C1 in the Current Lover is listed as 39n. It's the filter cap right at the input. This can't be a critical value, right? Can I sub in 22n or 47n? Thanks.
You can definitely try a different value in there, it may change the sound slightly from the original. I haven't built this so can't comment from experience.
47n is just fine.
For almost the entire run of the original Electric Mistress, the value was .1uf. So there aren't going to be any earth-changing effects by going higher than 39nf; you might even prefer the increased bass content and volume.