ROG Splitter-Blend + 3 pos rotary switch?

[Kyosanshugi]

Hi guys,

A while back I built theROG Splitter-Blend for my band's guitarist and he really likes it, but recently he asked if a couple mods would be possible. There was one thing he requested that I think could work but I'm not sure how to go about it: he'd like a switch to select loop 1, 2, or both. I was thinking that a 4 pole 3 position rotary switch between the returns and the second buffer stage would have to be able to do that, but I can't figure out how to wire it. Can anyone help me out with this?

[mth5044]

Sounds like an A/B/Y pedal? Check out the wiring of those types of switches for some ideas.

Perhaps it could be done with a DPDT on/on/on or a  2P/3T+ rotary and a summing stage.

Using the 2P3T rotary, the green return jack would go to one pole, the red to the other. On the first throw set, connect the green throw to the summing circuit and the red to nothing. On the second throw, connect both throws to their respective returns on the ROG schematic then connect the blend output to the summing circuit. On the third throw, connect green to nothing and the red to the summing circuit.

In the first postion, you only get green and red is unconnected (may need to ground it?), the second position it is as it normally is. The third is only red.

[Quackzed]

you could also use a spdt on/off/on type switch, middle pole to ground, top(up) pole to red return,grounds red signal when up,bottom(down) pole to green return, grounds green return when down, and when in the middle it works as normal.
only thing is that the blend always works, so if you have blend red/20% green/80% and you switch to ground the green side, red will still be at 20%, not full vol. you can also label it backwards, rather than red off / normal  / green off  you do green on / normal /red on.

[mth5044]

That blend pot does make it a slightly more difficult problem.

[ashcat_lt]

Sounds like an A/B/Y pedal? Check out the wiring of those types of switches for some ideas.

Perhaps it could be done with a DPDT on/on/on or a  2P/3T+ rotary and a summing stage.

Using the 2P3T rotary, the green return jack would go to one pole, the red to the other. On the first throw set, connect the green throw to the summing circuit and the red to nothing. On the second throw, connect both throws to their respective returns on the ROG schematic then connect the blend output to the summing circuit. On the third throw, connect green to nothing and the red to the summing circuit.

In the first postion, you only get green and red is unconnected (may need to ground it?), the second position it is as it normally is. The third is only red.

This, except the "summing circuit" is not necessary.  Straight wire to the wiper of the blend pot is almost like cranking the blend pot all the way one way. 

To get it to act like the pot is set to the middle, but one of the sides is silent, you'd want to build a 12.5K/12.5K voltage divider, which would require one more pole on the switch.  One resistor from each of P1T1 and P2T3 to the wiper, resistor from wiper P3T1 and then jumpered to P3T3 with the common to ground.

That completely overrides the blend pot in the A or B position, but leaves it working fine in the Y position

[Kyosanshugi]

Thanks for the help, guys! It amazes me that some people complain about this forum, they must be asking the wrong questions. You guys were quick! Before I posted about this I had already went out and bought a 4P3T rotary switch, anticipating that the solution would involve one, so good guess on my part, I suppose.   After reading your replies, I got to thinking, since the switch has 4 poles but I only need two to switch between signals, wouldn't it be possible to use the other two for the output of the buffer stages? Meaning, the wires from red and green would go to poles 3 and 4, position 1 and position 3 would be wired straight to the output before the 1M ground bypass, and position 2 would be wired to the blend pot's outer lugs, wiper to output like normal. That way I could just bypass the blend pot altogether in positions 1 and 3. Any reason why this wouldn't work? Would I maybe need a couple resistors to make up for the missing pot?

EDIT: ashcat_lt, did I just repeat what you posted, only I translated it into stupid?  

[Kyosanshugi]

Bump for posterity

[ashcat_lt]

So, with the blender as is, each of the signals is down about 6db when it's centered.  They might sum to something like unity, depending on what each side is doing, but if you mute one side somehow, the other side will still be about half the voltage you'd get if you turned the pot all the way to the unmuted side.

If you use straight wire, you will not have that attenuation.  It will be very much like just turning the lot all the way to one side or the other (though that blend pot isn't perfect, neither side is ever actually silent).

Somebody needs to decide if they want the "center attenuation" or not.  I can see arguments both ways, but since this is a rotary and not a stomp, I'd probably go for not.

If you want the attenuation, you need the resistors and one more pole.  If not, straight wire is best.  I think for most things in the guitar world you could probably get away with just lifting the end of the pot that's not being used, but bypassing it gives you a more predictable (and more likely lower) output impedance, and both need two poles, so...

[Kyosanshugi]

Excellent, you guys have been extremely helpful, especially you, ashcat_lt. Thanks so much! May the fortunes smile upon you and bestow upon you and your family 10,000 years of joy.

[Kyosanshugi]

 Just an update: the switching works exactly as planned! Yes, the signal is somewhat louder in positions 1 and 3, but I feel like it's hardly noticeable. Tomorrow I'm going to let my guitarist play with it and see if he thinks it absolutely needs correcting. Thanks again for your help!