account for OB roll-off rather than a shelving/ notch filter because I'd like the OB compensation to combine with the 2nd-order lowpass for 18db/octave. And, I don't need to notch out the peak in response from the baffle. This is for strictly <150hz, so a 1st-order lowpass is perfectly adequate.

Regards,
John