Removing certain controls for a stripped down Sea Machine/Gravity Wave.

[Andon]

Hey there. I've been trying my hand at some PT2399 chorus pedals as of late, and one that has really piqued my interest is the Sea Machine/Gravity Wave. I've followed all of the known issues with DIY builds of this pedal, and it works about as well as it should, but I would like to strip it down. Namely, removing the Animate and Dimensions (and maybe Shape) controls. Here's a schematic:

https://www.madbeanpedals.com/EP/schematics/GravityWave.gif

Like with the Animate knob, is it just connecting the R21 (22k) resistor to pin 6? The Dimension control isn't just replaced with a 5k resistor between the polarized caps, right? Just fiddling around with the PT2399 I know it's not always as simple as removing the pots and jumpering the connections, so I'm turning to y'all for any suggestions. Thoughts?

[Kevin Mitchell]

It's within your best interest to build it with the pot controls connected, dial it in to what you favor most and record the pot's resistance.

Shape and animate can easily be replaced with a single resistor each since the wipers are tied to one end.
With Dim you're going to want to measure both sides of the pot's wipers and use the approximate resistor values. For example, it's a 5K pot so if resistance between lugs 2 and 3 show 3.3K you'll want a 2.7K to ground (5K - 3.3K). 3.3k between C5 & C6 and the a 2.7K from the C6 side to ground.

Ideally you could replace the pots with trimpots. But that isn't always the easiest way due to the footprints of the pots.

[Andon]

Thanks for that! Yeah, Shape made the most sense to easily replace since it's in the negative feedback loop (R30/10k + whatever value), but animate sort of confused me since there was still the 2.2k (R20) going to ground after the pot from pin 6. Would I connect R21 (22k) before or after (pin side or ground side) of the resistor that would replace the pot?

[Kevin Mitchell]

Would I connect R21 (22k) before or after (pin side or ground side) of the resistor that would replace the pot?

For animate just tie R20 to pin 6 of IC2 instead of the pot and change it as you choose - no more than 4.2K, no less than 2.2K. All it's doing is changing the resistance to ground. Think of the ANIM pot and R20 as one component but can't go lower than 2.2K or higher than 4.2K. R21 goes straight to pin 6 of IC2 as is.

After a few edits I believe I've answered your question and then some   

[Andon]

You absolutely have - thank you very much!

[Kevin Mitchell]

My pleasure. And sorry for the constant edits. I keep confusing myself and giving answers to things you didn't even ask for 

I had found the layout and drawn the changes you'd have to make to "hardwire" the 3 pots you want to omit.
Purple are just jumpers, the two red lines are two resistors replacing the 50K pot.

Value changes after applying jumpers;
R20: Can be anywhere between 2.2k to 4.2k
R30: Can be anywhere between 10K to 110K
For dim, it's simple. Whatever two resistors you choose make sure they add close to the pot value (5K). It's best to use a pot first to and measure the outer lugs against the center to find what values you liked the most. If it's 50% rotation then that means both resistors are 2.5K or next best.