2N7000 mosfet in wah?

[Guitarist]

Hi folks—Merry Christmas,

I blew out my wah transistors and am wondering if I can swap in a the lower gain 2N7000 in for the two stock ones? Is the orientation the same—just drop it in? I have a load of those here. I am more into a vintage toneful effect that the higher gain Dunlop sound of today. My buds here have extra Crybabys about here too that may benefit from this, if just for variation..

It seems these are a sub for the BS170 which is great for Vox wahs.

[Dave H]

Is the orientation the same—just drop it in?

No, it's different.

2N7000
BS170

[Guitarist]

I think it just has to flipped.

[Dave H]

You are right

[Guitarist]

Awesome Dave, so much appreciated. I just saw the Gate is centre and the others are swapped.

The drain current is higher on the 2000. Any rebiasing? The stock values are 22k and 510Ω. I guess if it works, then great for starters... I am NO expert but my ears seem so.

[Guitarist]

And if yours is stock with MPSA18 then a direct swap (no flipping orientation) with a 2N7000 should work. Verify? The A18 seems most common in wahs.

[Jazz P Bass]

Uhmm.

Isn't the MPSA18 an NPN bipolar transistor where the 2N7000 is an N channel small signal mosfet?

[Enzo]

Since the MOSFETs are wired as diodes, perhaps that explains it?

[Guitarist]

Though that's an idea if you wanted some OCD flavour in your wah'd solos, I was hoping that the 2N7000 mosfet would work in the circuit. I'm more familiar with tubes than transistors though...