Questions about ROG Double D

[bcalla]

Hi -

I just breadboarded the layout posted by stringsthings and I like it a lot.  But (as a relative newbie) I do have a few questions that I hope someone can answer.

1. I didn't add the 10k resistors on the gain pots.  What do they do?
2. I'm planning on building it with 2 dual gang pots.  I would like to be able to adjust the relative volume between the jiggle & bounce sides so that I can adjust the volume of one relative to the other.  Could I add a trimpot to the layout to accomplish this?  If yes, what value, and what is the best location for it?
3. When I raise the volume on the bounce side above ~ 7 I start to get a lot of hiss. Can this be tamed?

Thanks,
Bob

[hannibal827]

1) Without the 10k resistors, you are grounding the inverter inputs [the 22n cap on pin 5 of the IC and the 47n cap on pin 9] when the gain knobs are turned fully counterclockwise.  When I breadboarded this circuit, I didn't find that the resistors made a huge difference.  I built my circuit with the resistors anyway.
2) No idea, but it isn't clear what this would accomplish for you that isn't also accomplished with the separate volume knobs and channel switching, as designed.  Unless you are planning to run the signal through both channels at once and blend them?
3) You could probably stick a lowpass filter between the electrolytic cap [4u7 on IC pin 15] and the Bounce volume knob.  But the hiss is just a limitation of the IC--in the Bounce channel you're running the signal through 3 inverter stages instead of 2 [which I'm guessing is why you don't hear the hiss in the Jiggle channel?]
That said--in my build 7 on the Bounce volume is ridiculously loud, WAY WAY past unity gain, even at minimal gain settings.  I guess the hiss doesn't bother me because I haven't found a reason for that big a volume increase from clean or "jiggle."  Your mileage may vary, obvs.

I'm no expert and someone else could probably answer these questions with more accuracy and detail than me.  Good luck.

[bcalla]

Thanks for the feedback.
1. I tried going back and forth with/without the 10k resistors on the pots.  I didn't hear any difference, but like you I will add them in my final build.
2. I am trying to keep the finished pedal smaller and less cluttered, so I was hoping to go with 1 gain & 1 volume pot, each dual ganged.  That means that the knob position applies to both, so I wanted to be able to set the relative volume difference so that I don't jump out of my skin when I go from jiggle to bounce.  I experimented on the breadbord and discovered that if I replace the 220K resistor between pins 11 & 12 with a 100k trimpot I can accomplish that.  From what I have read, I think that reduces gain (not volume), but it seems to make the difference more manageable.
3. You're right, I didnt hear the hiss on the jiggle channel.  You're also probably right that I would never have it up loud enough to hear it.

[hannibal827]

Don't get me wrong, I think you will still hear some hiss in the Bounce channel even when your levels are matched.  I just decided I could live with it.  It's not the best distortion in the world, but it was a fun build and I'm glad to have the pedal.