Splitter/blender: OK, I'm ready to drop the all-FET for op amps now. which ckt?

[blackieNYC]

A smaller bit of help here please? OK, OK, I think I'm ready to drop the all-FET blender mixer looper idea and go op amp.  TL072. Thanks for all the help and for sticking with me on the FET obsession.  My 9volt requirement, all-FET design, and gain boost criteria are getting me nothing but crunchy guitar sounds.  Taking this thread:http://www.diystompboxes.com/smfforum/index.php?topic=104317.0 into new territory, if you wish to review.  Not necessary.
If I were to give up on the all-FET dream, can anyone testify to the runoffgroove splitter blend?  http://www.runoffgroove.com/splitter-blend.html  I would add a third channel, each op amp with a bit of gain, and a passive three ch mixer. (Or another op amp to sum?)
OR, one could mash up the AMZ splitter http://www.muzique.com/lab/splitter.htm and the beavis Multiple Input Mixer With Boost http://www.beavisaudio.com/techpages/BlocksFragments/ which will call for me to duplicate the common drain MPF102s.  Maybe the return input buffers could be dropped and the op amp would sum from a passive mixer?
The TL072 will save me.  I want to be playing with this thing, making wacky loops, adding feedback controls, and switchable filters, phase flipper switches, series/parallel options. Wait till you hear what this thing does with two pitch shifters through a...  nevermind for now. Instead, I'm at the breadboard swapping FETS, replacing every resistor with trimpots, and scribbling down dozens of distortion measurements for many weeks.

[GibsonGM]

I'd just go with the ROG spllitter/blend, Blackie, and get yourself PLAYING!  lol   Drop the THD worries, let your ear be the judge, throw it together, and SPLIT STUFF! 

Don't forget, the 07X series of opamps has....JFET inputs!  You will get the sweetness of FETs without all the hassle.   

[R.G.]

Take a look at the Adjusticator while doing your research:
http://www.geofex.com/circuits/Adjusticator.gif
and the polarity reverser:
http://www.geofex.com/Article_Folders/polarity_reverser/polarity_reverser.htm

By the way, "Splitter" gets a lot of abuse. Very often you don't need the latest optimistically names "Uber-Mekablitz Splitifier Module" to split audio signals. The only point of a splitter at all is to prevent loading on one of the outputs from pulling down the others. So buffer followed by several 1Ks, one to each "splitter" output is often good enough. One buffer per output is generally overkill, and super-hyper splitters are - well, they exist for some reason.

[blackieNYC]

That's great RG. Questions: so I would take the adjusticator single channel input circuit, and follow the cap and 2.2M with three series 1 k resistors going to my three channels?  My input may be a guitar or pedal, so I should go with the high Z adjusticator - is there a downside to that if there's a pedal? 
I have seen the light.  Or drank the Kool aid.  Either way I'm going op amp. And yes, the ROG also looks good.  I'm going to try mr Keens first just cuz there's less op amps. Thanks dudes.

[blackieNYC]

RG- would you have a schematic for the phase inverter that includes R values?  Can't find one, and the design's a little beyond me. I would prefer to have a switch insert a unity gain op amp, so the extra op amp stage is gone when I don't need it.  I want the adjusticator driver and the summer to have a little gain.  If I could insert a unity gain inverting op amp into the mixer before the summer, what would that look like?

[psychedelicfish]

Look at the RunOffGroove Splitter Blend; it has a version of RG's Polarity Reverser in it, with R values. TBH I think you'd be best just making a Splitter Blend, the THD and noise from 2 extra op amps is not going to be noticable after you put your signal through even one guitar pedal. You could also use a nice op amp like an OPA2134 If you're worried about what the op amps are doing to your signal. One question: you say in the first post that you would add a third channel, how would you do the blend knob? You'll probably have to replace the 1M resistors at the inputs of the return op amps with the outer lugs of 1M pots, connecting the wiper to the + input, giving you a volume control for each channel.

[blackieNYC]

Yeah, not a pan-type blender, but a mixer is what I'm after. I'm almost ready.  About to breadboard a Klon front end, passive splitter with 1k series resistors, phase inverters, then send and return jacks.  Then 3 channel killswitches within Mr Keen's Adjusticator 3 ch mixer with master volume. 6-10dB boost stompswitch there. Thought about having the channel on/off switch on the send side, to get the delay trails I often hear people speak of, but I'd be saddled with the output of a string of noisy pedals coming into my mixer with no shutoff.  I see enough trails already.
(Those phase flipper op amps are just a sittin' there doing nothing.  What could a bored op amp have to offer, while still having a phase switch?)

[glops]

I built the amz splitter thing for two parallel loops. Can't remember how I mixed them back. Works ok but I've been meaning to build the adjusticator mixer for ages...