Advice needed on building dual Rat re: Input setup and output mixer

[appliancide]

I would like to build a dual Rat using the idea of separate paths for high and low tones (as suggested in Jack Orman's tone clipper article). 

First, I'm wondering what I will need to change (if anything) in front of the opamp, and at what point along the input path should the node that divides the signal into the two opamps be.

Second, I would like the high and low signal path to have their own volume controls which will then feed into a unity gain mix out. That seems like it might be a bit more flexible than a mix control feeding a volume control. Could I use another FET to make the mixer or would I need another opamp?

Thanks!
Paul

[sean k]

http://www.moosapotamus.net/THINGS/paraloop/paralooperSCH.gif

As the above splits the signal out and to another input you could be fine just splitting a signal two ways. I think I've actually split after the input cap and run a resistor from bias and then split to the two + inputs. The above has a balance out control before the last opamp. Or you could use two volume pots then summimg resistors.

[appliancide]

So I will just take the input for the second opamp from the input of the first one. Seems like that should be fine.

You think I could just use summing resistors to tie the two signals together? That would be great if I didn't have to use an opamp based summer. What would be a good value for the resistors?

Paul

[sean k]

10k might be alright. A fet or even a normal transistor should workout fine. Two 10k's, off each volume centre lug, tied to another single 10k then cap then transistor as emitter follower or regular collector out. I'd try it and breadboard till it sounds right... maybe you're like me and want to etch the finished PCB and want to make sure. Well, do it so you have options.

Maybe just do what I've done on the end of this except omit the mix and have one 10k joining the output ones.

[appliancide]

I think that may be more than I need. I was hoping to get away with something simple like this to bring the signals together...

[appliancide]

Would a pair of higher-wattage low value resistors (10-20ohms) work to keep from losing too much volume?