Splitting and mixing stages

[KarenColumbo]

Me again with a question I hope the answer for is easier than I suspect.

The situation is thus: I want to input a signal, split it into two separate signal paths, where they are treated independendly (but very similarly), then I want to put them back together right before the output.
From what I gathered by googling this, I don't really need some splitting circuit before treatment. Just run the signal in parallel after some initial buffering.

BUT. After treatment of those two signals – I'll call them Pat and Patachon – they HAVE to be mixed, if possible, actively. There are schematics of some active mixing stages with an opamp on virtual ground - Pat and Patachon join together after a 10k resistor each (or VRs) and get re-energized through the opamp into the output. Is this correct so far? Or os there an easier way to it?

[Kipper4]

Amz has this Karen

http://www.muzique.com/schem/mixer.gif

then there's this

http://sound.whsites.net/articles/audio-mixing.htm

Dont forget some input caps.

[KarenColumbo]

Thanks again, Rich! Yeah, the Elliott page was my first stop, but I like the AMZ better Will proceed as computed

[blackieNYC]

In the AMZ circuit, you can add a 100k pot after the cap.
Then there's always this inverted phase thing. You might skip that, if you know exactly what pedals will be involved, until you find you need a polarity reverser. (At geofex)

[KarenColumbo]

So - I hope you have patience - how about that? VREF is already there (will be 4,5V from the circuits I wanna mix together). I could replace the input resistors with a pot to balance them, couldn't I?

[Kipper4]

Separate pot for each in might work better. Wired as a variable resistance.

[Kipper4]

You can  make input caps np. And 100nf should be fine imo.

[antonis]

Reverse C1 & C2 polarity..
(or better use Non- polarized caps..)

Alternatively to Rich suggestion, make Balance pot 100k (supposing you don't need so much gain..) and place equal value resistors between lug 3 & 1 to GND..
(resistor values uppon your taste of signal attenuation..)

A much better (but more complicated) way should be to place resistors after caps, resistors (optional) after upper & lower lugs going to pin 2 and pot middle lug to GND..

[KarenColumbo]

Like this? I'd like to keep the part count low - I already have 5 pots now Am I on the right track with this mix of both your suggestions?

[antonis]

My bad...!! 

Didn't realise that you also need caps from R1 & R3 to GND for rolling off DC gain to unity...

(I had in mind to make gain variable mix..)

[KarenColumbo]

Like this? (THANK you, guys  )

[KarenColumbo]

This is gonna be soldering mayhem

[antonis]

Yes, but better carry out what Rich said about variable resistors..
(use just one dual-gang pot with reverse wiring..)

The more plain the more effective & less prone to faults..    

edit: You probably messed up threads..   

[KarenColumbo]

Okay - I will take a dual pot - already have 4 of them in this circuit, so one more won't induce critical mass. Thanks again, gentlemen, much obliged

Why have I mixed up threads? This is an extention of an existing one. They just seem to kinda merge at the moment. Dunno why - could be my stupid questions all the time