Splitter-Blend modification (swap phase on either fx loop)

[stryker]

Hi guys

I'm working on a pedal for both me and a mate, based on the http://www.runoffgroove.com/splitter-blend.html.  He would like to be able to use it as a splitter with the ability to swap the phase of either A or B rather than just putting the inputs to the blend out of phase by flipping one.  And I kind of like the idea of getting both functionalities from the same box.

I'm hoping to can get there by adapting Paul R's suggestion from this earlier post regarding Splitter-Blend and double up the output section with the phase switches and put that before the SENDs.  That would mean the blend section will be a pair of followers essentially swapping the two sections. 

This will be my first op-amp project so have been reading up the theory but would appreciate any advice on the practicality before diving in.  The pedal also includes a dry output for a tuner, and a stomp switch to mute the outputs while you tune.  Power is switched by the presence of the input jack, and there's an additional LED to indicate mute.

Apologies in advance that KiCad's op-amp symbol is upside down compared with Paul R's schematic.



Please let me know if anything screams out at you that will result in a rookie fail.

Thanks, Geoff

[stryker]

I just noticed my "mute" LED should be on leg 6 of the stomp switch.  That's surely not my only error, but I'll call that one out right away 

[Mark Hammer]

If there are only two signals involved, then there is only a need for ONE of them to have phase-flipping.  Keep in mind that there are only two possible states: both in-phase, both out-of-phase.  Changing the phase of ONE of them can create the "other" state.

I have a box on the shelf awaiting finish that has a FET-based splitter (the AMZ circuit), and a 2-in/1-out mixer, with a phase-flipper toggle for one of the inputs, and level pots for the two inputs.  I recommend including level pots for the mixing/blending.  Not only because the sources being combined can vary widely in their levels, but also because interesting sounds can be obtained by adjusting the mix of two signals that are opposite phase, to provide different degrees of cancellation.

[stryker]

If there are only two signals involved, then there is only a need for ONE of them to have phase-flipping.  Keep in mind that there are only two possible states: both in-phase, both out-of-phase.  Changing the phase of ONE of them can create the "other" state.

Thanks for this.  I think his requirement comes from a misunderstanding now - he was looking to use it as a two amp splitter sometimes, without the returns and blending being used.  But even that would only need one side flipped to achieve what he's asking.  And that means I can run with something far nearer Paul R's design.

[stryker]

Do you see anything wrong with the idea of flipping one channel, prior to send though rather than after return?

[Mark Hammer]

Not really.

[marcelomd]

Hi,
You only really need one opamp for the input buffer (U1a, U1c). This saves you one stage, which you can use at the end, after the blend pot, as an output buffer.